Issue link: https://read.dmtmag.com/i/275392
different in the drape netting trial. Shoot extension was longer in the pod and drape trials than in the control. Fruit set and yield efficiencies were slightly less in the pods than the control. A hailstorm on August 6 caused minimal (5 percent) damage in the netted Granny Smith fruit but 80 percent damage in the trial's uncovered fruit. Dr. Ines Hanrahan, research scientist with the commission, is conducting similar netting trials in Gleed and Zillah, where she is drape netting individual rows of Honeycrisp. Thus far, nets at both sites have significantly reduced the amount and severity of sunburn. Dr. Stefano Musacchi, WSU's new pomologist from Italy, said hail is a major problem in Italy, occurring five to six times a year in some locations, and is the primary reason for netting. But Italian growers are finding other advantages, including reduced sunburn, nutrient leaching, and disease incidence, and less need for tree cooling. While in Italy, he saw less fireblight in netted pears because the trees were not subjected to physical damage from hail. In some regions of the country, growers are completely enclosing the nets as a physical barrier for insects like codling moth. "The main drawback to netting is the high cost of establishment," Musacchi said, adding that it also can be difficult to find companies with expertise to install good infrastructures. "Heavy snow loads can compromise the structure, so it's important to close the nets for the winter. Other drawbacks are a potential reduction in yield and fruit size, due to lower light, and the issue of replanting under an existing structure." In Italy, concrete posts and heavy gauge wire (12- to 16-gauge) are used. Netting structures are usually installed before trees are planted. Corner posts used to anchor the support system are a key part of the structure. In recent years, Italian scientists have begun studying the physiological effects on trees from using blue, red, gray, pearl, yellow, white, or green hail and shade nets (see "Italians study light and shading," March 15, 2011, Good Fruit Grower). Bird damage In Australia, bird damage is the main reason that growers net, said Craig Hornblow, researcher with Ag First New Zealand. "Growers can lose ten to fifteen bins per acre from bird damage." But hail is the main reason that New Zealand orchardists use nets, he added. New Zealand growers have discovered other benefits from netting, such as reduced sunburn and russetting, and significantly reduced water use. Growers use about 20 percent less water under netted structures, Hornblow said. Because of the expense of netting, many growers have resorted to draping the net over individual orchard rows, using a machine to roll out the net, instead of installing a permanent structure. Hornblow said that some growers report improved spray coverage and say they can spray for longer periods of time because wind speed is reduced inside the covers. Orchard covers reduce bee activity but increase tree vigor. Most growers do chemical thinning on the edges or boundaries of the netted orchard, but very little inside. Costs Schmidt said that South Africa has some of the most expensive orchard covers, costing about $15,000 per acre. Orchard covers in Italy cost around $9,800 dollars per acre, not including labor to install the infrastructure. "I think we can do it for less here in Washington than in Italy," he said. "We have to not think what the costs are but what the benefits are. We're pouring a lot of money into our crops, and we need to think about what is the return on investment for our high-value crops." Schmidt added that based on the popularity of netting in Italy and South Africa, it appears to make economic sense. "It should also make sense in Washington, especially if it can be done for less money." • "We have to not think what the costs are but what the benefits are." —Tory Schmidt TECH-FLO ® ZETA ZINC 22 ASK YOUR P.C.A. OR CALL NUTRIENT TECHNOLOGIES TOLL-FREE: 877/832-4356 FOR THE DEALER NEAREST YOU. 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 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. UNSURPASSED FOLIAR ZINC PERFORMANCE! …PUTTING ZINC ON PUTTING ZINC IN… PUTTING ZINC IN… Hail nets are closed in this Merano, Italy, apple orchard. PHOTO BY MELISSA HANSEN 28 MARCH 15, 2014 GOOD FRUIT GROWER www.goodfruit.com