Issue link: http://read.dmtmag.com/i/63050
availability varies with geographic loca- tion and supplier. NAA is not allowed for organic use. NAA rate—Main application factors are cultivar and fruit hanging time, which varies year to year and with target harvest maturity. The maximum rate for pears is 25 grams per acre (10 ppm) in one or two applications. University of California and industry trials in the 1960s and 1970s con- firmed previous research and field obser- vations that multiple applications and/or rates higher than 50 grams per acre could cause excessive and early ripening and core breakdown, as well as damaged or dead buds and shoots the following spring. A rate of 25 grams applied only once failed to reduce drop of Bartlett pears in the cool districts, which are more prone to premature ripening. Based on these find- ings, the California Department of Agri- culture authorized a rate of 37.5 grams (an above-label rate) applied to control drop, and one NAA product label continues to maintain a Section 24(C) for pear in California at that higher rate. NAA timing—NAA is generally applied to pears 5 to 14 days prior to first antici- pated harvest. Applied too early, it may not last in the tissues long enough to be of use, and applied too late may miss the drop control window. Once stem loosen- ing begins, NAA only impedes further loosening; it cannot "retighten" the con- nection (reverse cellular changes that have already occurred). Labels vary most on the timing aspect, ranging from 5 to 30 days prior to first esti- mated harvest of untreated fruit. Pears are treated later than apples, from 5 to14 days prior to first anticipated harvest. It is important not to treat prematurely (and hence, ineffectively) by mistaking fruit "pushing off" due to short stems or multiples in a cluster for actual loosening. Physiological development should also be monitored to determine proper tim- ing. In pear-growing regions prone to pre- mature ripening, an option has been to apply NAA when the firmness of the largest fruit averages about 21.5 pounds of force, since ripening slows if it is warm in the month or so prior to harvest and hastens when preharvest temperatures are cooler. NAA application—NAA penetrates foliage through the leaf cuticle; absorp- tion at the stem abscission zone is not necessary as NAA is transported away from the leaf. Waxy leaves hinder uptake, thus uptake is said to be better in cloudy or moist, cool conditions. Soil moisture should be moderate, not too wet or dry, and trees should not be stressed, or uptake will be poor. Do not irrigate imme- diately before application or until after uptake and activity is evident. Absorption is best at between 70 and 85°F, followed by cooler, moist weather for several days to enhance and extend activity. Very hot weather reduces uptake and activity. NAA is applied at 100 to 250 gallons per acre, depending on tree size and spacing; good coverage is critical, and action is local to the absorption site. www.goodfruit.com Slightly acidic solutions may increase uptake, but surfactants are only needed if uptake conditions are poor. Cultivar—Bartlett and Bosc must be treated, and other pear cultivars generally benefit as well, depending on anticipated hanging time. Once active, NAA requires 2 to 4 days to "take;" fruit will drop in the meantime. Drop control should last at least 7 to 14 days, often longer, depending on cultivar, coverage, initial maturity, weather, tree vigor and stress level, and other factors. Drop will resume suddenly when the material ceases activity, and increase severely along with endogenous ethylene levels. Fruit softening should be moni- tored, and harvest timing adjusted. Fruit softening in storage is a possibility and should also be monitored. • Rachel Elkins is with University of California Cooperative Extension, Lake and Mendocino Counties; Kitren Glozer, Department of Plant Sciences, University of California, Davis; and Michael Devencenzi, Ag Pest Management and Research, Woodbridge, California. When it comes to fungicides, one star seems to stand out. The powerful broad-spectrum disease control of Inspire Super® fungicide stands out above all others. By combining a best-in-class triazole with a second highly effective fungicide, growers of pome fruit, almonds, grapes and many vegetables can depend on its superior performance. Proven across the world, it stops disease in its tracks. For power and reliability, there's no better choice than "top of the class" Inspire Super. ©2012 Syngenta. Important: Always read and follow all bag tag and label instructions before buying or using Syngenta products. The instructions contain important conditions of sale, including limitations of warranty and remedy. All crop protection products and seed treatments may not be registered for sale or use in all states. Please check with your state or local extension service before buying or using these products. Inspire Super® , the Alliance frame, the Purpose icon and the Syngenta logo are trademarks of a Syngenta Group Company. Syngenta Customer Center: 1-866-SYNGENT(A) (796-4368). www.FarmAssist.com MW 10CC2006-Super-NB2 04/12 GOOD FRUIT GROWER MAY 1, 2012 23