June, 1939] AcRicrLTURAL Research ix N. H. 23 



The Problem of Winter Injury 



A type of winter injury to the trunks of apple trees, which was 

 first noted in 1936 at Wolfeboro in an orchard of mature Mcintosh 

 trees under sod culture, is under investigation at this station. This 

 year's experiments, in charge of W. W. Smith, were made on the 

 18-year-old Mcintosh trees in the back field pruning orchard at the 

 horticultural farm. These trees, which had borne a heavy crop in 

 1937, were given a fall application of various nitrogenous fertilizers. 

 Plots which were laid out in the orchard included check plots with no 

 fertilizer ; treated plots receiving 4, 8, 12, 16, 20, 24, 30, 40 and 50 

 pounds of cyanamid per tree and plots receiving comparable amounts 

 of ammonium sulphate. All trees were sampled frequently with an 

 increment borer and the tissue examined histologically for any 

 changes in cell activity or for injury that could be observed under 

 the microscope. 



Although histological and microscopic examinations revealed no 

 difference in the treated and untreated trees and freezing of the 

 tissue gave the same result, and although chemical analyses showed 

 no difference in the amounts of nitrogen in the trunks of fertilized 

 and check trees, it was noted in February that on those trees receiv- 

 ing high applications of fertilizer the bark was loosening from the 

 wood. All those trees receiving 30 pounds or more of ammonium 

 sulphate developed the symptoms observed in the orchards in 1935 

 and 1936 which had been injured by fall applications of fertilizer. 

 That is, the bark became loose, the wood turned a purplish color 

 underneath and the leaves showed chlorosis, or yellowing. None of 

 the trees receiving the cyanamid even up to 50 pounds per tree 

 showed the injury. Neither did the trees receiving less than 30 

 pounds of ammonium sulphate. 



The experiment was also carried out on other Mcintosh trees in 

 a different location at the horticultural farm in much the same way 

 with appreciably the same results. 



While it is not yet possible to define the conditions under which 

 this type of injury is likely to occur, research workers here believe 

 that it may occur when no fertilizer is applied in autumn, though 

 according to observations in New England this happens very, very 

 rarely. Under other conditions, when it would not occur naturally, 

 small or "normal" amounts of fertilizer may induce it; under still 

 other conditions only excessive amounts of fertilizer will cause it. 



The young Baldwin trees in the 1926 orchard treated as described 

 in the 1936 report, and with treatment repeated again in the fall of 

 1937, have been examined periodically. These trees were not injured 

 in 1937-38 as they were the year before. The trees injured in 1936- 

 37 that survived have made a strong recovery. (Adams Fund) 



Changes of Apples During Storage 

 Storage Qualities of the Cortland Apple 



In the fall of 1937 Cortland apples from the horticultural farm 

 were picked on different dates—September 25, 30, October 5, 11, 21— 

 graded, packed and put in storage. Periodically during the winter  

 samples were taken from these lots, examined for spoilage and tested 

 for pressure, acidity, changes in ground color and overcolor. The 

 results are in accord with those found the previous season. In gen- 



