-2- 



IThil'J the amount of injury is generally less than a year ago, 

 the crop of sorae varieties will be reduced. In tiie college planting, Indian 

 Sunraer, Ca;,aiga, Chief, LathaiA, Sunrise, Tahoma, aiid Reoiere showed lO^J or less 

 of damage. Taylor, Ohta, Milton and Tennessee Autuian showed from 13 to 20^o; 

 Y/ashington, Lloyd George and Newburgh from 30 to bOfo; while Cuthbert, Marcy 

 and Viking had from 60 to yoj^o of their total cane growth killed. 



The above order of varieties, based on amount of injury, is con- 

 siderably different from that of a year ago. This offers further evidence 

 that a number of factors contribute to winter killing of bramble canes and 

 that varieties react differently to these several factors. 



— A. P. French 



FROST DAI il AGE 



The serious injury to fruit crops by frost on the morning of May 19 

 reminds us that even Massachusetts orchards occasionally suffer frost damage 

 Although injury has been reported in some orchards in the state in other 

 years, only once before in 37 years have we seen serious frost injury to 

 tree fruits in the College orchards. Orchards planted in frosty locations 

 suffer rather frequently , 



This year's experience emphasizes the oft repeated advice to plant 

 orchards only on sites considerably elevated above the stream level of the 

 vicinity with opportunity for free air drainage and without bare areas above 

 v/here heat radiation is considerable. 



The question has been raised as to what temperature will kill 

 blossoms or young fruits. Probably the temperature at which the tissues 

 are actually killed varies v/ithin rather narrow limits. Since ive measure 

 the temperature of tho ■ air, near or even at some distance from the tree 

 itself, v/e cannot easily tell vAiat is the exact temperature of the plant 

 tissue. These temperatures vifill differ somovjhat. Hence, one camiot toll 

 from a thermometer reading whether or not it has been cold enough to kill 

 the fruit tissue. 



Air temperatures at different points in an orchard on a still, 

 frosty morning may differ several degrees, or enou^ to cause injury varying 

 from none at all to complete. The differences in temperature between dif- 

 ferent orchards will be much greater. Hence, it will be found in some or- 

 chards that the crop has been completely killed while in others no injury 

 has occurred. 



It is probable that the tissue of young fruits will not survive 

 temperatures of more than 3 or 4 degrees below 32° F. Tissue temperature 

 tends to lag behind air temperature. Consequently, if the air minimum con- 

 tinues only a short time, the tissue temperature does not fall to that of the 

 air. But if it continues long enough, the temperatures will be the same, 

 Contrary to a comraon belief, young fruits in general are more easily injured 

 than blossoms, and peaches in the balloon stage are hardier than at a later 

 stage. 



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