Basil Downy Mildew update: First reports in the north are on garden plants

June 29, 2021

Meg McGrath, Long Island Horticultural Research & Extension Center, mtm3@cornell.edu:

Downy mildew on basil plants for retail sale at garden centers was reported during June in NJ, NY (Long Island), MA, ME, SC, and WI. This disease was also reported on basil in gardens in DE and NJ.  For information about the garden center reports, go to the Current Basil Reports list, sort by ‘Type of Planting’, and then click on ‘View Report’ for the ‘Store – Potted Plant’ entries.

Considering this pathogen produces copious amounts of wind-dispersed spores, there is the potential for affected plants in a home garden to serve as a source of inoculum for commercial plantings of basil.  Garden tomatoes infected when purchased were the source of late blight for the outbreak in 2009 in the northeast and in 2011 on Long Island.

To date an association has not been made between downy mildew occurring on garden basil plants and a commercial basil planting.