APRIL 1992 LAWN INSTITUTE Harvests Volume 39 Number 1 THE HARVEST MIX This issue completes a 10 year series of newsletters which have contained reviews of research on turfgrass and selected talks given at conferences. This has amounted to over 1,000 pages of tabloid and the editors hope that this endeavor has been of value to the readers. The new staff will no doubt take a different direction. With all best wishes for a successful future in lawn care and turf management. The Editors THRESHING THE JOURNALS A DECADE OF TURFGRASS PATHOLOGY AND ENTOMOLOGY RESEARCH ENTOMOLOGY - Nontarget Invertebrates - Thatch Biodegradation Pesticides - Japanese Beetles - Milky Disease Bacteria - Masked Chafers - Sod Webworms - Chinch Bugs - Greenbugs - Big-eyed Bugs - Mole Crickets - Predatory Arthropods - Other Insect Pests PATHOLOGY - Fungicides - Non-Target Effects - Patch Diseases - Take-all Patch - Summer Patch - Spring Dead Spot - Rhizoctonia - Dollar Spot - Pythium - Fusarium Blight - Stripe Smut - Flag Smut - Yellow Tuft - Microdochium Nivale - Gray Snow Mold - Superficial Fairy Rings - Root Cortical Death - Nematodes - Pathogenicity - Conditions Influencing. This review illustrates the areas of research emphasis outside of the well publicized testing and evaluation of fungicides and insecticides. Each paper is documented so that it may be studied in its entirely by referring to the original publication. Entomological research reports concerning turfgrasses are published regularly in the following journals: America; - Agronomy Journal; - Annals of the Entomological Society of - Environmental Entomology; - HortScience; - Journal of Economic Entomology; - Journal of Entomological Science; - The Canadian Entomologist; - The Coleopterists Bulletin; - The Great Lakes Entomologist; Pathological research reports concerning turfgrasses are published regularly in the following journals: - Agronomy Journal; - Botanical Gazette; - Canadian Journal of Botany; - Canadian Journal of Plant Science; - Crop Protection; - Crop Science; - Hort Science; - Journal of Nematology; - Journal of the Sports Turf Research - Mycological Research; - Phytopathology; - Plant Disease; - Plant Physiology; - Soil Biology and Biochemistry; - Transactions of the British Mycological Institute; Society. The Lawn Institute continually monitors all turfgrass papers published in: Agronomy Journal, Crop Science, HortScience, but has not regularly reviewed research papers in these other publications. In order to more adequately study and evaluate turfgrass insect and disease research reports, 67 contacts were made with leading research entomologists and pathologists requesting reprints of their research papers published during the past decade. Not all responded to this request * but those that did presented 24 papers on Turfgrass Entomology and 59 papers on Turfgrass Pathology for review. These 83 papers are featured here under the following headings: THRESHING THE JOURNALS continued NONTARGET INVERTEBRATES IMPACT OF A HIGH-MAINTENANCE LAWN-CARE PROGRAM ON NONTARGET INVERTEBRATES IN KENTUCKY BLUEGRASS TURF T B Arnold and D A Potter Environmental Entomology Volume 16 Number 1 Pages 100-105 1987 The impact of a high-maintenance program on predators, decomposers, and nontarget herbivorous insects was determined from pitfall-trap collections, soil and thatch extractions and sweep-net and formalin-drench samples. Trap catches of predaceous Araneae, arthropods, specifically and Carabidae were Stophylinidae, significantly reduced by insecticides, particularly late-summer soil treatment with Predators repopulated treated Diazinon. plots by the following spring. Chrysomelidae were more abundant on high-maintenance plots in spring. Soil and thatch pH decreased significantly and thatch accumulation more than tripled under the high maintenance program. However, earthworms were relatively unaffected, and oribatid mites were generally more abundant in high maintenance plots. This suggests that thatch accumulation was probably more a consequence of increased vegetative production than of decreased decomposition due to depletion of soil invertebrates. Although high-maintenance lawn-care programs affect many groups of nontarget invertebrates, this study suggests that the effects are variable and in some cases less severe than would be expected, given the quantity and frequency of pesticide and fertilizer use. EFFECT OF NITROGEN FERTILIZATION ON EARTHWORM AND MICROARTHROPOD POPULATIONS IN KENTUCKY BLUEGRASS TURF D A Potter, B L Bridges and F C Gordon Agronomy Journal Volume 77, May-June Issue Pages 367-372 1985 Earthworms and microarthropods are abundant in turfgrass and may be important to thatch decomposition and nutrient recycling. Increasing the rate of nitrogen fertilization resulted in a significant decline in soil and thatch pH and in exchangeable calcium and potassium and caused a significant increase in thatch. A highly significant linear decrease in earthworm density and biomass was noted as annual rates of nitrogen Collembola were fertilization Increased. more abundant at an intermediate fertilizer rate, whereas Acaridae were unaffected by nitrogen fertilization. Cyrptostigmata were the most abundant arthropod decomposers in turf. Each of the seven oribatid mite species differed in its response to nitrogen fertilization. The study indicates that when nitrogen fertilizer is applied to Kentucky bluegrass at rates sufficient to cause soil acidification, populations of earthworms and certain other decomposers may be severely reduced. Thatch accumulation was negatively correlated with earthworm density and biomass, although other factors probably also contributed to thatch development. NOTICE TO HARVESTS SUBSCRIBERS Since the Headquarters Office of The Lawn Institute will be moving very soon, and the direction of programs may change under new leadership, we have not issued invoices for Harvests subscriptions during the last few months. As soon as the new staff is settled into a new office, the future of the newsletter will be determined and you will be. notified. Thank you for your support. THRESHING THE JOURNALS continued THATCH - BIODEGRADATION PESTICIDES PERSISTENCE AND MOBILITY OF ISAZOFOS IN TURFGRASS THATCH AND SOIL H D Niemczyk and H R Krueger Journal of Economic Entomology Volume 80 Number 4 Pages 950-952 1987 The thatch contained 96-99 percent of detectable residues recovered with a range of 0.123 parts per million at 8 weeks to 3.57 parts per million at 3 hours after treatment. Immediate posttreatment irrigation resulted in significantly higher residues in the thatch during the first 2 weeks of sampling. Although useful in moving the insecticide off the grass blades and into the thatch, posttreatment irrigation had no significant effect on movement of the Insecticide into the soil. JAPANESE BEETLES THE INFLUENCE OF APPLICATION TIMING AND POSTTREATMENT IRRIGATION ON THE FATE AND EFFECTIVENESS OF ISOFENPHOS FOR CONTROL OF JAPANESE BEETLE LARVAE IN TURFGRASS H D Niemczyk Journal of Economic Entomology Volume 80 Number 2 Pages 465-470 1987 During 1984 isofenphos resulted in 92 percent average reduction of over-wintered Japanese Beetle larvae 48 days after application in April. Of treatments applied April through August only August applications significantly reduced summer larvae. Residues in samples taken August 6 from April, May, June and July treatments showed that 79,92,94 and 97 percent isofenphos respectively remained in the thatch. Mean oxyisofenphos residues at this time were 54,45,54 and 63 % respectively of total residue. Oxyisofenphos residues 5-6 days after the April 11 and August 14 applications were 7 and 15 percent respectively, of the total. Immediate posttreatment irrigation, plus regular subsequent irrigation and rainfall, did not improve isofenphos penetration into the soil or enhance larva control. larva mortality decreases with increased conversion of isofenphos to oxyisofenphos. EVIDENCE OF ENHANCED DEGRADATION OF ISOFENPHOS IN TURFGRASS THATCH AND SOIL H D Niemczyk and R A Chapman Journal of Economic Entomology Volume 80 Number 4 Pages 880-882 1987 Isofenphos disappeared 91-99 percent in 3 days when supernatant from aqueous dispersions of turfgrass thatch and soil in which spring application of isofenphos failed to control summer generation scarabaeid larvae were injected into a solution of 10 parts per million isofenphos. No degradation occurred with samples from an untreated site. The phenomenon of enhanced biodegradation has developed as a result of microorganisms adopting to the presence of a pesticide to the point of being able to use it as a source of energy. THRESHING THE JOURNALS CONTINUED EFFICIENCY OF JAPANESE BEETLE TRAPS IN REDUCING DEFOLIATION OF PLANTS IN THE URBAN LANDSCAPE AND EFFECT ON LARVAL DENSITY IN TURF F C Gordon and D A Potter Journal of Economic Entomology Volume 78 Number 4 Pages 774-778 1985 Although attractant traps are commonly used to protect ornamental and garden plants from defoliation by Japanese Beetles neither the utility of this practice nor its effect on larval density around traps has been studied. In experiments on a golf course and in home landscapes, single traps positioned at 3.1 or 9.3 meters [10 to 30 feet] upwind or downwind from test plants failed to reduce defoliation compared with that which occurred on plants without traps. In fact, defoliation was nearly always greater with the trap present. Japanese Beetle larvae densities were not significantly altered in the vicinity of traps. JAPANESE BEETLE TRAPS: EVALUATION OF SINGLE AND MULTIPLE ARRANGEMENTS FOR REDUCING DEFOLIATION IN THE URBAN LANDSCAPES F C Gordon and D A Potter Journal of Economic Entomology Volume 79 Number 5 Pages 1381-1384 1986 Single traps, positioned 3.1 meters [10 feet] or 9.3 meters [30 feet] downwind of pin oak trees resulted in significantly greater defoliation than on trees without traps. None of the multiple trap arrangements reduced defoliation and four of the five placements resulted in significantly greater damage than without traps. Use of single Japanese Beetle traps or small scale multiple trap arrangements will not prevent or reduce defoliation of nearby plantings and will probably increase the damage inflicted upon both highly preferred and relatively less attractive hosts. MILKY DISEASE BACTERIA PATHOGENICITY OF BACILLUS POPILLIAE AND OTHER MILKY DISEASE BACTERIA IN GRUBS OF THE SOUTHERN MASKED CHAFER G W Warren and D A Potter Journal of Economic Entomology Volume 76 Number 1 Pages 69-73 1983 Virulence of the Cyclocephala strain of Bacillus popilliae in Southern Masked Chafer is comparable to that of Bacillus popilliae type A in the Japanese Beetle. Virulence of 16 other species of strains of milky disease from 15 different hosts was tested via injection in the Southern Masked Chafer. Strains from three Australian Scarabs and a native strain from Phyllophaga fusca were the most infective, producing disease in 36 to 58 percent of the grubs. Failure of sporangia- talc applications to significantly increase milky disease in field tests is attributed to insufficient time for sporangia to have become incorporated into the soil. There was, however, a consistent trend toward increased infection in treated sod. MASKED CHAFERS FLIGHT ACTIVITY AND SEX ATTRACTION OF NORTHERN AND SOUTHERN MASKED CHAFERS IN KENTUCKY TURFGRASS D A Potter Annals of the Entomological Society of America Volume 73 Number 4 Pages 414-417 1980 Flight and mating of Southern Masked Chafers begins at dusk and terminates about 2 hours later, while peak activity of Northern Masked Chafers occurs between midnight and 4 AM. Trapping experiments indicated that both females produce a potent volatile sex pheromone which is attractive to males of either species. Previous mating reduced but did not entirely suppress female attractiveness. Female rinses in cyclohexane and ether were effective baits for luring males to traps. Although the 2 species apparently utilize a common airborne sex attractant, they remain reproductively isolated through temporal differences in their mating activity. THRESHING THE JOURNALS CONTINUED INFLUENCE OF FEEDING BY GRUBS OF THE SOUTHERN MASKED CHAFER ON QUALITY AND YIELD OF KENTUCKY BLUEGRASS D A Potter Journal of Economic Entomology Volume 75 Number 1 Pages 21-24 1982 Grubs of the Southern Masked Chafer are serious pests of turfgrass in home lawns, golf courses, parks and other urban areas. On the basis of visual ratings and clipping weights, initial densities of 24 to 48 grubs per 0.1 square meter [1 square foot] caused significant reductions in quality and yield after only 2 weeks, and reduced growth by up to 65 percent after 6 weeks of feeding. Regular irrigation or adequate rainfall masked differences between infested and uninfested plots. in many instances, the economic threshhold for Masked Chafer grubs is considerably higher than the usual rule of-thumb estimate of 6 to 8 grubs per 0.1 square meter [1 square foot]. Apparently, SEASONAL EMERGENCE AND FLIGHT OF NORTHERN AND SOUTHERN MASKED CHAFERS IN RELATION TO AIR AND SOIL TEMPERATURE AND RAINFALL PATTERNS D A Potter Environmental Entomology Volume 10 Number 5 Pages 793-797 1981 The temperature threshold for pupation of overwintering Southern Masked Chafer grubs was determined experimentally as 10.8 degrees Centigrade [53.2 degrees Fahrenheit]. Trapping studies during 1979 and 1980 indicated that the first emergence and peak flight of males occur approximately 1 to 2 weeks earlier for the Northern Masked Chafer than for the Southern Masked Chafer. Thermal unit accumulations in air and soil were closely correlated with the first emergence of beetles, but they were less useful for predicting the date of 50 and 90 percent flight. Once emergence has begun, activity of Masked Chafers is more closely related to rainfall patterns than to temperature. EFFECT OF SOIL MOISTURE ON OVIPOSITION, WATER ABSORPTION, AND SURVIVAL OF SOUTHERN MASKED CHAFER EGGS D A Potter Environmental Entomology Volume 12 Number 4 Pages 1223-1227 1983 Eggs of Cyclocephala immaculata absorb water from the soil, increasing threefold in weight during the first 10 days of embryonic development. Eggs developed normally at soil moistures of 12.5 percent and above, but- shriveled and died in drier soils. Length of incubation period, survival, and final egg weight did not differ at soil moistures within the range required for survival; however, few eggs were laid in dry soil or when soil moisture approached field capacity. Oviposltion in soil moisture gradients indicated that the depth at which eggs are laid can vary in response to moisture levels. Eggs are most susceptible to desiccation when newly laid or close to hatching, but are relatively resistant during the middle stage of development. SUSCEPTIBILITY OF CYCLOCEPHALA IMMACULATA EGGS AND TMMATURES TO HEAT AND DROUGHT IN TURF GRASS. D A Potter and F C Gordon Environmental Entomology Volume 13 Number 3 Pages 794-799 1984 Eggs of the Southern Masked Chafer are laid under turfgrass in the upper 3 centimeter [1 inch] of soil, where they are vulnerable to heat and desiccation. The ability of eggs to survive periods of drought was found to depend upon egg age, stress duration and temperature. At 25 degrees Centigrade [77 degrees Fahrenheit] the minimum soil moisture level at which eggs developed was between 10.3 and 12.3 percent. Eggs surviving a stress period early in development required several days longer to hatch. In field tests, no eggs survived in desiccated turf, where afternoon soil temperatures exceeded 40 degrees Centigrade [104 degrees Fahrenheit] and soil moisture dropped to less than 8 percent. Egg survival ranged from 55 to 73 percent in irrigated turf. THRESHING THE JOURNALS continued SOD WEBWORMS PREDATION ON SOD WEBWORM EGGS AS AFFECTED BY CHLORPYRIFOS APPLICATION TO KENTUCKY BLUEGRASS TURF S D Cochfield and D A Potter Journal of Economic Entomology Volume 77 Number 6 Pages 1542-1544 1984 Predators consumed or carried off up to 75 percent of sod webworm eggs within 48 hours of exposure in turfgrass. One application of Chlorpyrifos applied to Kentucky bluegrass turf reduced the predator-induced mortality of sod webworm eggs for at least 3 weeks after treatment. As evidenced by pitfall traps, the insecticide simultaneously reduced the number of ants and spiders moving through the turf. Ants and mites forage on sod webworm eggs in turf. Four species of mites, five species of Carabidae, five species of Staphylinidae and two other insect species fed on sod webworm eggs in the laboratory. CHINCH BUGS PESTICIDE SCREENING TEST FOR THE SOUTHERN CHINCH BUG R L Crocker and C L Simpson Journal of Economic Entomology Volume 74 December issue Pages 730-731 1981 A filed cage technique for pesticide screening was developed for Blissus insular is in St Augustinegrass in Texas. The method provides reliable results even when large natural populations are not available. With this technique, we are able to make use of a natural population which our presampling had disclosed to be too low and irregularly distributed to be useful in a standard field plot test. BIOASSAY OF ST AUGUSTINEGRASS LINES FOR RESISTANCE TO SOUTHERN CHINCH BUG AND TO ST AUGUSTINE DECLINE VIRUS R L Cocker, R W Toler and C L Simpson Journal of Economic Entomology volume 75 Number 3 Pages 515-516 1982 Twelve experimental accessions and the varieties Floratam, Florida common and Texas common St Augustinegrass were bioassayed for resistance to Blissus insular is. Two hybrid accessions, one accession from Africa and Floratam showed combined resistance to Southern Chi rich Rug and to St August ine Decline Virus. Four other hybrid accessions and three accessions from Africa exhibited virus resistance only. GREENBUGS RESISTANCE OF SELECTED COOL, AND WARM SEASON TURFGRASSES TO THE GREENBUG D W Jackson, K J Vessels and D A Potter HortScience Volume 16 Number 4 Pages 558 559 1981 Three genetically diverse Kentucky bluegrasses - Kenblue, Vantage and Adelphi and 6 other turfgrasses were evaluated for susceptibility to greenbug. Nine common lawn weed species were also tested as potential Heavy greenbug alternative hosts. populations and feeding damage occurred on all 3 bluegrasses and on tall fescue Kentucky 31 and Chewings fescue - Jamestown. Creeping bentgrass - Penncross, bermudagrass - Midiron, perennial ryegrass Derby and zoysiagrass - Meyer were not suitable hosts. No greenbugs survived on the 9 weed species tested. THRESHING THE JOURNALS continued BIG-EYED BUGS FEEDING NICHES OF THE BIG-EYED BUGS GEOCORIS BULLATUS, G PUNCTIPES AND G ULIGINOSUS R L Crocker and W H Whitcomb Environmental Entomology Volume 9 October issue Pages 508-513 1980 As opportunistic polyphagous predators, Geocorls species are probably of great importance in the prevention of pest outbreaks in many agricultural, turfgrass and natural habitats. Under natural conditions, these Geocoris species fed on 67 species of small prey from 3 classes of arthropods Insecta, Arachnlda, and Diplopoda. Sessile, ambulatory, saltatory and winged forms, many representing pest species, were successfully attacked. MOLE CRICKETS A RATING SYSTEM FOR EVALUATING TAWNY MOLE CRICKET DAMAGE P P Cobb and T P Mack Journal of Entomological Science Volume 24 Number 1 Pages 142-144 1989 Mole cricket abundance as determined from soap flush counts increased with an increase in rating. Cricket damage was rated by visual and touch evaluations of mounds and tunnels. Limitations of the rating system restrict its use to those periods of time when mole crickets are large enough to produce visible mounds and/or tunnels. PREDATORY ARTHROPODS INSECTICIDAL SHORT-TERM EFFECTS OF APPLICATIONS ON PREDACEOUS ARTHROPODS AND ORIBATID MITES IN KENTUCKY BLUEGRASS TURF S D Cockfield and D A Potter Environmental Entomology Volume 12 Number 4 Pages 1260-1264 1983 Chlorpyrifos and isofenphos had the greatest impact on predaceous arthropods, with some taxa significantly reduced for at least 6 weeks. Effects of Bendiocarb and Trichlorfon were generally less severe and more temporary. Oribatid mite populations were apparently unaffected by the insecticides. Bendiocarb increased trap catches of ants for up to 2 weeks after application. PREDATORY INSECTS AND SPIDERS FROM SUBURBAN LAWNS IN LEXINGTON KENTUCKY S D Cockfield and D A Potter The Great Lakes Entomologist Pages 179-183 1984 Predatory arthropods were caught in pitfail traps in suburban lawns in Lexington, Kentucky. Nine species of Lycosidae were collected from both bluegrass and tall fescue lawns. More species or phena of Carabidae were collected from bluegrass than from tall fescue turf. More than 40 species or phena of Stophylinids were collected from each grass habitat. Both Kentucky bluegrass and tail fescue are inhabited by an abundant and diverse array of predatory arthropods. PREDATORY ARTHROPODS IN HIGH AND LOW MAINTENANCE TURFGRASS S D Cockfield and D A Potter The Canadian Entomologist Volume 117 April issue Pages 423-429 1985 Tall fescue supported fewer predators than Kentucky bluegrass, specially the families Erigonidae, Linyphiidae and Carabidae. Populations of Erigonidae, Linyphiidae and Carabidae were lower in high-maintenance bluegrass than in low-maintenance bluegrass. The Carabids and a Staphylinid were particularly uncommon in high-maintenance sites. Hierarchical classification of sites suggested that the structure of the Staphylinid and Carabid communities differs in tall fescue and Kentucky bluegrass turf and differs in high and low maintenance bluegrass. THRESHING THE JOURNALS continued OTHER INSECT PESTS ANATOMICAL ADAPTATIONS FOR A FOSSORIAL EXISTENCE IN THE STAPHYLINID BEETLE R L Smith, G C Lanzaro and K G Ross The Coleopterists Bulletin Volume 33 Number 4 Pages 439-444 1979 A study of the external anatomy of the Staphylinid Beetle revealed that these animals possess several structural adaptations to fossorial life. These include a nearly cylindrical shape, shortened appendages, expanded digging tibiae, reduced tarsi, mandibles modified for digging and carrying sand grains and setae around the The oral setae are apparently mouth. functional analogs to ammochaetae which occur on certain fossorial ants. ECOLOGY AND BEHAVIOR OF OSORIUS PLANIFRONS R L Smith, G C Lanzaro, J E Wheeler and A Snyder Annals of the Entomological Society of America Volume 71 Number 5 Pages 752-755 1978 The ecology and behavior of the fossorial Stophylinid Beetle were studied on golf course greens and in the laboratory. Under ideal conditions, they occur in dense aggregations on golf course greens. The life cycle is completed in subterranean galleries, with adults leaving to disperse and male. Tn the laboratory the Stophylinid Beetle requires high soil moisture and probably subsists on soil microbes. PUBLICATIONS LISTS NOTEBOOK [385 pages]..... $30.00 LAWN & SPORTS TURF BENEFITS.... 5.00 ABC’S OF BENEFITS........ 1.00 THE LAWNSCAPE: OUR MOST INTIMATE EXPERIENCE WITH ECOLOGY........ 5.00 LAWN & SPORTS TURF HISTORY....... 5.00 Send check to: The Lawn Institute P O Box 108 Pleasant Hill TN 38578 THRESHING THE JOURNALS continued FUNGICIDES NON TARGET EFFECTS INCREASE TN INCIDENCE AND SEVERITY OF TARGET TURFGRASS DISEASES BY CERTAIN FUNGICIDES H B Couch and B D Smith Plant Disease Volume 75 Number 1.0 Pages 1064-1067 1991 There has been a significant increase in recent years in the amount of fungicides used in turfgrass culture. Pesticide marketing figures for 1989 show that more fungicide was sold in the United States for use on turfgrass than any other commodity, including various food crops. For United States golf courses, fungicides comprise 48 percent of the total pesticide budget. Field and laboratory studies were conducted to determine if in a situation of fungicide resistance, the use of the fungicide in question might increase the severity of the target turfgrass disease. Applications of either a mixture of Cycloheximide3 and Thiram or Triphenyl tin hydroxide to tall fescue colonized by a strain of Rhizoctonia soloni resistant to these fungicides increased the Rhizoctonia blight. incidence of Applications of Benomyl, Thiophanate-methyl and Thiophanate ethyl to creeping bentgrass colonized by a Benzimidazole-resistant strain of Sclerotinia homoeocarpa resulted in significant increases in the incidence and severity of Sclerotinia dollar spot. The Benzimidazole-induced increase in dollar spot was detected within 7 days of the second fungicide application and continued for an additional 28 days in the absence of additional Treatments of creeping bentgrass with Triphenyl tin hydroxide also exhibited an increase in dollar spot. This increase was first detected 3 weeks after the third and final fungicide application and continued for 36 days. applications. fungicide OXIDATION STATUS AND GAS COMPOSITION OF WET TURFGRASS THATCH AND SOIL D C Thompson, R W Smiley and M C Fowler Agronomy Journal Volume 75 July-August issue Pages 603-609 1983 Turfgrasses often develop an organic horizon composed of dead, sclerified, vascular tissue. This thatch horizon is often 1 to 4 centimeters [1/2 to 2 inches] thick and is often underlain by a compacted, poorly drained mineral soil layer. When thatch layers become thick, plant crowns may become elevated into it, and subsequent growth of roots, rhizomes and stolons occurs mostly in the thatch rather than the underlying mineral soil. Excess thatch in turfgrasses is often associated with decreased plant vigor and increased disease susceptibility. Thatch is the primary rooting medium for many grasses and is a substrate that possesses many prerequisites for anaerobiosis. Conditions of poor oxidation, including low redox potentials and oxygen and carbon dioxide concentrations and accumulations of ethylene were measured in thatch on poorly drained soils. Applications of lime and calcium arsenate amplified the extent of poor oxidation in thatch, whereas calcium nitrate improved the oxidation status. Thatch depth and a coring procedure did not influence thatch oxidation. Poorly oxidized conditions for periods over 7 hours were measured in moist but unsaturated thatch in the field. The temperature of thatch appeared to be important in governing the oxidation status. Phytotoxic products of poorly oxidized environments may accumulate in wet thatch on warm sunny days. These results are relevant to the occurrence of diseases such as Fusarium blight. THRESHING THE JOURNALS continued Seven applications of Benomyl or Iprodione per year caused thatch to become deeper than in untreated turf; however, three applications per years did not. Increased thatch accumulation did not occur with Cycloheximide, Metalaxyl, Propiconazol or Triadimefon. None of the fungicides significantly reduced the decomposition rate of burled thatch or altered the thatch pH or microbial composition. FUNGICIDE EFFECTS ON THATCH DEPTH, THATCH DECOMPOSITION RATE AND GROWTH OF KENTUCKY BLUEGRASS R W Smiley, M C Fowler, R T Kane, A M Petrovic and R A White Agronomy Journal Volume 77 July-August issue Pages 597-602 1985 Development of improved management strategies for controlling thatch on turf is limited by an incomplete understanding of thatch biology. Compounds that caused thatch to become deeper than in the nontreated control included Benomyl, cadmium succinate, Fenamiphos, Iprodione and Mancozeb. Treatments in which these pesticides were used were characterized by sod shear strengths greater than in the control. Thatch accumulations were related mostly to the amounts of roots in the surface 4 centimeters [2 inches]. None of the fungicides studied significantly reduced the apparent rate of thatch decomposition. Fungicides in this study therefore appeared to induce thatchiness in Kentucky bluegrass by increasing the rates of root and rhizome production and not by reducing the rate of litter decomposition. MICROFLORA OF TURFGRASS TREATED WITH FUNGICIDES R W Smiley and M M Craven Soil Biology and Biochemistry Volume 11 Pages 349-353 1979 Diseases are a constant menace to the maintenance of quality turfgrasses. Frequently, the uncertainties involved with cultural control procedures lead turfgrass managers to rely upon fungicides. Fungicide use can adversely affect the composition of microbial populations. Combinations of fungicides have been found to suppress fungi and stimulate bacteria and actinomycet.es more than individual toxicants. Collective microbial groups were generally less affected by each fungicide than were individual species within each group. The rate of decrease of ammonia concentrations in fertilized turf [presumably via nitrification] was only slightly influenced by fungicides. The more harmful effects of some fungicides to turfgrass may involve induced acidity rather than direct suppression of specific microbial groups. TURFGRASS THATCH COMPONENTS AND DECOMPOSITION RATES IN LONG-TERM FUNGICIDE PLOTS R W Smiley and M C Fowler Agronomy Journal Volume 78 Number 4 Pages 633-636 1986 The balance of organic litter accumulation and decomposition in grasses is determined by complex processes. When routinely treated with certain fungicides, this balance is shifted in favor of accumulatory processes in turfgrasses. Certain fungicides induce thatch accumulation in turf but do not always significantly inhibit or alter the population or composition of the soil microflora. Some fungicides may induce thatch accumulation by increasing the rate of plant tissue production rather than by reducing the rate of litter decomposition. THRESHING THE JOURNALS continued NONTARGET EFFECTS OF PESTICIDES ON TURFGRASSES R W Smiley Plant Disease Volume 65 Number 1 Pages 17-23 1981 That pesticides can exert many effects on nontarget organisms and processes in tuffgrasses is readily apparent. In addition to direct effects, each chemical and biological change may cause secondary, tertiary and other changes until the entire management program becomes improved or hindered by the use of certain pesticides. The effects may be so slight as to be unnoticeable but large enough to increase expenses for certain management, procedures, it can be theorized that frequent use of certain pesticides does alter the long term costs of such management procedures as controlling pests, thatch and soil acidity. These nontarget effects need greater attention in the original decision-making process. If, for instance, four fungicides were known to be almost equally effective against a target pathogen but three were much more likely to increase thatchiness or weediness, the means of selection could be improved. The long term costs of thatch and weed control are certainly greater than the immediate cost differences among competitively priced fungicides. Although product costs, application costs, technical services provided, immediate availability of a product, and personal preferences are very important considerations, it. is also important for scientists to provide additional facts on which to base pesticide­ use decisions. PLANT GROWTH-REGULATING EFFECTS OF SYSTEMIC FUNGICIDES APPLIED TO KENTUCKY BLUEGRASS R T Kane and R W Smiley Agronomy Journal Volume 75 May-June issue Pages 469-473 1983 Fungicides which exhibit systemic activity in plants often have a high specificity for sites of action and exhibit long term disease control activity. These systemic fungicides are the only compounds that consistently control Fusarium blight, a disease that causes widespread losses to Kentucky bluegrass turfs in North America. Contact protectant fungicides have little or no activity against this disease. Plant growth retardants have been shown to increase resistance to drought stress, probably by reducing transpiration and/or the wafer use rate. The reduced metabolic activity of inhibited plants may also affect carbohydrate status, respiration, ion uptake, or other factors. Results of these studies indicate that the systemic fungicides tested have nontarget plant growth regulating effects on Merion and Fylking Kentucky bluegrass seedlings grown under controlled conditions. Preliminary field studies with the same compounds were inconclusive. The growth retarding effects of Pyrimidinemethand and Triazole fungicides may be important influences on plant stress tolerance and resistance to opportunistic pathogens. FUNGICIDES IN KENTUCKY BLUEGRASS TURF: EFFECTS ON THATCH AND pH R W Smiley and M M Carven Agronomy Journal Volume 70 November-December issue Pages 1013-1019 1978 Management of thatch and pH are important aspects of turfgrass culture. The use of disease-preventive fungicides is a standard practice on highly maintained turfgrasses, and fungicides may be toxic to many thatch decomposing microorganisms. The influence of 14 fungicides, one nematicides and of five mixed fungicide programs, applied over a 3 years period, on thatch decomposition and the resultant pH of underlying soil was investigated on a blended Kentucky bluegrass sod. Thatch depths among fungicide treatments ranged from 2.8 to 22.0 millimeters and the pH of the surface 3 centimeters [1 inch] ranged from 5.6 to 6.5. Thatch depth and pH were inversely related - more thatch, lower pH. Fungicide induced reductions in pH occurred to depths exceeding 20 centimeters [8 inches]. Acidification of soil was apparently not the result of organic acids leaching from decomposing thatch but was related to the contributions of sulfur from the fungicides. Oxidation of sulfur from decomposing fungicides reduced the soil pH which, in turn, reduced the activity of microorganisms responsible for degradation of thatch. Thatch accumulation was not considered to be due to inhibitory effects of fungicides toward earthworms. THRESHING THE JOURNALS continued PATCH DISEASES TEMPERATURE AND OSMOTIC POTENTIAL EFFECTS OF PHIALOPHORA GRAMINICOLA AND OTHER FUNGI ASSOCIATED WITH PATCH DISEASES OF KENTUCKY BLUEGRASS R W Smiley, M C Fowler and R T Kane Phytopathology Volume 75 Number 10 Pages 1160-1167 1985 Fusarium blight syndrome of Kentucky bluegrass was recently recognized to be a mixture of two or more patch diseases caused by ectotrophic root infecting fungi related to Gaeumannomyces graminis. Two of these ectotrophs are Phialophora graminicola which causes summer patch and Leptosphaeria korrae which causes necrotic ring spot. Several Fusarium fungi are typically the most prevalent when isolated from foliage, crowns and roots of plants expressing symptoms of patch diseases. Temperature and osmotic potential effects on growth and pathogenicity of isolates of these fungi from the United States have been determined. Rapid necrosis of colonized plants occurred only at 29 degrees Centigrade [84 degrees Fahrenheit] ana, through a system of elevation in the incubation temperatures, this property has been used to assay the extent of the pathogen’s growth through sods at lower temperatures. Susceptibility of plants was more pronounced when plants were mowed at 2 centimeters [1 inch] compared to being Leptosphaeria korrae colonized unmowed. roots but did not affect plant health under conditions examined in this study. Fusarium crookwellense thoroughly colonized and halted further growth by cultures of the other fungi on agar medium, but did not contribute to progress of disease caused by Phialophora graminicola, or to symptom expression on plants colonized by Leptosphaeria korrae. THE ETIOLOGIC DILEMMA CONCERNING PATCH DISEASES OF BLUEGRASS TURFS R W Smiley Plant Disease Volume 71 Number 9 Pages 774-781 1987 Two popular concepts used for diseases of grasses in North America must be deemphasized. Names of fungal genera should not be used to describe diseases of subterranean or surface oppressed plant parts. Likewise, the "single pathogen for a single disease" concept does not accurately account for successions or complexes of organisms that occur during the process of patch disease development. Disease names become part of the public domain and are* not easily, uniformly, or fairly changed if circumstances indicate that isolates of I he originally described genus can no longer be considered the primary agent or it the taxonomic assignment of a well-defined agent is changed. Examples of this can be drawn from diseases caused by fungi that were, once classified as species of Corlicium, Sclerotinia, Helminthospor ium and Ophioboln These fundamental changes in philosophy will enable much more rapid progress toward understanding and coni rolling diseases on turfgrasses and toward much higher uniformity in our ability to communicate information about specific diseases. GARDEN WRITER SURVEY A survey conducted by Hinsdale Marketing Services for Aquapore Moisture Systems showed that only 14 % of the garden writers who responded were convinced that "products described as environmentally correct were what they claimed to be." The writers were split on the issue of using terms such as "environmentally correct", "environmentally friendly" or "environ­ mentally preferred" to help sell products. The garden writers did claim to have a responsibility to inform readers about water conservation and environmental issues. - Landscape Management April 1992 THRESHING THE JOURNALS continued TAKE-ALL PATCH MANAGEMENT OF TAKE-ALL PATCH OF CREEPING BENTGRASS WITH NITROGEN, SULFUR AND PHENYL MERCURY ACETATE P H Dernoeden Plant Disease Volume 71 Number 3 Pages 226-229 1987 Take-all Patch disease incited by Gaeumannomyces graminis is a destructive disease of bentgrass turf. Ammonium chloride alone and phenyl mercury acetate plus ammonium sulfate effectively controlled the disease in both years of a field study. Ammonium sulfate and urea reduced disease severity to an acceptable level only in the second year. Granular sulfur was ineffective No in controlling Take-all Patch. correlation was found between disease injury and thatch or soil pH. Failure to find a correlation between disease and pH was probably due to the highly buffered nature of thatch and to the use of basic [pH 8.2] irrigation water. Data indicate that treatment effects on thatch and soil pH [pH 6.1-6.8] had no important impact on the disease control observed. Treatments that effectively reduced disease increased thatch biomass, which was attributed to stimulation of plant growth accorded by nitrogen. GAEUMANNOMYCES INCRUSTANS, A ROOT-INFECTING HYPHOPODIATE FUNGUS FROM GRASS ROOTS IN THE UNITED STATES. P J Landschoot and N Jackson Mycological Research Volume 93 Number 1 Pages 55-58 1989 A root-infecting hyphopodiate fungus with a Philalophora anamorph was isolated from the roots of several turfgrass species in the United States. The teleomorph was produced by crossing opposing mating types on sterile wheat stems. Various root-infecting fungi have received attention for their role in the development of patch diseases of turfgrass. OCCURRENCE OF GAEUMANNOMYCES PATCH DISEASE IN MARYLAND AND GROWTH AND PATHOGENICITY OF THE CAUSAL AGENT. P H Dernoeden and N R O’Neill Plant Disease Volume 67 Number 5 Pages 528-532 1983 Gaeumannomyces Patch, formerly known as Ophiobolus Patch is a serious disease of bentgrass turf in many countries. The disease was observed on Penncross creeping bentgrass turf at four locations in Maryland in 1979 and 1980. Affected turf appeared as bronzed, reddish brown or light yellow patches 15-60 centimeters [6-24 inches] in diameter. Dead or thinning turf was observed in the centers of these patches. Dark brown runner hyphae and simple hyphopodia were present on roots, crowns and basal sheaths of diseased plants. Pathogenicity tests showed that seedlings of all bentgrass species used as turf are very susceptible to the disease. Exeter colonial bentgrass seedlings, however, showed a significantly higher level of resistance than Astoria colonial and Penneagle creeping bentgrass. THRESHING THE JOURNALS continued TECHNIQUES FOR INDUCING SUMMER PATCH SYMPTOMS ON KENTUCKY BLUEGRASS R W Smiley and M C Fowler Plant Disease Volume 69 Number 6 Pages 482-484 1985 Distinct circular to arc-shaped patch diseases of turfgrasses are caused by soilborne pathogenic fungi that produce darkly pigmented, ectotrophic runner hyphae that spread along roots, rhizomes, and stolons of Gramineae and move from one plant to another. Representative diseases include Take-all Patch of bentgrass and Spring Dead Spot of bermudagrass. Fusarium Blight, also named Fusarium Blight Syndrome is another important diseased characterized by distinct patches. Phialophora graminicola did not induce disease symptoms on sod at 14 degrees Centigrade [57 degrees Fahrenheit] but did so very slowly at 21 degrees Centigrade [70 degrees Fahrenheit] and rapidly at 29 degrees Centigrade [84 degrees Fahrenheit]. The pathogen grew through sods at 21 degrees Centigrade [70 degrees Fahrenheit] but did not kill plants quickly unless the temperature was increased to 29 degrees Centigrade [84 degrees Fahrenheit], Characteristically pathogens form circular zones of restricted root growth before foliar After the symptoms are expressed. temperature was increased to 30 degrees Centigrade [86 degrees Fahrenheit] the ring [frog-eye] pattern of well-developed or older patches, a sunken-pocket effect and heat­ stress banding of leaves on tillers marginally affected by root rot was noted. SUMMER PATCH ARSENATE HERBICIDE STRESS AND INCIDENCE OF SUMMER PATCH ON KENTUCKY BLUEGRASS TURFS R W Smiley, M C Fowler and R C O'Knefski Plant Disease Volume 69 Number 1 Pages 44-48 1985 Investigations were conducted on the relationships between arsenical weed control programs on Kentucky bluegrass and the incidence of Summer Patch caused by Phialophora graminicola. At locations where the disease is likely to occur, applications of calcium arsenate caused extreme amplifications of disease, enough to render it uncontrollable with fungicides. Where the disease is not known to occur, large excesses of arsenate failed to induce new occurrences These results seem of Summer Patch. correlated to soil moisture extremes known to predispose bluegrasses to the disease and to stress caused by arsenicals in the root zones of plants. MAGNAPORTHE POAE, A HYPHOPODIATE FUNGUS WITH A PHIALOPHORA ANAMORPH FROM GRASS ROOTS IN THE UNITED STATES P J Landschoot and N Jackson Mycological Research Volume 93 Number 1 Pages 59-62 1989 Magnaporthe poae a hyphopodiate root­ infecting fungus with a Phialophora anamorph was isolated from Kentucky bluegrass and annual bluegrass roots in the course of an investigation into the aetiology of Summer In growth chamber and Patch Disease. greenhouse studies the fungus was pathogenic to both species at temperatures of 28-30 degrees Centigrade [82-86 degrees Fahrenheit]. THRESHING THE JOURNALS continued SPRING DEAD SPOT GROWTH AND PATHOGENICITY OF LEPTOSPHAERIA KORRAE IN BERMUDAGRASS J N Crahay, P H Dernoeden and N R O'Neill Plant Disease Volume 72 Number 11 Pages 945-949 1988 Spring Dead Spot is a destructive disease of bermudagrass in North America and Australia. First documentation of symptomatology took place in 1960, but at that time the cause was not determined. Maryland isolates of Leptosphaeria korrae from Tufcote bermudagrass affected with Spring Dead Spot were compared with a New York and a Rhode Island isolate of the fungus from Kentucky bluegrass. Pseudothecia produced on inoculated bermudagrass roots were identical and contained ascospores of similar length for all three isolates, confirming a common identity. The three isolates grew similarly at temperatures ranging from 15 to 30 degrees Centigrade [59 to 86 degrees Fahrenheit] with most rapid growth occurring at 25 degrees Centigrade [77 degrees Fahrenheit]. Tufcote bermudagrass plants inoculated with the Maryland isolate were severely damaged at 15 degrees Centigrade [59 degrees Fahrenheit]. Mortality at 20 degrees Centigrade [68 degrees Fahrenheit] was 44 percent, but at 25 and 30 degrees Centigrade [77 and 86 degrees Fahrenheit] no disease symptoms were visible. The fungus was reisolated from diseased or necrotic plants and greenhouse studies revealed significant differences in isolate virulence and susceptibility of bermudagrass cultivars to disease. CONTROL OF SPRING DEAD SPOT OF BERMUDAGRASS WITH FUNGICIDES IN NORTH CAROLINA L T Lucas Plant Disease Volume 64 Number 9 Pages 868-870 1980 Spring Dead Spot of bermudagrass was first described in Oklahoma in 1960. The disease occurs in the northern range of bermudagrass adaptation across the southern United States where winter weather is cold enough for periods of dormancy to develop. Spring Dead Spot was controlled with five monthly applications of Benomyl, PCNB, or a combination of fungicides during July- November in 1973 and 1974. Applications of Chloroneb, Nabam, Maneb or Carboxin did not control the disease. The severity of Spring Dead Spot increased in plots without fungicides that received extra nitrogen in August and September. RHIZOCTONIA SUPPRESSION OF BROWN PATCH DISEASE OF CREEPING BENTGRASS BY ISOLATES OF NONPATHOGENIC RHIZOCTONIA SPECIES L L Burpee and L G Goulty Phytopathology Volume 74 Number 6 Pages 692-694 1984 Fungi that are similar to Rhizoctonia solani, but have binucleate rather than multinucleate - more than 2 hyphal cells - have been isolated from aerial and subterranean parts of several plant species, including turfgrasses. Binucleate Rhizoctonia were studied as potential antagonists of Rhizoctonia solani. In each of three field experiments, creeping bentgrass developed significantly less disease when inoculated with binucleate Rhizoctonia 24 hours before inoculation with Rhizoctonia solani than when inoculated with Rhizoctonia solani alone. Disease was not observed in plots inoculated with the binucleate type alone. Significant differences in suppressive ability were observed among binucleate type isolates. THRESHING THE JOURNALS continued RHIZOCTONIA CEREALIS CAUSES YELLOW PATCH OF TURFGRASSES L L Burpee Plant Disease Volume 64 Number 12 Pages 1114-1116 1980 Isolates of a binucleate Rhizoctonia species that cause chlorosis and blight of turfgrasses fit the species concept of Mycelial and Rhizoctonia cerealis. sclerotial characteristics, temperature­ growth relations, and hyphal anastomosis of 10 of these binucleate Rhizoctonia isolates, which had previously been assigned to anastomosis group CAG1 were compared with the characteristics of three isolates of Rhizoctonia cerealis from small grains. The 10 unidentified isolates and the isolates of Rhizoctonia cerealis exhibited similar cultural morphology and were assigned to the common anastomosis group CAG1. Isolates of Rhizoctonia cerealis, thus, are assumed to be the cause of chlorosis and blight of turfgrasses, and the descriptive name "yellow patch" is proposed for the disease caused by Rhizoctonia cerealis on turfgrass species. A QUALITATIVE BAITING TECHNIQUE FOR SELECTIVE ISOLATION OF RHIZOCTONIA ZEAE FROM SOIL A S Windham and L T Lucas Phytopathology Volume 77 Number 5 Pages 712-714 1987 A baiting technique was developed for selective isolation of Rhizoctonia zeae from naturally (infected soil using fungicide- treated stem segments of cotton and a selective medium consisting of 2 percent water agar and Benomyl, Metalaxyl, Penicillin G and Streptomycin sulfate. Cotton stem segments soaked in Benomyl and Metalaxyl, or in Benomyl at double the concentration were successfully used to isolate the fungus from two naturally infected soils. Fungicide- treated stems were colonized in significantly higher numbers than untreated stems. The selective medium also increased recovery of the fungus from colonized stems. Untreated stems were colonized by Rhizoctonia solani, binucleate Rhizoctonia-like fungi, Pythium species and a number of other common soil­ inhabiting fungi. COMPARATIVE SENSITIVITY OF RHIZOCTONIA SOLANI AND RHIZOCTONIA-LIKE FUNGI TO SELECTED FUNGICIDES IN VITRO S B Martin, L T Lucas and C L Campbell Phytopathology Volume 74 Number 7 Pages 778-781 1984 The form-genus Rhizoctonia presently contains nearly 100 species including basidiomycetes, ascomycetes and imperfect fungi. Several of these species have been shown to induce various diseases on turfgrasses and other crops. Benomyl, Carboxin, PCNB, Iprodione, Chlorothalonil, and Triadlmefon were added to agar in order to study the Inhibition of linear growth of 16 isolates of Rhizoctonia solani, binucleate Rhizoctonia-like fungi and Rhizoctonia zeae from several sources. Rhizoctonia solani and binucleate Rhizoctonia-like fungi were sensitive to Benomyl. Isolates of Rhizoctonia zeae were tolerant to Benomyl but sensitive to other fungicides. Fungi were most sensitive to Iprodione, but growth inhibition in response to other fungicides differed considerably. HORIZONTAL DISTRIBUTION AND CHARACTERIZATION OF RHIZOCTONIA SPECIES IN TALL FESCUE TURF S B Martin, C L Campbell and L T Lucas Phytopathology Volume 73 Number 7 Pages 1064-1068 1983 Rhizoctonia solani induces Brown Patch, a foliar blight of tall fescue and other turfgrasses. This disease often causes severe damage to cool-season turfgrasses in the warm, humid areas of the United States, and frequently is severe during the summer months on tall fescue used throughout central North Carolina. A 12 year old stand of tall fescue turf with a history of Brown Patch was divided into 225 contiguous quadrats and the soil sampled for propagules of Rhizoctonia in June 1980 and 1981 by direct assay of soil organic debris. Fifty-three isolates in 1980 and 54 isolates in 1981 were recovered and identified as Rhizoctonia solani, Rhizoctonia zeae, or binucleate Rhizoctonia-like fungi. Rhizoctonia solani was recovered 9 percent of the total in 1980 and 1981; Rhizoctonia zeae 45.3 percent in 1980 and 48.2 percent in 1981; and binucleate Rhizoctonia-like fungi 39.6 percent in 1980 and 42.6 percent in 1981. These data indicated that populations of overwintered propagules of Rhizoctonia in tall fescue organic debris are diverse. DOLLAR SPOT EVALUATION OF TWO DOLLAR SPOT FORECASTING SYSTEMS FOR CREEPING BENTGRASS L L Burpee and L G Goulty Canadian Journal of Plant Science Volume 66 April issue Pages 345-351 1986 Dollar Spot, caused by Lanzia species and/or Maelleradiscus species is a serious disease of turfgrass in cool humid climates. Fungicide programs based on the Hall and Mills and Rothwell [M and R] Dollar Spot forecasting systems for creeping bentgrass were compared with fungicide application schedules of 7,14 and 21 days in 1983 and a schedule of 10 days in 1984. In both years, programs based on the Hall system failed to provide acceptable disease control. Failure of the Hall System was attributed to its ability to predict disease on only 17 percent of the occasions when increases in disease incidence were observed. The M and R system's critical weather criteria, used to select the time for fungicide applications were met on 48 and 35 days in 1983 and 1984, respectively. This over-estimation of disease indicated that the success of the M and R system was a result of prediction frequency and not prediction accuracy. THRESHING THE JOURNALS continued PATHOGENICITY OF RHIZOCTONIA ZEAE ON TALL FESCUE AND OTHER TURFGRASSES S B Martin and L T Lucas Plant Disease Volume 67 Number 6 Pages 676-678 1983 Several species of Rhizoctonia are capable of turfgrass Inducing disease on several species. Tall fescue, perennial ryegrass, Kentucky bluegrass, creeping bentgrass, common bermudagrass and centipedegrass were inoculated with each of five isolates of Rhizoctonia zeae and one isolate of Rhizoctonia solani. Rhizoctonia zeae isolates blighted cool-season turfgrasses more severely than warm season turfgrasses. Isolates of Rhizoctonia zeae originally obtained from lesions on grasses were more virulent on cool-season grasses than an isolate from corn roots and one from bentgrass affected with a summer dry wilt condition. Isolates of Rhizoctonia zeae were only mildly pathogenic on warm season grasses. The Rhizoctonia solani isolate was more virulent than any of the Rhizoctonia zeae isolates tested. PATHOGENICITY AND CHARACTERIZATION AND OF RHIZOCTONIA SPECIES BINUCLEATE RHIZOCTONIA-LIKE FUNGI FROM TURFGRASS IN NORTH CAROLINA S B Martin and L T Lucas Phytopathology Volume 74 Number 2 Pages 170-175 1984 Fungi with, mycelium resembling Rhizoctonia solani were described in 1967 and were distinguished by the binucleate condition of hyphal cells in comparison with the multinucleate condition of hyphal cells of Rhizoctonia solani. Most isolates of Rhizoctonia solani induced foliar blight symptoms on cool-season grasses, but in greenhouse inoculations one isolate from symptomatic bermudagrass [Tifton 419] induced a crown rot. similar to symptoms observed in Similar inoculations with the field. isolates of Rhizoctonia solani indicated greater virulence on cool-season grasses than warm season grasses with the exception of the bermudagrass crown rotting isolate. Isolates of Rhizoctonia cerealis were obtained during periods of cool damp weather and were associated with a foliar chlorosis of creeping bentgrass. Rhizoctonia zeae was isolated three times from diseased tall fescue and once from creeping bentgrass during hot weather. Isolates of Rhizoctonia zeae were as virulent on tall fescue and Kentucky bluegrass as the Rhizoctonia solani isolates tested in greenhouse experiments under hot weather conditions. THRESHING THE JOURNALS continued PYTHIUM SYNERGISTIC AND ANTAGONISTIC INTERACTIONS OF FUNGICIDES AGAINST PYTHIUM APHANIDERMATUM ON PERENNIAL RYEGRASS H B Couch and B D Smith Crop Protection Volume 10 October issue Pages 386-390 1991 The increasing use of single-site fungicides and the accompanying reports of resistance on the part of certain of the target organisms to these materials has heightened interest in the development of disease control programs that utilize mixtures of fungicides with different modes of action, but effective against the same pathogen. The Mancozeb plus Chloroneb mixture was antagonistic whereas the combinations of Mancozeb plus Propamocarb, Fosetyl-Al plus Metalaxyl, and Fosetyl-Al plus Propamocarb were synergistic in the control of the Metalazyl-sensitive strain of Pythium aphanidermatum. Mancozeb plus Metalaxyl was synergistic in the control of the Metalaxyl-sensitive and the Metalaxyl- resistant strains. The null hypothesis (additivity] was not rejected for the other combinations. The level of disease control provided by the synergistic combinations tested was equal to or greater than that provided by each of the components applied singly at their full label rates. PYTHIUM-INDUCED ROOT DYSFUNCTION OF SECONDARY HOOTS OF CREEPING BENTGRASS C F Hodges and L W Coleman Plant Disease Volume 69 Number 4 Pages 336-340 1985 Foliar or Cottony Blight is caused by several species of Pythium and is one of the more serious diseases of creeping bentgrass golf greens. Various Pythium species also are associated with the primary and secondary root systems of creeping bentgrass and other perennial grasses. New Pythium pathogens have been found associated with secondary roots of creeping bentgrass grown on golf greens with mixtures of high sand content. Some Pythium fungi have been isolated but not found to be pathogenic. Where pathogenic types exist, total shoot and root dry weights of plants decreased in sand and to a lesser extent in sand-loam media. Pathogens develop throughout the cortical and vascular tissues of roots but did not produce lesions or rot. Infected roots occasionally had a light buff coloration. Mycelium was observed in root hairs and infected root tips were bulbous and ultimately devitalized. Sporangia and oospores were rarely observed in infected roots. FUSARIUM BLIGHT FUSARIUM BLIGHT AND PHYSICAL, CHEMICAL, AND MICROBIAL PROPERTIES OF KENTUCKY BLUEGRASS SOD R W Smiley, M M Craven and J A Bruhn Plant Disease Volume 64 Number 1 Pages 60-62 1980 Kentucky bluegrass may become . severely damaged by Fusarium Blight. The disease was positively correlated with the thatch decomposition rate, negatively correlated with the plant growth variables, and not correlated with any microbial group, including all species, section and composite numbers of Fusarium. Sod pH and Fusarium numbers were associated with thatch decomposition rates. Fusarium Blight was least severe when the percentage of Fusarium- Infected plant crowns was highest. These results are considered in relation to the possible role of phytotoxic substances that are produced during thatch decomposition and act as incitants of Fusarium Blight of Kentucky bluegrass. THRESHING THE JOURNALS continued LEPTOSPHAERIA KORRAE AND PHIALOPHORA GRAMINICOLA ASSOCIATED WITH FUSARIUM BLIGHT SYNDROME OF KENTUCKY BLUEGRASS IN NEW YORK R W Smiley and M C Fowler Plant Disease Volume 68 Number 5 pages 440-442 1984 Kentucky bluegrass is the most important and widely used turfgrass species in temperate regions of North America. Numerous cultivars have resulted from intensive selection and breeding programs. Two fungi with growth habits similar to that of Gaeumannomyces graminis were found to be associated with a patch disease in New York. Both pathogens have been shown capable of causing the disease, which is indistinguishable from the poorly understood Fusarium Blight Syndrome. This is the first report of Leptosphaeria korrae and Phialophora graminicola in North America and of their occurrence on Kentucky bluegrass. IN VITRO EFFECTS OF FUSARIUM BLIGHT­ CONTROLLING FUNGICIDES ON PATHOGENS OF KENTUCKY BLUEGRASS R W Smiley and M M Craven Soil Biology and Biochemistry Volume 11 Pages 365-370 1979 Fusarium Blight of Kentucky bluegrass turf is a crown rot which has been attributed to Fusarium tricinctum and to Fusarium roseum. Although these Fusaria can easily infect leaves under glasshouse conditions, and are nearly always associated with both healthy and diseased turfgrasses, the field symptoms of this disease have only once been artificially induced in the glasshouse with inocula of Fusarium. The etiology of Fusarium Blight remains to be clarified. An experimental Iprodione fungicide controls Fusarium Blight of Kentucky bluegrass, but it also amplifies the proportion of crowns colonized by Fusarium and the number of its propagules in the soil. In contrast, the disease, the proportion of infected crowns and the numbers of propagules in soil are generally suppressed by Benomyl. Triadimefon also controls the disease but is not stimulatory or inhibitory of Fusaria. with selective These investigations fungicides indicate that the primary causal agent of Fusarium Blight is not among the Fusaria and that re-interpretation of the disease and its etiology is necessary. SOIL AND ATMOSPHERIC MOISTURES ASSOCIATED WITH FUSARIUM CROWN ROT AND LEAF BLIGHT OF KENTUCKY BLUEGRASS R W Smiley and D C Thompson Plant Disease Volume 69 Number 4 Pages 294-297 1985 Fusarium species are ubiquitous inhabitants of organic litter [thatch] in Kentucky They become the dominant bluegrass. facultative parasites in thatch during the summer and are therefore likely to become the principal colonists of grasses subjected to stresses at that time. Severity of leaf blight was significantly increased by drought stress, especially when followed by periods of flooding, high humidity or both. Plants that had not been predisposed by drought were resistant to leaf blight even when subsequently flooded but sustained low levels of infection during prolonged periods [up to 8 days] of high relative humidity. FUSARIUM SPECIES IN SOIL, THATCH AND CROWNS OF KENTUCKY BLUEGRASS TURFGRASS TREATED WITH FUNGICIDES R W Smiley and M M Craven Soil Biology and Biochemistry Volume 11 Pages 355-363 1979 Little information exists concerning the effects of long-term fungicide programs on the qualitative and quantitative characteristics of Fusaria in turfgrasses and in turfgrass soils. These effects were studied on Kentucky bluegrass turfgrasses at three locations using 14 fungicides, one nematicide and five mixed fungicide programs. Some fungicides increased the numbers of Fusaria in soil and thatch; some had no effect; and others greatly reduced the numbers. Changes in fusarium species compositions occurred independently from the changes in propagule numbers. The proportion of Fusarium-colonized turfgrass crowns was generally higher in fungicide treated than in non-treated turfgrasses. THRESHING THE JOURNALS continued STRIPE SMUT - FLAG SMUT LEAF AND ROOT GROWTH OF WATER-STRESSED KENTUCKY BLUEGRASS INFECTED BY USTILAGO STRIIFORMIS OR UROCYSTIS AGROPYRI J L Nus and C F Hodges Crop Science Volume 25 January-February issue Pages 97-101 1985 The relative growth of the shoot vs roots has proven to be a useful parameter in investigations of drought tolerance. In addition, overall plant growth has been used as a measure of tolerance to water stress. Kentucky bluegrass infected with Stripe Smut or Flag Smut exhibits greater mortality than healthy plants during periods of water stress and is suggestive of decreased drought tolerance as a result of infection. Infection of Stripe Smut increased total and leaf dry weight and decreased root weight and root-shoot ratios of plants grown in nutrient solution. Plants infected by flag Smut exhibited decreased total, leaf and root weights and root-shoot ratios. Total, leaf and root weights of healthy, Stripe Smut and Flag Smut infected plants decreased and root­ shoot ratios increased with decreasing osmotic potentials of nutrient solutions. The increases in total and leaf weights of Stripe Smut infected plants compared with healthy plants grown in nutrient solution were lost as osmotic potentials decreased. Healthy plants maintained higher root-shoot ratios than infected plants at all stress levels. The decreases in root-shoot ratios of infected plants represent a morphological basis for reduced stress tolerance and subsequent increased mortality of infected plants during periods of water stress. EFFECT OF WATER STRESS AND INFECTION BY USTILAGO STRIIFORMIS OR UROCYSTIS AGROPYRI ON LEAF TURGOR AND WATER POTENTIALS OF KENTUCKY BLUEGRASS J L Nus and C F Hodges Crop Science Volume 25 March-April issue Pages 322-326 1985 Plant tolerance to water stress can be measured, in part, by calculating the plants ability to maintain turgor during periods of Kentucky bluegrass water stress. systemically infected by either Stripe Smut or Flag Smut exhibits greater mortality than noninfected plants during periods of water stress suggesting decreased drought tolerance with infection. Infection by either pathogen decreased leaf turgor and water potentials during light and dark periods as compared with noninfected controls. In addition, noninfected plants maintained higher leaf turgor and water potentials than infected plants as nutrient solution osmotic potentials were lowered with polyethylene glycol. Water stress lowered leaf osmotic potentials and relative water contents at zero turgor and decreased the turgid weight/dry weight ratios of noninfected and infected leaves. Noninfected plants exhibited lower osmotic potentials at zero turgor and maintained smaller turgid weight/dry weight ratios after water stress than infected plants, suggesting that infection by either pathogen inhibited osmotic adjustment and cell wall thickening in leaves of Kentucky bluegrass in response to water stress. COMPARATIVE WATER-USE RATES AND EFFICIENCIES, LEAF DIFFUSIVE RESISTANCES AND STOMATAL ACTION OF HEALTHY AND STRIPE SMUTTED KENTUCKY BLUEGRASS J L Nus and C F Hodges Crop Science Volume 26 March-April issue Pages 321-324 1986 Infection by Stripe Smut results in lower leaf-water and turgor potentials of diseased vs healthy Kentucky bluegrass. Pathogen induced water stress is common in diseased plants and may result from a number of factors. Water uptake may be limited by pathogen induced root growth inhibition or vascular blockages. Pathogen induced water stress may arise, in part, from increases in host transpiration due to decreases in cuticular resistance or an inhibition of stomatai movement. Leaves of Merlon Kentucky bluegrass infected with Stripe Smut with immature sori and no visible rupturing of the epidermis did not differ in water use rate or in water use efficiency from healthy plants. Leaves of infected plants with mature sori and moderate to heavy sporulation and subsequent epidermal damage showed sharp decreases in water use rate and water use efficiency compared with healthy plants or infected leaves with immature sori and a visibly intact epidermis. Stomatai closure on infected leaves with immature sori occurred at lower leaf water potentials than on healthy leaves, suggesting a degree of osmotic adjustment in response to pathogen induced water stress. THRESHING THE JOURNALS continued TEMPERATURE AND THE CONTENT OF SPECIFIC SOLUBLE SUGARS OF KENTUCKY BLUEGRASS INFECTED BY USTILAGO STRIIFORMIS OR UROCYSTIS AGROPYRI J P Madsen, C F Hodges and J L Nus Botanical Gazette Volume 144 Number 3 Pages 407-411 1983 Plants of Merion Kentucky bluegrass that are systemically infected with Stripe Smut or by Flag Smut are readily killed by high temperature and drought. Irrigation of infected plants throughout the high temperature and dry periods of the summer substantially reduces the death of Stripe Smut Infected plants but only slightly reduces the death of Flag Smut infected plants. Survival of Stripe Smut infected plants under irrigation is a primary contributing factor to the perennial nature of the pathogen in infected plants and to development of epiphytotics in managed turf. The mean total soluble sugar content of sucrose, glucose and fructose of Kentucky bluegrasss infected by Stripe Smut or by Flag Smut was determined at 10,20 and 30 degrees 68 and 86 degrees Centigrade [50, Fahrenheit]. Sugar content of healthy plants was greatest at 20 degrees Centigrade [68 degrees Fahrenheit], intermediate at 10 degrees Centigrade [50 degrees Fahrenheit] and lowest at 30 degrees Centigrade [86 Sucrose was most degrees Fahrenheit]. abundant at all temperatures. Sucrose and glucose were most evenly distributed among leaves, crowns, roots and rhizomes at 20 degrees Centigrade [68 degrees Fahrenheit]. The greater proportion of sucrose and glucose was in leaves at 10 and 30 degrees Centigrade [50 and 86 degrees Fahrenheit]. Fructose was very low in healthy plants at 30 degrees Centigrade [86 degrees Fahrenheit]. Plants infected with Stripe Smut or by flag Smut showed a substantial decrease in mean total sugar content at all temperatures. The decrease in sugars induced by Flag Smut was greater than that caused by Stripe Smut at 10 and 20 degrees Centigrade [50 and 68 degrees Fahrenheit]. RESIDUAL STRIPE SMUT CONTROL IN KENTUCKY BLUEGRASS WITH REDUCED FUNGICIDE LEVELS P H Dernoeden HortSclence Volume 24 Number 5 Pages 796-798 1989 Stripe Smut is a destructive disease of Merion and several other cultivars of Kentucky bluegrass. Stripe Smut infection can result in severe injury. when turf is subjected to drought stress, and may be enhanced under high nitrogen alone or high nitrogen plus low phosphorus and potassium fertility. Fungicides were foliar-applied to a diseased stand of Merion Kentucky bluegrass in spring while disease symptoms were evident. Sequentially applied [14 day interval] of Triadimefon and Terbuconazole provided excellent control and commercially acceptable turfgrass quality. Propiconazole also provided good disease control. Observations and data collected over three years do not support the view that Stripe Smut infected plants die during summer stress periods, thereby controlling the disease by reducing large populations of perennially infected plants. YELLOW TUFT MANAGING YELLOW TUFT DISEASE P H Dernoeden and N Jackson Journal of the Sports Turf Research Institute Volume 56 Pages 9-17 1980 Yellow Tuft disease of turfgrass is caused by a downy mildew fungus. Severe infection mars the appearance and playability of putting surfaces and may render Kentucky bluegrass sod temporarily unsalable. Application of six nitrogenous fertilizers reduced the intensity of Yellow Tuft disease symptoms in a heavily infected Jamestown Chewings fescue, Kingstown velvet bentgrass sward. Reduction of disease symptoms by the fertilizers was ascribed to improved color and density afforded by nitrogen. Nutrients applied to a sand medium supporting plants infected with Scleropthora macrospora enhanced the spore producing capacity of the mycelium contained within these plants. Fertilizers, therefore, masked disease symptoms, but did not cure the disease. The fungicide Subdue or Ridomil arrested any further mycelial colonization of developing leaves and rhizomes from crowns of infected Kentucky bluegrass plants. Jamestown Chewings fescue plants infected with Yellow Tuft persisted for a minimum of two years. Developing axillary buds can escape systemic invasion of mycelium from infected crowns and eventually those downy mildew free tillers may replace the original diseased plant. This may account for the ephemeral nature of this disease. THRESHING THE JOURNALS continued SUPERFICIAL FAIRY RINGS EFFECT OF FUNGICIDES ON THE OCCURRENCE AND GROWTH IN VITRO OF BASIDIOMYCETES ASSOCIATED WITH SUPERFICIAL FAIRY RINGS IN CREEPING BENTGRASS K E Kackley, P H Dernoeden and A P Grybauskas Plant Disease Volume 73 Number 2 Pages 127-130 1989 Superficial fairy rings in turf are incited by numerous thatch-inhabiting Basidiomycetes. The term superficial fairy ring was first used in 1981 to identify the diverse group of diseases also described in the literature as white patch, superficial white patch or rings or simply as circular patches. A majority of the causal fungi remain unidentified. The appearance of superficial fairy rings has previously been associated with lite use of Benomyl. It also develops in the absence of Two isolates of fungicide use. Basidiomycetes exhibiting similar colony characteristics and temperature optima for growth were obtained from fairy rings where Benomyl was either riot used or was used extensively. Growth of the isolates was not stimulated by incubation at 25 degrees Centigrade [77 degrees Fahrenheit]. Observations of growth in vitro and in the field do not support the premise that Benomyl predisposes turf to Fairy Ring by stimulating mycelial growth. MTCRODOCHIUM NIVALE VARIATION AMONG ISOLATES OF MTCRODOCHIUM NIVALE COLLECTED FROM WHEAT AND TURFGRASSES L Litschko and L L Burpee Transactions of the British Mycological Society Volume 89 Number 2 Pages 252-256 1987 Isolates of Microdochium nivale collected from turfgrasses in southern Ontario could not be differentiated from isolates collected from winter wheat on the basis of conidia! morphology, conidlogenesis, response in vitro to several fungicides, growth at 10 or 20 degrees Centigrade [50 or 68 degrees Fahrenheit] or asexual compatibility among thalli. Four isolates from wheat produced perithecia homothallically. isolates from turfgrasses produced perithecia only when paired with other isolates from turfgrass or wheat. GRAY SNOW MOLD SUPPRESSION OF GRAY SNOW MOLD ON CREEPING BENTGRASS BY AN ISOLATE OF TYPHULA PHACORRHIZA L L Burpee, L M Kaye, L G Goulty and M B Lawton Plant Disease Volume 71 Number 1 Pages 97-100 1987 At least six species of low temperature- tolerant plant pathogenic fungi incite snow mold diseases of turfgrasses in cool, humid and cool, subhumid climates. Field studies were conducted in 1983 and 1984 to determine the effects of Typhula isolates alone and in combination on creeping bentgrass. Isolate T011 was nonpathogenic; isolate T004 caused Foliar Blight and Crown Decay. Significantly less foliar necrosis was observed on bentgrass inoculated with a combination of isolates T011 and T004 than on bentgrass inoculated with isolate T004 alone. Sections of a creeping bentgrass golf green with a history of infection by Typhula ishikariensis showed 44 and 70 percent less Gray Snow Mold when infested with wheat grain inoculum of Typhula phacorrhiza in 1983 and 1984, respectively. THRESHING THE JOURNALS continued ROOT CORTICAL DEATH The natural senescence in root ROOT CORTICAL DEATH IN RELATION TO INFECTION OF Kentucky BLUEGRASS BY PHIALOPHORA GRAMINICOLA R W Smiley and D E Giblin Phytopathology Volume 76 Number 9 Pages 917-922 1986 Nonpathogenic lysis of nuclei in the cortex cells of roots has been termed root cortical death. cortices and root cortical death is a highly regulated process, occurring first in the epidermal layer, then continuing, one cortical layer at a time, toward the endodermis. Numbers of dead cortical cells increase with increasing distance from the root apex, but cells of the innermost cortical layer and the endodermis often retain their nuclei much longer than cells of the epidermis and outer and middle cortex. Adelphi, Merlon, Nassau and Nugget Kentucky bluegrasses were examined for influence of temperature and shading on natural autolysis of nuclei in root cortex cells, a process called Root Cortical Death. Higher temperatures increased the magnitude of Root Cortical Death and shading reduced the rate of anucleation in the presence of the root­ infecting pathogen Phialophora graminicola. Root Cortical Death assessments in Kentucky bluegrasses may be useful in breeding and selecting cultivars with improved resistances to root pathogens and environmental stresses. NEMATODES POPULATION DYNAMICS OF BELONOLAIMUS LONGICANDATUS AND CRICONEMELLA ORNATA AND GROWTH RESPONSE OF BERMUDAGRASS AND OVERSEEDED GRASSES ON GOLF GREENS FOLLOWING TREATMENT WITH NEMATICIDES L T Lucas Journal of Nematology Volume 14 Number 3 Pages 358-363 1982 Belonolaimus longicaudatus has been associated with severe damage on bermudagrass in sandy soils of the Southeastern United States, and nematicides are often needed to grow good quality turf when this nematode is present. Improvements in turf quality were observed within 4 weeks after treatment with Phenamiphos and Fensulfothion. These two nematicides varied in reduction of nematodes depending on specific nematode, time following treatment and time of year. The percent area covered by prostrate spurge the year following treatment was reduced with Phenamiphos, but not with Fensulfothion. PATHOGENICITY - CONDITIONS INFLUENCING PATHOGENICITY OF SOME SELECT SOILBORNE DEMATIACEOUS HYPTOMYCETES ON GERMINATING SEED OF RED FESCUE J P Madsen and C F Hodges Phytopathology Volume 70 Number 1 Pages 21-25 1980 Seed inoculation and soil and seed infestation methods with Drechslera sorokiniana reduced the amount and rate of seedling emergence and increased seedling mortality. Curvularia genicularia reduced seedling emergence, but had no effect on rate of emergence or on seedling mortality. Pathogenicity of both organisms was greater in autoclaved soil than in nonautoclaved soil. Seedling emergence in soil infested with the combination of both fungi was greater than that in response to either organism alone which suggests competition between the organisms in the soil environment. A synergistic pathogenic interaction between the organisms is suggested. THRESHING THE JOURNALS continued INTERACTION OF SEQUENTIAL LEAF SENESCENCE OF KENTUCKY BLUEGRASS AND PATHOGENESIS BY DRECHSLERA SOROKINIANA AS INFLUENCED BY POSTEMERGENT HERBICIDES C F Hodges Phytopathology Volume 70 Number 7 Pages 628 630 1980 Leaf Spot on Kentucky bluegrass is chronic throughout the growing season and numerous cultural practices influence disease The influence of four development. 2,4 D, 2,4,5 T, 2,4,5 TP, chorophenoxy - MCPP - and one benzoic acid - Dicamba postemergent herbicides on pathogenesis by Drechslera sorokiniana on progressively older leaves of Kentucky bluegrass was determined. Disease increased on each successively older leaf of untreated control plants and a direct relationship was established between increasing leaf senescence and pathogenesis. The soil drench application of 2,4-D and the spray and soil-drench application of 2,4,5 T, MCPP and Dicamba increased the level of disease on leaves of all ages above that of the controls and on each older leaf of the plants in the respective treatments. Extensive chlorosis and straw-colored blighting was associated with pathogenesis on the two oldest leaves of shoots exposed to 2,4,5 T, MCPP and Dicamba and was suggestive of premature leaf senescence. It was hypothesized that the Increase in pathogenesis on progressively older leaves of plants exposed to auxin like herbicides is the function of a host pathogen herbicide interaction that enhances the rate of sequential leaf senescence. INFLUENCE OF PREEMERGENCE HERBICIDES ON PATHOGENESIS BY DRECHSLERA SOROKINIANA ON SEQUENTIALLY SENESCENT LEAVES OF KENTUCKY BLUEGRASS C F Hodges Canadian Journal of Botany Volume 60 Pages 186-190 1982 Preemergence herbicides, Benefin, Bensulide, DCPA and Siduron, stimulated, had no effect on, or inhibited Leaf Spot on shoot leaves of various ages. Stimulation of Leaf Spot primarily occurred on the two youngest visible leaves of the shoot and was induced by Bensulide and DCPA. Benefin and Siduron had no effect on Leaf Spot development on the two youngest leaves and none of the herbicides inhibited Leaf Spot on the two youngest leaves. The various herbicides were primarily inhibitory of Leaf Spot development oh the two oldest leaves of the shoot. PREEMERGENCE HERBICIDES AND THE SEVERITY OF LEAF SPOT CAUSED BY DRECHSLERA SOROKINIANA ON KENTUCKY BLUEGRASS C F Hodges Phytopathology Volume 71 Number 7 Pages 720-722 1981 The ability of herbicides to stimulate or inhibit diseases induced by fungal pathogens is well documented. The Leaf Spot induced in Kentucky bluegrass generally is stimulated by auxin-like postemergent herbicides 2,4-D, 2,4,5-T, MCPP and Dicamba. The stimulation is associated with an interaction between the herbicides and sequential leaf senescence that enhances pathogenesis on each older leaf. Four preemergence herbicides, Benefin, Bensulide, DCPA and Siduron, were evaluated for effect on the severity of Leaf Spot on Kentucky bluegrass. The results suggest that, except for Benefin and Bensulide stimulation or inhibition of Leaf Spot by preemergence herbicides is concentration specific. THRESHING THE JOURNALS continued NITROGEN-INDUCED CHANGES IN THE SUGARS AND AMINO ACIDS OF SEQUENTIALLY SENESCING LEAVES OF KENTUCKY BLUEGRASS AND PATHOGENESIS BY DRECHSLERA SOROKINIANA P W Robinson and C F Hodges Phytopathology Z Volume 101 Pages 348-361 1981 The effect of ammonium nitrate on the soluble sugar and free amino acid content of sequentially developing and senescing leaves of Kentucky bluegrass was determined and evaluated relative to pathogenesis by Drechslera sorokinlana. Ammonium nitrate induced a differential redistribution of soluble sugars in leaves of different ages. Total sugars [fructose, glucose, sucrose, raffinose] increased in the two youngest leaves of the shoot and decreased in the *two oldest leaves. Total free amino acids increased significantly only in leaf three [leaf 1 youngest and leaf 4 oldest] in response to ammonium nitrate. Leaves 2 and 3 were most responsive to pre and post infection development of Drechslera sorokinlana on ammonium nitrate treated plants. These observations suggest that the "high-low" sugar concept of plant disease must be differentially applied to sequentially developing and senescing leaves and that cultural factors [nitrogen fertilization] may further modify such interactions. The results also suggest that the amino acid pool may have a greater influence on the preinfection germination and growth of conidia on the leaf surface than that of sugars. SOLUBLE SUGARS AND FREE AMINO ACIDS OF KENTUCKY BLUEGRASS EXPOSED TO CHLOROPHENOXY HERBICIDES AND PATHOGENESIS BY DRECHSLERA SOROKINIANA J P Madsen and C F Hodges Phytopathology Volume 73 Number 5 Pages 737-740 1983 Leaf Spot of Kentucky bluegrass caused by Drechslera sorokinlana [Helminthosporium sativum P K and B] is influenced by cultural practices such as nitrogen fertilization and mowing height and by such environmental factors as light and temperature. The influence was evaluated of two postemergence herbicides, MCPP and 2,4,5-TP, on total and individual soluble sugars and free amino acids of leaves of herbicide tolerant Kentucky bluegrass and on the severity of Leaf Spot. The incidence of Leaf Spot on plants growing in soil treated with MCPP was more severe than Leaf Spot of the untreated controls. 2,4,5-TP had no influence on the severity of the Leaf Spot. Leaves of plants growing in soil treated with either herbicide had lower sucrose and total soluble sugar amounts than did control leaves. The decrease in sucrose and total soluble sugars in uninoculated leaves of herbicide-treated plants was significantly correlated with increased Leaf Spot severity of inoculated leaves of herbicide treated plants. DEVELOPMENT OF DRECHSLERA SOROKINIANA ON SEQUENTIALLY SENESCENT LEAVES OF KENTUCKY BLUEGRASS EXPOSED TO POSTEMERGENCE HERBICIDE COMBINATIONS C F Hodges Plant Disease Volume 68 Number 3 Pages 213-215 1984 Combinations of 2,4-D, 2,4,5-TP, MCPP and Dicamba were applied as soil drenches to Kentucky bluegrass to determine their effect on development of Drechslera sorokinlana. Disease response to the herbicide combinations differed between the two youngest and two oldest leaves of the shoot. Disease severity on the youngest leaves decreased in response to combinations including 2,4,5-TP. Disease development was inhibited by 2,4-D plus Dicamba on the two youngest leaves. Only MCPP plus Dicamba showed on additive stimulatory effect on disease on the two youngest leaves. Most herbicide combinations induced an additive stimulation of Leaf Spot on the two oldest leaves. Only 2,4-D plus 2,4,5-TP on leaf 3 and MCPP plus Dicamba on leaves 3 and 4 failed to stimulate disease additively. THRESHING THE JOURNALS continued EFFECT OF CHLOROPHENOXY HERBICIDES ON FREE AMINO ACIDS IN SEQUENTIALLY SENESCENT LEAVES OF KENTUCKY BLUEGRASS AND ON PATHOGENESIS BY BIPOLARIS SOROKINIANA J P Madsen and C F Hodges Phytopathology Volume 74 Number 12 Pages 1407-1411 1984 The herbicides MCPP and 2,4,5-TP were evaluated for effect on the free amino acid content of four sequentially aged leaves of herbicide tolerant Kentucky bluegrass and on subsequent Leaf Spot severity after infection by Bipolaris sorokiniana. The content of free amino acids in uninoculated leaves of herbicide untreated control plants generally declined from the youngest to the oldest leaf. The herbicides had no influence on total amino acids in leaves of any age. Infected leaves of plants treated with either herbicide generally were more severely diseased than leaves of herbicide untreated control plants, but only MCPP treated plants had Increased Leaf Spot on the youngest leaf. The results suggest that changes in free amino acid levels in leaves after treatment of Kentucky bluegrass with chlorophenoxy herbicides may be a component of physiological changes that are similar to changes during senescence. Changes in amino acid content induced by chlorophenoxy herbicides may promote leaf senescence in Kentucky bluegrass and the subsequent enhancement of Leaf Spot. However, changes in amino acid content independent of other metabolic changes occurring during senescence probably have limited direct Influence on leaf spot severity. NITROGEN EFFECTS ON THE PATHOGENICITY OF DRECHSLERA SOROKINIANA AND CURVULARIA GENICULATA ON GERMINATING SEED OF RED FESCUE J P Madsen and C F Hodges Phytopathology Volume 70 Number 11 Pages 1033-1036 1980 Creeping red fescue is a fine-textured species adapted to turf culture and is susceptible to Drechslera sorokiniana which induces Leaf Spot, Seed and/or Seedling Rot and Root Rot. Creeping red fescue also is susceptible to Leaf-tip Dieback and Seed and/or Seedling Rot caused by Curvularia geniculata. The effects of ammonium sulfate and calcium nitrate on the pathogenicity of these two fungi singly and in combination on germinating seed of creeping red fescue were evaluated. Total seedling emergence from uninoculated seed in nonautoclaved soil was less than that in autoclaved soil in response to both nitrogen sources. These responses were suggestive of direct nitrogen toxicity to the germinating seed in autoclaved soil and of stimulation of unknown biotic factors in nonautoclaved soil that when combined with direct toxicity, additively reduced total emergence. The combination of the pathogens, together with the highest concentration of either nitrogen source, produced the most severe reduction in total seedling emergence. These results suggest a combination of direct, toxicity to germinating seed and an enhancement of the pathogenicity by nitrogen containing compounds. EFFECT OF CHLOROPHENOXY HERBICIDES ON SOLUBLE SUGARS AND ON PATHOGENESIS BY DRECHSLERA SOROKINIANA TN SEQUENTIALLY SENESCENT LEAVES OF KENTUCKY BLUEGRASS J P Madsen and C F Hodges Phytopathology Volume 73 Number 9 Pages 1296 1299 198 3 Tn studies of the four most recently formed leaves on shoots of Kentucky bluegrass, severity of Leaf Spot increased on progressively older leaves of control, 2,4,5- TP and MCPP treated plants. Each progressively older leaf generally was more severely diseased on herbicide treated plants than on control plants except for leaf three. Total soluble sugar content of plant leaves treated with either herbicide was less than that of controls; sucrose, glucose and fructose constituted the loss. Inoculation of the two youngest leaves of control plants also decreased total soluble sugars; inoculation of leaf three of control plants increased sugars and had no effect on leaf four. Inoculation of leaves of all ages on plants treated with MCPP or 2,4,5-TP induced an increased in soluble sugars, primarily in glucose and fructose. Herbicide induced changes in the soluble sugar content of sequentially developing and senescing leaves are believed to be related to factors that promote senescence and enhance leaf spot severity. THRESHING THE JOURNALS continued EFFECTS OF NONIONIC SURFACTANTS ON ETHYLENE AND CHLOROPHYLL CONTENT OF KENTUCKY BLUEGRASS LEAVES INFECTED WITH BIPOLARIS SOROKINIANA C M Ciaccio and C F Hodges Plant Disease Volume 71 February issue Pages 149-152 1987 Use of surfactants on turfgrasses to improve effectiveness of foliar-applied pesticides and to increase water infiltration and percolation through' hydrophobic soils is increasing. There is evidence that besides reducing surface tension at interfaces, surfactants are capable of exerting favorable and adverse biochemical effects on living organisms. Research was initiated to determine the effects of Aqua-Gro, Hydro-Wet, and Surf-Side 37 on the endogenous ethylene and chlorophyll content of healthy and Bipolar is sorokiniana- infected leaves of Kentucky bluegrass. Short and long exposure of uninoculated plants to the surfactants failed to cause any changes in endogenous ethylene. After inoculation, plants from all treatments showed an increase in endogenous ethylene that peaked 48 to 72 hours and then declined by 96 hours. Surfactants induced increases and decreases in leaf chlorophyll content. Inoculation of leaves of plants exposed to surfactants resulted in a progressive loss of chlorophyll over time. Ethylene chlorophyll interactions are important in disease relationships. PHOTOMORPHOGENICAILY DEFINED LIGHT AND RESISTANCE OF KENTUCKY BLUEGRASS TO DRECHSLERA SOROKINIANA K N Nilsen and C F Hodges Plant Physiology Volume 65 Pages 569-573 1980 The fungus pathogen Drechslera sorokiniana infects the leaves, stems and roots of numerous grass and cereal species. Accurate resolution of Drechslera sorokiniana Leaf Spot development required evaluation of separate leaf ages due to the sequential appearance, development, and senescence of Kentucky bluegrass leaves. Disease development under varying light treatments was greatest on leaf 4 [oldest, post mature] followed by leaf 1 [youngest, premature]. Low levels of disease occurred on leaves 2 and 3 [mature]. Light greater than natural light was most disease promotive on leaf 1. Light less than natural light was most disease promotive on leaf 4. These responses indicate that inherent resistance or susceptibility expressed by Kentucky bluegrass to pathogenesis by Drechslera sorokiniana is regulated in part by leaf age [developmental senescent stage and by photomorphogenically defined light quality. ETHYLENE-INDUCED CHLOROSIS IN THE PATHOGENESIS OF BIPOLARIS SOROKINIANA LEAF SPOT OF KENTUCKY BLUEGRASS C F Hodges and L W Coleman Plant Physiology Volume 75 Pages 462-465 1984 Ethylene production in plants infected by fungal pathogens often exceeds that produced by healthy plants. Endogenous ethylene of Kentucky bluegrass leaves infected by Bipolaris sorokiniana was evaluated as a factor in leaf chlorosis during pathogenesis. Detectable increases in edogenous ethylene of leaves of in tact plants under normal ambient pressure occurred 12 hours after inoculation and was maximum at 48 hours; from 48 to 96 hours the ethylene progressively decreased. Necrotic lesions surrounded by chlorotic halos occurred on infected, leaves between 24 and 48 hours. Midvein chlorosis Interconnecting individual lesions and complete chlorosis of all tissues not directly affected by the lesions occurred between 72 and 96 hours, after maximum production of ethylene at 48 hours. The chlorophyll loss in infected leaves by 96 hours was 44 percent compared with controls. Observations suggest that ethylene may function late in pathogenesis of this host­ pathogen interaction and is responsible for much of the chlorophyll loss after its maximum production at 48 hours. THRESHING THE JOURNALS continued THE EFFECT OF METHIONINE ON ETHYLENE AND 1- AMINOCYCLOPROPANE-l-CARBOXYLIC ACID PRO­ DUCTION BY BI POLARIS SOROKINIANA L W Coleman and C F Hodges Phytopathology Volume 76 Number 9 Pages 851-855 1986 Bipolaris sorokiniana is a serious pathogen of numerous grass species. Leaves of Kentucky bluegrass infected by this pathogen often produce a Leaf Spot that. is characterized by a necrotic lesion surrounded by a chlorotic halo. progresses, symptoms are characterized by midvein chlorotic streaking, interconnecting lesions and eventually complete chlorosis of all leaf tissue not directly infected. Research was initiated to determine the effect of exogenous methionine on the ability of this fungal pathogen to produce ethylene and intermediates of the ethylene biosynthetic pathway of higher plants. Differences in the use of 1- aminocyclopropane-l-carboxylic acid [ACC] and Methionine for ethylene production by the pathogen suggests that the pathogen does not efficiently convert ACC to ethylene and that ethylene may be produced via more than one pathway. As the disease ETHYLENE BIOSYNTHESIS IN KENTUCKY BLUEGRASS LEAVES IN RESPONSE TO INJURY OR INFECTION BY BIPOLARIS SOROKINIANA L W Coleman and C F Hodges Phytopathology Volume 77 Number 9 Pages 1280-1283 1987 Ethylene production by stressed, mechanically wounded and diseased plants has been studied extensively. Biosynthesis of ethylene in host-pathogen interactions is believed to differ from that of wounded plants or plants undergoing changes in development. Research was initiated to evaluate 1-amino­ cyclopropane-1 carboxylic acid [ACC] synthase activity, content and endogenous ethylene of Kentucky bluegrass leaf blades subjected to wounding or infection by Bipolaris sorokiniana. Infection resulted in peak ethylene product ion 36 hours after inoculation followed by peak ACC synthase activity at 72 hours. Endogenous ethylene produced in response to infection was somewhat greater than that produced in response to wounding and peak ACC synthase activity was more than five times greater in response to infection than to wounding. YOU WANT THE DAY OFF ? "Let’s look at what you are asking for: There are 365 days per year available for work. There are 52 weeks per year in which you already have 2 days off per week, leaving 261 days available for work. Since you spend 16 hours each day away from work, you have used up 170 days, leaving only 91 days available. "You spend 30 minutes each day on your coffee break - that accounts for 23 days each year, leaving only 68 days available. With a 1 hour lunch period each day, you have used up another 48 days, leaving only 22 days available for work. "You normally spend 2 days per year on sick This leaves you only 20 days leave. available for work. We offer 5 holidays per year, so your available working time is down to 15 days. We generously give you 14 days vacation per year, which leaves you only 1 day available for work, and I'll be darned if you're going to take that day off !" George White, VP Assn of Community Travel Clubs St Louis In AssociationTrends 11/17/89 TURF MANAGEMENT DIGEST Dr William Knoop is Editor of this complete reference guide to effective turf management published by Farm Press Publications [P 0 Box 1420, Clarksdale MS 38614]. This will be published annually in January. Twenty one chapters range from Turfgrasses, Establishment, Soils, Equipment Management, Small Engines and chapters on various maintenance procedures,. There is a Turf Meeting Calendar, Conversion Tables and a Glossary of Terms. 168 pages Cost single copy: shipping] $14.95 [plus $3.00 TURFGRASS AGRONOMY MONOGRAPH 32 Turfgrass. Agronomy Monograph 32, edited by Drs Waddington, Carrow and Shearman, updates some of the topics from Monograph 14 published in 1969. Five sections contain 22 chapters written by Turfgrass Specialists. The first section explores the turfgrass industry and includes "Turfgrass Science - An Overview" by Dr Eliot Roberts, Dr Wayne Huffine, Dr Fred Grau and Mr Jack Murray. Other sections are: Turfgrass Physiology, Soils & Water, Management and Research Methods. teachers, This source of information will be a valuable resource for turfgrass professionals, and industry representatives. American Society of Agronomy Book Order' Department 677 So Segoe Road, Madison WI 53711-1086 828 pages 1992 $42.00 HEALTHY TURF, HEALTHY EARTH A 10 page booklet with color pictures and graphics that attempts to answer questions and clear up some confusion about lawn care products used to maintain a healthy yard. Benefits of the grass system, what makes healthy turf, products, especially fertilizer are covered in an easy to read format. The Fertilizer Institute 501 2nd St NE Washington DC 20002 202/675-8250 COMPENDIUM OF TURFGRASS DISEASE, Second Edition The American Phytopathological Society has released the second edition of The Compendium of Turfgrass Disease by Drs Richard Smiley, Peter Dernoeden and Bruce Clarke. The Lawn Institute is one of the four financial sponsors. This is a general and practical reference for all those involved in the culture of fine turf. It blends descriptive terminology with the more technical language of plant pathology to serve a diverse audience. The emphasis is on diseases of North America. Following the Introduction, there are sections on: Noninfectious Diseases; Infectious Diseases; Other Agents, Diseases and Disorders; Ecology and Taxonomy of Pathogenic Fungi; Disease Control Strategy; and Disease Diagnosis. The American Phytopathological Society 3340 Pilot Knob Road St Paul, Minnesota 55121-2097 98 pages 1992 PENNSYLVANIA TURFGRASS SURVEY The Pennsylvania Turfgrass Council and PA Department of Agriculture sponsored a survey which has recently been released. The Summary Report shows that Pennsylvania had 1,999,408 acres of turfgrass in 1989. Home lawns covered 1,355,000 acres and roadsides 102,073 acres. Total turf maintenance expenditures were $1.46 billion with 77 % of this being for home lawns. The value of al] equipment used for turf maintenance was $2.95 billion. Dr Peter For more information contact: Landschoot or Dr Thomas Watschke, Department of Agronomy, 116 ASI Bldg, Pennsylvania State University, State College PA 16802 [814/863- 1017]. THE LAWNSCAPE: A NATURAL SCIENCE LABORATORY The lawn is an excellent and an easily available ecosystem that, in fact, is a wonderful science laboratory. An introduction to biology, ecology, entomology, pathology, microbiology, chemistry, mineralogy, and other basic sciences can be taught using experiments on the school and/or students lawns. Material on the lawnscape has been adapted by Dr Richard Duble of Texas A & M University for use by teachers in schools with an overview, exercises and tests. This is an excellent beginning for a curriculum in sclence/math based on the lawn. It would seem that this forms the basis for a variety of materials that might be used with youngsters who will in a few years have their own lawns and presently pass information on to their parents. WHAT A WONDERFUL OPPORTUNITY FOR THE LAWN AND TURF INDUSTRY TO DISTRIBUTE ACCURATE INFORMATION AND TO HAVE POSITIVE IMPACT ON THE PUBLIC ! For more information contact: Dr Richard Duble, Soil & Crop Sciences Dept, Texas A & M University, College Station TX 77843 [409/845-4826]. Bulk Rate U.S. Postage PAID Pleasant Hill TN Permit No. 3 THE LAWN INSTITUTE County Line Road P. O. Box 108 Pleasant Hill. Tennessee 38578-0108 ADDRESSEE.... HELP US KEEP YOUR ADDRESS CORRECT........................ If address is wrong in any respect, please correct directly, and return to us. THANK YOU JAMES SNOW GREEN SECTION GOLF HOUSE FAR HILLS NJ 07931 Lawn Institute Harvests is published four times a year by The Better Lawn and Turf Institute. The headquarters office address is P O Box 108, Pleasant Hill, Tennessee 38578-0108. Phone: 615/277-3722. Inquiries concerning all aspects of this publication may be addressed to the headquarters office. The Better Lawn and Turf Institute is incorporated as a nonprofit business league formed exclusively for educational and research purposes concerned with agronomic, horticultural and landscape concepts. Lawn Institute Harvests is dedicated to improved communications among turfgrass seed and allied turf industries and other firms, businesses, organizations and individuals with lawngrass research and educational interest and concerns. Editor: Eliot C Roberts, PhD Associate Editor: Beverly G Roberts, MA Printer: Crossville Chronicle (Tennessee)