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Research Topic:

Impact of Chemical and Biological Fungicides for Preventative Control of Anthracnose on an Annual Bluegrass Green (2008), B. B. Clarke, Rutgers University

Abstract: Anthracnose (Colletotrichum graminicola) has become a major disease problem on golf course putting greens. An integrated approach is the most effective management strategy for lessening the severity and incidence of this disease, including the utilization of appropriate cultural practices and a rotational fungicide program. Low mowing heights, low N or unbalanced fertility, and plant stress will increase the risk for disease development. The objective of this trial was to determine the effect of highly efficient foliar fertilizers, including those that contain potassium phosphite applied alone or in combination with low label fungicide rates on anthracnose incidence and severity on an annual bluegrass (Poa annua) putting green. Similar to 2007, PK Plus^TM [3-7-18 + micronutrients + potassium phosphite (K₂PO₃)] applied in combination with Daconil Ultrex (1.8 fl. oz/M) provided excellent anthracnose suppression which was significantly better than the untreated check (Figure 1). This combination treatment was consistently better, on average, than either Daconil Ultrex (1.8 oz./M) or PK Plus (6 fl. oz./M) applied alone, and statically similar to Daconil Ultrex (3.2 oz./M) and Chipco Signature (4 oz./M) treatments (Figure 1). The best turf quality** was provided by Chipco Signature (4 oz./M), followed by a combination treatment of Daconil Ultrex (1.8 oz./M) and PK Plus (6 fl. oz./M), Daconil Ultrex (3.2 oz./M) applied alone, and Gary’s Green Ultra (9 fl. oz./M) combined with PK Plus (6 fl. oz./M) (Figure 2). Based on these results, utilize PK Plus regularly (7-14 days), and start prior to when environmental conditions become conducive to disease development. Apply PK Plus in combination with a low label rate of Daconil Ultrex (1.8 oz./M) as an effective and integrated anthracnose management strategy.

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