CHAPTER XII 



PECAN DISEASES, AND SPRAYING OUTFITS 



The pecan is subject to a considerable number of distinct 

 diseases, only a few of which are known to cause serious 

 damage. Not all of those herein mentioned are sufficiently 

 harmful at present to be of particular economic importance, 

 but it is well for the grower to be able to differentiate them 

 from the more serious diseases, and to know some of their 

 outstanding characteristics in case they develop more de- 

 structive tendencies in the future. 



PECAN SCAB (Plate X) 

 (Fusicladium effuswn, Wint.) 



Scab is probably the most serious disease of the pecan, and 

 when the infection is heavy the entire crop of nuts may be 

 destroyed. The disease is caused by a fungus attacking the 

 leaves, twigs, and nuts. It is characterized by a dark velvety 

 superficial growth confined to rounded spots or pustules rang- 

 ing in size from mere specks to an eighth of an inch or more 

 in diameter. In these pustules the spores of the fungus are 

 developed. The spores may be scattered from tree to tree by 

 wind or insects, so that the disease may spread rapidly when 

 susceptible varieties are present. When these spores fall upon 

 leaves, twigs, or nuts, in the presence of moisture, they germi- 

 nate and send mycelium or the vegetative part of the fungus 

 into the green and tender tissues, causing new pustules. 



Severe infection may kill the tips of the leaves, but the 



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