PEAR DISEASES 



1635 



tions through water-sprouts and low fruit 

 spurs. Water-sprouts coining up from 

 the root system, even at some distance 

 from the base of the tree, have caused 

 fatal infections. Fruit spurs, when lo- 

 cated on the body or main forks and be- 

 coming infected, soon introduce the 

 germs into the thick, fleshy bark, which 

 carries much of the sap, and destruction 

 is very rapid" if the tree is growing rap- 

 idly and if it happens to be a very sus- 

 ceptible variety. Water-sprouts from the 

 French stocks on which the majority of 

 our commercial varieties are grafted are 

 very susceptible and should be removed 

 with the greatest care. It needs no argu- 

 ment, therefore, to state that the re- 

 moval of water-sprouts and fruit spurs 

 well up on the limbs is an important 

 subsidiary practice in the control of pear 

 blight. Much of the cutting of water- 

 sprouts is done by farm hands, who re- 

 move them so as to leave a stub an inch 

 or so long. The result is that several 

 water-sprouts come from the same place 

 the next year. Water-sprouts should 

 always be cut out as far in as the wood, 

 and a gouge or sharp saw, although pro- 

 ducing a larger cut surface, effectually 

 removes the spur for all time. Heavy 

 pruning back of the tops of the trees, as 

 generally practiced throughout the Coast 

 as a means to secure heavy fruit yields, 

 encourages the pushing of these water- 

 sprouts so that the problem is really an 

 important one. 



Crown galls, which may be found on 

 any part of the root system or the body 

 and branches of a tree, should always be 

 removed when found. The Spitzenburg 

 is very susceptible to crown gall, and it 

 is not infrequent to find numerous galls 

 on the body and limbs. The peculiar 

 nature of these crown galls is such that 

 pear-blight germs find a ready entrance. 

 I have seen hundreds of infections which 

 entered the trees through crown galls. 

 In cutting away crown galls, which in 

 themselves are caused by a bacterial or- 

 ganism, the bark and cambium should be 

 peeled away at least an inch from the 

 edge of the gall, and the gall itself com- 

 pletely cut out with a chisel or rrouge. 



Then thoroughly sterilize the exposed 

 surface. The reason for going well be- 

 yond the outer margin of the gall in 

 removing it is because we find the organ- 

 isms causing the crown gall in greatest 

 numbers along this margin. 



Resistant Stocks 



One matter of very great importance, 

 and which has been mentioned before, 

 is the possibility of working all the non- 

 resistant varieties of pears and apples on 

 resistant stocks or bodies. It has been 

 stated that the Winter Nelis an^ the 

 Kieffer varieties of pears are the most 

 resistant of commercial varieties. Un- 

 der Eastern and Southern conditions the 

 Kieffer pear is really the only one that 

 has stood against the ravages of the 

 blight. By this I do not mean to say 

 that it is wholly immune, because under 

 extreme conditions it will blight. How- 

 ever, the conditions on the Pacific coast 

 are such that if the Kieffer were used as 

 a stock or body there would be little 

 danger of losing the tree by root and 

 body infections. Experience in Califor- 

 nia has shown that while Bartlett and 



Crown Gall on Branch of Spitzenburg Apple 

 showing pear blight infection. Note the 

 ooze coming out both sides of the crown 

 gall. (Original.) 



