Turf

Summer 2015 - 77 www.turftrends.com Recommendations • Supply adequate soluble nitrogen (N) – Low dose and frequent applications of N (0.1– 0.2 lbs/M) will reduce disease pressure. • PK-Plus alone will provide some level of suppression but not acceptable. • A significant interaction between PK-Plus and contact fungicides occurs—compared to the sum of each individual part (PK-Plus or contact fungicide applied alone). Consistent research results document the synergy associated with repeat applications of 6 fl. oz./M of PK- Plus combined with 1.8 oz/M of Daconil Ultrex. This combination, even under severe disease pressure, provided excellent anthracnose suppression and equal to more elaborate fungicide programs. • The contact fungicide (Daconil Ultrex, Medallion, Chipco 26GT) rates were preventative and low label rates. • Better suppression was achieved when the rate of contact fungicide was increased under climatic conditions conducive to severe disease pressure. (eg. Daconil Ultrex 1.8 oz/M 3.2 oz./M) • Combining PK-Plus with Daconil Action (3 oz./M) provided the best suppression compared to Daconil Ultrex. Importantly, the nutritional value associated with the Grigg Brothers Proven Foliar nutrient program(s) also provide excellent turfgrass color and overall quality. These results clearly demonstrate the effective use of a highly efficient foliar nitrogen (N) source and PK- Plus, applied in combination with 1.8 oz./M chlorothalonil under moderate pressure and 3.2 oz./M under heavy disease pressure for the best anthracnose management results. Recently scientists from Rutgers University have identified critical soil test (50 ppm–Mehlich 3 extractant) levels and plant tissue levels (2%) for potassium (K), as it relates to anthracnose incidence and severity. They discovered an inverse correlation—as soil and tissue K increase the incidence of anthracnose decreases. This discovery provides valuable insight for further study. Is this what makes PK-Plus (K 2 PO 3 - ) such an effective tool for anthracnose management? And do different phosphite salt formulations (Ca or N – PO 3 - ) perform differently in this regard? Grigg Brothers will address these questions and attempt to answer them during the 2015 growing season—so stay tuned.

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