WEST LAFAYETTE, Ind. — The Purdue University Plant and Pest Diagnostic Laboratory has confirmed late blight infecting tomatoes in several Indiana counties, including Tippecanoe, Vermillion and Bartholomew.

“Both home growers and commercial growers of tomatoes should be vigilant and scout,” said Dan Egel, Purdue Extension plant pathologist. “Indiana is second in the nation in growing processing tomatoes, so there is a lot of potential for economic impact.”

Symptoms are large (at least nickel sized) olive green to brown spots on leaves with a slightly fuzzy, white fungal growth on the underside when conditions have been humid, Egel said.

“Sometimes the lesion border is yellow or has a water-soaked appearance,” he said. “Leaf lesions begin as tiny, irregularly shaped brown spots. Also, brown to blackish lesions develop on upper stems, while firm, brown spots develop on the tomato fruit.”

Photos of late blight are available at http://www.ppdl.purdue.edu/PPDL/hot09/8-6.html, http://www.hort.cornell.edu/department/Facilities/lihrec/vegpath/photos/lateblight_tomato.htm and http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Spin/Tom_Spin.html

Growers who identify late blight should plow under or pull out and destroy infected plants, Egel said.

“Home growers should discard the infected plants in trash bags and not place them in compost piles,” he said. “It’s important to also remove neighboring plants because they will be infected, too.

“Commercial growers should assume that the disease will infect their plants and apply the appropriate fungicide. Good fungicide coverage is critical. Pathogen spores can be moved on equipment and workers; therefore, growers should spray and work in affected fields last and clean equipment between fields.”

The most recent information will be posted at the Purdue Plant and Pest Diagnostic Laboratory Web site at http://www.ppdl.purdue.edu/PPDL/hot09/8-6.html and on the Vegetable Crop Hotline Web site at http://extension.entm.purdue.edu/veg/

Late blight can be slowed, but there are no tools to completely stop its spread. The last time Egel said he saw late blight in Indiana was in 1998 on potatoes in Knox County.

“It is believed that infected tomato plants were shipped to large retail stores throughout the northeast region of the country,” said Gail Ruhl, senior plant disease diagnostician. “The fact that infected plants were introduced early in the season and that we’ve had wet, cool conditions have excelled the spreading of spores.”

Late blight is a fast-moving and highly destructive disease of tomatoes and potatoes if conditions are right.

“I had a report that a lady called and said she checked her tomato plot July 30 and then went back three days later and they were all melted down,” Ruhl said. “They went from looking great to looking bad.”

For questions and more information, contact Egel at 812-886-0198, egel@purdue.edu

WEST LAFAYETTE, Ind. — Vegetable growers and master gardeners can tour plots by wagon and compare different varieties of pumpkins and sweet corn at the Sept. 9 twilight meeting in Wanatah, Ind., at the Pinney-Purdue Agricultural Center.

The Pumpkin and Sweet Corn Twilight Meeting will begin with registration at 6 p.m. EDT (5 p.m. CDT). Participants will have an opportunity to look at synergistic and supersweet sweet corn varieties, powdery mildew resistant pumpkin varieties and the cucurbit downy mildew sentinel plot.

“We have done some different things with our plots this year,” said Liz Maynard, Purdue University Cooperative Extension Service vegetable crops specialist. “This is the first year we have sprayed for powdery mildew in only half the pumpkin plots, so growers can see a difference.”

During the wagon tours, Rick Foster, Purdue Extension vegetable and fruit crops pest management specialist, will discuss insect management in sweet corn and give an update on corn earworm. Dan Egel, Purdue Extension plant pathologist, will point out various diseases in the fields, and participants will have the chance to see symptoms and ask questions. Maynard will highlight the different varieties in plots and discuss production methods and weed management strategies.

Registration is due by Sept. 2 and costs $5, which can be paid at the door and includes dinner. If the weather permits and the sweet corn is ready for harvest, participants will be able to taste some of the different varieties from the plots at dinner. Those interested can register by contacting Maynard at (219) 785-5674, emaynard@purdue.edu. Registration for those wanting to receive private pesticide applicator recertification credit (PARP) is $15.

Pinney-Purdue Agricultural Center is located at 11402 S. County Line Road. More information is available online at http://www.hort.purdue.edu/fruitveg/events/PumpkinTwiliteTour08.pdf. For additional questions, contact Maynard.

The meeting is sponsored by Purdue Extension and the Northwest Indiana Commercial Horticulture Program, a part of Purdue’s Department of Horticulture and Landscape Architecture.