COMMUNITY STUDIES 



161 



late in the fall by certain weather conditions or by certain cultural 

 practices, such as heavy fertilization and pruning and late soil cultiva- 

 tion, are less resistant to low temperatures than trees which stop growth 

 earlier in the season. This is especially true of young trees, although 

 the difference is not so marked in young peaches. 



Apparently an accumulation of carbohydrates in the tissues is one 

 thing which is associated with maturity, and such trees appear to be 

 better able to withstand low temperatures. In young trees which grow 

 vigorously late in the season, and are often severely injured, most of 

 the carbohydrates apparenly are used in growth so that the accumula- 

 tion of these materials in the tissues is comparatively small. 



Trees which lose their foliage early in the summer because of the lack 

 of proper spraying are usually injured more severely than similar trees 

 which carry healthy foliage throughout the season. 



Growth of the trees should be checked in late summer and the wood 

 allowed to mature. The use of vigorously growing cover crops which 

 will compete with the trees late in the season for moisture and nitrates 

 will assist greatly in checking growth and bringing about this desirable 

 condition. 



COMMUNITY STUDIES 



1. After severe winters, make a survey of the winter injury in your 

 section. Determine : 



a. The kinds of fruit injured. 



b. The relative resistance of the different fruits. 



c. The relative resistance of different varieties of the same fruit. 



d. The different types of injury. 



2. Were some orchards injured more than others? Determine the 

 reason if possible. 



3. Was the injury worse with vigorous or weak trees? 



4. If frosts or freezes occur at blossoming time, keep a record of the 

 temperatures and determine the percentage of injury of the blossoms of 

 several varieties by examining the pistils. 



5. Make a list of the varieties of the different tree fruits, and arrange 

 it in order of the smallest percentage of injury to blossoms. 



6. If the wood has been injured and the buds of peach trees have been 

 killed, arrange an experiment to determine the effects of different 

 amounts of pruning and of nitrate of soda on the subsequent recovery 

 of the trees. 



