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Source: Insights, Northeastern IPM Center newsletter

Fungus-resistant lines can lower grower costs and reduce environmental impact. Above, Martha Mutschler (right) and Tom Zitter (center) discuss their early findings with IPM Center co-director Carrie Koplinka-Loehr. Photo by Dede Hatch

In 2010, growers will have access to new tomato varieties that resist some of the most threatening tomato diseases and can be grown in ways that are gentler to the environment.

As a commercial crop grown throughout the region, tomatoes were valued at nearly $90 million last year in New Jersey, New York, and Pennsylvania alone. They are an emblem of northeastern gardens, prized for their extraordinary flavor and rich in the antioxident lycopene, which protects cells from free radicals that can potentially lead to cancer.

Both conventional and organic growers have voiced a need for improved control of early blight and late blight, two of the main fungal diseases of tomato. Conventional growers rely on fungicide applications that can cost up to $200 per acre each season, using compounds that have high environmental impact yet still fail to adequately control the diseases. Copper fungicides are used in organic fresh market tomato production, but copper has been shown to suppress only late blight.

Plant breeder Martha Mutschler and plant pathologist Tom Zitter (both Cornell Univ.) rose to this IPM challenge, and with Regional IPM funding assembled a team of breeders, pathologists, horticulturists, and conventional and organic growers from several states. The team tested tomato lines and hybrids with late blight and early blight resistance to see if the diseases could be controlled using low-impact products.

The resistant lines that Mutschler developed provided outstanding control of both early blight and late blight when treated with pesticides that have low environmental impact (as measured by the environmental impact quotient formula). The new lines also work well when treated with biological fungicides in combination with fixed copper.

U.S. and international seed companies are using the early- and late-blight-resistant lines in varietal development and expect new hybrids to be commercially available in 2010. Growers are likely to reduce losses and also realize cost savings, since they will not need to rely so heavily on the use of pesticides. They will also be able to grow healthier crops with organic products or fungicides that present lower environmental risks. Home gardeners should be able to use the new varieties without having to spray their tomatoes for early blight and late blight.

The urgent need for development of these new disease-resistant tomato varieties became clear when the team found that some early blight pathogens were not controlled by strobilurin fungicides. Mutschler and Zitter also discovered a high occurrence of Septoria leaf spot in the study’s early stages, prompting them to launch a new effort to add Septoria resistance, creating triple resistant lines to control all three fungal diseases. The promise of their results has helped them obtain additional funding so the team can continue their work and bring these benefits to fruition.

The Northeastern IPM Center is supported by the USDA’s Cooperative State Research, Education, and Extension Service, and is jointly administered by The Pennsylvania State University and Cornell University.

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