Michael Mazourek, Cornell UniversityDowny mildew poses a particularly tough challenge to organic cucumber growers, since they can't use synthetic fungicides.A new strain of downy mildew has cucumber growers in a pickle.
Despite the limited control measures available to organic growers, such as soil building, rotation, variety selection and organic pesticides, the disease has taken its toll, according to a news release.
Since 2003, the acreage devoted to organic pickling cucumbers in New York has declined by 20 percent because of the disease and the costs associated with it.
A group of East Coast researchers, led by Cornell University, is trying to tackle the problem, thanks in part to a four-year $2 million grant.
The funding from the Naitonal Institute of Food and Agriculture Organic Agriculture Research and Extension Initiative will allow eight Cornell breeders, plant pathologists, entomologists, economists and Extension specialists to fight downy mildew.
Among their efforts will be:
• Using existing germplasm to develop open-pollinated cucumber, melon and squash cultivars with reduced attractiveness to stripe cucumber beetles and resistance to aphid-vectored viruses;
• Evaluating and selecting cucurbit cultivars and breeding lines for performance under natural pest pressures;
• Developing effective and affordable management strategies to combat these pests; and
• Conducting extensive outreach to aid adoption of the results in the East and Southeast.
Michael Mazourek, a professor of plant breeding and principal investigator, said he hopes these strategies will help organic growers who currently avoid cucurbits because of the pests.
Some cultural practices appear to be effective.
Growing cucurbits under unheated or minimally heated greenhouses, for example, extends the Northeast growing season.
Early studies show the practice also helps reduce or eliminate downy mildew.
Strategic inter-row cropping of other vegetables, such as the legume Sericea lespedeza, may provide virus depositories when aphids enter fields.
In addition, entomologist Michael Hoffmann is examining whether induced plant volatiles or trap crops, such as early flowering squash, may help controlled striped cucumber beetle.
Other collaborators include researchers and growers in North Carolina and Alabama.