Update [2022-01-25]: After this article was posted in March 2021, these resistant varieties plus another were evaluated and shown to have good resistance. Result summaries with links to reports with photographs are posted at the LIHREC website.
Cucurbit downy mildew (CDM) has been a major constraint to producing cucumbers in the northeast since a new pathogen strain appeared in the U.S. around 2004. This strain is able to overcome the highly resistant cucumber varieties available then. CDM has occurred every year in the region since 2004, sometimes starting as early as mid-July. Cantaloupe is the second most commonly affected cucurbit crop type. CDM in other cucurbit crops is caused by a different pathogen strain that has been present in the region more sporadically.
Leaf tissue affected by CDM can quickly die. Premature death of leaf tissue results in reduced fruit quantity and quality: misshapen cucumber fruit, poor flavor of cantaloupe due to low sugar content, and sunburn. Loss can be quite extensive as fruit production declines substantially in severely affected cucumber plants and they die prematurely.
Brickyard is a new improved cucumber variety resistant to CDM worthy of consideration for production on LI. Bristol and DMR 401 are two resistant varieties that have been available for a few years and exhibited good suppression of CDM when evaluated at LIHREC previously. Bristol reportedly is now being grown widely in the northeast. Brickyard is described as having better color and similar degree of resistance.
There are now two CDM resistant cantaloupe varieties: Trifecta and Edisto 47. Fruit of Trifecta, bred at Cornell, is described as being firm, aromatic, sweet, and having deep orange interior plus good keeping quality. Edisto 47 fruit are described as sweet with salmon colored flesh and weighing 3 to 5 pounds. Both are also resistant to powdery mildew, the most common foliar disease on LI. Organic seed of both are marketed by Southern Exposure Seed Exchange.
More information/prepared by:
Margaret Tuttle McGrath
Associate Professor
Long Island Horticultural Research and Extension Center (LIHREC)
Plant Pathology and Plant-Microbe Biology Section
School of Integrative Plant Science
College of Agriculture and Life Sciences
Cornell University
mtm3@cornell.edu