![]() Start the system a couple of hours before temps get too cold to prevent freezing up the system (perhaps 2 to 4 F). Under-tree micro-sprinklers will provide heat from groundwater into the orchard.Check the MSU Enviroweather tower sites for inversion information: Sparta Tower, Williamsburg Tower. Frost fans mix warm air into the orchard when inversions are present (perhaps 2 to 5 F).Mitigating activities (potential temperature gain) ![]() This detaches the surface from the heat reservoir in the soil and guaranties a cold surface. The worst thing you can do before a freeze is cultivate the ground. Growers need to think of ways they can minimize or replace the heat lost during the freeze. Weed-free soil retains more heat than freshly cultivated or unmoved sites and a few degrees may make a difference in a freeze. By modifying the soil surface to capture and retain more heat, you can reduce spring freeze injury. Moist, weed-free soil retains more heat.Improving your farm's air drainage can pay benefits when spring frosts come. Analyze and improve your farm's air drainage.Using ground-based fans to increase the movement of cold air past obstructions and constrictions in natural drainage paths can decrease the likelihood of freeze injury during spring freezes. Use air moving fans for improved air drainage.One thing you can do is prepare for the freeze by improving the air drainage on the farm or irrigating to increase the soil’s ability to store heat. If the dewpoint is lower than the critical temperature that will damage the fruit, injury is likely. In dry air, the temperature will drop quickly to the dewpoint and then slowly after the dew point is reached. The dewpoint is when the air becomes saturated with water and water needs to be condensed out of the air for the temperature to drop further. See “ What are radiation freezes?” from Michigan State University Extension for more information.Īnother thing to look for is the projected dew point. Freezes under relatively calm conditions offer more opportunities for growers to work with. Windy conditions called advective or wind freezes are almost impossible to protect from. This chart allows you to quickly see if the projected lows are in the range that will hurt your crop. Reference tables of the critical temperatures that damage different fruit are posted as a PDF file at Critical Minimum Temperature Chart. ![]() At bloom temperatures below 29 F, damaged open flowers and most flowers die before the temperatures drop to 25. As the buds swell, they can be damaged by temperatures above 20 degrees Fahrenheit. As plants start to grow in the spring, they become susceptible to warmer and warmer temperatures. The risk of losing all or part of your crop focuses their attention every spring. Spring freezes are feared by all fruit growers.
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