green world AN INDUSTRYWIDE PUBLICATION OF THE NEW JERSEY TURFGRASS ASSOCIATION VOL. 14 No. 3 November/December 1984 Pythium Induced Root Dysfunction: A Disease of Creeping Bentgrass on High Sand Content Greens Clinton F. Hodges Professor of Horticulture and of Plant Pathology Department of Horticulture Iowa State University Ames, Iowa 50011 A new Pythium disease of creeping bentgrass has been recognized that at­ tacks the roots of plants grown in high sand content greens. The disease oc­ curs primarily on old golf courses where the greens have been rebuilt with sand; the disease is rarely found on newly constructed golf courses with sand greens. Creeping bentgrass established on the renovated greens in the fall of the growing season grows well and establishes a good cover by winter. The grass grows well during the mild periods of spring and early summer of the following year. With the arrival of hot, humid weather, the turf begins to die in a pattern typical of Pythium—induced “cottony blight’’ or “foliar blight.’’ Close examination of diseased plants, however, fails to show any Pythium in­ fection of above ground portions of the plants. Examination of root systems of diseased plants reveals white, normal appearing roots that are field diagnos­ ed as being healthy. No lesions or rot are present on the roots. When such roots are incubated under laboratory conditions, Pythium species frequently grow from the root tips, cortical cells, and vascular system within 6 to 12 hours. The Pythium—infected roots can result in the complete killing of a green within 7 to 10 days. Case histories of greens that have been attacked show that the disease may reoccur up to three growing seasons after the first outbreak of the problem. After three years, the disease may cease to be a problem or may occur at a much reduced level of activity. Research has established that Pythium arrhenomanes and P. aristosporum are the pathogens respon­ sible for the disease. P. arrhenomanes Fig. 1. Growth of eight week old creeping bentgrass plants root inoculated with Phythium arrhenomanes or P. aristosporum and grown in sand. From left to right: healthy control plant, P. arrlenomanes infected (Canadian isolate), P. arrhenomanes infected (Iowa isolate), and P. aristosporum infected (Iowa isolate). is the more common of the pathogens and occurs in all regions of the North American continent. This species causes a root rot of cereals in Canada and northern U.S.A. and has been a severe pathogen on roots of sugarcane in the southern U.S.A. P. aristosporum is restricted to the cooler regions of the north central and northwest United States and Japan. This pathogen causes snow blight of cereals and grasses in Japan. Inoculation of creeping bentgrass roots with either Pythium species in controlled studies results in a severe reduction of plant growth. Total weight of plants with roots infected by P. ar­ rhenomanes or P. aristosporum is 16% and 32%, respectively, of healthy con­ trol plants (Fig. 1). Examination of roots 3 to 4 weeks after inoculation reveals Pythium mycelium in root hairs and in somewhat swollen regions behind root tips. It seems that root hairs and root tips provide the primary sites for infec­ tion. Roots examined 8 weeks after in­ oculation are completely penetrated by the mycelium; the pathogens are found in abundance in the cortex, vascular tissue, and root tips. Some root tips are devitalized and the roots may be slight­ ly buff colored compared with healthy roots. It is remarkable, however, that with the extensive infection of the roots there is no rot and visible lesions are ex­ tremely rare. The fact that growth of in­ fected plants is severely reduced and that there are no rotted roots suggests that the reduction in growth of infected plants is due to the inability of infected roots to function properly. Infection may interfere with water uptake and/or other metabolic functions of the root. Because infection seems to interfere with root function, the disease has been termed “Pythium — induced root dysfunction.’’ (continued page 4) Comments and Opinions . . Yours and Ours A Granular Nematicide MOCAP 10G, a nematicide/insec- ticide is now labeled for use on home lawns by the certified applicator. Profes­ sional turf persons can legally treat Ken­ tucky bluegrass or zoysiagrass lawns before they are damaged by nematodes. This chemical should be applied only to well established lawns with a drop spreader. Granules must be swept from walks and driveways. Sod and soil should not be handled for 21 days. While the nematicide should be applied only over dry foliage, 1/2 inch of water is used to wash the active ingredient into the soil to avoid contact with unprotected humans and animals. A dose rate of 5-7 pounds of MOCAP 10G is used on 1,000 square feet or 200-300 pounds per acre. Ronald F. Myers Professor—Plant Pathology Rutgers University A government that robs Peter to pay Paul can always depend upon the sup­ port of Paul. George Bernard Shaw No amount of ability is of the slightest avail without honor. Andrew Carnegie Weed Control — 1930 Ground ivy, Gleconia hederacea, is the most familiar name for this lawn weed but there are others by which it is known in some localities: for example, Field Balm, Gill-over-the-ground, Gill- Ale, Ale-hoof, and Cat’s-foot. The old method of exterminating Ground Ivy was to skim off the shallow layer that contained the roots and relay new sod or reseed. Now (1930) it has been discovered that the plants can be entire­ ly destroyed without lasting injury to the grass by a single spraying with a solu­ tion of Sodium Chlorate. Care should be exercise in the use of Sodium Chlorate. It is inflammable and will ignite from friction if allowed to dry on clothing. (Lawn Care, February 1930). Comment: This was our best control until the modern herbicide era. Extra Warning. Keep your bluejeans wet or be ready for instant removal before a flash chlorate fire. DECEMBER LAWN FERTILIZATION Unscientific Elimination of Chemicals For those who have responsibility for a Kentucky bluegrass-fine fescue turf area that has not received enough fer­ tilization for adequate growth, late fall application can improve the color and density by late winter or early spring. Treatment with a N-P-K fertilizer that supplies 1 — 1-1/2 lbs. N/M per square foot will give a good response. If the area has had considerable fertilization in the past, nitrogen alone may be ade­ quate. During fall it is easier to apply quick-acting types of nitrogen without turf injury. Late fall application usually reduces the need for spring fertilization. ABSTRACT: Effect of Shading on Root Growth of Transplanted Sod. By: BB. Hessweltine and C.R. Skogley ASPA Turf News, January-February 1984. Grass root initiation and growth is a seasonal phenomenon. Studies were in­ itiated in 1976 at the Rhode Island Agricultural Experiment Station for the purpose of studying sod establishment in a shade environment. Two locations were used for these studies: the first received full sunlight while the second, in an adjacent area of mature white oak trees, received about 18% of incident sunlight. By the end of the season it was concluded that lack of adequate light reaching sod in the shaded location was primarily responsible for poor root initia­ tion and growth. With these conclu­ sions, it was decided to do a further study in 1977 to establish the effect of shade level and time of year on rerooting of transplanted sod. After a 28-day growth period, rooting of the sod was tested. Sod used in this study was a one-year-old blend of three Kentucky bluegrasses with a small percentage of red fescue. Plots receiving full sun had significantly greater root strength from April through August than all shade levels tested; however, in September the check and 80% sunlight treatments were statistically similar. In most cases, a decrease in percentage of incident sunlight received appeared strongly cor­ related with a decrease in rooting. It is apparent that sod should be transplanted in shade locations as ear­ ly in spring as possible. With a signifi­ cant degree of shade, prolonged post­ installation care, particularly regarding irrigation, will be necessary. BFC Chemicals Inc. has decided not to challenge the recent decision by the Environmental Protection Agency to cancel most use of the pesticide tox- aphene. “We have reviewed the tox- aphene decision document prepared by the EPA and, although we disagree with the EPA conclusions, we do not intend to challenge the cancellation because of the extreme cost associated with legal proceedings,” BFC Chemicals wrote in a prepared statement. “EPA has made it clear that its evaluation of hazard is based on a worst possible case analysis. Many assumptions of an extreme nature, some of which are con­ trary to known facts, have been used in EPA’s risk assessment.” ’’Moreover, the (EPA) document also fails to acknowledge the more than 30 years of manufacture without any in­ dication of any form of illness in employees representing about 1,000 man years of exposure,” the statement continued. (Landscape and Irrigation, March 1983, pp 24). OFFICERS OF THE N.J.T.A. Dave McGhee, President Joe DeSantis, Vice President Ralph Engel, Secretary William Ritchie, Treasurer Dennis DeSanctis, Past President Henry Indyk, Expo Chairman EXECUTIVE BOARD Samuel Leon Joseph Dodgson John Zajac Joseph W. Manning, Jr. William H. Peterson Robert Dobson William A. Nist John Poksay Douglas Moody Green World is published three times a year by the New Jersey Turfgrass Association, P.O. Box 231, New Brunswick, NJ 08903. Ralph Engel, con­ sulting editor; Veronica M. Malone, managing editor. Please address in­ quiries concerning advertising to William Nist, Lebanon Chemical Co., Dayton, NJ 08810. (201) 329-4011 Aabar, Inc. A-L Services, Inc. Aquashade, Inc. Blue Ridge Peat Farms Brickman Industries Brower Turf Equipment Burton Landscaping Chemlawn Corp. Chevron Chemical Co. D & J Landscaping Dow Chemical, U.S.A. Double Eagle Equipment Co. DuBrow’s Nurseries Elite Land Care, Inc. Farmstead Golf and Country Club Florence Landscaping Svc. Inc. G & G Lawn Service, Inc. Garden Dynamics Garden State Goodall Garfield Williamson, Inc. Green Grass Lawn Maintenance Green Hill Turf Supply Hoffmann LaRoche, Inc. Hummer Turfgrass Systems, Inc. Jade Run Turf & Sod Farm Sustaining Members JEP Sales, Inc. Keystone Lawn Spray Leon’s Sod Farm Limestone Products Corporation Lofts Seed, Inc. A. Lombardi Landscaping MacAndrews & Forbes Co. Wilfred MacDonald, Inc. Metro Milorganite, Inc. Montco/Surf Side National Chemsearch Newton Country Club Nor. Am Chemical Co. Rapp Sod Farms Reid Sod Farms Rockland Chemical Co. O.M. Scott and Sons Seacoast Laboratories, Inc. Somerville Equipment Co. Storr Tractor Co. Sweeny Seed Co. The Terre Co. Tuckahoe Turf Farms Turf Seed, Inc. Vaughan-Jacklin Corp. Andrew Wilson edible — not toxic; nutritious, as a worm to a chicken, a chicken to a man, and a man to a worm. Weed Science Parkmaster The Professional for large areas. COUNTRY CLUB Professional Turf Products The Toro' Parkmaster mows swaths from 30 inches to 18 1/2 feet wide up to 80 acres a day. With a 7 or 9 unit hydraulically-controlled frame, it has a compact pattern of gangs for easy mowing, easy transporting. The Parkmaster is the mowing tractor built to take Spartan gangs. Comes with powerful gas or diesel engine with cab and roll over protection system (ROPS) optional. Storr Tractor Co 3191 US Highway 22 Somerville. NJ 08876 201/722-9830 The Professionals That Keep You Cutting ABSTRACT: White-Rot Fungi and Topdressing Influence on the Composi­ tion of Thatch of Four Turfgrasses, by J. B. Sartain and B.G. Volk. Agronomy Journal 76:359-362,1984. Cores of four highly-thatched turfgrasses (ber- mudagrass, Cynodon dactylon (L.) Pers.; centipedgegrass, Eremochloa ophiuroides; Kentucky bluegrass, Poa pratensis L.; and St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kunt- zel were placed in pots and inoculated with one of four species of white-rot fungi (Polyporous giganteus, Coriolus versicolor, Phebia gigantea, or Phanerochaete chrysosporium). Pots were reinoculated with the appropriate fungus 14 days after the initial inocula­ tion and after the 6-month sampling. Subplot treatments of the split-plot design were three topdressings (none, 0.31 cm sand and 0.31 cm sand contain­ ing 4% colloidal phosphate). Cellulose content of bermudagrass and centipedegrass-thatch cores was significantly reduced by inoculation with Phebia gigantea. The white-rot fungi, Coriolus versicolor, produced the largest reduction in the lignin content of all four turfgrass species. Total ox­ idizable organic material of the ber­ mudagrass and centipedegrass thatch was significantly reduced by the white- rot fungi. In general, topdressing reduc­ ed the cellulose and lignin content of the turfgrasses. Centipedegrass thatch consistently contained higher levels of cellulose and lignin than the other turf­ grass species. Kentucky bluegrass thatch contained the lowest quantity of lignin, and St. Augustinegrass thatch the least cellulose. The overall magnitude of decrease in the com­ ponents of thatch, which were determin­ ed in this study, was not great. Many factors influence the effectiveness of white-rot fungi in degrading cellulose and lignin; therefore, more information is needed on the factors before recom­ mending one or more of these fungi. Comment: Many have thought about this approach. Is there an efficient organism? 18-3-12 70% 18-4-10 90% 18-5-9 50% Soluble Spray Grade s SCU Blends PESTICIDES LEBANON 25% 29-3-5 13-25-12 8-4-24 30% 20-8-8 50% 20-4-10 40% Special Mixes HERBICIDES LEBANON CHEMICAL CORPORATION P O. Box 189 Dayton, NJ 08810 PO. Box 180 Lebanon, PA 17042 Jacobsen Turfcat II GW 224 Wilfred Mac Donald, Inc. 340 Main Avenue Clifton, NJ 07014 201-471-0244 •Jacobsen •National •Giant Vac •Cushman •FMC •Olathe • Gravely • Broyhill • Howard • Smithco •Terra-Care Phythium Dysfunction continued from page 1 There are, at present, more questions surrounding the nature of Pythium— induced root dysfunction than there are answers. There are two questions of im­ mediate interest. 1) Why does the disease occur only on high-sand con­ tent greens and almost exclusively on renovated greens on older golf courses? 2) Can control methods be developed to prevent the disease or to stop it after it has started? The Pythium species responsible for root dysfunction are commonly associated with soils in which grasses are grown. They are not, however, known to cause any problems in a soil medium. It is hypothesized that the microbiology of sand may be dif­ ferent or inadequate to the extent that there is little competition for the Pythium species involved. It is believed that the Pythium species may be pre­ sent in the old collar and apron soils of renovated greens. When the Pythium species comes into contact with the sand it is rapidly colonized and roots are infected. The Pythium infected roots may function adequately during mild growing conditions with damage occur- FERTILIZERS COMBINATIONS OF NITROFORM I.B.D.U. S.C.U. And And WITH INSECTICIDES PRE-EMERGENCE CRABGRASS KILLERS HERBICIDES GRANULAR LIQUID SELECTIVE AND TOTAL FUNGICIDES GRANULAR FLOWABLE WETTABLE POWDERS INSECTICIDES GRANULAR LIQUID WETTABLE POWDERS Ask your supplier or write: ROCKLAND CHEMICAL CO., INC. Passaic Ave.. West Caldwell. N.J. ring only during periods of stress. The fact that the disease remains a serious problem for about three years after reconstruction and then diminishes in severity also is suggestive of a sand microbiology imbalance. Over a period of three years, a high sand green ac­ quires organic matter and probably some wind blown silt. These changes may provide the basis for development of a microbiology more typical of soil. With a larger and/or more diverse microbiology, the potential competition for the Pythium species may increase and result in a decrease in their activity and subsequently the disease. Other in­ fluences on the disease may include ir­ rigation and fertility practices on sand greens, and potential mechanical injury of roots by sand particles. Control of Pythium—induced root dysfunction is not promising with pre­ sent technology. Contact and systemic fungicides specific for Pythium species are not effective for control of root dysfunction. The primary problem is that there is no effective means of get­ ting the fungicides in the root zone and there also is some question as to their effectiveness in the root zone. At pre­ sent, intense aerification with applica­ tion of the fungicides into the aerifier holes may slow the disease, but this procedure will not stop the disease. Wetting agents in conjunction with the fungicides have sometimes proven useful. Unfortunately, our experience to date indicates that most efforts to con­ trol the disease chemically are futile and on most diseased greens the turf must be reestablished after the stressful period of the growing season. Acknowledgement The research conducted at Iowa State University on “Pythium—induced root dysfunction’’ of creeping bentgrass has been partly supported by a grant from the O.J. Noer Research Foundation. A home without a lawn to see lacks grandeur true externally. by Dr. Charles Straham at 94 years Deputy Commissioner of Education, State of New Jersey 1922-1940. North America broke off from Europe and Africa 180 million years ago. American Scientist - Vol. 72. 1984. Editorial Comment: Plusorminusa few years. When tillage begin, the other arts follow. The farmers, therefore, are the founders of human civilization. Daniel Webster 1840 Mystic KENTUCKY BLUEGRASS Mystic is so aggressive it rapidly fills in divot scars and fights Poa annua invasion making it ideal for use on golf course fairways and tees. It possesses the following characteristics: Tolerant of close mowing (3/4”) Provides a dense and aggressive turf Resists Poa annua invasion Fine texture Bright green color Mystic was evaluated at Rutgers University by Dr. Ralph Engel and Dr. C.R. Funk under the experi­ mental designation P-141. For more information contact your local Lofts distributor, or Lofts Seed, Inc. Bound Brook, NJ 08805 (201) 356-8700 LOFTS