As previously reported in this blog, researchers are investigating possible fungicide resistance to the pathogen that causes Alternaria leaf spot and head rot in broccoli. New strains of Alternaria are resistant to commonly used fungicides, so growers should plan their management with current information on effectiveness. To help them with that task, Cornell Vegetable Specialist Christy Hoepting developed a Fungicide “Cheat Sheet” for Alternaria Leaf Spot and Head Rot in Broccoli. It is available for download from the CVP website.  A link is also posted on the Production Resources page of this website.

The “cheat sheet” summarizes products available to New York growers for use against Alternaria, along with rotation restrictions and seasonal maximum use rates. It also provides guidance on how to put together an effective spray program that targets products to appropriate plant growth stages while alternating fungicide classes to avoid resistance. Growers are advised to design a program before the season begins.

Hoepting has first-hand experience with battling Alternaria in her Extension work and in her role as Eastern Broccoli Project Yield trial leader. Her cheat sheet recommendations are based on results of a 2018 trial she conducted to find better management options after previously successful programs failed under high disease pressure. Hoepting is also part of the Control Alt Delete project that is studying the fungus and developing management strategies.