The evidence, whatever it is, is strong enough that Dave Rosenberger and Kerik Cox are recommending that growers not use captan in sprays at petal fall and first cover. From their article in Scaffolds (my bold):
"We are suggesting for the first time this year that apple growers avoid captan in their petal fall and first cover sprays. Growers who choose to follow this suggestion will need to avoid any prebloom applications of mancozeb or Polyram that exceed 3.2 lb/A, because mancozeb will be needed as a contact fungicide in the petal fall and first cover sprays. If mancozeb is applied at more than 3.2 lb/A in any spray, then the label does not allow for any use of mancozeb after bloom. "Our suggestion for avoiding captan in petal fall and first cover sprays is based on the increasing complexity of tank mixtures applied at those timings. Tank mixes at petal fall frequently include one or two plant growth regulators, two or three fungicides, one or two insecticides, foliar nutrients, pH buffers, water conditioners and/or spreader-stickers, and perhaps streptomycin for controlling fire blight on late flowers. These complex mixtures increase the likelihood that something in the mixture will enable the transport of captan across the cuticle into plant cells where it will cause leaf injury and/ or fruit russeting. The potential for injury from captan in complex tank mixtures is especially high if the weather between late bloom and first cover is cool, overcast, and wet. We observed or received numerous accounts of fruit and foliar damage throughout the northeastern U.S. in 2013, but the frequency of damage from captan has gradually been increasing over the past decade. Therefore, in the interests of minimizing risks of crop damage, we believe it would be wise to avoid captan in the petal fall and first cover sprays when tank mixes are complex and fruit are most vulnerable to damage.” --- Daniel R. Cooley, Professor of Plant Pathology Stockbridge School of Agriculture Fernald Hall 103 University of Massachusetts, Amherst, MA 01003 Office: 413-577-3803 | FAX 413-545-2115 http://people.umass.edu/dcooley On Apr 2, 2014, at 2:24 PM, Arthur Kelly <kellyorcha...@gmail.com> wrote: > Is there other than anecdotal evidence as to Captan/Captec's role in the > russeting we saw in 2013? What about the effect of adjuvants such as LI700? > Also, who has experience with bloom thinning with ATS? > > -- > Art Kelly > Kelly Orchards > Acton, ME > _______________________________________________ > apple-crop mailing list > apple-crop@virtualorchard.net > http://virtualorchard.net/mailman/listinfo/apple-crop
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