-4- 



In studies with peach trees, D.B. Carrick stated that it 

 is not easy to assign an arbitrary limit within which the roots are 

 injured by freezing. "This is because of the great variation in the 

 root tissues. The peach cambium certainly is as hardy as the pear 

 cambium though less so than the apple. Regardless the size of root, 

 most of the peach material tested showed some injury at -10° C. 

 (14° F.) , and except in unusual cases, serious injury occurred at 

 -11° C. (12° F.)". 



Winter Weather, 1978-79 



Temperatures in December, 1978 in Central Massachusetts (where 

 most orchards are located) averaged 0.8° F. higher than normal, and 

 the maximum snow depth varied from 4 to 11 inches depending on loca- 

 tion of the weather station. Temperatures in January continued to 

 be somewhat higher than normal and maximum snow cover varied from 3 

 to 11 inches. At the Horticultural Research Center (FiRC) in Belcher- 

 town, there were 4 snow storms in January: 2 inches on the 5th and 

 13th, and 3 inches on the 17th and 20th. However over 8 inches of 

 rain fell after these storms and eliminated the snow cover: 2.3 

 inches on the 7th and 8th, 1.1 inches on the 13th, 2.5 inches on 

 the 20th and 21st, and 2.5 inches on the 24th and 25th. 



Temperatures in Central Massachusetts were 8.6° P. lower than 

 normal in February, snow fall averaged 6 inches, and the maximum 

 depth of snow on the ground varied from 3 to 10 inches, depending 

 on the location of the weather station. There was one snowstorm of 

 2.5 inches in February at the HRC prior to -10 to -14° F. tempera- 

 tures from the 9th through the 17th. Although the air temperatures 

 were not extremely low, soil temperatures at 8 and 30 inch depths 

 in one block of trees in sod were 19° F. and 30° F. , respectively, 

 on February 16th. 



Symptoms of Injury 



Apple . The first symptoms of injury to apple trees at the HRC 

 was observed on May 7 at the full pink stage of blossom development. 

 Blossoms on 1 limb, 2 or 3 limbs, or the entire tree were white in 

 color rather than pink and leaf margins were brown. Maximum air 

 temperatures of 84° F. , 93° F. , and 91° F. were recorded on May 8th, 

 9th and 10th, respectively. The symptoms worsened considerably dur- 

 ing this time, with more trees exhibiting injury, and the blossoms on 

 the affected branches failed to open and eventually wilted and aborted, 

 Examination of the roots revealed that the wood was brown which in- 

 dicated winter injury had occurred. 



Severely affected trees died as the growing season progressed. 

 Other trees began to exhibit light-colored foliage, with interveinal 

 mottling that was orange in color. These trees made little terminal 

 growth and had a light crop. It is possible that many of the severely- 

 weakened trees will have to be replaced in 1980. Injury symptoms did 



