Efficacy of Azoxystrobin, Pyraclostrobin, Potassium Phosphite, and Mefenoxam for Control of Strawberry Leather Rot Caused by Phytophthora cactorum

Abstract

Efficacy of azoxystrobin, pyraclostrobin, mefenoxam, and potassium phosphite for control of strawberry leather rot, caused by Phytophthora cactorum, was evaluated on a commercial farm. Foliar sprays of azoxystrobin, pyraclostrobin, and potassium phosphite were applied weekly from bloom through harvest and mefenoxam was applied twice as a soil drench at early plant growth and at fruit set. All fungicide treatments had significantly less leather rot than the untreated control and there were no significant differences in leather rot incidence between any fungicide treatment during both years of testing. Mefenoxam (Ridomil Gold) and potassium phosphite (ProPhyt) are currently registered for control of strawberry leather rot in the U.S. Although they are registered for use on strawberry, leather rot is not on the azoxystrobin (Abound) or pyraclostrobin (Cabrio) labels. Results from these studies indicate that both of these strobilurin fungicides provide excellent control of strawberry leather rot. Accepted for publication 28 November 2004. Published 7 January 2005.