You Are Here: Management Updates 2006 Archive July 18, 2006

Date: July 18, 2006
Category: Diseases
Subject: Pythium/Fungicide Insensitivity

Due to the excessively rainy weather this summer, the UMass Extension Plant Diagnostic Lab has seen a lot of Pythium root rot and now foliar blight is coming in. Isolates of Pythium recovered from one golf course were completely resistant to metalaxyl and mefenoxam, the active ingredients in Subdue™ and Subdue MAXX™. These chemicals are some of the better materials for control of Pythium diseases and the occurrence of fungicide insensitivity is of great concern. We will now be assessing metalaxyl/mefenoxam sensitivity of isolates on golf courses in specimens received (see the UMass Extension Plant Diagnostic Lab web site for instructions on collecting and sending a sample). In the meantime, avoid sequential applications of metalaxyl or mefenoxam and rotate with materials in other chemical groups such as fosetyl-AL (Signature™, Aliette™), phosphonate (ProPhyt™, Alude™), propamocarb (Banol™), etridiazole (Koban™), or chloroneb (Terraneb SP™).

Submitted by: M. Bess Dicklow

DISCLAIMER - As always, it is the responsibility of the applicator to verify the registration status of any pesticide BEFORE applying it. Different states have different regulations as well. The author and the University of Massachusetts are not liable for any consequences of any pesticide "recommendations". Mention of any trade name is not to be considered endorsement of a product.

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