(Oneida County, NY – July 11, 2013) Late blight is a highly contagious air borne disease that caused the Great Potato Famine in the 1800’s and wiped out much of 2009’s tomato crop. The cool, damp weather that we had that year, provided the perfect environment for the disease to take hold and spread quickly.
Our weather has not been much better this year so it is no surprise that late blight has been found in Oneida County. Late blight does not survive in the soil. It can however, overwinter on diseased potatoes that may have been left in the ground or fresh spores can stick to clothing, hands, or tools.
Large quarter size spots may appear on the leaves or the stems of both tomato and potato. Infected plants may look fine one day and be dead three days later. Once the disease takes hold there is no cure. Below is a partial list of some fungicides that contain the chemical CHLOROTHALONIL. Follow the manufacturer’s suggestions for rates and frequency. Unfortunately organic products containing copper have not proven to be highly effective against Late Blight.
Bonide Fung-onil Multi-purpose Fungicide: EPA Reg # 4-410,
Bonide Fung-onil Multi-purpose Fungicide Concentrate: EPA Reg # 60063-9-4,
Fruit Tree, Vegetable & Ornamental Fungicide: EPA Reg # 60063-9-54705,
Garden Disease Control Concentrate – Ortho Group: EPA Reg # 239-2522,
Gardentech Daconil Fungicide Concentrate:EPA Reg # 67572-82-71004, or
Gardentech Daconil Fungicide RTU: EPA Reg # 67572-2-71004
If you do have Late Blight immediate attention is required. To prevent the spread of the disease all parts of the plant, including fruit should be bagged and sent to the landfill. Do not compost and do not burn. That would release the spores into the air causing greater contamination (spores can travel several miles via the wind).
If you suspect Late Blight do not take infected plant parts to local nurseries as this may contaminate their crops. Instead visit this website: www.usablight and view the video. If you still believe you have late blight, create an account and the then report your occurrence. Once you have submitted your on line photos you will receive a submission number which should be placed on a live sample and sent to Bill Fry, Cornell University 334 Plant Science Bldg Ithaca, NY 14853 E-mail: wef1@cornell.edu Office Phone: 607-255-7863 Lab Phone: 607-255-3188
Some Tomato varieties are reportedly resistant to Late Blight. These include: Mountain Magic, Plum Regal, Legend and Iron Lady.
Have more tomato blight questions download the Tomato Blight fact sheet from our webpage http://cceoneida.com or call the Horticulture Hotline, maintained by the Master Gardener Volunteers of Oneida County, at 315-736-3394 x127. Calls are answered Wednesday and Friday from 9-noon.