For high maintenance turfgrasses, disease management requires an integrated approach. This includes using the correct cultural practices to maximize plant health, correct pathogen identification and proper fungicide selection. Fertility and thatch management influence the incidence and severity of turfgrass diseases. Adequate and balanced mineral nutrition remains a foundation for plant health and will maximize turf performance during periods conducive to disease development. In addition, pathogen growth can be enhanced or discouraged by fertility practices, most importantly nitrogen rates, source, and application timing. Fertility and Plant Health Turfgrass species have different optimum fertility requirements that need to be addressed prior to finalizing a fertility program. Maximize nutrient uptake by selecting the appropriate formulation and application timing. For example, granular fertilizers are available in slow-release or quickly-available sources and are often applied at higher rates during periods of increased shoot and root growth. Conversely, foliar fertilizers are best applied frequently and at lower rates prior to and during times when environmental conditions are conducive for disease development and/or when root growth and nutrient uptake may be compromised. This strategy will maximize turfgrass nutrient uptake and subsequently overall turf vigor.
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Disease and Fertility Interactions Fertility, whether too high or low, can impact disease development. Increased incidence of anthracnose and dollar spot may occur in nitrogen (N) limiting conditions. Brown patch and snow mold incidence might increase from high tissue N concentrations. Take-all-patch incidence may increase when soil manganese (Mn) availability is limited. Maintaining optimum fertility and understanding key nutrient pathogen interactions will reduce the potential for disease pressure.
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Best Disease Management Programs The best disease management programs utilize an integrated approach. This includes: • Improving plant health (Host) • Utilize an appropriate mowing strategy (Host) • Correct pathogen identification (Pathogen) • Establish disease thresholds (Pathogen) • Evaluate the growing environment for shade and air circulation (Environment) • Maintain environmental safety (Environment)
Improve plant health by correcting major soil drainage or chemical problems, managing thatch, limiting shade, maintaining good airflow, and providing optimum turfgrass fertility. This is the cornerstone of turfgrass management. Proper equipment calibration and selection of the best nozzles and water volume carrier will maximize fungicide efficacy. Establishing and maintaining disease thresholds starts with scouting and mapping and requires meticulous record keeping. Historical data tell us when conditions are conducive to disease development. Implement a disease control program based on this information. Maintain environmental safety by developing pesticide and fertility programs that are safe for ground and surface water, animals, and humans.
Use of Phosphonates Current research exists to substantiate the benefits of phosphites (H2PO3-) as one component of an integrated approach to disease management, specifically anthracnose and pythium blight. Phosphites work both directly and indirectly to enhance disease suppression and should be used exclusively as one component to a preventative disease management program. (See reverse for research data.)
Foliar Fertilizer and Fungicide Synergy Grigg Brothers® has developed research protocols designed to assess the use of foliar fertilizers applied in combination with fungicides for enhanced disease suppression. The objective is to determine how highly efficient Grigg Brothers® foliar fertilizers, including those that contain phosphite (H2PO3-), affect disease suppression when applied alone or tank-mixed with low label fungicide rates. In addition, how do these treatments compare with traditional pesticide programs using multiple fungicides at high label rates? Results PK Plus® (14% phosphite) (6 oz/M) combined with Daconil Ultrex (1.8 oz/M) provided better anthracnose suppression than the untreated control or each product applied alone and similar to high rates of various fungicides (Figure 1). Potassium phosphite treatments, including PK Plus® and Fairphyte, provided a reduction in pythium blight severity and were similar to fungicide treatments (Figure 2). Chelated manganese (Mn) fertilizer treatments provided a level of take-allpatch suppression similar to fungicide treatments, and significantly better than the untreated control (Figure 3). These results provide meaningful information for additional disease control tools, including nutritional science to consider when planning and implementing best disease management strategies.
Optimum Disease Management Strategies Include:
Maximize plant health culturally
Correct major soil drainage or chemical problems
Become a keen observer and meticulous record keeper
Fine tune fungicide programs by choosing the best nozzles and optimum dilution rate
Utilize fertilizers that contain phosphite (H2PO3-) for preventative anthracnose foliar blight and pythium blight management
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