| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00747 | |
| Title | Management of Turf and Ornamental Diseases in Colorado |
| Investigator(s) | Tisserat, NA; |
| Department | Bioagricultural Sciences and Pest Mgmt. |
| Objectives | 1) Increase ability of urban landscape managers to identify problems in the field by developing web-based, syndromic diagnostic keys for turfgrass and tree pests. 2) Identify optimal management strategies for the control of necrotic ringspot disease of Kentucky bluegrass in home landscapes and gray snow mold disease of turfgrasses in golf course fairways, tees, and putting greens. |
| Approach | Extensive information (including extension fact sheets, reference books, digital images) on the identification and control of the major abiotic and biotic problems of Kentucky bluegrass, annual bluegrass, and creeping bentgrass in our region can be integrated into a web-based diagnostic system. Commercially available software (Lucid 3 Software, Centre for Biological Information Technology, University of Queensland, Brisbane Australia, http://www .lucidcentral.org/) will be used to construct lists of symptoms and descriptors for individual turfgrass problems. The key works by progressively eliminating problems that do not match the chosen descriptors of a particular pest. The software has been used to develop taxonomic keys for identifying a number of insect and fungal taxa. The system will be developed to help in diagnosis of insects, weeds, pathogens, and abiotic stresses of these turfgrasses and will be tested with landscape managers in Wyoming, Kansas and Colorado. Biology of Ophiosphaerella korrae, the cause of necrotic ringspot of Kentucky bluegrass will be studied with emphasis on environmental conditions associated with initial root colonization. Experiments will be conducted in growth chambers to ascertain optimal temperatures for ectotrophic growth of the pathogen on roots as well as penetration and colonization of the root cortex. A time course study will be used to monitor root colonization. Replicated field trials will be established to follow development of NRS symptoms in relation to temperatures in the soil profile (measurements at 2 cm intervals) and thatch. These experiments will elucidate optimal infection condition and indicate critical environmental conditions for fungicide applications. Replicated field plots (2 X 3 m) will be established to determine efficacy and rates of synthetic fungicides (dimethylase inhibitors, quinone outside inhibitors, benzimidazoles) for control of NRS. The effect of nitrogen fertilization on disease severity will be evaluated by applying moderate (200 kg a .i. N/ ha) or heavy (500 kg/ha) nitrogen applications. Nitrogen formulations, including slow and fast release forms as well as organic fertilizers will be evaluated. The use of amendments (SAR inducers, composts and others) that trigger induced defense responses in the host, will also be studied. Systematic surveys will be conducted to determine the frequency and geographic distribution of snow mold fungi on golf course fairways and putting greens in Colorado. Incidence of various snow molds (pink, gray, snow scald) will be determined. A subset of turf cores taken from gray snow mold patches will be removed to determine the species and variety of Typhula. Efficacy of fungicide and biological controls will be assessed in replicated field plots as previously described for NRS. |
| Keywords | syndromic keys, integrated pest management, necrotic ringspot, Ophiosphaerella korrae, gray snow mold, Typhula sp. |
| Progress Reports | |
| 2005 | Snow mold diseases of turfgrasses are caused by a number of psychrophilic fungi but their frequency and distribution in Colorado has not been fully documented. Snow mold samples were systematically collected from courses located above 2,000 m altitude in north central, central, south central and southwest regions of the state. The most frequently isolated species on all courses (greater than 90 percent) was Typhula ishikariensis var. ishikariensis . Typhula incarnata, T. ishikariensis var. canadensis, and Myriosclerotinia borealis were also recovered at low frequencies (les than 5 percent). Pythium paddicum was isolated from a sample collected at Steamboat Springs and represents the first report of this oomycete in the Rocky Mountain region. Snow mold caused primarily by T. ishikariensis var ishikariensis was controlled by applications of PCNB, or by combinations of chlorothalonil and QoI or triazole fungicides. Split applications in the fall did not enhance fungicide efficacy. |
| 2006 | Golf course superintendents at high elevations in Colorado apply fungicides in late October before permanent snow cover to prevent gray snow mold development caused by Typhula spp. However the most commonly used product (PCNB) is slated for registration cancellation by the EPA. We found that combinations of chlorothalonil, iprodione, QoI and ttriazole fungicides were as effective as PCNB. Split applications in the fall did not enhance fungicide efficacy. Superintendents also remove snow from putting greens in late February or early March and keep greens snow-free to help suppress snow mold and prevent ice damage. However, the benefit of late winter snow removal in snow mold suppression has not been documented. We compared snow mold severity in fungicide-treated Kentucky bluegrass and annual bluegrass plots with permanent snow cover through winter to plots where snow was removed from late October through mid-November and to plots where snow was removed from mid-March to spring snow melt. Snow removal in fall caused significant turf damage due to desiccation. Snow removal in March resulted in fluctuating surface temperatures but did not result in low temperature damage to the turfgrasses. It also did not significantly alter snow mold severity compared to plots with no snow removal. |
| Impact | |
| 2005 | Pythium paddicum was first described on wheat in Japan and was subsequently reported in the Pacific Northwest on turfgrasses exhibiting snow mold symptoms. This is the first report of this oomycete in the Rocky Mountain region. Further studies are required to determine the distribution of this pathogen and to ascertain whether it is an introduced species. Fungicide applications for snow mold control are an expensive but necessary management tool for golf course superintendents on golf courses with extensive winter snow cover. To reduce costs but maintain control, superintendents often rely on the fungicide PCNB. However, PCNB has been under EPA review and may injure certain turfgrasses (e.g. creeping bentgrass). These studies show that several other fungicide combinations are as efficacious in controlling snow mold as PCNB, but may be more expensive. |
| 2006 | Our studies show that several other fungicide combinations are as efficacious in controlling snow mold as PCNB, a product that will soon lose registration for turfgrass, but may be more expensive. We found that late fall and late winter snow removals were not effective in reducing snow mold severity. Thus the practice of removing snow in late winter to reduce snow mold injury may not be cost effective. Compacting snow during winter is effective in reducing temperatures at the turf/snow interface and suppressing snow mold development but this practice may have other detrimental effects including damage to buried irrigation pipes due to freezing. |
| Publications | |
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