![]() ![]() Links to previous late blight posts from the 2019 season: June 20, July 10, July 20, August 7, August 14, August 21, August 28. Project collaborators: Tomecek Agronomic Services, Sporometrics, Phytodata, and Genevieve Marchand (AAFC).įunding acknowledgement: Ontario Tomato Research Institute, Fresh Vegetable Growers of Ontario, and the Ontario Agri-Food Innovation Alliance. Cheryl is away on parental leave and will not be available for the remainder of the growing season. If you suspect late blight in your tomato crop, please reach out to Amanda Tracey ( 51) to confirm the diagnosis. Pennsylvania on tomato, but there are no reports of symptoms on any crops in Ontario or Michigan.Ī summary of fungicides for late blight management is available here. Late blight caused by the US-23 genotype has been observed in Wisconsin on potato and in New York and Pennsylvania on tomato and potato. Late blight symptoms have been confirmed on a potato plants in Norfolk County. * first sampling period with a positive detection for late blight. Number of sites out of eight (8) in Kent County, with a positive detection for Phythophthora infestans, the organism that causes late blight. Pack up diseased plants in a plastic garbage bag and discard – don’t leave them in the field or garden or on a compost pile, where the pathogen can be released into the air and spread to other plants.Table 1. Home gardeners should consider spraying tomatoes and potatoes with a fungicide containing chlorothalanil, and should prune out diseased tissue. The disease may overwinter in plant debris or cull piles (potato or tomato). The fungus grows most actively from 15- 21☌ (59- 70☏). This is particularly important for organic tomato or potato growers. Spores are produced from 10- 27☌ (50- 81☏). If the disease is mainly found in one or a few foci, it is a good idea to remove and destroy the diseased plants. NOTE: It is critical to apply fungicides prior to infection – these fungicides (and most for conventional use as well) are not effective once plants have become infected. Actinovate, EF-400 and Zonix might be used in a program with copper. OMRI-approved copper fungicides (Champ WG, Nordox 75 WG, and others) generally rank highest for control among organic approved products. They mention Actinovate AG, EF-400 and Zonix as products approved for organic that can be effective in reducing late blight – but will not completely control the disease. ![]() So far, Ohio late blight strains have been sensitive to Ridomil, so that is another option (but may be risky).įor organic producers, there is a good webinar on late blight and its management in organic potatoes and tomatoes originally presented in January 2014 and featuring leading researchers on late blight from New York, Pennsylvania, Wisconsin and Florida. I just researched ‘Phomopsis leaf blight is a common disease of strawberry’. I was not aware they were also susceptible to blight. You raise an interesting point about strawberries. Needless to say I felt cheated as the seeds were expensive. ![]() Note the Pre-Harvest Interval (PHI) for these fungicides ranges from 0 – 5 days. The pot with the cherry tomato plant was sold as ‘blight resistant’. Orondis Opti (3 day PHI), Zing! (5 day PHI) and Gavel (5 day PHI) are pre-mixes containing mancozeb or chlorothalanil. Under cool wet conditions when late blight is likely, or if late blight has been found on the farm or nearby, use one of the following, tank mixed with one of the above protectants: Curzate (3 day PHI),Orondis Ultra (1 day PHI),Presidio (2 day PHI), Previcur Flex (5 day PHI), Ranman (0 day PHI), or Tanos (3 day PHI). Good protectants are chlorothalanil (Bravo, Equus, Echo), mancozeb (Penncozeb, Manzate, Dithane), and to a lesser extent, copper-based products – use according to label instructions. If late blight has not been observed and weather conditions are generally dry and warm, use a protectant fungicide on a 7-10 day schedule, depending on how fast the plants are growing. This should continue as long as rainy conditions, high humidity and/or heavy dews are expected. Growers need to maintain an effective fungicide program on tomatoes and potatoes. We appreciate hearing from you if late blight is suspected so that we can confirm and alert others. Wayne Ellett Plant and Pest Diagnostic Clinic in Reynoldsburg. If late blight is suspected, it can be confirmed by bringing or sending a sample to the OSU Vegetable Pathology Lab in Wooster or the OSU C. I t is very important that both potatoes and tomatoes be scouted regularly (at least twice per week) for late blight. That means that inoculum of the late blight pathogen is active in the region, and given the rainy/overcast, cool conditions of the last week or so, it is time to make sure tomato and potato crops are protected from this disease. Our colleagues in Ontario reported late blight today on tomatoes in Chatham-Kent. ![]()
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