![]() The onset of late blight was considered to be at a time in the growing season that left unmanaged it could adversely affect other experiments and commercial crops nearby. Sonata ASO (3 qt/A) was also applied on 7 September. The copper fungicide Badge X2 (1.75 lb/A) was applied with Actinovate AG (12 oz/A) on 14 and 22 August, and with Regalia (2 qt/A) on 17 August, 31 August and 7 September. Following standard procedure for fresh-market tomato production on Long Island, plants were staked and trellised as they grew using the Florida weave trellising system with 4-ft stakes placed between plants.įungicides approved for organic production were applied to all plots to suppress late blight after finding symptoms in the plots. Tomato seedlings were transplanted by hand on 5 July into holes opened in the plastic mulch by a Waterwheel transplanter that also placed in the holes a starter fertilizer, Neptune’s Harvest Benefits of Fish (2-4-1 N-P-K). Annual ryegrass was planted between rows of plastic mulch to establish a living mulch. Next drip tape was laid as the rows were covered with black plastic mulch. Pro-Grow 5-3-4 organic fertilizer at 2000 lb/A (100 lb/A N) was spread over rows to be planted, then incorporated. The experiment was conducted in a field dedicated to research on organically-produced crops since 2001. Varieties from this program with resistance to late blight plus other diseases developed subsequently are being commercialized. Evaluations also included experimental (numbered) varieties from the Cornell tomato breeding program. Researchers at the Cornell Long Island Horticultural Research and Extension Center evaluated tomato varieties for their resistance to late blight in trials conducted in 20. Additionally, resistant varieties are good “insurance” in areas where late blight occurs erratically in order to minimize need for preventive fungicide applications. Left unmanaged, late blight is much more likely than other diseases to completely destroy a crop and also to have devastating impact on other tomato plantings in a region due to the quantity of pathogen spores that can be produced and easily dispersed by wind. That’s because it can be very difficult to control this disease with fungicide applications started after onset with a susceptible variety, and the disease cannot be “tolerated”. Resistant varieties are a valuable tool for managing diseases, particularly late blight. Many were more aggressive on tomato and more tolerant of warm temperatures than genotypes like US-1 and US-8 that previously were dominant and mostly affected potato. It started in 2009 when a new pathogen genotype (US-22) was introduced into the region on tomato transplants sold to home gardeners, which is how the epidemic started that year. From 2009 to 2012 on Long Island, symptoms were first observed in late May to mid June.Ĭhanges in occurrence of late blight was at least partly due to the fact there were new genotypes (strains) of the pathogen in the USA. ![]() Starting in 2009, the disease began occurring routinely in the northeastern USA, starting early in the growing season and severely impacting tomatoes. since 2011.īefore 2009, late blight occurrence on Long Island, N.Y., was sporadic with symptoms never found or not seen until October in most years. Maps of late blight reports by county in U.S.Additional information about late blight and its management plus photographs.Those with same resistance genes as varieties evaluated in this study can be expected to exhibit similar ability to resist late blight. Find more resistant tomato varieties released since these studies in the disease-resistant tomato variety lists.Technical reports on these and related experiments have been published.
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