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Overhead sprinklers meanmore water use, which may compromise deficit-irri- gation goals and result inhigh vigor, berry splitting and bunch rot, Keller said. Coming up with heat-tolerant variet- ies requires field grafting, replanting and breeding. Vineyard relocation requires vineyard removal and redevelopment. Keller said mitigating heat stress will require better knowledge of existing va- rietal diversity and responses to heat and drought stress. It also will require vari-
ety-specific, cost-effective irrigation and heatmitigation strategies. Oneof themore innovativeways ofmit- igating heat stress, he said, involves cool- ing the canopy using a misting evapora- tive-cooling system. Misting nozzles are attached to drip lines strung to foliage wire on the vine’s west side. Feedback controls maintain temperature and avoid leaf wetness and water runoff. Keller said the system pro- videsmore than a 90% reduction inwater
use, comparedwith overhead sprinklers. “Canopy temperature is maintained around32 to35degreesCelsius (89.6 to95 Fahrenheit) during heat waves,” he said. One goal of the system, he said, is that “none of the water droplets ever hit the vineyard floor.” The cooling systemhasnoeffect ondis- ease incidence, yield, berry weight, total soluble solids and titratable acidity, Keller said, but it does lower pH. He said researchers harvested fruit for winemaking using the system last autumn and are eager to see “the actual effects on wine.” (Denni s Pol lock i s a repor t er in F r e s no . He ma y b e c on t a c t e d a t agcompollock@yahoo.com.) Insecticides earn DPR registration Two new insecticides have gained reg- istration from the California Department of Pesticide Regulation. SummitAgroUSAannounced lastweek that DPR had approved registration of its products Harvanta and Verdepryn. Both contain the active ingredient Cyclapryn. The company said Harvanta is labeled for leafy, fruiting and Brassica vegeta- bles, plus cucurbits and strawberries. Verdeprynis labeledfor treeandfruit crops including pome fruit, stone fruit, grapes, berries, citrus and tree nuts. Eric Tedford of Summit Agro said the productsprovidebroad-spectrumcontrol of chewing and sucking insects. “They are diamide insecticides that of- fer a control spectrum that is competitive with, or better than, most other diamide insecticides,” Tedford said. “For some pests, Harvanta and Verdepryn provide adulticidal and larvicidal activity. In ad- dition, Harvanta and Verdepryn are fast actingwith long residual control.” More information about the products is available on the company website, summitagro-usa.com.
brings a conflict between goals of wa- ter conservation and quality enhance- ment through deficit irrigation. “Stomata close and the canopy heats up,” he said. Heat mitigation with shade netting is expensive, costing about $30,000 for 2.5 acres. It also brings less light and lower photosynthesis, andhesaid it isnot known how it affects yield and quality.
Fruit Growers Laboratory, Inc. Precision Analyses for Improved Crop Quality & Yield www.fglinc.com
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10 Ag Alert March 24, 2021
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