Issue link: http://read.dmtmag.com/i/54939
Diseases & Disorders New fungicides benefit from LESSONS OF BENLATE Fungicide resistance management is too important to be left to chance. by Richard Lehnert generation succinate dehydrogenase inhibitors (SDHI), similar in action to boscalid, one of the components of Pristine (the first in this new generation, registered in 2003), and they are being sold in a similar manner. They come in packaged premixtures, in which the new SDHI component is combined with an older fungicide with a different Fungicide Resistance Action Committee (FRAC) code and different mode of action. These premixtures are designed to prevent develop- F ment of resistant disease organisms, which can and do destroy the value of good fungicides, Dr. George Sundin, Michigan State University plant pathologist, explained during the Great Lakes Fruit, Vegetable, and Farm Market Expo in Grand Rapids, Michigan, in December. ruit growers will have new fungicides this year to help manage diseases as diverse as leaf spot in cherries, scab in apples, and brown rot and scab on peaches. The new materials are so-called second- Packaged premixtures currently registered or soon to be available within the next year are: • Luna Sensation containing fluopyram (a SDHI, FRAC Group 7) plus trifloxystrobin (a strobilurin, FRAC Group 11) from Bayer CropScience; • Merivon containing Xemium, commonly known as fluxapyroxad (SDHI, FRAC Group 7) plus pyra- clostrobin (a strobilurin, FRAC Group 11) from BASF; • Inspire Super containing difenoconazole (a DMI, FRAC Group 3) plus cyprodinil (an anilinopyrimidine, FRAC Group 9) from Syngenta Crop Protection; and • Quadris Top containing azoxystrobin (a strobilurin, FRAC Group 11) plus difenoconazole (a DMI, FRAC Group 3) from Syngenta Crop Protection. Fontelis, a new product coming from DuPont contains the new active ingredient penthiopyrad, and will be sold mixed with other fungicides. BASF's Pristine is a combination of pyraclostrobin and boscalid (SDHI, FRAC Group 7). The companies announced last year that they were introducing or had introduced the new fungicides and, in the case of Bayer CropSciences, announced that they would market the products with different names depend- ing upon the combination of fungicide in the products. Luna Sensation 500 SC is a mixture of fluopyram and tri- floxystrobin, and Luna Experience is fluopyram plus tebuconazole. Luna Tranquility is another mixture being tested on grapes. Luna Sensation has been tested on cherries and apples for leaf spot and scab. University scientists have recommended for some years that new fungicides with narrow modes of action be tank-mixed with broad-spectrum protectant fungicides to which disease organisms have a low chance of devel- oping resistance, according to Sundin. These protectants include the inorganic materials copper and sulfur; the dithiocarbamates maneb, mancozeb, and thiram; the chloronitrile chlorothalonil; and the dicarboximide phthalimide captan. Andy Wyenandt, a plant pathologist at Rutgers …PUTTING ZINC ON PUTTING TECH-FLO® Just because you put a foliar zinc on doesn't mean the job's done. Some zinc products are so ineffective they are better suited as sun- screens or paint. In trial after trial, TECH- FLO® ZETA ZINC 22 (22% Zinc) has been shown to be the most effective foliar zinc University in New Jersey, says protectant fungicides are contact fungicides, meaning they must be present on the leaf surface prior to the arrival of the fungus and must then come into direct contact with the fungus. "Protectant fungicides can be redistributed on the leaf surface with rainfall or overhead irrigation, but can also be washed off by too much of either," he warned. "With pro- tectant fungicides, any new growth is unprotected until the next protectant fungicide is applied. In other words, protectant fungicides are not systemic and do not have translaminar activity like some of the newer chemistries. Protectant fungicides should be tank-mixed with fungicides with higher risks for resistance development." Generally, plant pathologists recommend using pro- tectant materials early in the season to prevent buildup of disease and saving the new fungicides for use later, when fruit is most vulnerable and disease pressure is strong. They usually recommend growers include a protectant fungicide in every spray application. And they recom- mend rotating fungicides, paying attention to FRAC groups to avoid cross-resistance. It is also pretty much agreed that growers should not ZINC IN… ZETA ZINC 22 product on the market today, getting the zinc into the tree where it is needed. For the best value for your nutritional dollar, choose TECH-FLO® ZETA ZINC 22. ASK YOUR P.C.A. OR CALL NUTRIENT TECHNOLOGIES TOLL-FREE: 877/832-4356 FOR THE DEALER NEAREST YOU. 28 FEBRUARY 15, 2012 GOOD FRUIT GROWER wait for disease to be observed in their orchards, as they might when using IPM practices against insects. Fungi- cide sprays should be applied early, before disease symp- toms appear, and based primarily on weather conditions that govern risk of disease development in the orchard. This wise advice developed from experience. Fungi- cide resistance has been a problem since the first of these narrow (site-specific) mode of action fungicides, Benlate (benomyl), was introduced in 1972. Sundin suggested that the chemical companies, weary of seeing their products become ineffective and less mar- ketable because of resistance, are now marketing their new products in mixtures designed to reduce resistance development. They are, in effect, insurance policies against the potential rapid development of resistance. The new products are translaminar or locally systemic—they move up and down on the leaf surface or inside the plant—and they have curative as well as preventive modes of action. www.goodfruit.com UNSURPASSED FOLIAR ZINC PERFORMANCE!