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DON'T GAMBLE ON FROST WITH STRAWBERRIES 



Dominic A. Marini 

 Regional Fruit & Vegetable Specialist 



Most growers who are serious about growing strawberries are 

 now equipped with sprinkler irrigation systems for applying water 

 during dry periods. This same system can be used to protect straw- 

 berries from spring frosts. Strawberries have been protected from 

 temperatures as low as 22 F with irrigation. 



of frost protection with irrigation 

 Iter at 32°F become ice at 32°F. As 



The underlying principle 

 is that heat is released as wai 

 long as water is continually applied during the time that the air 

 temperature is below freezing, the plant temperature remains at 

 32 F even though it is coated with ice. Sprinklers should be ^ 

 turned on when the temperature at plant height drops to 33 or 34 F 

 and water should be slowly, but constantly, applied until all of 

 the ice on the plants has melted and the air temperature has risen 

 above freezing. 



Temperatures should be watched closely when frost is a threat. 

 Thermometers should be placed in the coldest part of the field - 

 usually the lowest part - and the bulb of the thermometer should 

 be at plant level, not above it or below it. 



Very little water is needed to provide frost protection. As 

 little as 50 gallons per acre per minute or one-tenth inch per 

 hour is enough. This can be applied using number 20 Rainbird heads 

 with a single 1/8 inch nozzle, or number 70 heads with a single 

 3/16 inch nozzle. Nozzle pressure may vary from 35 to 55 pounds 

 with pump pressure at 45 to 65 pounds. Irrigation lines should 

 be spaced 40 feet apart with nozzles 40 feet apart in a staggered 

 pattern for complete coverage. 



Spring frost is always a threat, but damage to strawberries 

 from frost can be prevented with sprinkler irrigation. One Massa- 

 chusetts grower used his sprinkler system on 13 different nights 

 in May, 1969, and picked 17,000 quarts of strawberries per acre. 



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