A. H. Lees 27 



POSSIBLE REMEDIES. 



Since there may be several causes of Reversion it is important to 

 determine in any given case which are acting. Reversion caused by the 

 presence of mite can obviously only be cured by the elimination of the 

 mite. There is no satisfactory method yet of doing this though some 

 means of control might be found by using the information afforded by 

 Tables I and II. Investigation will be continued in this direction. 

 Reversion caused by terminal fruit bud formation is evidence either 

 of faulty pruning or of poor condition of the bush as a whole. Correct 

 pruning assisted by judicious manuring or other necessary cultural 

 operations should give a permanent cure. Reversion caused by aphis 

 should be curable by pruning away superabundant terminals; at the 

 same time care should be taken that the bush is making strong growth. 



SUMMARY. 



1. Reversion is characterised by four symptoms: 



(o) "running off" of the fruit, 



(b) unusual amount of lateral wood grow^th, 



(c) sharp pointed leaves, 



(d) long, thin, internodes. 



2. It is associated with and apparently caused by a check to the 

 terminal growth through change of the terminal wood bud into : 



(a) a big bud, 



(b) a killed bud or blind bud, 



(c) a fruit bud. 



It may also be associated with aphis attack. 



3. Mite resistant varieties revert under conditions 2 (b) and 2 (c). 



4. Seabrook's Black is mite resistant because in normal climates and 

 seasons the mite kills the attacked growing point and thus starves itself. 

 This only happens when both climate and variety favour an early and 

 strong continued check to the growth of the bush. 



5. There is a form of reversion occurring in young bushes before 

 mite or aphis are present. This form is at present unaccountable. 



