12/31/2023 0 Comments Blight resistant tomato varietiesThis also makes pesticide treatment easier as many materials registered on ornamentals are not registered for vegetable transplants.Ĥ). This prevents cross-infection from ornamental plants which can harbor Late blight, TSWV (tomato spotted wilt virus), INSV (impatiens necrotic spot virus) and other potential vegetable pathogens. Grow vegetable transplants separately from bedding plants. Start transplant production in a clean greenhouse free from previous crops, pet plants, and weeds. If possible, isolate new plants and inspect them regularly until their disease-free status is confirmed.ģ). If you must bring transplants from the south, carefully inspect all tomato plugs before accepting shipment and reject any with symptoms of disease (or insect infestations). Tomato plugs imported from the south may be a potential source of the disease organism. Phytophthora infestans does not survive in or on tomato seed.Ģ). Grow tomato plants from seed or purchase starter plants produced locally. Steps to prevent Late Blight from occurring in your greenhouse or garden center:ġ). Oospore production is common in central and South America as well as Europe and the disease is a perennial problem in these regions. Both mating types have been observed in the US and mating is known to occur in the Pacific Northwest. If both mating types of the organism occur in the same field, sexual reproduction and therefore persistence outside a living host as oospores (long lived spores in the soil) is possible. Currently, the late blight pathogen is only known to survive on living plant tissue unlike Alternaria solani, the cause of early blight. ![]() This means a potential source of inoculum persists until crops are being produced north of Florida and a 'green bridge' exists for the pathogen to progress on until it reaches the northeast. Late blight has also been active into the spring as late as May indicating an increased tolerance for warmer temperatures. Diseased tomato plants in south Florida have survived cold periods in winter allowing the pathogen to persist. The late blight pathogen has recently undergone changes in Florida that affect disease occurrence there and in other eastern states. An exception would be where plantings are located where fog occurs periodically. Hot, dry summers, like 2010 are not conducive to late blight development. Pathogen Biology: Phytophthora infestans needs cool (below 77 F) wet weather. Other more recent sources of the pathogen have been infected tomato transplants, infected petunia bedding plants, and infected crops in frost-free areas producing wind dispersed spores. Sources of Phytophthora infestans in New England include potatoes saved year to year for seed, tubers that survive the winter unfrozen in the soil, and volunteer potato and tomato plants in compost, cull piles, or fields. These genotypes differ in mating type, host aggressiveness, and fungicide resistance. In 20, the continually evolving pathogen was again primarily a problem for tomato crops US23 (2012) and US24 (2013).īackground: Late Blight has occurred in New England in recent years and different strains of the pathogen have been responsible: US11 (1994-1998), US8 (1992-2010), US17 (1996-1997), and US 22 (2009-2010). ![]() ![]() US22 was detected in tomato plants for sale in garden centers in numerous states by extension specialists. First reports of the pathogen were recorded in late June, the earliest incidence of widespread disease ever observed in our region. This new genotype of late blight, US22, caused a disease epidemic throughout the Northeast. Typically, potato is the main crop affected in 2009, a strain aggressive on tomato was present on tomato transplants. In 2009, the disease was widespread and developed early. Late Blight outbreaks from 2005 to 2008 developed during late summer/early fall and were the result of inoculum (sporangia) carried on storm systems that originated in southern areas where the disease was active. Late Blight caused by the fungus-like organism, Phytophthora infestans, occurs sporadically in most of New England in most growing seasons. Photos of Late Blight on Tomatoes, Many good close-up photos from the Long Island Horticultural Research and Education Center
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