-7r 



blossoms. Rrane Beauty pollen xvas apparently injured to a greater extent by the 

 cold than that of the other varieties." 



— ¥. J*. Lord 



//////////////// 



WATER SPRIMLING FOR FROST PREVENTION 



Some fruit growers sprayed water on their apple trees vilth their orchard 

 sprayers in an attempt to prevent frost injury. In one orchard where this vras 

 done, the writer observed that the blossoms were injured more on the sprayed trees 

 than on unsprayed trees. In addition, considerable foliage injury occurred on the 

 sprayed trees. 



Water must be sprayed on the trees continuously as would be applied by an 

 oscillating type sprinkler to provide enough heat to keep the plant from freez- 

 ing, VJith orchard spray equipment it would be very difficult to supply contin- 

 uous water. The folloYJing paragraphs were written by Dr. W, D, Weeks and appear 

 in Special Circular #13ll titled "Frost Prevention for the Orchard", 



Sprinkling plants vrLth water duidng a frost has long been considered as a 

 possible method of preventing injury. There hare been reports of both success 

 and failure where this has been done. 



The underlying principle by vrhich water is able to prevent frost injury is 

 based on the latent heat which is released when water is changed to ice. Some 

 heat is released as water is cooled to 320F,5 but the main effest is produced when 

 the water is changed to ice, When 1000 gallons of vrater are changed to ice as much 

 heat is released as when 800 gallons of boiling water is cooled to 320F, The temp- 

 erature of any object remains near 32°Fc so long as water is freezing on it. Fruit 

 blossoms are not critically injured by temperatures of 30° to 32°F. so if they can 

 be kept at temperatures of 30° to 32°F,, even though encased in ice, frost injury 

 can be prevented. 



It is quite obvious that frost protection by irater sprinkling depends upon an 

 adequate supply of water and equipment which can apply the water during the period 

 of frost. Overhead irrigation equipment of the oscillating type may be adapted for 

 frost protection. It must be capable of operating v/ithout clogging with ice and of 

 applying the required amount of water continuously. The amount of water to apply 

 depends on the severity of the frost. In one experiment conducted in England, 

 l/lO inch of water per hour v:as able to give protection for about 8°F, of frost, 



YiTater should be applied just as soon as the air temperature reaches 32° and 

 should be applied continuously just as long as the air temperature remains below 

 freezing. If sprinkling stops before thawing takes place, the temperatui^e of the 

 wet flower drops rapidly and it is killed. 



Water sprinkling as a method of frost protection for the average liassachusetts 

 orchardist does not appear to be too practical. It vdll require considerable 



