10 ”i <3 (9 3 7 (o w... I]! Ill/ll Ill/I Ill/lll/lllllll/llll/l 3 1293 00059 1994 llBRARY Michigan State University This is to certify that the thesis entitled POSTEMERGENCE CONTROL OF CRABGRASS DIGITARIA SPP. IN TURFGRASS WITH FENOXAPRORifl ETHYL AND TRIDIPHANE presented by Bruce Alan Jacobs has been accepted towards fulfillment of the requirements for Masters Crop and Soil Sci. degree in MAW Major professor Date August 12L 1988 0-7 639 MS U is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES ” RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. POSTEMERGENCE CONTROL OF CRABGRASS [219115815 SPP.] IN Tuareaass WITH FENOXAPROP-ETHYL AND TRIDIPHANE BY Bruce Alan Jacobs A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crop and Soil Sciences 1988 5 / 7 757X ABSTRACT POSTEMERGENCE CONTROL OF CRABGRASS [QLQLIAELA SPP.] IN TURFGRASS WITH FENOXAPROP-ETHYL AND TRIDIPHANE BY Bruce Alan Jacobs Studies were conducted to evaluate the effectiveness of fenoxaprop-ethyl and tridiphane for control of crabgrass within turf and non-turf situations. Efficacy and timing of fenoxaprop-ethyl and tridiphane with preemergence herbicides, Kentucky bluegrass and creeping bentgrass cultivar sensitivity to fenoxaprop-ethyl, and antagonism of fenoxaprop-ethyl and tridiphane with broadleaf herbicides were studied. ’ Results indicated fenoxaprop-ethyl to be effective for control of four tiller crabgrass. Tridiphane provided erratic crabgrass control during both seasons. Fenoxaprop- ethyl applied as a split treatment (0.14 + 0.14 kg ha“) or tank-mixed with preemergence herbicides (0.20 + 8.4 kg ha") produced season-long crabgrass control. Creeping bentgrass cultivars were severely injured by fenoxaprop-ethyl (0.14 and 0.20 kg ha‘l). Temporary injury was observed on most Kentucky bluegrass cultivars with fenoxaprop-ethyl (0.14 and 0.28 kg ha“). Both turfgrass species recovered by four weeks after application. 2,4-D amine, 2,4-D ester, and clopyralid antagonized fenoxaprop-ethyl, while tridiphane was not affected. ACKNOWLEDGEMENTS The author expresses appreciation to his major professor, Dr. Bruce E. Branham, for guidance, practical ideas, and encouragement throughout the project, and also to ' commitee members Drs. J.J. Kells, D. Penner, and J.A. vargas for their assistance and support. Gratitude is extended to The Dow Chemical Company, Hoeschst-Roussel Agri-Vet Company, and the Michigan Turfgrass Foundation for financial support. Thanks to John Cudnohufsky for his advocating the idea of completing a master's degree. The assistance of maintaining research sites by Mark Collins is greatly appreciated. Extreme thanks to my wife, Beth, for her love, motivation, and understanding throughout the entire project. Special thanks to my family for their support and faith in my abilities, and to my daughter, Katie, for her smiles and giggles. iv TABLE OF CONTENTS LIST OF TABLES. ........... O ....... O 000000 00. 00 0000000000 v1 INTRODUCTIONOOOO......OOOOOOOOOOOO0.0. ........... O. ...... 1 CHAPTER 1 — REVIEW OF LITERATURE......... ....... . ........ 3 Factors Influencing Crabgrass Germination...........3 Preemergence Herbicides ..... ................ ..... ...5 Postemergence Herbicides...........................13 Literature CitEd. O O 0.. O. I I O O O 00000000000 O .0. O ..... .22 CHAPTER 2 - EFFICACY AND TIMING OF FENOXAPROP-ETHYL AND TRIDIPHANE ALONE AND IN COMBINATION WITH PREEMERGENCE HERBICIDES FOR CRABGRASS CONTROL Abstract........................... .............. ..31 Introduction.......................................32 Materials and Methods.......... ................. ...34 Results and Discussion .............. ...............37 Literature Cited...... .......... ...................44 CHAPTER 3 - KENTUCKY BLUEGRASS AND CREEPING BENTGRASS CULTIVAR SENSITIVITY TO FENOXAPROP-ETHYL Abstract....................... ................... .46 Introduction........... ......... ... .............. ..48 Materials and Methods......... ......... . ........... 51 Results and Discussion... ............ ..... ......... 54 Literature Cited.............. ..................... 68 CHAPTER 4 - EFFICACY AND ANTAGONISM OF FENOXAPROP-ETHYL AND TRIDIPHANE ALONE AND IN COMBINATION WITH BROADLEAF HERBICIDES Abstract........................... ............... .70 Introduction................ ...................... .72 Materials and Methods.......... ........ . ........ ...75 Results and Discussion... ................. . ....... .80 Literature Cited............ ....................... 90 APPENDIX.. ..................................... .. ...... .92 Table Table Table Table Table Table Table Table Table Table A1. A2. A3. LIST OF TABLES Efficacy of fenoxaprop-ethyl and tridiphane alone and in combination with preemergence herbicides for crabgrass control ........... . ............... 42 Injury ratings for Kentucky bluegrass cultivar study treated with fenoxaprop-ethyl during 1986 and 1987. Hancock Turfgrass Research Center, E. Lansing MI...........................62 Injury evaluations of fenoxaprop-ethyl applied to a creeping bentgrass cultivar trial. Hancock Turfgrass Research Center, E. Lansing, MI. 00.0... OOOOOOOOOOOOOO 00.00.0000 ........ 0.0.0.066 Grass and broadleaf control with postemergence herbicide combinations applied to Poa annua L. Hancock Turfgrass Research Center, E. Lansing, M10000......000......00.0.0.0...0000000000 ...... 86 Grass and broadleaf control with postemergence herbicide combinations applied to Kentucky bluegrass. Fairway Driving Range, Okemos, MI...87 Grass and broadleaf control with postemergence herbicide combinations applied to a Kentucky bluegrass blend. Hancock Turfgrass Research Center, E. Lansing, MI.................... ...... 88 Grass and broadleaf control with postemergence herbicide combinations applied to a Kentucky bluegrass/perennial ryegrass turf. Clio Country Club, Clio, MI ........ ..........................89 Daily temperatures for Lansing, MI, during summer months of 1986 and 1987 (Temp = C)..............92 Daily temperatures for Flint, MI, during August and Septemeber, 1987. (Temp = C).... ..... .......93 Daily precipitation for Lansing and Flint, MI, during the summer months of 1986 and 1987. (Prec1p=M)000.0 ..... .... 00000 0.0.0.0.... ..... 94 vi INTRODUCTION Highly maintained turfgrass has become well known as a valuable commodity in increasing property value. Since the early 1900's, crabgrass (Digitaria spp.) has been a difficult weed to control in established turfgrass. Mainly a native of Europe, the genus Digitaria consists of more than 325 annual and perennial species. They can be found in both tropical and temperate regions of the world. Inside the United States, there are approximately 24 native species of crabgrass. Most are weedy and thrive in moist, disturbed situations. In the southern United States, crabgrass has been used for forage and occasionally cut for hay. Large crabgrass (Digitaria.§anguinalls (L.) Scop.) and smooth crabgrass (2131£§11§.iafih19m2m (Schreb.) Schreb.) are often found in both cultivated soil and fine turfgrass stands. Crabgrass is a C. plant which can fix C02 more efficiently than C; plants, producing greater biomass under warm temperatures and high light. During the hot, dry summer months when most turfgrass plants are dormant, crabgrass can overtake a lawn within weeks. Many preemergence and postemergence herbicides have been evaluated throughout the previous 25 years, producing variable crabgrass control results. Two new postemergence herbicides, fenoxaprop-ethyl [(1)-ethyl 2-[4- [(6-chloro-2-benzoxazoyl)oxylphenoxyl propanoatel and 1 tridiphane l2-(3,5-dichlorophenyl)-2-(2,2,2—trichloroethyl) oxiranel have demonstrated excellent results for crabgrass control. The objectives of this study were to evaluate the efficacy of combinations of preemergence and postemergence herbicides as influenced by rate, application timing, and stage of growth of crabgrass plants for effective control; evaluate phytotoxic effects from fenoxaprop ethyl to various turfgrass species; and examine postemergence and broadleaf herbicide combinations for potential antagonism in weed control. CHAPTER 1 REVIEW OF LITERATURE To gain an appreciation of the difficulty involved in controlling the crabgrass plant, a brief background of its characteristics is included. Preemergence and postemergence herbicide application research is also discussed to determine if past or present control strategies merit improvement. a o nfl nci ra e m n n Crabgrass seed can lie dormant in the soil for up to 30 years (19). DeFrance (24) observed that dormant, hard crabgrass seed appeared extremely difficult to kill, and it is doubtful that crabgrass seed could be harmed with solutions that do not injure turfgrasses. Once crabgrass seeds have been established in a turf stand, the area has a potential problem for many years. King and Kramer (69) have found that seeds of large crabgrass and smooth crabgrass germinated from a depth of 3.5 centimeters. Peters (82) witnessed emergence from a soil depth of 6.4 centimeters with smooth crabgrass and at least 7.6 centimeters with large crabgrass. When soil temperatures reach 18 C, crabgrass begins to germinate, given adequate moisture and light (9). Once 3 established, crabgrass plants can grow at cutting heights of 4.8 mm, and in unmowed situations, plants can reach one meter (3). Peters (82) found that spaced smooth crabgrass plants could produce over 1,000 tillers, while large crabgrass could form over 780 tillers per plant. One undisturbed smooth crabgrass plant generated 210,000 seeds, while a large crabgrass plant produced 145,000 seeds. This demonstrates that crabgrass is a vigorous and abundant reproducer under proper environmental conditions. Since germination is dependent on adequate environmental conditions, crabgrass can germinate at various times when exposed to differing climates. In California, new crabgrass seedlings were found during every winter month, with heavy seed germination occurring in January and February (107). Large crabgrass has been reported to germinate in late March in the Piedmont Region of Georgia (60). In Maryland, Dernoeden and Mathias (33) reported smooth crabgrass germination from March throughout May. In the Northeastern United States, crabgrass germinates primarily from April to July. Timely preemergence and postemergence herbicide applications are necessary to reduce the infestation of this troublesome weed. PREEflERQENCE HERBICIDES The effectiveness of a preemergence herbicide is based upon its ability to provide good initial control, and then to remain effective throughout the season without noticeable turfgrass phytotoxicity (9). For the past 40 years, preemergence herbicides have been extensively tested to determine the ideal herbicide for crabgrass control. The common preemergence herbicides examined include calcium methanearsonate (CMA), tricalcium arsenate (tricalcium arsenate), disodium monomethylarsenate (DMA), octyl-dodecyl ammonium methanearsonate (AMA), phenyl mercuric acetate (PMA), dimethyl tetrachloroterephthalate (DCPA), 1,2,4,5,6,7,8,8a-octachloro-2,3,3a,4,7,7a-hexahydro-4,7- methanoindene (chlordane), Q,Q-diisopropyl phosphorodithioate S-ester with N-(Z—mercaptoethyl)benzene sulfonamide (bensulide), l-(2-methylcyclohexyl)-3-phenylurea (siduron). 5,5,5-trif1uoro-2,6-dinitro-N,N-dipropyl-p- toluidine (trifluralin), polychlorodicyclopentadiene isomers (bandane), Q-(2,4-dichlorophenyl)Q-methyl isopropyl- phosphoramidothioate (DMPA), N-(l-ethylpropyl)-3,4-dimethyl- 2,6-dinitrobenzamine (pendimethalin), 2-tert-butyl-4-(2,4- dichloro-S-isopropoxyphenyl)-A3-l,3,4-oxadiazolin—5-one (oxadiazon), and N-butyl-N-ethyl-g,£,£-trifloro-2,6-dinitro- p-toluidine (benefin). A preemergence herbicide is applied at a rate to give season long control. Engel (37) found that bandane applied in early spring at a rate of 67.2 kg ha“ produced good control in a Kentucky bluegrass turf. Tricalcium arsenate was also effective in a variety of turfgrass stands (3, 5, 83). Ahrens et al. (2) demonstrated that calcium arsenate provided acceptable residual control the year following application. Nelton and Carroll (105) observed that lead arsenate at 871.2 and 1089 kg ha‘:L provided effective crabgrass control. Calcium arsenate at rates of 731.8 kg ha" or higher was more effective than lead arsenate but injured the turfgrass significantly. Turfgrass injury caused by both lead and calcium arsenate did not appear until a year or more after application. Soil analysis revealed that elemental arsenic had penetrated to a depth of over 25.4 cm, and water soluble arsenic was found at 10.2 cm (105). Increasing problems with the arsenate chemicals led to the development of safer herbicides requiring less material per hectare. Limpel et a1. (72) reported that DCPA at 11.2 kg ha" was more effective than chlordane at 67.2 kg ha"1 or calcium arsenate at 497.3 kg ha'l. DCPA demonstrated excellent results at low rates which would reduce soil residual. DCPA has provided excellent preemergence crabgrass control in Kentucky bluegrass and fine fescue areas (17, 44, 45, 47, 72, 84, 97, 101) but occasionally has caused severe phytotoxicity and thinning of red fescue stands at rates of 11.8 kg ha“ (52, 81, 95, 97, 98, 103). 'DCPA has been shown to cause thinning of creeping bentgrass at rates of 11.2 kg ha“1 (51), while Cisar et a1. (22) reported that rates up to 23.5 kg ha‘1 did not injure a Penncross creeping bentgrass green in Rhode Island. These conflicting results could be due to cultural and/or environmental differences. Bensulide, a phosphorothioate herbicide, has been reported to provide excellent preemergence crabgrass control at rates of 8.5 to 13.4 kg ha‘“1 throughout the United States (8, 15, 17, 27, 36, 62, 90). Bensulide has been found to inhibit the formation of roots of germinating seeds (38). In Rhode Island, bensulide applied at 3 and 7 weeks before crabgrass germination produced good control with slight turf injury (50). Bhowmik (9) found that bensulide at 11.2 kg ha“ gave excellent crabgrass control in a Kentucky bluegrass-red fescue mixture over the entire season. Peters et a1. (83) reported that bensulide restricted rooting of bluegrass sod at 4 weeks but not at 8, 16, or 18 weeks, demonstrating that at least 2 months are required before sod should be laid on the treated area. Bingham noted that when bensulide was applied to the soil prior to sod establishment, both 'Merion' Kentucky bluegrass and 'Kentucky 31' tall fescue roots could not penetrate the herbicide barrier (12). Another promising herbicide was DMPA, which provided excellent control from a preemergence application to Kentucky bluegrass (40, 68, 83) and also to a mixture of Colonial bentgrass, Kentucky bluegrass, and red fescue (3). Siduron, a substituted urea, has been reported to be selective on germinating grasses (38). Kerr (67) found siduron to be an effective preemergence herbicide which can be applied safely before or after seeding or sodding Kentucky bluegrass. Siduron has been reported to be safe on Penncross creeping bentgrass (34), but not on young or recently sodded bermudagrass areas (12, 35). Tweedy reported that siduron (13.4 kg ha'l) produced excellent seasonal crabgrass spp. control without phytotoxicity to cultivars of perennial ryegrass, tall fescue, creeping red fescue, Kentucky bluegrass, and red top (92). Unfortunately, variable crabgrass control with siduron has been reported by other researchers (26, 27). Single applications of benefin at 2.2 kg ha':L have been reported to provide unacceptable crabgrass control (17, 25, 33, 51). Dernoeden noted that one 2.2 kg ha‘1 application of benefin failed to provide adequate control the first season, but during the third year a single treatment provided effective crabgrass control (27). Other research has shown that a higher single rate (3.4 kg ha'l) or split applications (2.2 + 2.2 kg ha'l) can produce effective crabgrass control (44, 62). Presently in the United States, bensulide, benefin, DCPA, oxadiazon, pendimethalin, siduron, and trifluralin are the most frequently used preemergence products. Cultural practices were found to influence herbicidal activity. Raising the cutting height from 2.5 to 5.1 cm improved the effectiveness of DMPA and DCPA along with reducing crabgrass populations (1). Irrigation after preemergence herbicide application can be critical for season long crabgrass control. Dernoeden (26) reported that delaying irrigation on turf treated with bensulide reduced its effectiveness when compared to benefin or DCPA. Irrigation immediately following a DCPA application has been shown to greatly improve efficacy (26). Cultivation practices following a preemergence herbicide application have not been recommended in the past for fear of disturbing the herbicide zone. Jagschitz (57) found that a renovation protocol of glyphosate, scalping and disk seeding reduced crabgrass control in areas treated with bensulide, benefin, pendimethalin, DCPA, or low rates of prodiamine at 9 and 15 weeks after treatment. Johnson (64) found that core cultivation to a common bermudagrass turf before or after oxadiazon, bensulide, benefin, or bensulide + oxadiazon applications did not affect preemergence crabgrass control. In Michigan, Branham and Rieke (18) reported that core cultivation or vertical mowing immediately following herbicide treatment did not affect crabgrass control with benefin (2.2 kg ha‘l), DCPA (11.8 kg ha’l), or bensulide (11.2 kg ha'l). Timing of the preemergence herbicide application is important. Numerous researchers conducted trials to 10 determine if a fall treatment might maintain control throughout the following year. Perkins et a1. (81) applied DCPA (11.2 kg ha"), bensulide (14 kg ha"), and siduron (11.2 kg ha") in the fall and evaluated crabgrass control during the next season. Both bensulide and DCPA provided excellent results, but DCPA thinned the fine fescue. A fall application of siduron was not effective. Ahrens et al. (1) found that calcium arsenate, chlordane, DCPA, and DMPA performed better when applied in the spring than in the fall. Vitolo, Ilnicki, and Else (94) found that spring treatments of benefin, bensulide, oxadiazon, and prodiamine gave greater crabgrass control than fall treatments of these herbicides. Jagschitz (51) noted bandane, bensulide, and DMPA applied in the fall or spring to be effective in controlling crabgrass with minimum turf injury. In Pennsylvania, napropamide applied at 2.2 kg ha" provided greater crabgrass control and less turf injury when applied late April than in late March (100). Engel et a1. (39) found that a DCPA treatment in April was more efficacious than a May application, while a May treatment of benefin gave greater crabgrass control than an April application. In Rhode Island, March and May split applications of oxadiazon (1.7 + 1.7 kg ha") performed better than May and June treatments, while siduron (5.6 kg ha'l) applied in May provided greater crabgrass control than an application in March (93). Johnson (61) concluded that split applications 11 of DCPA (5.6 + 5.6 kg ha'l) did not produce greater large crabgrass control than a single application of 11.2 kg harl. Annual reapplications of preemergence herbicides have improved crabgrass control (104). Half rates of bensulide, bandane, DCPA, siduron, and nitralin applied in the second year after previous spring applications provided good to excellent crabgrass control in Rhode Island (52). watschke et al. (104) found similar results using reduced rates the following year with prosulfalin, bensulide, benefin, and DCPA in Pennsylvania. Research has also shown that reduced rates of oxadiazon (2.2 kg ha'l), following 4.5 + 4.5 kg ha“ applications the previous summer, were effective in controlling crabgrass (25, 26). Chemical formulation can have a dramatic impact on herbicide performance, turfgrass injury, and soil residual. In New Jersey, researchers reported dry formulations of DCPA and benefin outperformed liquid applications. Bingham and Schmidt (15) noted that fine granular benefin formulations outperformed both sprays and coarse granules. In Pennsylvania, the emulsified formulation of pendimethalin did not produce good crabgrass control while the granular formulation produced excellent results (96). Turgeon (90) noted that the wettable powder formulation of DCPA provided the best crabgrass control over granular and flowable formulations. Several researchers found the wettable powder formulation of DCPA to be more injurious to creeping red fescue than the granular formulation (96, 102). Bingham and 12 Schmidt (14) found that a granular bensulide formulation applied at 16.8 kg ha’1 once annually for four consecutive years was detected 11 months after the final application to a depth of 13 cm. An emulsifiable concentrate of bensulide applied at the same rate was not found in detectable quantities 11 months after application. Research has demonstrated the practicality of sub- stituting fertilizer for herbicide treatments in controlling weeds and annual grasses. Turner et a1. (91) noted phosphorus fertilizer application to significantly reduce crabgrass encroachment in Merion Kentucky bluegrass. Johnson and Sawyer (65) found that DCPA, oxadiazon, bensulide, or prosulfalin in combination with nitrogen fertilizer applied to the same turf areas for four consecutive years controlled a higher percentage of large crabgrass when compared to either applied alone. Murray et a1. (77) have shown that an interaction exists between crabgrass spp. control by both OSHA and siduron and high fertilizer rates (300 kg N ha‘l), in which the fertilizer increases the effectiveness of both preemergence herbicides. Soil and environmental factors can influence a preemergence herbicide's activity. Johnson and Burns (66) found that large crabgrass control by DCPA or napropamide increased with decreasing soil pH levels from 5.6 to 5.0. Johnson (61) noted a correlation between soil temperature prior to DCPA treatment and the amount of large crabgrass control in Georgia, which indicated that poor control was 13 related to crabgrass germination prior to herbicide application. Daniel (23) reported that application of preemergence herbicides prior to soil temperatures of 12 C under turfgrass conditions in Indiana can prevent emergence of many annual grasses. When problems arise from an improper application or from a lack of soil residual of preemergence herbicides, postemergence herbicides can provide effective control. In previous years, arsenical and mercurial chemicals proved effective for postemergence crabgrass control (70). Beard and Daniel (7) concluded that DMA was the most effective and safest postemergence chemical available for home use in the mid 1950's. Research conducted in 1957 showed AMA to provide faster crabgrass control than DMA, but both products required two applications (7). Kesler et a1. (68) showed that DMA, AMA, and CMA provided satisfactory postemergence results, but single applications did not maintain season-long control. watschke (95) stated that a single application of monosodium methanearsonate (MSMA) did not give season-long postemergence control. This disagreed with Johnson (60) who stated that a single June application of MSMA (2.2 kg ha’l) produced excellent large crabgrass control in a bermudagrass turf. These discrepancies could be due to varying levels of crabgrass pressure within 14 locations, different growth stages, or environmental factors. Later research has demonstrated that split treatments of disodium methanearsonate (DSMA) and MSMA are more effective than single applications and give little or no discoloration to the turf (6, 93). Johnson (59) found that 12 days between MSMA applications (1.1 kg ha'll provided the best large crabgrass control. He further noted that a 12 to 19 day delay between applications of MSMA was the most effective when using higher rates of 1.7 or 2.2 kg ha‘1 (59). Jagschitz reported that a 2—week interval between DSMA treatments for postemergence crabgrass control was the most effective while 3-week intervals resulted in poor control (55). Jagschitz (53) also found that three applications of DSMA (4.5 kg ha'l) or MSMA (3 + 2.2 + 2.2 kg ha“) produced excellent results, but there was considerable injury to fescue and bentgrass. Perkins et al. reported that an MSMA-dicamba combination produced excellent results, but there was considerable thinning to the turf (81). PMA (4.5 kg ha") and trifluralin (4.5 kg ha") gave acceptable postemergence control (83), but both can also cause turfgrass discoloration (56, 81). Granular trifluralin exhibited excellent control when applied as an early post treatment. Phillips reported that a liquid combination of trifluralin and DSMA (0.56 + 3.9 kg ha") worked well as a postemergence crabgrass control method (84). Jagschitz (54) noted that increasing the spray volume from 189.3 to 658.6 liters using DSMA reduced Kentucky bluegrass injury. 15 Researchers in Maryland (34) observed that 'Tufcote' bermudagrass recovered 2 weeks following excessive applications of MSMA (4.5 kg ha“), DSMA (8.3 kg ha"), and PMA (0.12 kg ha"). In Arkansas, MSMA (2.2 kg ha’l) and sethoxydim (2-(1-(ethoxyimion)butyl)-5-(2-(ethylthio) propyl)-3-hydroxy—2-cyclohexen-l-one) at 0.44 kg ha“ produced fair crabgrass control and also caused yellowing of tall fescue, creeping bentgrass, and common bermudagrass turf (76). Dernoeden and Fry (30) observed that MSMA at 1.1 kg ha‘1 applied three times weekly or 2.2 kg ha’1 applied two times biweekly produced excellent postemergence control of three to six tiller stage crabgrass plants, but it was phytotoxic to perennial ryegrass. Due to the constant concerns with phytotoxicity, poor seasonal control, and timing of sequential herbicide applications, new postemergence herbicides are constantly being sought. Desirable characteristics would include excellent control with one application, predictable results in a variety of climatic situations, an acceptable level of phytotoxicity to turfgrass, and low application rates. Fenoxaprop ethyl ((il-ethyl 2-[4-[(6-chloro-2- benzoxazoylloxylphenoxy] propanoatel is a promising new postemergence herbicide for controlling large and smooth crabgrass, johnsongrass (Sorghum halepense L. Pers.), panicum spp. (Panicum spp.), goosegrass (Eleusine indica L. Gaertn.), barnyardgrass (Echinochloa crus-galli L. Beauv.) and foxtail spp. (Setaria_spp.) within most cool season 16 turfgrass stands (48, 87). Fenoxaprop ethyl, tested under the experimental designation HOE A2501, has demonstrated great potential as a postemergence crabgrass herbicide (9, ll, 13, 20, 28, 29, 32, 71, 94). Cisar and Jagschitz (21) reported on field and greenhouse evaluations of fenoxaprop ethyl. In the field, fenoxaprop ethyl applied in June was not injurious to Kentucky bluegrass or bentgrass at rates of up to 0.2 kg ha‘l. Applications of fenoxaprop ethyl in May at rates from 0.2 to 0.56 kg ha'1 damaged perennial ryegrass and Kentucky bluegrass but was safe on red fescue. In greenhouse studies, fenoxaprop ethyl produced injury up to 15 weeks on Kentucky bluegrass at rates as low as 0.08 kg ha". Red fescue was noted to be the most tolerant and Kentucky bluegrass the most sensitive to fenoxaprop ethyl. Cisar and Jagschitz further believed that Kentucky bluegrass could be more sensitive to fenoxaprop ethyl in early May than in mid June (21). Further research is necessary to determine which Kentucky bluegrass cultivars are more or less susceptible to fenoxaprop ethyl. Dernoeden and Fry (31) observed that older leaves of 'Midiron' bermudagrass treated with fenoxaprop ethyl and bensulide (0.17 + 8.4 kg ha‘l) developed a purple color. Fenoxaprop ethyl (0.17 kg ha") alone or tank mixed with DCPA (11.8 kg ha‘l) produced a yellowish color and a density reduction was evident in all treatments. When applied to 'Tufcote' bermudagrass, fenoxaprop ethyl (0.17 kg ha“) caused a yellow-brown color less than 1 week after 17 application, but no thinning of the bermudagrass occurred (31). McCarty et al. observed that single applications of fenoxaprop ethyl (0.07 kg ha") severely injured centipedegrass for approximately 42 days (75). Fry et a1. (45) indicated that fenoxaprop ethyl produced excellent control of two to four leaf smooth crabgrass with no discoloration to zoysiagrass turf. Other experiments indicated that a single treatment of fenoxaprop ethyl at either 0.17 or 0.28 kg ha“ effectively controlled one to five tiller stage crabgrass, but was ineffective at the four to six tiller stages (30). In Massachusetts, fenoxaprop ethyl provided excellent control of two to four leaf crabgrass, but reinfestation occurred later in the season (10). These results demonstrate the need for further rate and timing experiments. Watschke (95) observed that fenoxaprop ethyl at 0.17, 0.28 and 0.39 kg ha"l did not successfully control water stressed crabgrass, but when soil moisture was adequate, fenoxaprop ethyl provided excellent control. In Rhode Island, Kentucky bluegrass sod rooting was not inhibited when fenoxaprop ethyl was applied 3 to 6 weeks before transplanting (58). Applying fenoxaprop ethyl in split applications or along with preemergence herbicides has provided excellent results (30, 78). Dernoeden and Fry (30) found that fenoxaprop ethyl tank mixed with either DCPA or oxadiazon provided excellent season-long control. These promising 18 results warrant further preemergence/postemergence combination studies. When two or more herbicides are combined in a tank mix, synergistic or antagonistic interactions can occur. Anderson (4) stated that a mixture is said to be antagonistic when the expected response induced by the herbicide combination is less than the expected sum total of the responses induced by each herbicide applied alone. Synergism occurs when the expected response induced by the herbicide combination is greater than the expected sum total of the responses induced by each herbicide applied alone. In row crop situations, reseachers have reported antagonism with various herbicide tank mixtures or sequential applications. Godley and Kitchen (46) reported that acifluorfen (5-[2-chloro-4-(trifluoromethyl)phenony-Z- nitrobenzoic acid) at 0.4 kg/ha applied in combination with, or one to three days prior to fluazifop ((:)-2-(4-[[5- (trifluoromethyl)-2-pyridinylloxylphenoxylpropanoic acid) at 0.4 kg ha" greatly reduced crabgrass control when compared to fluazifop alone. They also noted that the antagonism was not apparent when acifluorfen was applied at l, 3, or 5 days after the fluazifop treatment, while the degree of antagonism with the tank mixture of fluazifop and acifluorfen was dependent upon climatic conditions. Whitwell et al. (106) reported acifluorfen to be highly antagonistic to the postemergence johnsongrass herbicides sethoxydim and difenopenten (4-(4-[4-(trif1uormethyl) 19 phenoxyl-Z-pentenoic acid). Similarly, Rhodes and Cable (86) found bentazon to dramatically suppress the absorption of sethoxydim within goosegrass when applied in a mixture. Researchers have reported antagonistic properties between diclofop-methyl (methyl 2-[4(2',4'- dichlorophenoxy)phenoxylpropanoate) and 2,4-D, where the injury symptoms from diclofop-methyl were nullified on wild oat (Avena fatua L.) (42, 49). Todd and Stobbe (89) also reported 2,4-D to be antagonistic to diclofop-methyl in controlling wild oat in a greenhouse situation. They determined that the antagonism caused by 2,4-D reduced the movement of the free acid diclofop to meristematic areas. Shimabukuro et al. (88) reported that reciprocal antagonism in corn and soybeans existed between diclofop-methyl and 2,4-D and was dependent upon the cOncentration of the other herbicide. In Alberta, Canada, 2,4-D has been shown to be antagonistic to diclofop and also flamprop (N-benzoyl-N-(3- chloro-4-f1uorophenyl)-DL-alanine) for wild oat control (79, 80). Another phenoxy herbicide, MCPA, when tank mixed with diclofop, has been shown to inhibit herbicidal transport within wild oat (85). Qureshi and VandenBorn (85) attributed this problem to a formulation incompatability when both are combined. Antagonism has also been reported with annual grass and broadleaf weed herbicides used in turfgrass situations. Johnson (63) reported a reduction in preemergence crabgrass control when combining bensulide (11 kg ha“) with 2,4-D, 20 mecoprop, and dicamba (1.1 + 0.6 + 0.11 kg ha") as compared to bensulide alone. Freeborg and Daniel (43) reported a reduction in postemergence crabgrass control with fenoxaprop-ethyl (0.28 kg ha“) tank mixed with 2,4-D plus mecoprop plus dicamba (0.43 + 0.22 + 0.04 kg ha") when compared to fenoxaprop-ethyl alone. watschke and Hamilton (99) also noted similar results and showed that by increasing the fenoxaprop-ethyl rate in the combination, crabgrass control also increased. Tridiphane [2-(3,5-dichlorophenyl)-2-(2,2,2— trichloroethyl)oxirane] is another interesting new postemergence annual grass herbicide. Tridiphane has been successfully used for annual grass control in row crop situations. Research suggests that tridiphane either decreases or inhibits the metabolism of atrazine in giant foxtail (Setaria faberii) (16, 74). Ezra et al. has noted that tridiphane is synergistic with EPTC and alachlor, providing increased control of proso millet (Panicum miliaceum) in corn (41). Further research has shown that temperature has a dramatic effect on penetration, desorption, volatility, and metabolism of tridiphane when applied to giant foxtail (73). Tridiphane has been tested along with MSMA and fenoxaprop ethyl to compare efficacy in turfgrass situations. Neal et. a1 (78) observed that early post applications of tridiphane, fenoxaprop ethyl, and MSMA provided excellent crabgrass control, although some 21 reinfestation occurred. Tridiphane (1.1 kg ha‘l) was less effective when applied to one to three tiller crabgrass than fenoxaprop ethyl (0.2 kg ha") or MSMA (2.2 kg ha"), although Vitolo et. al (94) found that tridiphane applied post to small plants provided excellent control at all rates tested. Jagschitz (56) reported that tridiphane (1.7 kg ha") is safe on Kentucky bluegrass and perennial ryegrass, but injurious to red fescue. Higher rates or sequential applications of tridiphane were needed to control larger crabgrass. Due to the limited amount of research literature evaluating tridiphane, further investigations are needed in areas of preemergence-postemergence combinations, efficacy on mature crabgrass plants, and also broadleaf herbicide tank mixes. 10. 110 12. 13. LITERATURE CITED Ahrens, J.F., R.J. Lukens, and A.R. Olson. 1962. Preemergence control of crabgrass in turf with fall and spring treatments. Proc. Northeastern Weed Control Conf. 16:511-518. . 1963. Single and repeated applications of preemergence crabgrass killers on turf. Proc. Northeastern Weed Control Conf. 17:483-484. Ames, R.B. and C.R. Skogley. 1962. Pre- and post- emergence crabgrass control in lawn turf. Proc. Northeastern weed Control Conf. 16:528-535. Anderson, W.P. 1983. Weed science:principles. West Publishing Company. St. Paul, Mn. Barrett, L.H., and J.A. Jagschitz. 1975. Control of crabgrass and goosegrass with preemergence chemicals in turfgrass. Proc. Northeastern Weed Sci. Soc. 29:359-364. . 1976. Control of crabgrass and fall panicum in turfgrass with postemergence herbicides. Proc. Northeastern Weed Sci. Soc. 30:372-376. Beard, J.B., and W.H. Daniel. 1958. Post-emergence crabgrass control studies. North Cent. Weed Control Conf. Proc. 15:37. Bhowmik, P.C., and J. Troll. 1983. Preemergence crabgrass control in turfgrass. Proc. Northeastern Weed Sci. Soc. 30:391-395. Bhowmik, P.C. 1984. Control of crabgrass in lawn turf with herbicides. Am. Lawn Applicator. 5:12-14. . 1985. Crabgrass control in lawn turf with UC 77892 and fenoxaprop ethyl. Proc. Northeastern Weed Sci. Soc. 39:270. . 1986. Fenoxaprop-ethyl for postemergence crabgrass control in Kentucky bluegrass turf. HortScience. 21:457-458. 1974. Influence of selected herbicides on rooting of turfgrass sod. Proc. Second Intern. Turfgrass Res. Conf. 2:372-377. . 1985. Fenoxaprop-ethyl for crabgrass and goosegrass control in turfgrasses. Proc. Southern Weed Sci. Soc. 38:101. 22 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 23 Bingham, S.W., and R.E. Schmidt. 1967. Residue of bensulide in turfgrass soil following annual treatments for crabgrass control. Agron. J. 59:327-329. . 1983. Influence of pre-emergence herbicides on root development of Agrostis stolonifera sod. Weed Res. 23:339-346. Boydston, R.A., and F.W. Slife. 1986. Alteration of atrazine uptake and metabolism by tridiphane in giant foxtail (Setaria faberi) and corn (Zea mays). Weed Sci. 34:850-858. Branham, B.E. 1984. 1983 herbicide evaluations. 54th Annual Mich. Turfgrass Conf. Proc. 13:27-34. Branham, B.E., and P.E. Rieke. 1986. Effects of turf cultivation practices on the efficacy of preemergence grass herbicides. Agron. J. 78:1089-1091. Carleton, R.M. 1955. You can kill growing crabgrass but not the dormant seed. Park Maintenance. 8:26-27. Cisar, J.L. and J.A. Jagschitz. 1984. Postemergence control of smooth crabgrass in lawn turf. Proc. Northeastern weed Sci. Soc. 38:276-280. . 1984. Turfgrass tolerance to post- and preemergence herbicides. Proc. Northeastern Weed Sci. Soc. 38:298-302. Cisar, J.L., J.A. Jagschitz, and R.C. Skogley. 1983. Preemergence herbicides on putting green bentgrasses. Proc. Northeastern Weed Sci. Soc. 37:71-76. Daniel, W.H. 1969. Annual grass weed control. Proc. of the First Intern. Turfgrass Res. Conf. 1:393-400. DeFrance, J.A. 1948. Crabgrass control in turf. Northeastern Weed Control Conf. Proc. 2:99-112. Dernoeden, P.H. 1982. Efficacy of reduced rates of preemergence herbicides for crabgrass control in turf in the transition zone. Agron. Abs. p.141. . 1982. Single versus repeat application of preemergence crabgrass herbicides using reduced rates the second year. Proc. Northeastern Weed Sci. Soc. 36:315-319. . 1984. Management of preemergence herbicides for crabgrass control in transition-zone turf. HortScience. 19:443-445. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 24 . 1986. Postemergence control of crabgrass with tridiphane and fenoxaprop. Proc. Northeastern Weed Sci. Soc. 40:287-288. . 1987. Tolerance of perennial ryegrass and tall fescue seedlings to fenoxaprop. Agron. J. 79:1035-1037. Dernoeden, P.H. and J.D. Fry. 1984. Developing crabgrass and goosegrass control strategies in turf with HOE-A2501. Proc. Northeastern Weed Sci. Soc. 38:289-294. . 1984. Sensitivity of bermudagrass and zoysiagrass to HOE-A2501 and preemergence herbicides. Proc. Northeastern Weed Sci. Soc. 38:303-304. . 1985. Crabgrass control in turf with fenoxaprop-ethyl, MSMA, tridiphane, and UC 77892. Proc. Northeastern Weed Sci. Soc. 39:282-285. Dernoeden, P.H., and J.K. Mathias. 1981. Single versus repeat application of various preemergent herbicides for crabgrass control. Northeastern Weed Sci. Soc. Proc. 35:294-298. Dernoeden, P.H., and A.S. Nash. 1981. Effects of excessive levels of some postemergent crabgrass herbicides on Tufcote bermudagrass and Penncross creeping bentgrass. Northeastern Weed Sci. Soc. Proc. 35:337-341. Dunn, J.H., D.D. Hemphill, and C.W. Lobenstein, Jr. 1972. Phytotoxicity of preemergence herbicides to newly planted warm-season turfgrasses. North Central Weed Control Conf. Proc. 27:63-64. Elmore, C.L., K. Mueller, K. Gowans, and B. Fischer. 1972. Progress report on crabgrass control in turf 1971. California Turfgrass Res. 22:14-16. Engel, R.E. 1963. Crabgrass control obtained on turf treated with several new and developmental preemergence herbicides. Proc. Northeastern Weed Control Conf. 17:490-492. . 1969. Selectivity of turfgrass herbicides. Proc. First Intern. Turfgrass Res. Conf. 1:396-400. Engel, R.E., C.W. Bussey, and P. Catron. 1975. Crabgrass and goosegrass control in turfgrass with several preemerge herbicides. Proc. Northeastern Weed Sci. Soc. 29:369-374. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. so. 25 Engel, R.E., R.N. Cook, and R.D. Ilnicki. 1962. crabgrass control obtained in established turf with pre- emergence herbicides. Proc. Northeastern weed Control Conf. 16:543-544. Ezra, G., J.H. Dekker, and G.R. Stephenson. 1985. Tridiphane as a synergist for herbicides in corn (Zea mays) and proso millet (Panicum miliaceum). Weed Sci. 33:287-290. Fletcher, R.A., and D.M. Drexler. 1980. Interactions of diclofop-methyl and 2,4-D in cultivated oats (Avena sativa). Weed Sci. 28:363. Freeborg, R.P., and W.H. Daniel. 1983. Post emergence control of Digita11§,i§gh§gmgm and turf response to fenoxyprop-ethyl. Northcentral Weed Control Conf. Proc. 38:69. Fry, J.D., and P.H. Dernoeden. 1984. Evaluation of experimental herbicides for preemergence control of crabgrass in turf. Proc. Northeastern Weed Sci. Soc. 38:271-275. Fry, J.D., P.H. Dernoeden, and J.J. Murray. 1986. establishment and rooting of zoysiagrass (Zoysia japonica) as affected by preemergence herbicides. Weed Sci. 34:413-418. Godley, J.L., and L.M. Kitchen. 1986. Interaction of acifluorfen with fluazifop for annual grass control. Weed Sci. 34:936-941. Hesseltine, B.B. and J.A. Jagschitz. 1978. Control of crabgrass with pre- and postemergence herbicides in turfgrass. Proc. Northeastern Weed Sci. Soc. 32:308-314. Hoechst-Roussel Agri-Vet Company. 1987. Acclaim 1EC herbicide, technical information bulletin. Hoechst- Roussel Agri-Vet Company, Agric. Chemicals, Somerville, NJ pp. 11. Jacobson, A., R.M. Shimabukuro, and C. McMichael. 1985. Response of wheat and oat seedlings to root-applied diclofop-methyl and 2,4-Dichlorophenoxyacetic acid. Pesticide Biochemistry and Physiol. 24:61-67. Jagschitz, J.A. 1967. Effect of application date on preemergence crabgrass herbicides in turfgrass. Proc. Northeastern Weed Control Conf. 21:470-477. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 26 . 1969. Fall and spring use of preemergent crabgrass control chemicals in turfgrass. Proc. Northeastern Weed Control Conf. 23:398-404. . 1970. Pre and postemergence chemical crabgrass control studies in turfgrass 1968-69. Proc. Northeastern Weed Control Conf. 24:379-386. 1975. Postemergence crabgrass and nutsedge control in turfgrass with herbicides. Proc. Northeastern weed Sci. Soc. 29:376-381. . 1977. Tolerance of nutsedge, crabgrass and turfgrasses to postemergence herbicides. Proc. Northeastern Weed Sci. Soc. 31:350-356. 1979. Postemergence herbicides for crabgrass and nutsedge control in turfgrass. Northeastern weed Sci. Soc. Proc. 33:274-279. . 1985. Crabgrass control in turfgrass with herbicides. Proc. Northeastern Weed Sci. Soc. 39:274-278. . 1986. Establishment of turfgrass, crabgrass and annual bluegrass following herbicide use. Proc. Northeastern Weed Sci. Soc. 40:270-271. . 1986. Herbicide effects on development and rooting of Kentucky bluegrass sod. Proc. Northeastern Weed Sci. Soc. 40:280-281. Johnson, B.J. 1975. Postemergence control of large crabgrass and goosegrass in turf. Weed Sci. 23:404-409. . 1977. Sequential herbicide treatments for large crabgrass and goosegrass control in bermudagrass. Agron. J. 69:1012-1014. . 1977. Sequential DCPA treatments for weed control in turfgrasses. Agron. J. 69:396-398. . 1981. Combinations of MSMA with preemergence herbicides for large crabgrass (Digitaria sanguinalis) control in turf. Weed Sci. 29:386-389. . 1983. Response of weeds in bermudagrass (Cynodon dactylon) turf to tank-mixed herbicides. Weed Sci. 31:883-888. 1987. Effect of core cultivation on preemergence herbicide activity in bermudagrass. HortScience. 22:440-441. 650 66. 67. 68. 69. 7o. 71. 72. 73. 74. 75. 76. 27 Johnson, B.J., and T.H. Bowyer. 1982. Management of herbicide and fertility levels on weeds and Kentucky bluegrass turf. Agron. J. 74:845-850. Johnson, B.J., and R.E. Burns. 1984. Influence of pH, fertility, and herbicide treatments on quality of bermudagrass. Agron. Abs. p.151. Kerr, H.D. 1969. Selective grass control with siduron. Weed Sci. 17:181-186. Kesler, C.D., R.H. Cole, and C.E. Phillips. 1962. Preemergence and postemergence crabgrass control in turfgrass. Proc. Northeastern Weed Control Conf. 16:524-527. King, L.J., and J.A. Kramer. 1955. A review of the crabgrass, Digitaria ischaemum and D. sanguinalis with notes on their preemergence control in turf. Proc. Northeastern Weed Control Conf. 9:359-363. Kollett, J.R. and J.A. DeFrance. 1959. Crabgrass control with postemergence chemical treatment. Proc. Northeastern Weed Control Conf. 13:155-159. Lewis, W.H. 1985. Fenoxaprop-ethyl for smooth crabgrass and goosegrass control in turf“ Proc. Southern Weed Sci. Soc. 38:104. Limpel, L. E., P. H. Schuldt, and F. Batkay. 1961. The responses of turf and certain turf weeds to Dacthal. Northeastern Weed Control Conf. Proc. 15:296-297. McCall, P.J., L.E. Stafford, and P.D. Gavit. 1986. Compartmental model describing the foliar behavior of tridiphane on giant foxtail. J. Agric. Food Chem. 34:229-232. McCall, P.J., L.E. Stafford, P.S. Zorner, and P.D. Gavit. 1986. Modeling the foliar behavior of atrazine with and without crop oil concentrate on giant foxtail and the effect of tridiphane on the model rate constants. J. Agric. Food Chem. 34:235-238. McCarty, L.B., J.M. Higgins, L.C. Miller, and T. Whitwell. 1986. Centipedegrass tolerance to postemergence grass herbicides. HortScience. 21:1405-1407. Miller, E.M., and J.W. King. 1982. Postemergence herbicide control of crabgrass in three turf species. Agron. Abs. p.144. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 28 Murray, J.J., D.L. Klingman, R.C. Nash, and E.A. Woolson. 1983. Eight years of herbicide and nitrogen fertilizer treatments on Kentucky bluegrass (Poa pratensis) turf. Weed Sci. 31:825-831. Neal, J.C., A. Senesac, and A. Bing. 1986. Influence of crabgrass growth stage on efficacy of fenoxaprop and tridiphane. Proc. Northeastern Weed Sci. Soc. 40:284-285. O'Sullivan, P.A. 1983. Influence of picloram alone or plus 2,4-D on control of wild oats (Avena fatua) with four postemergence herbicides. Weed Sci. 31:889-891. O'Sullivan, P.A. and W.H. VandenBorn. 1980. Interaction between benzoylprop ethyl, flamprop methyl or flamprop isopropyl and herbicides used for broadleaved weed control. Weed Res. 20:53-57. Perkins, A.T., J.M. Duich, and D.V. Weddington. 1969. Pre and postemergence crabgrass control results for 1967 and 1968. Proc. Northeastern Weed Control Conf. 23:391-397. Peters, R.A. 1964. Crabgrass - a successful weed. New England Agricultural Chemicals Conference and Herbicide Workshop. 1:25-26. , Peters, R.A., H.C. Yokum, and K.C. Stevens. 1962. Observations on chemical control of crabgrass in turf (1961). Proc. Northeastern Weed Control Conf. 16:519-523. Phillips, C.E. 1963. Chemical control of crabgrass in lawn turf. Proc. Northeastern Weed Control Conf. 17:485-489. Oureshi, F.A., and W.H. vandenBorn. 1979. Interaction of diclofop-methyl and MCPA on wild oats (Avena fatua). Weed Sci. 27:202-205. Rhodes, G.N. Jr., and H.D. Cable. 1984. Influence of bentazon on absorption and translocation of sethoxydim in goosegrass (Eleusine indica). Weed Sci. 32:595-597. Robinson, P., S. Harrison, and H. Miller. 1986. Evaluation of fenoxaprop-ethyl under an experimental use permit in turf in 1985. Proc. Northeastern Weed Sci. Soc. 40:286. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 29 Shimabukuro, R.H., W.C. Walsh, and R.A. Hoerauf. 1986. Reciprocal antagonism between the herbicides, diclofop- methyl and 2,4-D, in corn and soybean tissue culture. Plant Physiol. 80:612-617. Todd, B.G., and E.H. Stobbe. 1980. The basis of the antagonistic effect of 2,4-D on diclofop-methyl toxicity to wild oat (Avena fatua). Weed Sci. 28:371- 377. Turgeon, A.J. 1973. Evaluation results of preemergence herbicides for crabgrass control in turf. North Cent. Weed Control Conf. Proc. 28:108-109. Turner, T.R., D.V. Weddington, and T.L. Watschke. 1979. The effect of soil fertility levels on dandelion and crabgrass encroachment of Merion Kentucky bluegrass. Northeastern Weed Sci. Soc. Proc. 33:280-283. Tweedy, J.A. 1972. Evaluation of herbicides for crabgrass control in a spring seeding of several turfgrass species in southern Illinois. North Cent. weed Control Conf. Proc. 27:62-63. van Yahres, R.D., and J.A. Jagschitz. 1982. Pre- and postemergence herbicides for the control of crabgrass in lawn areas. Proc. Northeastern Weed Sci. Soc. 36:292-297. Vitolo, D.B., R.D. Ilnicki, and M.J. Else. 1986. Crabgrass control in rye and bluegrass turf. Proc. Northeastern Weed Sci. Soc. 40:272-275. watschke, T.L. 1985. Pre- and postemergence crabgrass control in 1983 and 1984. Proc. Northeastern Weed Sci. Soc. 39:279-281. Watschke, T.L., and J.M. Duich. 1978. Control of crabgrass in Kentucky bluegrass and red fescue turf using preemergence herbicides. Northeastern Weed Sci. Soc. Proc. 32:303-307. Watschke, T.L., J.M. Duich, and D.J. Wehner. 1975. Crabgrass control in 1974 using preemergence herbicides. Proc. Northeastern Weed Sci. Soc. 29:365- 368. Watschke, T.L., J.M. Duich, and M.S. Welterlen. 1979. Crabgrass control with single and split applications of preemergence herbicides. Northeastern Weed Sci. Soc. Proc. 33:270-273. 99. 100. 101. 102. 103. 104. 105. 106. 107. 30 Watschke, T.L. and G. Hamilton. 1986. Crabgrass control in 1985. Proc. Northeastern Weed Sci. Soc. 40:278-279. Watschke, T.L., D.J. Wehner, and J.M. Duich. 1976. Pre- and postemergence crabgrass control in turf. Proc. Northeastern Weed Sci. Soc. 30:358-361. . 1977. Control of smooth crabgrass in Kentucky bluegrass and red fescue using pre- and postemergence herbicides. Proc. Northeastern Weed Sci. Soc. 31:340-343. Watschke, T.L., and M.S. Welterlen. 1981. Preemergence control of crabgrass in 1979 and 1980. Northeastern Weed Sci. Soc. Proc. 35:299-303. 1982. Preemergence crabgrass control in turf. Proc. Northeastern Weed Sci. Soc. 36:298-300. watschke, T.L., M.S. Welterlen, and J.M. Duich. 1980. Control of smooth crabgrass in turf using reduced rates the second year. Northeastern Weed Sci. Soc. Proc. 34:353-355. Welton, F.A., and J.C. Carroll. 1938. Crabgrass in relation to arsenicals. J. Am. Soc. Agron. 30:816-826. Whitwell, T., G. Wehtje, R.H. Walker, and J.A. McGuire. 1985. Johnsongrass (Sorghum halepense) control in soybeans (Glycine max) with postemergnce grass herbicides applied alone and in mixtures. Weed Sci. 33:673-678. Younger, V.B. 1961. Winter survival of Digitaria sanguinalis in subtropical climates. weeds. 9:654-655. CHAPTER 2 EFFICACY AND TIMING OF FENOXAPROP-ETHYL AND TRIDIPHANE ALONE AND IN COMBINATION WITH PREEMERGENCE HERBICIDES FOR CRABGRASS CONTROL ABSTRACT Field studies were conducted during 1986 and 1987 to determine the effectiveness of fenoxaprop-ethyl (0.14, 0.20, 0.28, and 0.40 kg ha") and tridiphane (1.1, 1.7, and 2.2 kg ha“1) in controlling various crabgrass growth stages. Treatments of fenoxaprop-ethyl and tridiphane tank-mixed with preemergence herbicides were included to compare length of crabgrass control throughout the season. Fenoxaprop- ethyl (0.20 kg ha“) provided 91% control of eight tiller plants in 1986, and 83% control of four tiller crabgrass in 1987. Tridiphane (1.7 kg ha") provided 95% and 73% control of six tiller plants in 1986 and 1987, respectively. Fenoxaprop-ethyl tank-mixed with bensulide (0.20 + 8.4 kg ha“) produced effective season-long crabgrass control during both years. Split applications of fenoxaprop-ethyl (0.14 + 0.14 and 0.20 + 0.20 kg ha“) provided excellent control throughout the summer months. 31 32 INTRODUCTION Initial crabgrass (Digitaria spp.) emergence within a particular geographic location can vary considerably from season to season (7, 16). The extended germination period makes it difficult to maintain effective crabgrass control (4). If a preemergence herbicide is applied 2 to 4 weeks before crabgrass emergence, much of the herbicide residue may be lost. To gain the longest soil residual possible, a preemergence-postemergence tank mix can be employed. Researchers have reported excellent results with this combination (6, 9, 11, 12, 13). This concept utilizes crabgrass germination as a guide to correctly time the preemergence treatment. The postemergence herbicide could effectively control the initial flush of crabgrass, while the preemergence herbicide can prevent further infestation during peak germination periods. Another alternative is to apply split treatments of a postemergence herbicide. Researchers have reported excellent crabgrass control with this method (1, 6, 10, 12). This treatment could eliminate the need for a preemergence grass herbicide and allow overseeding to be performed without the fear of chemical residues in the soil. Fenoxaprop-ethyl and tridiphane are new postemergence graminicides for selectively controlling annual grasses in turfgrass stands. Recommended labeled rates for fenoxaprop- ethyl range from 0.13 kg ha'1 to 0.40 kg ha"1 for crabgrass 33 growth stages from two leaves up to four tillers, respectively (8). Limited research is available on the largest crabgrass stages these herbicides can control. If a large tillered plant can be controlled by the postemergence herbicide, the preemergence-postemergence combination could be postponed for several weeks. This could extend the preemergence soil residual further into the summer and fall. The purpose of this research was to evaluate the preemergence-postemergence strategy for season-long crabgrass control, and also determine the largest crabgrass stage of growth which can be controlled using fenoxaprop- ethyl and tridiphane. 34 MATERIALS AND METHODS Two field studies were conducted from June through September during 1986 and 1987 at the Hancock Turfgrass Research Center, East Lansing, MI. The soil type was an Owosso-Marlette sandy loam complex (Fine-loamy, mixed, mesic, Typic Hapludalfs). All herbicide applications were applied with a compressed CO; small plot sprayer, using a four nozzle boom equipped with 8002 flat fan nozzles. The spray volume was 520 L ha“L with a pressure of 0.21 MPa. Plot dimensions were 1.2 by 1.8 m. The experimental design consisted of a randomized complete block with three replications. The site was not fertilized, mowed at 3.8 cm when needed, and supplemental irrigation was applied only during drought periods to encourage crabgrass germination. Prior to 1986, the test site consisted of a dense population of crabgrass along with many annual and perennial weeds and grasses. In early May of both seasons, the area was treated with a broadcast application of glyphosate at 1.12 kg ha" to eliminate all grassy and broadleaf weeds. The site was then verticut with a Ryan (OMC Lincoln, Lincoln, NE) Ren-O-Thin“ to a depth of 1.3 cm and overseeded with smooth crabgrass (Digitaria ischaemum) in 1986, and large crabgrass (D. sanguinalis) in 1987 to supplement the natural seed reservoir. Plots were visually evaluated at two week intervals for percent crabgrass groundcover and all data was converted to percent control. Treatment means were 35 separated using the least significant difference (LSD) technique. The herbicide treatments consisted of tridiphane at rates ranging from 1.1 kg ha" to 2.2 kg ha" alone and in combination with bensulide (8.4 kg ha‘l), pendimethalin (2.2 kg ha’l), and fluroxypyr (4-amino-3,5-dichloro-6-fluoro-2- pyridyloxyacetic acid methyl heptylester) at 0.28 and 0.56 kg ha'l. Fenoxaprop ethyl was tested at rates of 0.14, 0.20, 0.28, and 0.40 kg ha'1 applied alone, sequentially, and in combination with bensulide (8.4 kg ha"), pendimethalin (2.2 kg ha'l), and DCPA (8.4 kg ha"). All herbicide combinations were applied as a tank mix. Single applications of both tridiphane and fenoxaprop ethyl were applied at two week intervals to evaluate crabgrass control at various growth stages. " In 1986, treatments 1 through 17 (Table 1) were applied on 3 June and in 1987 treatments 1 through 19 (Table l) were applied on 2 June to a crabgrass growth stage of two leaf to one tiller. Treatments 20 through 24 (Table l) were applied to three leaf, three tiller crabgrass on 17 June 1986, while numbers 20 through 25 (Table l) were applied to two to three leaf, one to three tiller plants on 15 June, 1987. Applications 26 through 33 (Table l) were applied on July 1 in both 1986 and 1987 to a three leaf, two to four tiller crabgrass stage. Treatments 34 through 39 (Table l) were applied to three to five leaf, four to six tiller crabgrass on 15 July 1986, and 14 July 1987. Treatments 40 through 47 36 (Table l) were tested on four to six leaf, five to twelve tiller plants on 30 July 1986, and 29 July 1987. 37 RESULTS AND DISCUSSION Tridiphane at 1.7 kg ha"1 applied to crabgrass at the two leaf to one tiller stage produced excellent control (92%) 4 weeks after treatment in 1986 (Table 1). Increasing the tridiphane rate to 2.2 kg ha"1 did not provide additional control. Control decreased by the sixth and eighth week for both rates due to newly germinating seeds within the area. The test site lacked a turfgrass canopy, resulting in rapid reinfestation. This explains the decreased control occuring at 4 weeks after treatment for most applications. In 1986, June and July produced rather mild temperatures (Table A1), with adequate precipitation (Table A3). These conditions were favorable in obtaining effective control. In June and Ju1y of 1987, the higher temperatures and lower precipitation could have caused the poor results attained with tridiphane at the 1.7 kg ha“ rate. Dernoeden (5) also noted that the effectiveness of tridiphane was reduced by hot and dry conditions. The highest level of control (71%) was obtained 4 weeks after treatment and fell sharply when new seeds germinated during July. Increasing tridiphane to 2.2 kg ha“1 provided good control (89%) 4 weeks after application. Similar to 1986, control diminished by the sixth week. A lower rate of tridiphane (1.1 kg ha") was tank mixed separately with pendimethalin (2.2 kg ha'l) and bensulide (8.4 kg ha") to examine seasonal crabgrass control. In 38 1986, the addition of pendimethalin and bensulide dramatically improved the length of control through 8 weeks after treatment. Research has shown that higher rates of tridiphane (2.2 kg ha") in combination with pendimethalin or DCPA provided excellent season-long crabgrass control (5). In 1987, neither preemergence herbicide provided additional control beyond 4 weeks when compared to tridiphane alone. Unpublished research (Bruce Branham, Michigan State University, E. Lansing, MI.) has shown fluroxypyr to exhibit sufficient postemergence crabgrass activity, warranting inclusion in this study. Fluroxypyr applied alone to the two leaf to one tiller plants in June provided 88% control up to 4 weeks in 1986, but received lower ratings in 1987. The 1 July fluroxypyr treatment prOvided less control when applied to maturing crabgrass. Very little postemergence activity was seen on five to twelve tiller plants in both years following the late July treatment. Tridiphane (1.7 kg ha'l) applied on 3 leaf to 3 tiller crabgrass provided fair control (75%) through a six week period in 1986, and extremely poor control in 1987. Increasing tridiphane to 2.2 kg ha‘1 provided significantly greater control during the first four weeks in 1986, and doubled the percent control to 64% in 1987 when compared to the lower tridiphane rate. The 1 July 1986 application of tridiphane (1.7 kg ha‘l) provided fair control (76%) of two to four tiller crabgrass for a four week period, while 39 tridiphane in 1987 resulted in poor control (56%). Increasing tridiphane to 2.2 kg ha’1 resulted in slightly better control in 1986, and a dramatic improvement in 1987. Tridiphane at 1.7 kg ha'1 also provided good to excellent control of 4 to 6 tiller crabgrass in 1986, lasting for approximately six weeks. During 1987, this treatment provided 73% control at 4 weeks after application. The higher tridiphane rate produced excellent control through 6 weeks after treatment in the first season, and good control by 4 weeks in 1987. Late July applications of tridiphane could not effectively control mature crabgrass. Treatments in 1986 provided improved control, but the results were not considered acceptable. In 1986, fenoxaprop-ethyl at all rates produced excellent control of plants up to eight tillers at 2 weeks after treatment. During the season, the main flush of crabgrass germination occurred from 1 June to 1 July. Consequently, plots treated with fenoxaprop-ethyl on 3 June and 17 June became reinfested with new plants, resulting in lowered percent control. Fenoxaprop-ethyl applications from 1 July to 30 July provided better season-long control due to less crabgrass germination. Results in 1987 indicate that fenoxaprop-ethyl alone effectively controlled crabgrass ranging from one to four tillers. All fenoxaprop-ethyl treatments on 14 July and 29 July 1987 resulted in poor control, possibly due to the crabgrass plants becoming water stressed during mid-summer. watschke (14) also observed 40 reduced control with fenoxaprop-ethyl when moisture was limiting. Sequential applications of fenoxaprop-ethyl at rates of 0.14 + 0.14 and 0.20 + 0.20 kg ha“ gave effective season- long control during both years. Researchers in Massachusetts (2) and Pennsylvania (13) also indicated excellent results with fenoxaprop-ethyl sequential treatments. Combinations of bensulide + fenoxaprop-ethyl provided the best seasonal control in both years as compared to DCPA and pendimethalin. All three preemergence- postemergence combinations performed well in 1986, but a late season reduction in control was evident with the DCPA and pendimethalin + fenoxaprop-ethyl tank mixes in 1987. When treating immature crabgrass plants, it is not necessary to increase the fenoxaprop-ethyl rate from 0.14 to 0.20 kg ha“ in these preemergence-postemergence combinations. When comparing the two postemergence herbicides, fenoxaprop-ethyl treatments provided more consistent crabgrass control than tridiphane throughout both seasons. Tridiphane was observed to be a slower acting herbicide, usually requiring two weeks or more for effective control. Bhowmik and Spokas (3) indicated that tridiphane at 2.2 kg ha‘iL required at least eight weeks to provide excellent control of two to three leaf crabgrass. Crabgrass control from fenoxaprop-ethyl applications was evident within 1 week. 41 Fenoxaprop-ethyl + preemergence herbicide combinations applied to larger tillered plants warrants further investigation. If a fenoxaprop-ethyl rate greater than 0.20 kg ha“ in combination with a preemergence herbicide were applied later in the season, longer control might be maintained. 42 TABLE 1: ERRICACY OR RENOXAPROR AND TRIOIPHANE ALONE AND IN COMBINATION WITH PREENEREUUCE NERBICIOES ROR CRABGRASS CONTROL. 1986 RATINGS. 1987 RATINGS RATE W (@01qu 1. TRIOIPHANE (TRIO) 1.7 82 92 63 60 20 71 5 0 2. TRIO 2.2 82 90 55 56 50 89 49 21 3. TRIO + PENDINETN. 1.1 + 2.2 76 86 88 82 62 83 50 13 4. TRIO + BENSULIOE 1.1 + 8.4 98 97 85 98 59 75 40 20 5. TRIO + RLUROXYRYR 1.1 + 0.28 86 89 49 64 47 58 27 27 6. TRIO + RLURO!YPYR 1.7 + 0.56 88 91 58 47 69 91 61 47 7. RLUROXYRYR 0.56 88 88 66 56 52 46 0 0 8. RENO!APROP (RENO!) 0.14 92 38 25 43 91 79 65 50 9. RENO! 0.20 88 62 42 57 99 95 93 70 10. RENO! 0.28 -- -- -- -- 95 75 79 46 11. RENO! 0.40 -- -- -- -- 98 93 68 51 12. RENO! + RENO! 0.14 + 0 14 87 75 94 98 91 79 98 96 13. RENO! + RENO! 0.20 + 0 20 100 81 100 97 97 83 99 98 14. RENO! + BENSULIOE 0.14 + 8 4 98 93 93 97 92 86 87 75 15. RENO! + BENSULIOE 0.20 + 8 4 100 100 97 98 99 95 91 87 16. RENO! + DCPA 0.14 + 8.4 100 89 85 86 89 90 61 49 17. RENO! + DCPA 0.20 + 8.4 97 90 70 90 97 91 74 62 18. RENO! + PENOIHETH. 0.14 + 1.7 100 97 88 92 90 92 67 53 19. RENO! + PENDINETN. 0.20 + 1.7 190, 95 77 71 94 97 86 72 L80 (0.05) 8 16 20 30 35 22 24 48 46 20. TRIO 1.7 75 75 75 48 11 33 19 3 21. TRIO 2.2 93 96 91 72 10 64 36 11 22. RENO! 0.14 90 76 84 60 88 81 57 24 23. RENO! 0.20 92 84 84 69 96 87 76 52 24. RENO! 0.28 94 81 92 90 97 90 74 40 25. RENO! 0.40 -- -- -- -- 86 67 57 441 L80 (0.05) = 10 11 N8 N3 26 46 47 N8 26. TRIO 1 7 73 76 59 53 39 56 41 25 27. TRIO 2 2 78 88 85 70 26 94 80 50 28. TRIO + RLUROXYRYR 1.7 + 0 56 90 89 74 73 45 83 68 57 29. RLUROXYPYR 0.56 67 31 20 18 20 46 25 19 30. RENO! 0.14 -- -- -- -- 77 76 69 57 31. RENO! 0.20 98 93 98 92 59 83 56 23 32. RENO! 0.28 99 97 95 87 83 96 77 69 33. RENO! 0.40 99, 96 97 99 485 95 83 110 LSO (0.05) 8 12 17 23 30 34 26 43 46 34. TRIO 1.7 88 90 87 66 24 73 22 35. TRIO 2.2 93 95 91 82 32 87 36 36. RENO! 0.14 -- -- 4- -- l l 0 37. RENO! 0.20 91 70 80 68 0 0 8 38. RENO! 0.28 93 95 91 86 14 13 2 39. RENO! 0.40 96 97 98 83 30 12 9 LSD (0.05) = N8 N8 N8 N8 N8 29 27 43 TABLE 1 CONT: 1986 RATINGS. 1987 RATINGS RATE IEEAINENIEF iksLha1______2IAI_iEAI_fEA1.!!AI___Z!LI_1!LI_§!LI.8:5: 40. TRIO 1.7 41 75 44 87 I8 49 47 41. TRIO 2.2 82 61 58 62 23 31 12 42. TRIO + RLUROXTPIR 1.7 + 0.56 44 38 46 66 lo 29 36 43. RLUROXYPIR 0.56 38 34 5 42 23 15 13 44. RENO! 0.14 -- -- -- -- 4 0 0 45. RENO! 0.20 89 91 95 86 8 0 6 46. RENO! 0.28 96 95 98 96 14 4 22 47. RENO! 0.40 93 99 94 96 7 0 l 191.!NIRIATEB__, ---- 04 10! 104 01 5 l 0 LSD (0.05) = 35 41 37 30 N8 36 30 8 Ratings are percent groundcover converted to as percent control, with WAT: Weeks After Treatment. 4 1986 Untreated ratings taken at sale time as treatments l-l9. ‘ Application dates and stage of growth present: trt l-l9 3 June 1986, 2 June 1987, with 2 leaf to l tiller crabgrass. trt 20-25 17 June 1986, 15 June 1987, with up to 3 leaf, 3 tillers. trt 26-33 1 July 1986, 1 July 1987, with 3 leaf, 2-4 tiller crabgrass. trt 34-39 15 July I986, 14 July 1987, with 3-5 leaf, 4-6 tillers. trt 40-47 30 July 1986, 29 July 1987, with 4-6 leaf, 5-12 tillers. 10. 11. 12. LITERATURE CITED Barrett, L.H., and J.A. Jagschitz. 1976. Control of crabgrass and fall panicum in turfgrass with postemergence herbicides. Proc. Northeastern Weed Sci. Soc. 30:372-376. Bhowmik, P.C. 1984. New herbicides for crabgrass control in turfgrass. Proc. Northeastern Weed Sci. Soc. 38:282-288. Bhowmik, P.C., and L.A. Spokas. 1986. Tridiphane for postemergent crabgrass control in turfgrass. Proc. Northeastern Weed Sci. Soc. 40:282. DeFrance, J.A. 1948. Crabgrass control in turf. Northeastern Weed Control Conf. Proc. 2:99-112. Dernoeden, P.H. 1986. Postemergence control of crabgrass with tridiphane and fenoxaprop. Proc. Northeastern Weed Sci. Soc. 40:287-288. Dernoeden, P.H., and J.D. Fry. 1984. Developing crabgrass and goosegrass control strategies in turf with HOE-A2501. Proc. Northeastern Weed Sci. Soc. 38:289-294. Dernoeden, P.H., and J.K. Mathias. 1981. Single versus repeat application of various preemergent herbicides for crabgrass control. Northeastern Weed Sci. Soc. Proc. 35:337-341. Hoechst-Roussel Agri-Vet Company. 1987. Acclaim lEC herbicide, technical information bulletin. Hoechst- Roussel Agri-Vet Company, Agric. Chemicals, Somerville, NJ pp. 11. Jagschitz, J.A. 1970. Pre and postemergence chemical crabgrass control studies in turfgrass 1968-69. Proc. Northeastern Weed Control Conf. 24:379-386. Johnson, B.J. 1975. Postemergence control of large crabgrass and goosegrass in turf. Weed Sci. 23:404-409. . 1981. Combinations of MSMA with preemergence herbicides for large crabgrass (Digitaria sanguinalis) control in turf. Weed Sci. 29:386-389. Neal, J.C., A. Senesac, and A. Bing. 1986. Influence of crabgrass growth stage on efficacy of fenoxaprop and tridiphane. Proc. Northeastern Weed Sci. Soc. 40:284- 285. 44 13. 14. 15. 16. 45 Troutman, B.C., and J.A. Jagschitz. 1971. Evaluation of chemicals for crabgrass control in turfgrass - 1970. Proc. Northeastern Weed Sci. Soc. 25:91-95. watschke, T.L. 1983. Control of smooth crabgrass in turf using pre- and postemergence herbicides. Proc. Northeastern Weed Sci. Soc. 37:389-390. . 1985. Pre- and postemergence crabgrass control in 1983 and 1984. Proc. Northeastern Weed Sci. Soc. 39:279-281. Younger, V.B. 1961. Winter survival of Digitaria sanguinalis in subtropical climates. Weeds. 9:654-655. CHAPTER 3 KENTUCKY BLUEGRASS AND CREEPING BENTGRASS CULTIVAR SENSITIVITY TO FENOXAPROP-ETHYL ABSTRACT Forty-two cultivars of mature Kentucky bluegrass (£9; pra;ensig_L.) were treated with fenoxaprop-ethyl at rates of 0.00, 0.14, and 0.28 kg ha“ in June 1986 and July 1987. Visual injury evaluations were taken at 1, 2, 3, and 4 weeks after application for each cultivar. Temporary injury from a fenoxaprop-ethyl application at 0.14 kg ha'1 was considered to be acceptable for all cultivars tested in 1986 and 1987. In 1986, only the cultivar America was rated unacceptable two weeks after treatment with the 0.28 kg ha“ rate. 'Enmundi' was the only Kentucky bluegrass cultivar which did not exhibit injury from either fenoxaprop-ethyl rate tested in 1986 and 1987. In July 1987, fourteen mature creeping bentgrass (Agrgstis palgstrig Huds.) cultivars and one velvet bentgrass (Agrggtis canine L.) cultivar were treated with fenoxaprop-ethyl at rates of 0.00, 0.09, 0.14, and 0.20 kg ha". In a second study, fenoxaprop-ethyl at rates of 0.00, 0.04, 0.07, and 0.09 kg ha“ were applied in late August to the same cultivars. Visual injury evaluations were taken at 1, 2, 3, and 4 weeks 46 47 after application for the July study, and 2, 4, and 5 week evaluations were recorded for the August study. The most severe injury was apparent at 2 weeks after treatment for most cultivars in both experiments. The 0.20 kg ha"1 rate produced significant injury to all bentgrass cultivars when compared to untreated plots at l, 2 and 3 weeks after treatment. Most cultivars recovered from the 0.14 kg ha“ rate by the three week evaluation. In July, a rate of 0.09 kg ha"1 produced acceptable injury for all cultivars except 'Toronto'. This same rate applied in August produced unacceptable injury to most cultivars. The 0.07 kg ha" rate produced injury ranging from mild to severe, but all cultivars recovered by four weeks after treatment. Fenoxaprop-ethyl at 0.04 kg ha" produced slight injury at 2 weeks after treatment, with all cultivars recovering by the 4th week. Overall, 'Penncross', 'Penneagle', 'Carmen', and 'B853WWK' were most tolerant, while 'Toronto' was extremely sensitive to fenoxaprop-ethyl. Chemical name used: (’—)- ethyl 2-(4-l(6-chloro-2-benzoxazoyl)oxylphenoxyl propanoate. 48 INTRODUCTION Crabgrass (Digitaria spp.) infestations within turfgrass can be controlled with either preemergence or postemergence herbicides. Effectiveness of these herbicides varies considerably from region to region and year to year (2). Frequently used arsenical postemergence herbicides such as monosodium methanearsonate (MSMA) have been shown to be only marginally effective in controlling crabgrass (2, 10, 18), and can also severely damage desired turfgrass stands (17). Fenoxaprop-ethyl is a new selective postemergence graminicide which has been shown to be effective for control of annual grasses such as crabgrass (l, 4, 9, 10, ll, 14, 16, 17). Split applications of fenoxaprop-ethyl can provide season-long crabgrass control (2, 15) while other researchers have found that one properly timed application can provide season-long control (7, 10). Application timing and age of the turfgrass can affect the phytotoxicity obtained from a fenoxaprop-ethyl application. Bingham (3) observed fenoxaprop-ethyl applied mid-May to be more injurious than a mid-June treatment to a 'Glade', 'Plush', 'Ram' Kentucky bluegrass blend less than one year old. Fenoxaprop-ethyl has also been shown to significantly reduce the density of a seven month old 'South Dakota Common' Kentucky bluegrass turf (6). On mature turfgrass, Cisar and Jagschitz (5) noted objectionable injury to an established Kentucky bluegrass 49 stand from May fenoxaprop-ethyl (0.2 kg ha'*) treatments, however June applications to Kentucky bluegrass or bentgrass at the same rate did not cause injury. Dernoeden and Fry (10) observed injury to a three year old 'America' Kentucky bluegrass stand from fenoxaprop-ethyl to last for three to fOur weeks from a mid-May (0.28 kg ha") or late June (0.39 kg ha“) application, while a blend of 'Merion', 'Sydsport’, and 'Vantage‘ was only injured from the late June application. No phytotoxicity was noted on a four year old unirrigated stand of 'Sydsport', 'Vantage', 'Pennstar' Kentucky bluegrass treated with fenoxaprop-ethyl at 0.17 and 0.28 kg ha‘1 during periods of drought and heat stress in July (10). Bhowmik (2) reported 6 weeks of mild injury to 'Baron' Kentucky bluegrass caused by a late May treatment of fenoxaprop-ethyl (0.28 kg ha"). “When a second 0.28 kg ha'1 application was applied to the same area in mid July, no increase in injury was observed. Higgins et. al. (13) noted that the differential tolerance of a 'Tifgreen II' bermudagrass putting green to fenoxaprop-ethyl was related to application timing. The researchers reported that June applications ranging from 0.07 to 0.15 kg ha"JL produced injury for up to 7 weeks, while bermudagrass treated in August at the same rates recovered within 4 weeks (13). A safener consisting of nitrogen and chelated iron (24.4 kg N ha" + 0.6 kg ha“) has been reported by several researchers (8, 12) to be effective in reducing bentgrass phytotoxicity from fenoxaprop-ethyl. Dernoeden (12) noted 50 the addition of pendimethalin to the above fenoxaprop-ethyl + safener combination to be severely harmful to 'Penncross' creeping bentgrass. Cisar and Jagschitz (4,5) observed that crop oil in combination with fenoxaprop-ethyl slightly increased Kentucky bluegrass injury. Due to the variable results and limited information pertaining to cultivar sensitivity to fenoxaprop-ethyl, the objectives of this research were to evaluate Kentucky bluegrass and creeping bentgrass cultivar phytotoxicity to single fenoxaprop-ethyl applications. 51 MATERIALS AND METHODS Kentugky blueggass studies. Two field studies were conducted during June 1986, and July 1987 at the Hancock Turfgrass Research Center, East Lansing, MI. The Kentucky bluegrass cultivar trial was established in the summer of 1981. The soil type was an Owosso-Marlette sandy loam complex (Fine-loamy, mixed, mesic, Typic Hapludalfs). Soil tests indicated a pH of 7.2 and 7.1 in 1986 and 1987 respectively. Kentucky bluegrass plot dimensions were 1 by 2 meters. On 30 May 1986, MCPP (2-((4-chloro-o- tolyl)oxylpropionic acid) was applied at a rate of 1.4 kg ha'1 to control broadleaf weeds. On 13 July 1987, triclopyr (l(3,5,6-trichloro-2-pyridinyl)oxylacetic acid) + 2,4-D ((2,4-dichlorophenoxy)acetic acid) was applied at a rate of 0.42 + 0.84 kg ha“. Fertilizer was applied at rates of 220 and 137 kg N ha"1 yr"1 in 1986 and 1987 respectively. The area was maintained at a 4.4 cm height, and supplemental irrigation was applied as needed to maintain a quality turf. The experimental design for both species was a split block design with three replications. Each main plot was subdivided into three smaller plots to receive herbicide treatments. Bluegrass plots were treated on 11 June 1986 and 1 July 1987 with fenoxaprop-ethyl at rates of 0.0, 0.14, and 0.28 kg ha“. Bentgrass plots were treated with fenoxaprop-ethyl at rates of 0.00, 0.09, 0.14, and 0.20 kg ha"1 on 1 July 1987, and 0.00, 0.04, 0.07, and 0.09 kg ha'1 52 on 21 August 1987. Treatments were applied with a C02 pressurized sprayer utilizing a four nozzle boom equipped with one 8002 flat fan tip and three plugs. The spray volume was 475 L ha‘l at a pressure of 0.21 MPa. Turfgrass injury was rated visually on a scale of 9 to l, with 9 representing no injury and 1 representing complete turfgrass kill. Ratings below 6.0 were considered unacceptable. Observations were recorded on 18 June, 25 June, 2 July, and 9 July 1986 and also on 8 July, 15 July, 22 July and 29 July 1987. Analysis of variance was performed for each experiment and treatment means were separated using the least significant difference (LSD) method. Creeping bentgrass studies. Two field studies were conducted on 1 July and 21 August, 1987 at the Hancock Turfgrass Research Center, East Lansing, MI. The test site consisted of a bentgrass cultivar trial containing 'Penncross', 'Penneagle', 'Toronto', 'Seaside', 'Emerald', 'Prominent', 'Carmen', 'B853WWK', 'V851WWK', 'V852WWK', 'V858WWK', 'C-18', 'C-28', 'C-38' creeping bentgrass and 'Kingstown' velvet bentgrass. The cultivar trial was established during the summer of 1981 on a modified loamy sand containing 83% sand, 11% silt, and 6% clay. Bentgrass plot dimensions were 2 by 3 meters. Soil tests indicated a pH of 7.3, and fertilizer was applied at 171 kg N ha“ Yr‘l. Supplemental irrigation, fungicides, and insecticides were applied as needed to maintain healthy turf. To control broadleaf weeds, 2,4-D ester (0.56 kg ha") and MCPP (1.1 kg 53 ha") were applied on 26 May 1987, and a package mix of 2,4- D + MCPP + dicamba (0.4 + 0.2 + 0.04 kg ha") was applied on 13 July and 31 August, 1987. The area was managed as a golf green and mowed at 4.8 mm. The cultivar trial received very little traffic throughout 1987. Visual phytotoxicity ratings were taken at weekly intervals, using a 9 to 1 scale as previously described. Analysis of variance was performed for both studies and treatment means were separated using the least significant difference (LSD) method. 54 RESULTS AND DISCUSSION ntu r s stu ies. Untreated plots of 'Fylking', 'Welcome', 'Merion', ’Kenblue', and 'Barblue' received a rating of 8.7 two weeks after treatment in 1986 (Table 2). Untreated 'Enoble' and 'Vantage' plots received 8.3 for this same date, and 8.7 three weeks after treatment for 'Vantage'. In 1987, untreated plots of 'Nugget', 'Harmony', and 'Welcome' received an 8.7 rating three weeks after treatment, while 'Adelphi' received 8.7 for one, two and three weeks after treatment. All other untreated plots received a rating of 9.0 for the dates evaluated. In 1986, fenoxaprop-ethyl at 0.14 kg ha‘1 did not significantly injure 'Enmundi', 'Sydsport', 'Cheri', 'Fylking', 'Birka', 'Vanessa', 'A-34', 'Geromino', ‘Nugget', ’Harmony', 'Welcome', 'Victa', 'Wabash', 'Eclipse', 'Baron', 'Plush', 'Mosa', and 'Bristol' when compared to controls for all evaluation dates. 'Plush', 'Bristol', 'Trenton', 'Bonnieblue', 'Shasta', 'Mystic', 'Columbia', 'Monopoly', 'Majestic', 'Glade', 'Kenblue', 'Ram-l', 'Barblue', 'Touchdown', and 'America' plots treated with 0.28 kg ha"1 of fenoxaprop-ethyl received ratings below 7.0 at two weeks after treatment. At three weeks after treatment, all cultivars except 'Columbia', 'Monopoly', 'Glade', 'Kenblue', 'Barblue', 'Touchdown', and 'America' received ratings higher than 8.0. By four weeks after treatment, all cultivars received a rating of 9.0 55 except 'Mystic' and 'Monopoly' treated with 0.28 kg ha“ and 'Ram-l' at both rates of fenoxaprop-ethyl. 'Ram-l' was the only cultivar that did not show an increase in injury as rates were increased from 0.14 to 0.28 kg ha“. In July of 1987, phytotoxicity did not develop as quickly as in June 1986 but remained approximately one week longer in most cultivars. In 1987, analysis of variance at one week after treatment demonstrated no differences between ! Kentucky bluegrass cultivars receiving the same rate. Only I ’Fylking', 'Geronimo', ’Parade‘, 'Majestic', 'Kenblue', 'Barblue', 'Touchdown', and 'America' had significantly lower ratings than the control plots when treated with 0.14 kg ha" of fenoxaprop-ethyl during the four week evaluation period. Injury of 'Vanessa', 'Nugget', 'Eclipse', 'Plush', 'Bristol', 'Merion', 'Enoble', 'Rugby', 'Vantage', 'Shasta', 'Majestic', 'Glade', 'Ram-l', 'Touchdown', and 'America' was increased dramatically at one week after treatment when the fenoxaprop-ethyl rate was raised to 0.28 kg ha‘l. At two weeks after treatment, all cultivars treated with 0.28 kg ha" received a rating of 7.0 or greater except 'Touchdown' (6.7) and 'America' (6.0). When comparing the two and three week after treatment ratings at 0.28 kg ha“, most cultivars either maintained or recovered from the injury caused by fenoxaprop-ethyl. 'Cello', 'Fylking', 'Victa', 'Wabash', 'Glade', and 'Touchdown' became slightly more injured at three weeks after treatment. At four weeks 56 after treatment, there were no differences between the fenoxaprop-ethyl rates within individual cultivars. In both years, the most phytotoxicity from 0.14 kg ha“ was evident at two weeks after treatment, with all injury judged to be acceptable. In 1986 cultivars treated with 0.28 kg ha"1 fenoxaprop-ethyl in June showed the most severe injury at two weeks after treatment. The July 1987 treatments of the same rate produced injury which extended into the third week after treatment. This could be due to slower turfgrass growth under the higher daily temperatures witnessed in mid to late July of 1987 (Table A1). In the 1986 experiment at 2 weeks after treatment, the newest, exposed leaf of injured Kentucky bluegrass plants became tan colored while still clinging to the next developing leaf. Dernoeden and Fry (10) observed similar results with Kentucky bluegrass. Once these dead leaf blades were mowed, overall appearance of the turfgrass improved dramatically. In 1987, this type of injury symptom was not observed. Creeping bentgrass studies. On 1 July, prior to fenoxaprop-ethyl treatments, all plots received a rating of 8.7 or higher (Table 3). The 0.20 kg ha“1 rate produced significant injury to all bentgrass cultivars when compared to the untreated plots for the 1, 2, and 3 week after treatment evaluations. At 1 week after treatment, injury on 'Penncross', 'Prominent', 'Carmen', 'B853WWK', 'C-l8', and 'C-38' was considered acceptable, while 'Penneagle', 'Toronto', 'Seaside', 'Emerald', 'Kingstown', 'V851WWK', 57 'V852WWK', 'V858WWK', and 'C-28' received ratings below 6.0. 'Toronto' was significantly more sensitive to the 0.20 kg ha'1 rate than other cultivars at 1 week after treatment. This could be due to stripe smut (Untilago striifgrnis (West.) Niessl) found only within the 'Toronto' plots. At 2 weeks after treatment, all cultivars were judged unacceptable except 'Kingstown' and B853WWK'. In Maryland, researchers (11) reported similar unacceptable injury to tee height 'Penncross' creeping bentgrass with fenoxaprop-ethyl (0.17 and 0.28 kg ha‘l). The highest level of injury was apparent during the second week after application for all cultivars except for 'Penneagle' and 'Kingstown'. 'Toronto' plots were severely damaged by this high rate at two weeks after treatment. At three weeks after treatment, most cultivars began recovering except for the vegetatively propagated cultivars 'C-18', 'C-28', and 'C-38' which received ratings of 2.7, 3.0, and 4.3, respectively. Injury of 'Penncross', 'Penneagle', 'Prominent', 'Kingstown', 'Carmen', 'B853WWK', 'V851WWK', and 'V852WWK' was considered acceptable. At four weeks after treatment, 'Penncross', 'Penneagle', 'Seaside', 'Prominent', 'Carmen', 'B853WWK', and 'V852WWK' were not significantly different from the untreated bentgrass plots. 'Toronto', 'Emerald', 'Kingstown', ‘V858WWK', 'C-l8', 'C-28', and 'C-38' received statistically lower ratings than untreated plots. 'Toronto', 'C-18', and 'C-28' were the only cultivars to exhibit unacceptable injury into the fourth week after 58 treatment with the 0.20 kg ha‘1 rate. Turfgrass density of 'Toronto' was severely thinned. At 1 week after treatment, the 0.14 kg ha“ rate of fenoxaprop-ethyl produced injury rated at or below 7.0 for all cultivars, with phytotoxicity considered acceptable for all cultivars except 'Toronto'. At 2 weeks after application, 'Kingstown' showed slight recovery, while injury remained unchanged for 'Penncross', 'Penneagle', 'Seaside', 'Carmen', 'V851WWK', 'V852WWK' and 'C-28'. Objectionable injury was apparent on 'Toronto', 'V858WWK', 'C-18', and 'C-38'. At 3 weeks after treatment, phytotoxicity of most cultivars improved to acceptable levels except for 'Toronto', 'C-18', and 'C-38'. Even though injury was acceptable, all cultivars exhibited significantly lower ratings than the untreated plots at three weeks after treatment. At 4 weeks, 'Toronto', 'Emerald', 'C-28', and 'C-38' remained slightly injured, but 'C-l8' was the only cultivar to receive unacceptable ratings at four weeks after the 0.14 kg ha“ treatment. All other bentgrasses recovered within four weeks when compared to the untreated plots. Injury from the 1 July 0.09 kg ha‘1 fenoxaprop-ethyl treatment was considered acceptable for all cultivars except 'Toronto' and 'C-18' from 1 to 4 weeks after application. Most cultivars received ratings from 7.0 to 7.7 for l, 2, and 3 weeks after treatment. The greatest level of phytotoxicity generally occured during the first week after 59 treatment and remained throughout the second week. Turfgrass recovery was apparent for mOst cultivars by the third week following treatment. By 4 weeks after fenoxaprop-ethyl application, 'Penncross', 'Penneagle', 'Seaside', 'Prominent', 'Kingstown', 'Carmen', 'B853WWK', 'V851WWK', 'V852WWK', 'V858WWK', and 'C-38' recovered, while 'Toronto', 'Emerald', 'C-l8', and 'C-28' received significantly lower but acceptable ratings when compared to untreated plots. In the August experiment, plots received ratings ranging from 7.7 to 9.0 prior to herbicide treatment. The 0.09 kg ha" fenoxaprop-ethyl rate produced greater levels of injury to all cultivars when compared to the same rate applied in July. These lower ratings in the second experiment were most likely caused by the bentgrass plots receiving two treatments within the same season. 'Penncross', '8853WWK', and 'C-38' were the only cultivars that were judged to have an acceptable tolerance to this rate at 2 weeks after treatment. All other cultivars received ratings of 5.7 to 4.3. 'Toronto' and 'C-18' were the most sensitive cultivars to the 0.09 kg ha'1 rate in both July and August studies at the two week evaluation. At four weeks after treatment, analysis of variance demonstrated no differences between 'Penncross', 'Penneagle', 'Toronto', 'Seaside', 'Prominent', 'Kingstown', 'Carmen', 'B853WWK', 'V851WWK', and V852WWK' and their respective control plots. By five weeks after treatment, 60 Phytotoxicity ratings of 'Emerald', 'V858WWK', 'C-18', and 'C-28' were significantly lower than the control plots, but were at or above 7.3. The 0.07 kg ha"1 rate of fenoxaprop-ethyl produced unacceptable injury to 'Toronto', 'Emerald', 'Carmen', 'V851WWK', 'V858WWK', and ‘C-18' creeping bentgrass at 2 weeks after treatment. All bentgrass cultivars were significantly injured when compared to untreated plot ratings except for 'B853WWK'. At 4 weeks after application 'Emerald', 'V858WWK', 'C-18', 'C-28', 'C-38' were still exhibiting lower injury ratings than control plots. At the 5 week evaluation, 'Penncross', 'Penneagle', 'Toronto', 'Seaside', 'Kingstown', 'Carmen', 'B853WWK', 'V851WWK', and 'V852WWK' had recovered. Dernoeden (8) observed similar results on 'Penncross' creeping bentgrass, with unacceptable injury lasting four weeks at rates above 0.06 kg ha’l. The 0.04 kg ha':L rate produced acceptable injury to all cultivars, with evaluations ranging from 8.7 to 6.0 at 2 weeks after treatment. This agreed with Dernoeden's observations with mid June treatments of the same fenoxaprop-ethyl rate on 'Penncross' (8). 'B853WWK' was completely unaffected, while 'Toronto' was the most sensitive to this rate. All treated plots were not different from the untreated plots at 4 weeks after treatment. Overall, 'Penncross', 'Penneagle', 'Carmen', and 'B853WWK' were judged the most tolerant, while 'Toronto' 61 creeping bentgrass was extremely sensitive to fenoxaprop- ethyl which may have been due to infection with stripe smut. Most cultivars recovered to acceptable injury levels at 4 weeks after treatment in both experiments regardless of fenoxaprop-ethyl rate. Future studies are needed to evaluate split applications of low fenoxaprop-ethyl rates on creeping bentgrass golf greens that receive daily traffic. 62 1987 RATINGS HANCOCK TURRGRASS 1986 RATINGSv INJURY RATINGS ROR KENTUCKY BLUEGRASS CULTIVAR STUDY TREATED WITH RENOKAPROP-ETHYL DURING 1986 AND 1987. RESEARCH CENTER, E. LANSING NI. U l. Enmundi TABLE 2: 000 . 999 000 a 0 o 999 0.0.0. 999 0.0.0. 9L0“ 999 030 O O O 909 070 O Q 0 909 070 O O O 909 000 O O 0 999 000 999 070 ... 909 0.nl.0. 989 2. Cello 000 999 0.0.0. 999 0.nl.0. 909 0.0.0. 999 000 . . . 999 000 . . . 999 0.30. ““09 «4.30. 009 3 . Sydsport 000 O O 0 999 000 o O o 999 «4.70. 889 condo. 989 000 o o o 999 000 O O O 999 o.~l.o. 97°“ 030 s s a 909 4. Cheri 0.00. CH9“. J30. 009 al.n4.0. 809 304.0. 089 000 0 . 0 999 nwnwnw 99°“ 0.1-al. 900 000 999 5. Rylking 000 999 070 0 0 . 909 070 0 . 0 909 000 0 999 000 . . . 999 0.0.0. 99.“ 700 s . . 079 070 o . a 919 Birka 6. 0.~l.0. 909 030 o o o 909 000 . 0 . 909 030 O O s 989 000 0 I 0 999 0.0.0. 999 070 979 070 909 7. vanessa 070 I 0 0 989 030 . . o 909 030 989 0.0.0. 9&9 0.nw0. 999 0.nl.0. 9&9 770 . . . 879 7.3nm 8.2“9 8. A-34 000 a o 999 700 o o e 099 030 a o s 989 330 o O o 889 000 as. 0.70. 0 909 030 989 al.00 009 9. Geronimo 0.0.0. 99.“ 077 . . . 900 no.0. 889 0.30. ones 0.n0.0. 999 0.00 999 070 O O 0 919 730 . 0 0 089 0.1 0.2 0.0 10. Nugget 000 0 . . 999 077 . . . 900 730 . . 0 889 770 o o s 009 0.0.0. ““99 0.30. 909 770 . . . 879 0.30. 90°“ 11. Harmony 000 999 70.nl. 090 0.0.0. 909 070 o s s 989 000 s s a 999 Oonloo. 98.“ 037 o a o 970 710 a . . 079 12. Welcome 63 TABLE 2 CONT: 1987 RATINGS 1986 RATINGSv RATE 030 989 000 . . 989 070 O O O 989 0.70. 989 000 . . o 999 000 999 7.1.0. Lang“ 700 889 13. Victa ooo . e 999 070 9'9 1.1.nv I O O 889 070 989 000 . o 999 070 989 330 . . . 879 700 . o 889 14. Bono 000 999 000 O C O ’89 J30 889 700 . . . 899 000 . . . 999 030 989 770 . o o 879 «1.0.0. 889 15. Habash 000 O I O 999 070 989 1.1.nv O o O 879 030 O O O 989 000 . . . 999 nu1.nu 989 nuaanu O O O 979 7.nunu I O 0 Run... 16. Eclipse 070 989 030 O O 989 0.30. 989 730 O O 889 0.0.0. 9&9 0.0.0. 999 030 I O O 979 «I70 0 o O 879 11. Baron 000 999 000 989 000 989 030 O O O 989 000 O O 999 030 O O 989 070 I O O 969 070 O O 989 18. Plush 070 ’89 J30. 889 0.0.nw 989 070 . C C 989 0.0.0. sans nvaanu O I I o.n.o. 7.1.nu . I . nv1.o. 1.nunu O O 0 avg... 19. Hosa 0.0.0. 9&9 700 . . . 889 o.nl.o. 98.9 070 . . . 989 000 O O I 999 0.30. 989 730 O o o 879 330 O 0 0 879 20. Bayside 030 989 000 O O O 989 700 889 000 . o . 999 000 O O O 999 0.00. 0 $99 al.-Jo. 879 370. ULQ“ 21. Herlt 000 999 1.1.nu Queue“ J30. 889 070 o o o 989 000 o o . 999 070 O O 989 000 879 al.-lo. 22. Holiday 000 999 000 . o . 989 700 I O C 889 0.30. 9.6.9 000 . . C 999 070 989 7.1.nu n.£.Q. 70° C O C ova... 23. Bristol 070 989 730 889 700 o o . 889 000 989 000 O O O 999 24. Merion 64 TABLE 2 CONT. 1987 RAIINGS 1986 RAIINGS" 1V T 423! RAE! LR 070 O O O 989 000 O O I 989 0.0.0. 989 070 C O C 989 000 O O . 999 0.30. 989 070 . 0 869 700 O O O 889 25. Trenton 000 O 999 030 o o 989 700 O O O 889 0.30. 989 26. Enable 000 999 737 o . o 888 737 888 737 o o o 888 000 o o o 999 030 O I O 989 1.1.nw B79 300 O o o 889 27. Adolph! 00° 0 o 0 999 0.0.0. 989 301.0. 8L9 000 O O O 999 000 O O O 999 0.30. 989 300 o . o 879 0.30. 87g“ 28. Parade 070 989 000 o o o 989 0.7.nw 97.9 030 . . o 989 000 . . . 999 0.30. 989 0.0.nw 8.~I.9 o.nl.o. 87.“ 29. Rugby 0.70 989 000 C I C 989 000 O I O 989 030 O O O 989 000 o . o 999 al.3nl. 888 703 0 o O 778 370 O 0 O 879 0.1 0.2 0.0 30. vantage 000 999 030 o . . 989 no.0. 889 070 989 000 999 0.30. 989 030 869 030 O o 0.1 31. Bonnieblue 000 O O O 999 070 O . o 979 770. 879 000 0 o 0 989 000 I O O 999 700 O O O 889 nw3o. 869 330 O t I 879 32. Shasta 000 999 000 989 0.0.0. $89 D.Jo. 989 030 C O . 989 aloo.o. 88C“ 300 O I O 869 o.~l.o. 86°“ 33. Mystic 000 999 700 O o 0 889 J30. 8L9 770 o o o 889 000 o o o 999 al.-Jo. 879 0.30. 869 no.0. 88!.9 34. Columbia 070 989 000 989 700 . C . 889 1.7.nu Aviva. 030 989 730. 8L9 070 869 330. 879 35. Monopoly 000 . . . 999 700 o o o 889 300 o o . 889 700 889 000 o o o 999 770 . C O 889 730 O O O 769 030 . . . 879 0.14 0.28 0.00 36. Majestic 65 TABLE 2 C01": 1906 RAIIIGSV 1907 RAIINGS RARE mm 3W” V V 37. Glade 0.14 0.7 0.0 9.0 9.0 0.7 9.0 0.7 9.0 0.20 0.0 6.0 7.7 9.0 0.0 0.0 7.3 0.3 0.00 9.0 9.0 9.0 9.0 9.0 9.0 9.0 9.0 30. Kenblue 0.14 0.3 7.7 9.0 9.0 0.7 0.3 9.0 9.0 0.20 7.0 6.3 7.7 9.0 0.3 0.0 0.0 0.7 0.00 9.0 0.7 9.0 9.0 9.0 9.0 9.0 9.0 39. Ralrl 0.14 0.0 7.3 0.0 0.3 9.0 0.7 0.7 9.0 0.20 0.0 6.7 0.0 0.3 0.3 7.3 7.7 0.7 0.00 9.0 9.0 9.0 9.0 9.0 9.0 9.0 9.0 40. Barblue 0.14 0.3 7.3 0.7 9.0 0.7 0.0 0.0 0.7 0.20 7.7 6.3 7.7 9.0 0.3 7.0 7.0 0.3 0.00 9.0 0.7 9.0 9.0 9.0 9.0 9.0 9.0 41. Touchdown 0.14 0.3 7.7 0.7 9.0 0.7 7.7 0.3 9.0 0.20 7.7 6.3 7.0 9.0 0.0 6.7 6.3 0.3 0.00 9.0 9.0 9.0 9.0 9.0 9.0 9.0 9.0 42. America 0.14 7.0 7.3 0.7 9.0 0.3 7.7 0.3 0.7 0.20 6.3 5.3 7.7 9.0 7.7 6.0 7.7 0.7 0.00 9.0 9.0 9.0 9.0 9.0 9.0 3.0 940 *LSD‘0.05)= 0.7 0.0 0.6 0.2 “.8. 0.6 0.6 0.3 'LSD(0.05)3 0.6 O O ~0 '006 ".3. 0.6 O a O O a z o In vHerbicide treatments applied on 11 June 1906 and 1 July 1987. 'Rated visually on a scale of 9 to l; 9300 Injury, l=Dead. Above 6.0=Acceptable ”VA? = Heeks After fenoxaprop-ethyl Treatment. ”LSD comparing two Kentucky bluegrass cultivars at one fenoxaprop-ethyl rate. 'LSD comparing two fenoxaprop-ethyl rates within one Kentucky bluegrass cultivar. h* 66 BEITCRABS CULTIVAR TRIAL. HANCOCK TUEECEABS RESEARCH CEETER, E. LANSING, HI. (TEEAIHEIT DARE8= 7-1-07, 0-21-07) INJURY EVALUATIOUS OP PEIOXAPEOP-ETHYL APPLIED TO A CREEPING TABLE 3: RATEx (0-21-07) RAIE PHYTOTOX' (7-1-07) '1) PHYTOTOX 1. PEIUCEOSS 3. TOEOITO SEASIDE ‘. 5. EMERALD PROHINENT 6. CARHEH 0053UVK 9. 10. V0519UK 67 TABLE 3 KAI!” PHYTOTOX' (7'1'677 .‘. all" . v. ...' . . . 11. VOSZHVK 0.09 9.0 7.7 7.3 7.3 9.0 0.10 9.0 6.7 6.7 7.7 0.7 0.20 9.0 5.7 5.3 6.3 0.3 0.00 9.0 9.0 9.0 0.7 9.0 12. VOSOUUK 0.09 9.0 7.0 6.7 7.7 9.0 0.10 9.0 6.0 5.3 6.3 6.3 0.20 9.0 5.7 0.7 5.7 0.0 0.00 9.0 9.0 9.0 9.0 9.0 130 C'la 0.09 8.1 7.3 503 5.0 103 0.10 9.0 6.0 5.3 3.3 5.3 0.20 9.0 6.7 0.0 2.7 5.0 0.00 9.0 9.0 9.0 0.7 9.0 10. C-20 0.09 0.7 6.7 7.0 6.7 7.7 0.10 9.0 7.0 6.0 6.0 7.3 0.20 0.7 5.7 0.7 3.0 5.3 0.00 0.7 0.3 0.7 0.3 0.7 150 C‘30 0009 900 800 607 700 8.3 0.10 9.0 6.3 5.0 5.3 7.7 0.20 9.0 7.0 5.0 0.3 7.3 0.00 *LSD (0.05): as 0.9 0.0 1.1 0.0 'LSD (0,05). NS 0.9 0.9 1.0 “0.7 Fenoxaprop-ethyl rate. VAT: weeks After Treatment. Velvet bentgrass cultivar. u e < x e x cultivar. RATE PBYTOTOX (0-21-07) .. .. .l. 0.3 0.0 0.7 0.7 0.3 6.7 0.3 0.7 0.7 5.7 0.3 0.3 0.3 0.3 0.7 0.7 0.7 7.7 0.3 9.0 0.7 5.7 6.3 7.3 0.7 5.7 7.0 7.3 0.7 9.0 0.7 9.0 7.7 7.0 0.3 0.7 7.7 4.3 6.0 7.0 7.7 0.3 6.7 7.7 7.7 0.7 0.7 0.7 0.0 7.7 0.3 0.7 0.0 6.3 7.0 0.0 0.0 5.3 6.0 7.3 0.0 0.7 9.0 9.0 9.0 0.3 0.3 0.7 9.0 7.0 6.3 7.3 0.3 7.0 6.7 0.3 0.0 1.1 1.0 0.9 NS 1.1 1.0 0.0 Phytotoxicity rating scale: 9 To 1, 9=Hea1thy green turfgrass, l=Dead turf. LSD comparing two creeping bentgrass cultivars at one fenoxaprop-ethyl rate. LSD comparing two fenoxaprop-ethyl rates within one creeping bentgrass 10. 11. 12. W Bhowmik, P.C. 1984. New herbicides for crabgrass control in turfgrass. Proc. Northeastern Weed Sci. Soc. 38:282-288. Bhowmik, P.C. 1986. Fenoxaprop-ethyl for postemergence crabgrass control in kentucky bluegrass turf. Hortscience 21(3):457-458. Bingham, S.W. 1985. Fenoxaprop-ethyl for crabgrass and goosegrass control in turfgrasses. Proc. Southern Weed Sci. Soc. 38:101. Cisar, J.L. and J.A. Jagschitz. 1984. Postemergence control of smooth crabgrass in lawn turf. Proc. Northeastern Weed Sci. Soc. 38:276-280. 1984. Turfgrass tolerance to post- and preemergence herbicides. Proc. Northeastern Weed Sci. Soc. 38:298-302. Dernoeden, P.H. 1984. Selective control of tall fescue in a kentucky bluegrass turf with diclofop. Proc. Northeastern Weed Sci. Soc. 38:310-311. 1987. Tolerance of perennial ryegrass and tall fescue seedlings to fenoxaprop. Agron. J. 79: 1035-1037. . 1987. Phytotoxic effects of some herbicides applied to bentgrass. Proc. Northeastern Weed Sci. Soc. 41:224-228. Dernoeden, P.H. and J.D. Fry. 1984. Developing crabgrass and goosegrass control strategies in turf with HOE-A2501. Proc. Northeastern Weed Sci. Soc. 38:289-294. Dernoeden, P.H. and J.D. Fry. 1985. Crabgrass control in turf with fenoxaprop-ethyl, MSMA, tridiphane, and UC 77892. Proc. Northeastern weed Sci. Soc. 39:282-285. Dernoeden, P.H. and J.A. Grande. 1983. Postemergence control of crabgrass in turf with MSMA and HOE-581. Proc. Northeastern Weed Sci. Soc. 37:384-388. Harrison, S.A., and J.A. Grande. 1987. Evaluation of safening agents for fenoxaprop-ethyl. Proc. Northeastern Weed Sci. Soc. 41:223. 68 13. 14. 15. 16. 17. 10. 19. 69 Higgins, J.M., L.E. McCarty, T. Whitwell, and L.C. Miller. 1987. Bentgrass and bermudagrass putting green turf tolerance to postemergence herbicides. Hortscience 22(2):248-250. Lewis, W.H. 1985. Fenoxaprop-ethyl for smooth crabgrass and goosegrass control in turf. Proc. Southern weed Sci. Soc. 38:104. Neal, J.C., A. Senesac, and A. Bing. 1986. Influence of crabgrass growth stage on efficacy of fenoxaprop and tridiphane. Proc. Northeastern Weed Sci. Soc. 40:284- 285. Vitolo, B.B., R.D. Ilnicki, and M.J. Else. 1986. Crabgrass control in rye and bluegrass turf. Proc. Northeastern Weed Sci. Soc. 40:272-275. Watschke, T.L. 1983. Control of smooth crabgrass in turf using pre- and postemergence herbicides. Proc. Northeastern Weed Sci. Soc. 37:389-390. watschke, T.L. 1985. Pre- and postemergence crabgrass control in 1983 and 1984. Proc. Northeastern Weed Sci. Soc. 39:279-281. Watschke, T.L. and 6. Hamilton. 1986. Crabgrass control in 1985. Proc. Northeastern weed Sci. Soc. 40:278-279. CHAPTER 4 EFFICACY AND ANTAGONISM OF FENOXAPROP-ETHYL AND TRIDIPHANE ALONE AND IN COMBINATION WITH BROADLEAF HERBICIDES ABSTRACT Field studies were conducted in 1986 and 1987 to evaluate combinations of fenoxaprop-ethyl (0.20 and 0.40 kg ha’l) and tridiphane (1.1 and 2.2 kg ha“) with broadleaf herbicides to determine if antagonism or synergism was evident. Crabgrass growth stages tested ranged from one to ten tillers. Broadleaf herbicides tested were 2,4-D amine, 2,4-D ester, bromoxynil, dicamba, mecoprop, fluroxypyr, DPX- L5300, chlorflurenol, triclopyr, clopyralid, and a package mixture of 2,4-D amine, mecoprop, and dicamba. Tridiphane (2.2 kg ha“) provided 88% control of five tiller crabgrass in 1986, and 80% control of one tiller plants in 1987. A11 broadleaf herbicides tested were not antagonistic with tridiphane. Fenoxaprop-ethyl produced greater than 90% control of one to five tiller plants during both years tested. Combinations of fenoxaprop-ethyl with 2,4-D amine, 2,4-D ester, clopyralid, bromoxynil, and the package mixture 2,4-D amine, mecoprop, and dicamba produced antagonism. Fenoxaprop-ethyl combined with fluroxypyr (0.40 + 0.56 kg ha“) provided 100% control of five to ten tiller crabgrass, 70 indicating synergism. 71 72 INTRODUCTION When two or more herbicides are combined in a tank mix, synergistic or antagonistic interactions can occur. Anderson (1) stated that a mixture is said to be antagonistic when the expected response induced by the herbicide combination is less than the expected sum total of the responses induced by each herbicide applied alone. Synergism occurs when the expected response induced by the herbicide combination is greater than the expected sum total of the responses induced by each herbicide applied alone (1). In row crop situations, researchers have reported antagonism with various herbicide tank mixtures or sequential applications. Godley and Kitchen (4) reported that acifluorfen (5-[2-chloro-4-trifluoromethyl)phenoxyl-Z- nitrobenzoic acid) at 0.4 kg ha‘1 applied in combination with, or one to three days prior to a fluazifop ((1)-2-[4- II5-(trifluoromethyl)-2-pyridinylloxylphenoxylpropanoic acid) treatment at 0.4 kg ha" greatly reduced crabgrass control when compared to fluazifop alone. They also noted that the antagonism was not apparent when acifluorfen was applied at l, 3, or 5 days after the fluazifop treatment, while the degree of antagonism with the tank mixture of fluazifop and acifluorfen was dependent upon climatic conditions. Whitwell et. a1 (15) reported acifluorfen to be highly antagonistic to the postemergence johnsongrass 73 herbicides sethoxydim and difenopenten (4-[4-[4- (trifluoromethyl)phenoxylphenoxy)-2-pentenoic acid). Similiarly, Rhodes and Cable (11) found bentazon (3- isopropyl-lfl-2,1,3-benzothiadiazin-4(Bfl)-one2,2-dioxide) to dramatically suppress the absorption of sethoxydim within goosegrass when applied in a mixture. Researchers have reported antagonistic properties between diclofop-methyl (methyl 2-[4(2',4'- dichlorophenoxy)phenoxylpropanoate) and 2,4-0, where the injury symptoms from diclofop-methyl were nullified on wild oat (Aygna_§§§ga L.) (2,5). Todd and Stobbe (13) also reported 2,4-D to be antagonistic to diclofop-methyl in controlling wild oat in a greenhouse situation. They determined that the antagonism caused by 2,4-D reduced the movement of the free acid diclofop to meristematic areas (13). Shimabukuro et. a1 (12) reported that reciprocal antagonism in corn (Ze§_mays L.)and soybeans (glycine max L.) existed between diclofop-methyl and 2,4-D and was dependent upon the concentration of the other herbicide. In Alberta, Canada, 2,4-D has been shown to be antagonistic to diclofop and also flamprop (N-benzoyl-n-(3-chloro-4- fluorophenyl)-DL-a1anine) for wild oat control (8,9). Another phenoxy herbicide, MCPA, when tank mixed with diclofop, has been shown to inhibit herbicidal transport within wild oat (10). Qureshi and vandenBorn attributed this problem to a formulation incompatability when both are combined (10). 74 Antagonism has also been reported with annual grass and broadleaf weed herbicides used in turfgrass situations. Johnson (6) reported a reduction in preemergence crabgrass control when combining bensulide (11 kg ha") with 2,4-D, mecoprop, and dicamba (1.1 + 0.6 + 0.11 kg ha") as compared to bensulide alone. Freeborg and Daniel (3) reported a reduction in postemergence crabgrass control with fenoxaprop-ethyl (0.28 kg ha") tank mixed with 2,4-D plus mecoprop plus dicamba (0.43 + 0.22 + 0.04 kg ha“) when compared to fenoxaprop-ethyl alone. Watschke and Hamilton (14) also noted similar results and showed that by increasing the fenoxaprop-ethyl rate in the combination, crabgrass control also increased. Due to the limited information pertaining to antagonism with postemergence graminicides and various broadleaf herbicides in turfgrass, the objectives of this research were to determine which broadleaf herbicides are antagonistic or synergistic to either fenoxaprop-ethyl or tridiphane, and also to examine various grass herbicide rates which could affect antagonism. 75 MATERIALS AND METHODS Four field experiments were conducted during the summer months of 1986 and 1987 to determine if the action of fenoxaprop-ethyl was antagonized by broadleaf herbicides. Greenhouse studies on the antagonism of 2,4-D ester in combination with fenoxaprop-ethyl were conducted in 1988. General procedures for field experiments. The experimental design consisted of a randomized complete block with three replications. Plot dimensions were 1.2 meters by 1.8 meters. All applications were applied with a C02 pressurized sprayer utilizing a four nozzle boom equipped with 8002 flat fan nozzles. The spray volume was 475 L ha"1 at a pressure of 0.21 MPa. Plots were visually evaluated for percent groundcover of crabgrass and all data was converted to percent control. Analysis of variance was performed for each experiment and treatment means were separated using the least significant difference technique. Field study 1. On 22 July 1986, a study was performed on an unirrigated site in Okemos, MI consisting of a mature Kentucky bluegrass and perennial ryegrass (Lolium perenng L.) turf. The soil type was a Marlette loam (Fine-loamy, mixed, mesic, Glossoboric Hapludalfs). On 1 July 1986, the site was core-aerified with a Ryanl (OMC Lincoln, Lincoln, NE) Greensaire' to alleviate compaction and stimulate crabgrass germination, and fertilized at a rate of 27 kg N ha‘l. At the time of application, a natural infestation of 76 smooth crabgrass was at a two to four leaf, five tiller growth stage, with an average 45% groundcover within all plots. The area was maintained at a 5.0 cm height. Fenoxaprop-ethyl at 0.00, 0.20, and 0.40 kg ha’1 along with tridiphane at 0.00, 1.12 and 2.24 kg ha“; were tested alone and in combination with 2,4-D amine (alkanolamine salts (of the ethanol isopropanol series) of (2,4- dichlorophenoxy)acetic acid) at 1.12 kg ha'l, dicamba (3,6- dichloro-Z-methoxybenzoic acid) at 0.56 kg ha", fluroxypyr (4-Amino-3,S-dichloro-G-fluoro-Z-pyridyloxyacetic acid methyl heptylester) at 0.56 kg ha", bromoxynil (3,5- dibromo-4-hydroxybenzonitri1e) at 0.28 kg ha‘l, and mecoprop (((:)-2-(4-chloro-2-methylphenoxy)propanoic acid)potassium salt) at 1.12 kg ha‘l. Combinations of fenoxaprop-ethyl at 0.20 kg ha'1 with bromoxynil + 2,4-D amine (0.28 + 0.28 kg ha-l), 2,4-DP ((2-(2,4-dichlorophenoxy)propionic acid) butoxyethyl ester) at 1.12 kg ha“, 2,4-D amine (dimethylamine salt of(2,4-dichlorophenoxy) acetic acid) + mecoprop (dimethylamine salt) + dicamba (1.1 + 0.56 + 0.11 kg ha"), triclopyr ester (([(3,5,6-trichloro-2- pyridinyl)oxy]acetic acid)butoxyethy1 ester) + 2,4-D ester (2,4-dichlorophenoxyacetic acid, butoxyethyl ester) (0.42 + 0.84 kg ha“), and DPX-M6316 (methyl 3-[[(4-methoxy-6- methyl-1,3,5-triazin-2-yl aminocarbonyllaminosulfonyll-Z- thiophenecarboxylate (8 g ha'l) were also included. Eielg_§§udy_2. On 20 August 1986, the identical treatment list as previously described was performed at the 77 Hancock Turfgrass Research Center, in East Lansing, MI on an irrigated annual bluegrass (Egg ennui var. renting (Hauskns) Timm.) turf maintained at 1.3 cm. The area was established by seed in the summer of 1981. The soil type was a Owosso- Marlette sandy loam complex (Fine-loamy, mixed, mesic, Typic Hapludalfs). Soil tests indicated a pH of 7.5, and fertilizer was applied at a rate of 484 kg N ha" yr'l. On 18 June 1986, the area was verticut in two directions utilizing a Ryan Ren-O-Thin' to a depth of 0.6 cm and overseeded with smooth crabgrass at a rate of 30 kg ha'1 to enhance the natural population. At time of application, smooth crabgrass ranged in size from two leaf to two tillers, with approximately 5 to 15% crabgrass groundcover throughout the area. In addition to percent groundcover ratings, visual annual bluegrass injury was recorded using a rating scale of 9 to l, in which 9 represents no injury and 1 represents complete turfgrass kill. Ratings below 6.0 were considered unacceptable. Field study 3: 0n 4 August 1987, an experiment was conducted at Clio Country Club, in Clio, MI on a mature stand of Kentucky bluegrass/perennial ryegrass turf. The soil type was a Ceresco fine sandy loam (Coarse—loamy, mixed mesic Aquic Fluventic Hapludolls). The area was maintained at 5.0 cm and irrigated daily. Fertilizer was applied at a rate of 118 kg N ha"1 yr". At time of application, the smooth crabgrass growth stage approached four leaves and 78 five to ten tillers. The average smooth crabgrass groundcover within plots was near 70 percent. Treatments included tridiphane (0.00, 1.12, and 2.24 kg ha“) alone and in combination with 2,4-D ester (1.12 kg ha“1), dicamba (0.56 kg ha“), fluroxypyr (0.56 kg ha“), bromoxynil (0.28 kg ha“), and mecoprop (1.12 kg ha'l). Fenoxaprop-ethyl (0.00, 0.20, and 0.40 kg ha") was tested alone and tank mixed with the identical broadleaf herbicides listed above plus triclopyr at 0.56 kg ha“, DPX-L5300 (Methyl 2-[[I[N-(4-methoxy-6-methyl-l,3,5-triazin-2- yl)methy1amino]carbony1laminolsulfonyllbenzoate) at 0.84 kg ha‘l, clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) at 0.28 kg ha‘l, and chlorflurenol (methyl 2-chloro-9- hydroxyfluorene-9-carboxylate) at 0.14 kg ha“1. Fenoxaprop- ethyl (0.20 kg ha") was also combined with bromoxynil + 2,4-D ester (1.12 + 0.28 kg ha'l), triclopyr ester + 2,4-D ester (0.42 + 0.84 kg ha"), 2,4-D + dicamba + mecoprop (1.12 + 0.60 + 0.10 kg ha"), and 2,4-DP (1.12 kg ha"). E_g1d¥§tudy 4: 0n 5 August 1987, the identical treatments as described in the third field study were applied to a six year old Kentucky bluegrass blend at the Hancock Turfgrass Research Center, in East Lansing, MI. The soil type consisted of an Owosso-Marlette sandy loam (Fine- loamy, mixed, mesic, Typic Hapludalfs). The site was irrigated and mowed regularly at 3.8 cm. Soil tests indicated a pH of 7.1, and fertilizer was applied at a rate of 122 kg N ha" yr“. 0n 7 July 1987, the turfgrass was 79 scalped to a height of 2.5 cm and verticut in four directions with a Ryan Ren-O-Thin‘ to a depth of 1.3 cm. The lifted thatch was removed and large crabgrass was overseeded at a rate of 40 kg ha'l. The area was mowed several times per week for 2 weeks at 2.5 cm to allow light to penetrate for adequate crabgrass germination. Supplemental irrigation was applied daily for several weeks to hasten crabgrass germination. Once adequate crabgrass pressure was obtained, the cutting height was raised to 3.8 cm. At time of herbicide applications, plots averaged 10 to 12 percent crabgrass groundcover, with a three leaf to one tiller growth stage. In addition to percent groundcover ratings, visual injury ratings of the Kentucky bluegrass were recorded at 2-week intervals utilizing a 9 to 1 scale as described previously in field study 2. 80 RESULTS AND DISCUSSION Field studies. Fenoxaprop-ethyl at both rates (0.20 and 0.40 kg ha‘l) provided greater than 90% control of one to five tiller crabgrass during 1986 and 1987. Fenoxaprop- ethyl applied alone at the above rates provided 64% and 60% control of five to ten tiller plants at four weeks after treatment in 1987. Tridiphane at 1.1 kg ha“ produced 81% control of two tiller crabgrass in 1986 (Table 4). During the same season, the identical rate provided very little control (11%) of five tiller plants (Table 5). Increasing the rate of tridiphane to 2.2 kg ha“ dramatically improved crabgrass control results of two tiller (98%) and five tiller plants (88%). Tridiphane applied at 1.1 kg ha"L in 1987 resulted in poor control of three leaf to one tiller crabgrass. Increasing the rate to 2.2 kg ha‘1 provided 80% control (Table 6). At Clio Country Club, both neither tridiphane rate (1.1 or 2.2 kg ha'l) provided control of five to ten tiller plants (Table 7). In 1986, fluroxypyr (0.56 kg ha“) applied alone gave 89% control of two tiller crabgrass, and 58% control of five tiller plants at 4 weeks after treatment. All other broadleaf herbicides lacked postemergence crabgrass activity. Combinations of 2,4-D amine, 2,4-D ester, dicamba, and mecoprop with tridiphane at 1.1 and 2.2 kg ha'1 were not considered antagonistic. In 1986, bromoxynil tank mixed 81 with tridiphane (1.1 + 2.2 kg ha‘l) significantly reduced percent control of five tiller crabgrass when compared to tridiphane alone at 8 weeks after treatment. In 1987, the identical combination also reduced one tiller crabgrass control to 17% compared to 80% with tridiphane alone. At Clio Country club, tridiphane plus bromoxynil at both rates (1.1 + 1.1 and 2.2 + 1.1 kg ha") significantly increased the percent control of five to ten tiller crabgrass when compared to tridiphane alone. Tridiphane in combination with fluroxypyr (1.1 + 0.56 kg ha“) significantly improved control of five tiller crabgrass when compared to tridiphane alone at 2, 4, and 8 weeks after treatment during 1986. The identical treatment also improved control of one tiller crabgrass in 1987. Antagonism was not observed with tank mixes of fenoxaprop-ethyl (0.20 or 0.40 kg ha") and chlorflurenol, dicamba, fluroxypyr, mecoprop, or triclopyr. Fenoxaprop- ethyl in combination with 2,4-D amine (0.20 + 1.1 kg ha“) produced 43% control of five tiller crabgrass (Table 5), compared to 100% control with fenoxaprop-ethyl alone. When the rate of fenoxaprop-ethyl was increased (0.40 kg ha'l) in the combination, percent crabgrass control improved to 77%, but was still considered antagonistic. When fenoxaprop- ethyl and 2,4-D amine (0.20 + 1.1 kg ha'l) were applied to two tiller crabgrass at the Hancock Turfgrass Research Center (HTRC), similar results were observed. The combination provided 67% control compared to 100% control 82 from fenoxaprop-ethyl alone, indicating antagonism. When fenoxaprop-ethyl was increased to 0.40 kg ha"1 in the combination, the antagonism was overcome, resulting in 95% control. Even though 2,4-D amine is antagonistic to fenoxaprop-ethyl, the increased rate of fenoxaprop-ethyl was enough to control the smaller crabgrass growth stage. It is possible that 2,4-D inhibited the movement of the free acid fenoxaprop within the plant, similar to results of diclofop and 2,4-D antagonism by Todd and Stobbe (13). In 1987, 2,4-D ester was tested in combination with fenoxaprOp-ethyl. At Clio Country Club, this combination also produced antagonism, resulting in extremely poor control of five to ten tiller crabgrass at both fenoxaprop- ethyl rates (Table 7). Fenoxaprop-ethyl and 2,4-D ester (0.2 + 1.1 kg ha'l) tested at the HTRC also provided poor control (40%) of one tiller crabgrass when compared to 93% control with fenoxaprop-ethyl alone. Similar to 1986 results with fenoxaprop-ethyl and 2,4-D amine, by increasing the rate of fenoxaprop-ethyl to 0.40 kg ha'1 with 2,4-D ester, excellent control was achieved due to the small crabgrass growth stage present. Fenoxaprop-ethyl at 0.20 kg ha‘1 combined with a package mixture of 2,4-D amine, mecoprop amine, and dicamba (1.1 + 0.56 + 0.11 kg ha‘l) also produced noticeable antagonism when applied to one tiller crabgrass. By increasing the fenoxaprop-ethyl rate to 0.40 kg ha’l, 91% control was achieved. At Clio, the low rate of fenoxaprop- 83 ethyl with 2,4-D + mecoprop + dicamba gave poor control of five to ten tiller plants. Increasing fenoxaprop-ethyl to 0.40 kg ha" in the combination improved control to 37%. Combinations of fenoxaprop-ethyl at 0.20 and 0.40 kg ha"-‘L with DPX-L5300 (0.84 kg ha‘l) produced significant antagonism of both one tiller and five to ten tiller crabgrass. The extremely high DPX-L5300 rate was applied by mistake, but revealed interesting results. DPX-L5300 applied alone produced significant injury to the Kentucky bluegrass (Table 6). When the higher rate of fenoxaprop- ethyl was combined with DPX-L5300, fenoxaprop-ethyl reduced the amount of turf injury caused by DPX-L5300, indicating reciprocal antagonism between these two compounds. Fenoxaprop-ethyl combined with clopyralid (0.20 + 0.28 kg ha‘l) provided poor control (21%) of five to ten tiller crabgrass. Antagonism was eliminated when the rate of fenoxaprop-ethyl was increased to 0.40 kg ha“, improving crabgrass control to 71%. In 1987, a combination of fenoxaprop-ethyl and bromoxynil (0.2 + 1.1 kg ha") provided poor control (30%) of one tiller crabgrass, unlike 1986 results. Fenoxaprop- ethyl at both rates tank mixed with bromoxynil also reduced control of five to ten tiller plants. Bromoxynil severely damaged the crabgrass leaf blades within 24 hours. This leaf necrosis restricted absorption and translocation of fenoxaprop-ethyl into the crabgrass plant, reducing percent control. These results were not observed in 1986, 84 warranting further research with various bromoxynil formulations and fenoxaprop-ethyl. As a general recommendation, all formulations of 2,4-D should not be tank mixed with fenoxaprop-ethyl. Tank mixing triclopyr ester with fenoxaprop-ethyl (0.56 + 0.20 kg ha") resulted in lower crabgrass control as compared to fenoxaprop-ethyl alone,regardless of plant stage. This combination was not considered antagonistic, yet there exists a trend toward antagonism. Therefore, a tank mixture of triclopyr ester and fenoxaprop-ethyl is not recommended. Future herbicide studies are needed to evaluate triclopyr amine and fenoxaprop-ethyl combinations. When attempting to control one to two tiller crabgrass along with broadleaf weeds, tank mixtures of fenoxaprop- ethyl with dicamba, fluroxypyr, mecoprop, chlorflurenol, or clopyralid were considered acceptable. After crabgrass reaches a five to ten tiller growth stage, only fenoxaprop- ethyl with mecoprop, and chlorflurenol provided comparable control to fenoxaprop-ethyl applied alone. The addition of fluroxypyr (0.56 kg ha’l) with fenoxaprop-ethyl (0.2 kg ha'l) improved control to 80% as compared to 64% with fenoxaprop-ethyl alone. When fenoxaprop-ethyl was increased to 0.40 kg ha‘1 in the combination, 100% crabgrass control was achieved, indicating synergism. This combination proved to be effective in eliminating crabgrass once considered too large to control. Future experiments with various rates of fenoxaprop-ethyl and fluroxypyr could provide valuable 85 postemergence crabgrass control information for the turfgrass industry. 86 TABLE 4: GRASS AND BROADLEAP CONTROL WITH POSTENERGENCE HEREICIDE CONDINATIONS APPLIED TO POA ANNUA L. (HANCOCK TURPGRASS RESEARCH CENTER, E. LANSING, HI. TREATNENT DATE 8 0-20-06). (DIGITARIA GROWTH STAGE8 2 LEAP TO 2 TILLERS.) \ CONTROL POA ANNUA RATE CRASGRASS’ PHYTDTOX' ' IKfiLflAL 2881.1!AI___Z!AI_1!81. l. FENOX 4 BROH 4 2,4-D A .20 4 1.1 4 .28 87 93 9.0 9.0 2. FENOX 4 TRICLOPYR 4 2,4-D E .20 4 .42 4 .84 82 06 9.0 9.0 3. FIND! 4 2,4-D A 4 MCPP 4 DIC .20 4 1.1 4 56 4 .11 65 50 9.0 9.0 4. FENDX 4 2,4-DP .20 4 1.1 93 100 8.7 9.0 5. FENOX 4 DPX-H63l6 .20 4 (8 q/ha) 83 97 9.0 9.0 6. FENOXAPROP-ETHYL .20 91 100 9.0 9.0 7. FENOX 4 2,4-0 AHINE .20 4 l l 65 67 9.0 9.0 8. FENDX 4 DICAHBA .20 4 .56 100 100 8.7 8.7 9. FENOX 4 FLUROXTPYR .20 4 .56 96 100 8.0 9.0 10. FENOX 4 BROHOXTNIL .20 4 1 l 96 100 9.0 9.0 11. FENOX 4 HCPP .20 4 1.1 98 98 9.0 9.0 12. FENOXAPROP-ETHYL .40 93 100 8.7 9.0 13. FENOX 4 2,4-D AHINE .40 4 i l 91 95 8.7 9.0 14. Pamox 4 DICAHBA .40 4 56 100 100 9.0 9.0 15. FENOX 4 FLUROXYPYR .40 4 56 100 100 8.0 8.7 16. FENOX 4 BROHOXYNIL .40 4 1.1 93 100 8.3 9.0 17. FENOX 4 MCPP .40 4 1 1 98 100 8.3 9.0 18. TRIDIPHANE 1.1 21 81 7.0 7.7 19. TRIP 4 2,4-D AHINE 1.1 4 1.1 51 93 7.7 6.3 20. TRID 4 DICAHBA 1.1 4 .56 38 72 7.3 7.0 21. TRID 4 FLURDXYPYR 1.1 4 .56 46 93 6.0 5.7 22. TRID 4 BROHOXYNIL 1.1 4 1.1 ' 68 91 7.7 6.7 23. TRID 4 MCPP 1.1 4 1.1 60 88 8.0 7.7 24. TRIDIPHANE 2.2 62 98 6.3 4.7 25. TRID 4 2,4-D AHINE 2.2 4 1.1 59 93 6.7 4.7 26. TRID 4 DICAHBA 2.2 4 .56 39 84 7.0 5.0 27. TRID 4 FLUROXYPYR 2.2 4 .56 66 95 5.3 3.3 28. T810 4 BRDHOXYNIL 2.2 4 1.1 78 96 6.7 5.0 29. TRID 4 MCPP 2.2 4 1.1 20 84 7.7 6.7 30. 2,4-D AHINE 1.1 7 10 8.7 9.0 31. DICAHBA .56 8 31 9.0 9.0 32. FLUROXYPYR .56 84 89 9.0 9.0 33. BROHOXYNIL 1.1 10 20 9.0 9.0 34. MCPP 1.1 0 22 9.0 9.0 1§l_£QHIEQL "' 0 0 9-0 941 LSD(0.05)= 22 18 0.7 0.8 V The abbreviated treatments are as follows: FENDX=fenoxaprop~ethyl, BROHsbromoxynil, 2,4-D E= 2,4-D ester, 2,4-D A=2,4-D amine, HCPP=mecoprop, Dic=dicamba, TRID=tridiphane. ‘ Percent crabgrass control scale: 0 to 100%, 100=dead crabgrass, 0=unaffected. ° Percent Poa annua L. phytotoxicity scale = 9 to l, 9=Healthy turfgrass, l=Dead turfgrass. 87 TABLE 5: GRASS AND BROADLEAP CONTROL WITH POSTEMERGENCE HERBICIDE COMBINATIONS APPLIED TO KENTUCKY BLUEGRASS. (FAIRWAY DRIVING RANGE, OKEMOS, MI). TREATMENT DATE = 7-22-06). (DIGITARIA GROWTH STAGE 3 3 LEAP, 5 TILLER.) PERCENT CONTROL RATE OF CRABGRASS' V (KQLflAl_, ZNAI jflfil §WAI 0!}: 1. RENO! 4 BROM 4 2,4-0 A .20 4 1.1 4 .20 50 09 77 52 2. FENOX 4 TRICLOPYR 4 2,4-0 E .20 4 .42 4 .04 60 03 50 47 3. EENOX 4 2,4-0 A 4 MCPP 4 DIC .20 4 1.1 4 56 4 .11 40 0 0 0 4. FENOX 4 2,4-DP .20 4 1.1 69 07 06 77 5. PENOX 4 DPX-M6316 .20 4 (0 g/ha) 09 100 100 100 6. FENOXAPROP-ETHYL .20 93 100 96 99 7. PENOX 4 2,4-0 AMINE .20 4 1.1 46 43 0 6 0. EENOX 4 DICAMBA .20 4 .56 09 95 90 99 9. RENO! 4 PLUROXYPYR .20 4 .56 99 100 100 100 10. PENOX 4 BROMOXYNIL .20 4 1.1 97 96 97 100 11. FENOX 4 MCPP .20 4 1.1 07 100 95 91 12. FENOKAPROP-ETHYL .40 100 100 100 100 13. FENOX 4 2,4-0 AMINE .40 4 1.1 73 77 40 13 14. FENOX 4 DICAMBA .40 4 .56 96 100 100 100 15. RENO! 4 PLUROXYPYR .40 4 .56 100 100 100 100 16. FENOX 4 BROMOXYNIL .40 4 1.1 90 100 99 99 17. RENO! 4 MCPP .40 4 1.1 100 100 100 100 10. TRIDIPHANE 1.1 13 37 63 11 19. TRID 4 2,4-0 AMINE 1.1 4 1 1 12 33 40 33 20. TRID 4 DICAMBA 1.1 4 56 ' 33 54 33 16 21. TRID 4 FLUROXYPYR 1.1 4 56 50 71 67 52 22. TRID 4 BROMOXYNIL 1.1 4 1 1 13 21 16 15 23. TRID 4 MCPP 1.1 4 1 1 37 53 20 20 24. TRIDIPHANE 2.2 20 72 03 00 25. TRID 4 2,4-0 AMINE 2.2 4 1 1 39 70 70 50 26. TRID 4 DICAMBA 2.2 4 56 21 71 00 S4 27. TRID 4 FLUROXYPYR 2.2 4 56 S4 79 02 95 20. TRID 4 BROMOXYNIL 2.2 4 1 1 57 00 75 51 29. TRID 4 MCPP 2.2 4 l l 54 79 04 02 30. 2,4-D AMINE 1.1 30 19 0 0 31. DICAMBA .56 30 15 0 0 32. FLUROXYPYR .56 26 50 13 0 33. SROMOXYNIL 1.1 4 0 0 0 34. MCPP 1.1 0 0 0 0 W '" 15 0 3 LL LSD(0.05)= 35 25 34 27 V The abbreviated treatments are as follows: FENOX=fenoxaprop-ethyl, 8ROH=bromoxynil, 2,4-D E! 2,4-D ester, 2,4-D A=2,4-D amine, HCPP=mecoprop, DIC=dicamba, TRID=tridiphane. ” Percent crabgrass control scale: 0 to 100‘, 100=dead crabgrass, 0=unaffected. 88 TAIL: 6: GRASS AND BROADLIAP CONTROL WITH POSTTHIROUICI HERIICIDE CONIINATIOIS APPLITD TO A KENTUCKY BLUIORASS 80880. (HTRC. E. LANSING. Hi 8-5-87). (DIGITARIA GROWTH STAB! s 3 LEAP TO 1 TILLRR.) \ CONTROL K8 RAT! or CRABGRASS' PHYTOTOT' 4K 2 1. PRIOXAPROP-RTRTL (FIND!) .20 92 93 88 7.7 9.0 2. 8880! 4 2.4-0 SSTIR (2.4-0 8) .20 4 1.1 40 4o 33 8.7 9.0 3. 8:00! 4 OICAHIA (01C) .20 4 .56 9o 9o 90 8.7 9.0 4. PRNOX 4 PLUROXTPTR .20 4 .56 100 100 94 8.0 9.0 5. FIND! 4 BROHOXYNIL .20 4 1.1 45 30 9 8.7 9.0 6. FIND! 4 HRCOPROP (HCPP) .20 4 1.1 92 95 97 8.3 9.0 7. FIND! 4 OPx-LSJOO .20 4 .84 0 0 0 6.3 6.0 8. FIND! 4 CHLORPLURTNOL .20 4 .14 87 93 84 8.3 9.0 9. 8880: 4 TRICLOPYR .20 4 .56 100 80 48 8.7 8.7 10. FIND! 4 CLOPTRALID .20 4 .28 86 98 96 8.0 9.0 11. PING: 4 2.4-0 A 4 MCPP 4 DIC .20 4 1.1 4 .56 4 .11 46 54 24 9.0 9.0 12. RENO: 4 2.4-OP .20 4 1.1 85 89 82 8.0 8.3 13. FIND! 4 BROH 4 2.4-0 8 .20 4 1.1 4 .28 59 32 32 8.7 9.0 14. £280: 4 TRICLOPYR 4 2.4-0 8 .20 4 .42 4 .84 92 87 65 8.0 9.0 15. FENOXAPROP-ETHYL .40 97 97 97 6.3 8.0 16. FRNOX 4 2.4-0 ESTRR .40 4 1.1 86 100 90 7.0 8.3 17. RENO! 4 DICAHBA .40 4 .56 95 97 95 8.0 9.0 18. RENO! 4 PLUROKYPYR .40 4 56 100 100 88 6.3 7.3 19. RENO! 4 BRONOXYNIL .40 4 1.1 92 93 79 7.0 8.7 20. P880: 4 MCPP .40 4 1.1 96 100 80 7.3 8.3 21. 8280! 4 OPx-LSJOO .40 4 .84 o 15 13 7.0 8.3 22. 8880: 4 CHLORPLURENOL .40 4 .14 100 100 100 7.3 8.0 23. FIND! 4 TRICLOPYR 40 4 .56 100 100 98 7.7 8.3 24. POND! 4 CLOPYRALID 40 4 28 93 96 91 6.3 8.7 25. PSNOX 4 2.4-0 A 4 MCPP 4 DIC .40 4 1.1 4 .56 4 ll 95 91 82 8.3 8.7 26. TRIOIPHANR (TRID) 1.1 0 17 0 9.0 9.0 27. TRIO 4 2.4-0 ESTER 1.1 4 1.1 38 37 13 8.7 9.0 28. TRID 4 OICANOA 1.1 4 .56 0 24 1 9.0 9.0 29. TRID 4 FLUROXYPYR 1.1 4 .56 45 56 75 8.7 9.0 30. TRID 4 BROHOXYNIL 1.1 4 1.1 8 8 0 9.0 9.0 31. TRIO 4 MCPP 1.1 4 1.1 24 7o 53 8.7 9.0 32. TRIDIPHANR 2.2 19 80 80 9.0 9.0 33. TRID 4 2.4-0 ESTER 2.2 4 1.1 43 92 67 8.7 9.0 34. TRID 4 DICAHSA 2.2 4 56 17 65 32 9.0 9.0 35. TRID 4 FLUROXYPYR 2.2 4 56 43 88 83 9.0 9.0 36. TRID 4 BROHOXYNIL 2.2 4 1.1 28 10 17 9.0 9.0 37. TRID 4 MCPP 2.2 4 1.1 15 83 84 8.7 9.0 38. 2.4-0 ESTER 1.1 o o 0 8.7 9.0 39. OICAHOA .56 o o 0 9.0 9.0 40. FLUROXYPYR .56 10 3 14 8.7 9.0 41. SROHOXYNIL 1.1 8 0 8 9.0 9.0 42. MCPP 1.1 o o 0 9.0 9.0 43. OPx-LSJOO .84 o o O 6.7 6.0 44. CHLORFLURENOL .14 0 O 0 9.0 9.0 45. TRICLOPYR .56 0 0 0 9.0 9.0 46. CLOPYRALIO .28 o o 0 8.7 9.0 47. 2.4-0 8 4 MCPP 4 DICAHSA 1.1 4 .56 4 .11 0 0 0 9.0 9.0 11L_gguTROL --- 0 o 0 8.7 9.0 05040.05)- 25 24 31 1.0 1.0 Rating scale s 9 to l. 9=dark green turf. lsdead turf. Percent crabgrass control scale: 0 to 1008. lOOsdead crabgrass. 0=unaffected. Phytotoxicity to Kentucky bluegrass caused by the herbicide treatments. 1984 formulation of fenoxaprop-ethyl. (All other fenoxaprop-ethyl treatments were 1986 formulations.) 89 TABLE 7: GRASS AND BROADLEAP CONTROL WITH POSTENERGENCE HERBICIDE CONEINATIONS APPLIED TO A KENTUCKY BLUEGRASS/PERENNIAL RYEGRASS TURF. (CLIO COUNTRY CLUB. CLIO. HI. TREATMENT DATE 3 8-4-87). (DIGITARIA GROWTH STAGE = 4 LEAP. 5 TO 10 TILLERS). \ CONTROL RATE OP CRAEGRASS' IBEATNINISZCO 1502881 ZEAI__;uuuL 1. PENOXAPROP-ETNYL (8880!) .20 21 64 2. PENOX 4 2.4-0 ESTER (2.4-0 E) .20 4 1.1 2 2 3. PENOX 4 OICANBA .20 4 .56 22 40 4. FENOX 4 PLUROXTPYR .20 4 56 S9 80 5. RENO! 4 ERONOXTNIL (BROH) 20 4 1.1 42 28 6. PENOX 4 MCPP .20 4 1.1 14 56 7. FENOX 4 DPx-LSJOO .20 4 .84 11 6 8. PENOX 4 CHLORPLURENOL 20 4 .14 31 52 9. PENOX 4 TRICLOPTR AMINE 20 4 .56 11 34 10. PENOX 4 CLOPTRALID .20 4 .28 0 21 11. PENOX 4 2.4-0 A 4 MCPP 4 01C 20 4 1.1 .56 4 .11 3 1 12. FENOX 4 2.4-DP .20 4 1.1 18 31 13. EENOX 4 BRON 4 2.4-0 E .20 4 1.1 4 .28 21 18 14. FENOX 4 TRICLOPTR E 4 2.4-0 E .20 4 .42 4 .84 24 32 15. FENOXAPROP-ETNTL .40 38 60 16. PENOX 4 2,4-0 ESTER .40 4 1.1 13 10 17. EENOX 4 OICAHBA .40 4 .56 41 51 18. FENOX 4 PLUROXTPYR .40 4 .56 67 100 19. PENOX 4 BROHOXTNIL .40 4 1.1 18 13 20. RENO: 4 MCPP .40 4 1.1 24 65 21. FENOX 4 OPx-L5300 40 4 .84 0 1 22. PENOX 4 CHLORPLURENOL 40 4 .14 44 68 23. PENOX 4 TRICLOPYR 40 4 .56 52 63 24. EENOX 4 CLOPYRALID 40 4 28 49 72 25. PENOX 4 2.4-0 A 4 MCPP 4 DIC .40 4 1.1 4 (56 4 .11 38 37 26. TRIDIPHANE (TRID) 1.1 2 10 27. TRID 4 2.4-0 ESTER 1.1 4 1.1 2 2 28. TRID 4 OICANBA 1.1 4 .56 2 20 29. TRID 4 PLUROXYPYR 1.1 4 .56 8 13 30. TRID 4 BROHOXYNIL 1.1 4 1.1 46 55 31. TRID 4 HCPP 1.1 4 1.1 6 3 32. TRIDIPNANE 2.2 S 6 33. TRID 4 2.4-0 ESTER 2.2 4 1.1 1 26 34. TRID 4 DICANBA 2.2 4 .56 3 7 35. TRID 4 ELUROXTPYR 2.2 4 .56 3 25 36. TRID 4 BRONOXYNIL 2.2 4 1.1 55 45 37. TRID 4 MCPP 2.2 4 1.1 2 10 38. 2.4-0 ESTER 1.1 0 0 39. DICAHBA .56 2 4 40. FLUROXYPYR .56 o 0 41. BROHOXTNIL 1.1 S 5 42. MCPP 1.1 0 0 43. DPx-LSJOO .84 0 o 44. CNLORFLURENOL .14 0 0 45. TRICLOPYR .56 0 0 46. CLOPYRALID .28 0 0 47. 2.4-0 E 4 MCPP 4 OICANBA 1.1 4 .56 4 .11 2 0 mm --- 5 1 LSD(0.05): 35 40 V The abbreviated treatments are as follows: HCPP=mecoprop. DIC=dicamba. ' Percent crabgrass control scale: 0 to 1008. 100=dead crabgrass, 0=unaffected. 10. 11. LITERATURE CITED Anderson, W.P. 1983. weed science:principles. West Publishing Company. St. Paul, Mn. Fletcher, R.A., and D.M. Drexler. 1980. Interactions of diclofop-methyl and 2,4-0 in cultivated oats (Avena sativa). weed Sci. 28:363. Freeborg, R.P., and W.H. Daniel. 1983. Post emergence control of Digitarialisghagmgm and turf response to fenoxyprop-ethyl. Northcentral Weed Control Conf. Proc. 38:69. Godley, J.L., and L.M. Kitchen. 1986. Interaction of acifluorfen with fluazifop for annual grass control. weed Sci. 34:936-941. Jacobson, A., R.H. Shimabukuro, and C. HcMichael. 1985. Response of wheat and oat seedlings to root-applied diclofop-methyl and 2,4-Dichlorophenoxyacetic acid. Pesticide Biochemistry and Physiol. 24:61-67. Johnson, B. J. 1983. Response of weeds in bermudagrass (Cynodon dactylon) turf to tank- -mixed herbicides. Weed Sci. 31: 883- 888. Olson, W., and J.D. Nalewaja. 1982. Effect of MCPA on a-‘C-diclofop uptake and translocation. Weed Sci. 30:59- 63. O'Sullivan, P.A. 1983. Influence of picloram alone or plus 2,4-D on control of wild oats (Avena fatua) with four postemergence herbicides. Weed Sci. 31:889-891. O'Sullivan, P.A. and W.H. VandenBorn. 1980. Interaction between benzoylprop ethyl, flamprop methyl or flamprop isopropyl and herbicides used for broadleaved weed control. Weed Res. 20:53-57. Qureshi, F.A., and W.H. VandenBorn. 1979. Interaction of diclofop-methyl and MCPA on wild oats (Avena fatua). Weed Sci. 27:202-205. Rhodes, G.N. Jr., and H.D. Cable. 1984. Influence of bentazon on absorption and translocation of sethoxydim in goosegrass (Eleusine indica). weed Sci. 32:595-597. 90 12. 13. 14. 15. 91 Shimabukuro, R.H., W.C. Walsh, and R.A. Hoerauf. 1986. Reciprocal antagonism between the herbicides. diclofop- methyl and 2,4-0, in corn and soybean tissue culture. Plant Physiol. 80:612-617. Todd, B.G., and E.H. Stobbe. 1980. The basis of the antagonistic effect of 2,4-D on diclofop-methyl toxicity to wild oat (Avena fatua). Weed Sci. 28:371- 377. Watschke, T.L., and G. Hamilton. 1986. Crabgrass control in 1985. Proc. Northeastern Weed Sci. Soc. 40:278-279. Whitwell, T., G. Wehtje, R.H. Walker, and J.A. McGuire. 1985. Johnsongrass (Sorghum halepense) control in soybeans (Glycine max) with postemergence grass herbicides applied alone and in mixtures. Weed Sci. 33:673-678. 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