Managing Basil Downy Mildew
Teresa Rusinek, Vegetable Specialist
Eastern New York Commercial Horticulture
There are already concerns from growers about downy mildew and with good reason; this disease is difficult to control and destructive. Basil downy mildew can be seed borne but does not persist long in the environment when the host plant is not present. It does not overwinter in the field, but can persist in a greenhouse if basil is grown continuously. Once basil is in the field is may be infected by wind- blown spores from other areas.
There are options to limit your risk. In the greenhouse, avoid favorable conditions for disease development. The basil downy mildew pathogen needs humidity of at least 85% in the plant canopy to be able to infect. This disease can be controlled effectively by keeping humidity low. Practices to achieve this include base watering, wide plant spacing, circulating fans, lights, and increasing temperature. Base heating is an especially effective method to reduce humidity. Set up sensors in the plant canopy to monitor humidity to ensure implementing practices are sufficient.
One of the most effective management strategies is planting a downy mildew resistant variety, and the good news is that there are more of these varieties available to growers. Below is an update from Margaret McGrath.
New Downy Mildew Resistant Basil Varieties: Devotion, Obsession, and Thunderstruck are the first varieties developed at Rutgers University through a USDA‐funded project that included evaluations at LIHREC, which documented high level of resistance in preceding experimental lines. Reports are posted at http://blogs.cornell.edu/liveg... These varieties are available from VanDrunen Specialty Seeds. Amazel is another new variety reported to be highly resistant. Emma and Everleaf (aka Basil Pesto Party and M4828Z when evaluated at LIHREC) have moderate resistance. Everleaf exhibited better suppression than Eleonora, the first commercially‐available resistant basil, when evaluated at LIHREC. To achieve acceptable control, all resistant varieties need to be used with other management practices, in particular fungicides, due to very low tolerance for symptoms in herbs especially when used fresh.
Long Island Fruit & Vegetable Update; No.4; April 26, 2018
Photo: Yellowing of the upper surface of affected basil leaves often occurs in sections of the leaf delineated by veins because the downy mildew pathogen cannot grow past major veins in leaves. Photo: Margaret McGrath
Photo: Purplish gray spores of the downy mildew pathogen only develop on the lower surface of leaves. Photo: Margaret McGrath
This article is from the May 3, 2018 edition of ENYCHP Vegetable News. To read the full newsletter,CLICK HERE.
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Upcoming Events
Ag Labor Road Show IX
December 1, 2025 : Save the Date! - Ag Labor Roadshow Webinar 1
In addition to the in-person Ag Labor Roadshow program in our region on December 9, two webinars are scheduled for December 1 and December 22. Each webinar will focus on different program content that is different from the in-person sessions. These webinars are an added benefit to program registration.
December 9, 2025 : Save the Date - Ag Labor Road Show In-Person Event (Greenwich, NY)
Greenwich, NY
The Roadshow delivers essential updates on labor law, regulations, and workforce best practices—tailored for farm owners, managers, and ag service providers. Sessions also focus on practical strategies to boost communication, strengthen retention, and build a positive workplace culture.
The in-person session for Eastern NY is December 9 - Elks Lodge, Greenwich, NY - full day in person session
Additional in-person sessions are:
December 10 - Hilton Garden Inn, Watertown, NY, December 17 - Cornell AgriTech, Geneva, NY, December 18 - Genesee Community College, Batavia, NY
December 22, 2025 : Save the Date! - Ag Labor Roadshow Webinar 2
In addition to the in-person Ag Labor Roadshow program in our region on December 9, two webinars are scheduled for December 1 and December 22. Each webinar will focus on different program content that is different from the in-person sessions. These webinars are an added benefit to program registration.
2026 Winter Cut Flower Webinar Series
January 6, 2026
The fifth annual CCE Cut Flower Webinar Series begins on January 6, 2026 and continues over 5 weeks on Tuesdays. This is a very popular series of online events you won't want to miss, with topflight speakers, a wide variety of subjects concerning growing cut flowers and plenty of interaction between speakers and attendees.
Tuesdays 1pm-3pm January 6, 2026 - February 3, 2026 (The webinar held on February 3 will run 1pm-4pm)
Cost: $60.00 for all five sessions, $20 for single sessions
Webinars will be recorded, and all the recordings will be sent to registrants for future review.
Expanding Farm Sales: Markets, Profits, and Branding Series
January 10, 2026
Looking to diversify where you sell your farm products? This four-part workshop series helps farmers explore new opportunities in direct-to-consumer, wholesale, and institutional markets. Learn how to meet buyer expectations, price for profitability, and build lasting relationships that support your business goals. Participants will strengthen marketing and communication skills, evaluate which sales channels best fit their farm, and connect with buyers, distributors, and local partners who can help expand their reach. Whether you're just starting out or ready to grow your market presence, this program will help you chart the right path for your farm's future.
Four Session Series: Saturdays from 10AM to Noon, January 10-January 31, 2026
Attend at one of three locations: Schoharie Extension Center - Cobleskill, NY; Otsego Education Center - Cooperstown, NY; Via Zoom
Pre-registration is requested! Fee: $25 Register Here
Any questions can be directed to Kelley Doolin at kmd322@cornell.edu