Issue link: https://read.dmtmag.com/i/138107
FROST protection spray manage the trees and crop differently after spring freezes. Crop insurance can provide a partial safety net for income loss, but the other effects can only be avoided by effective frost prevention. Sunburn Sunburn damage is more significant on open, highdensity plantings on dwarfing rootstocks because of their higher percentage of greater-exposed fruit, Fargione said. "Until recently, sunburn has been thought of as a problem primarily in hot, dry climates like Australia or Washington State, where damage levels are reported to reach or exceed levels of 10 percent where no protective measures are used." Managing the risk Cornell horticulturist Dr. Terence Robinson envisions New York and other northeastern growers adopting practices that are being used in other production areas but that, in the past, were not needed. Many of these practices involve high-cost installations, such as overhead cooling systems for sunburn prevention or nets for hail protection. But when high-value crops are at stake, these large investments can be paid for in one year where tragedy is prevented. "With the rather large investments tied up in new high-density orchards, it is an essential business practice to purchase crop insurance for protection against losses from hail and frost," he said. "The U.S. apple industry has the benefit of strong government support for crop insurance against hail and other risks with a 60 percent subsidy of the crop insurance premiums," he said. "We believe that every grower should invest in crop insurance to manage risk. The cost of the premium should be considered an essential business expense for precision orchard management." Still, crop insurance alone won't manage some kinds of risk. The loss or damage to a high-value variety like Honeycrisp or some of the new club varieties is not fully 12 July 2013 GOOD FRUIT GROWER compensated by crop insurance, he said. Moreover, if a volume of fruit is lost due to frost or hail, the entire marketing program for a club variety can be jeopardized. "Hail nets are not common in the United States due to our strong crop insurance program," he said, "but in many other parts of the world they are very common." Hail nets could prove more economical if installed at the time the orchard is planted, so that posts and cable that support the nets are also used in the trellis, he said. Even with a cost of $7,500 an acre for a hail net, the cost would be recouped in one year if an acre of Honeycrisp—containing a thousand $30 bushels of apples—were saved. Crop insurance would pay back only half that amount, leaving $15,000 in net loss that could be covered by the hail net system. Hail net also provides an every-year payback by reducing light intensity by 15 to 20 percent and thus reducing the risk of sunburn. "Historically, sunburn has been a minor problem for apple growers in the East," Robinson said. "It seems to be a growing problem with hotter summers, especially in the Hudson Valley. In several of the last ten years, high temperatures in late August have resulted in significant sunburn damage on Honeycrisp, McIntosh, Cortland, and other varieties." Overtree cooling with microsprinklers is commonly used in the West, Robinson said, and they are turned on automatically when temperatures reach 95˚F. In the East, light intensity is often less even with high temperatures, because of humid, hazy sky conditions, so automatic controls might need to be based on both light intensity and temperature. • W ind machines are selling like hotcakes and are probably the first choice for apple growers wanting to protect orchards from spring frosts and freezes. But perhaps the most exciting development in frost protection was the discovery last year that Promalin sprays, applied at about a pint to the acre in a dilute spray to an apple orchard after a freeze, could save apples by allowing some of the frozen flowers to set fruit. Experiments were conducted in the spring of 2012 both at the Geneva Experiment Station in New York, by Mario Miranda Sazo and Dr. Terence Robinson, and at North Carolina State University by Dr. Steven McArtney. In Good Fruit Grower's February 1 issue this year, McArtney reported: "While fruit on the treated trees grew to a normal size and shape at harvest, they had one distinguishing feature—they were largely without seeds, or parthenocarpic. It seems that Promalin increased fruit set and yield by stimulating the retention and growth of fruit that would otherwise have dropped due to the absence of viable seeds." Miranda Sazo and Robinson report that the results of their study support of the use of Promalin immediately after spring frost or full bloom to mitigate the frost damage to flowers, allowing more fruit to set. Yields in the frosted orchards were reduced. In a frosted Gingergold block, only 50 bushels per acre were produced, while the Promalin-treated block yielded 130. The increased crop value of $948 per acre more than offset the cost of the Promalin spray, they said. Tests were done on Gala and Jonagold as well. Promalin greatly increased Jonagold yield (550 bushels per acre versus 150), generating $4,897 in increased crop value. "For many years we have thought the western New York fruit region is one of the safest and most reliable places in the world for fruit production without the use of wind machines," Miranda Sazo said. "However, with the general warming of the climate, we are now questioning if the frost protection effect of Lake Ontario will be good enough in the future. If early springs and frost events become more common, we should start planning for effective use of technologies before, during, or after a frost event." Helicopters were very effective because they were able to reach higher altitudes than wind machines, could make height adjustments and cover larger areas, and pilots were able to find warmer air to circulate and push down to the orchard floor. During the Precision Apple Management Summit in Geneva, New York, last spring, fruit grower Russell Bartolotta, from Germantown, New York, in the Hudson Valley, reported spending $72,000 to hire five helicopters and his ground crew for the two frosty nights of April 29 and 30. But, he said, it saved his 400 acres of apples, pears, peaches, and plums. Four of the helicopters were Bell 407GXs, the big ones, capable of moving lots of air and covering 50 acres or more of orchard. The smaller R-22s cost much less but cover only about 15 acres, he said. Bartolotta said that a smart move by government would be to pay part of growers' cost of frost protection for growers who buy crop insurance. Since the government pays 60 percent of the premium on crop insurance, frost protection would lower the payout by saving crop. Growers who choose to protect their crop are, in effect, paying for insurance twice. —R. Lehnert www.goodfruit.com