Received this as an email from the Kansas Fruit Grower's Association yesterday.
Mark Angermayer KS A case of azoxystrobin fungicide toxicity was noticed in a central > Kentucky apple orchard last week. The phytotoxicity developed as a result > of a sprayer being used first on grapes and then on apples, even after > emptying and rinsing between uses. Azoxystrobin is the active ingredient > in the fungicide Abound, a fungicide used widely on grapes for management > of black rot, powdery mildew and downy mildew. This fungicide is also > sold as Quadris, which is used on vegetables, tobacco, and soybeans, and > Heritage, which is used on landscape ornamentals. > > > > Phytotoxicity symptoms observed on apple trees included leaf distortion > and chlorotic (yellow) blotches as well as fruit russeting. In more > severe cases, leaf and twig necrosis (dead tissue), leaf drop and fruit > drop can also occur. Chlorotic spots can occur when tiny spray droplets > applied nearby drift into the orchard. Not all apple varieties were > affected; indeed some trees in the orchard, located adjacent to affected > trees showed no effect. In the case recently observed, the episode > occurred a few weeks ago and now new shoot growth with normal leaves is > appearing. Nevertheless, for the sensitive varieties, the injury will > adversely affect fruit production. > > > > As it happens, only apple varieties genetically related to the variety > MacIntosh are affected. Thus, apple varieties known to be adversely > affected are Akane, Asahi, Bramley, Cortland, Cox's Orange Pippin, Cox, > Delbarestival, Discovery, Gala, Galaxy, Grimes, Imperial Gala, Kent, > Kizashi, Lurared, McCoun, MacIntosh, Molly Delicious, Mondial Gala, > Ontario, Queen Cox, Royal Gala, Spartan, Stark Gala, Starkspur Mac, > Summared, Warabi, Worcester, and Pearmain (information from Ohio State > University sources). We also noticed phytotoxicity on the variety Honey > Crisp. > > > > Conditions favorable for drift have caused problems to apples elsewhere, > e.g., azoxystrobin used in grape vineyards adjacent to apple orchards. The > current label warns about spray drift and prohibits sprayers used with > azoxystrobin for subsequent spraying of apple trees. Use of Quadris for > soybean rust management or for foliar diseases of corn could cause > problems for apple orchards or backyard trees adjacent to soybean fields, > especially under unanticipated conditions favorable for drift. > > > > Apple growers who are also growing vegetables or grapes need to be aware > of azoxystrobin phytotoxicity that can occur from use of a contaminated > sprayer or from spray drift. In such cases, a separate sprayer for apples > or the other crop might be a good solution along with spraying only on > very still days. Apple growers will also want to communicate with nearby > farmers who might be using azoxystrobin fungicide in their vineyards, on > vegetable plantings or on fields of soybean or corn. > > > -- > Megan Kennelly > Assistant Professor > Extension and Research: horticultural crops > > > 4603 Throckmorton PSC > Dept of Plant Pathology > Kansas State University > Manhattan, KS 66506
