128 DISEASES OF ECONOMIC PLANTS 



ing should be done in dry calm weather, during the middle 

 of the day, in order to avoid dew or frost upon the limbs. 



Pierce ' states that as a result of treatment of the peach 

 curl, in California, from 95 to 98 per cent of the spring 

 foliage was saved. A net gain of 600 per cent in the 

 foUage over that retained by adjoining unsprayed trees 

 resulted in the case of several different sprays. The Bor- 

 deaux mixture, when applied to the dormant tree, increased 

 the weight and starch-producing power of the leaves, and the 

 sprayed trees showed great gain over the unsprayed in the 

 number and quality of the fruit buds which they produced 

 for the following year. The gain in the number of spur 

 buds was over 100 per cent in some cases. The sprayed 

 trees also produced more vigorous growth of new wood, 

 the wood to produce the crop for the next year. Thus, in 

 one experiment the spring growth of the unsprayed tree 

 averaged 7.85 inches ; on the sprayed trees it was 24.75 

 inches. The average value of fruit, per tree, in rows 

 treated with the most effective Bordeaux mixture ranged 

 as high as $6.20 above that in adjoining untreated rows, 

 or the equivalent of a net gain of $427.80 per acre. Over 

 one thousand per cent net gain in the set fruit has resulted 

 from the use of some of the more effective sprays. 



The trees should be sprayed each season, since experi- 

 ments prove that treatment one season will not prevent the 

 disease the following year. Spraying should be done even 

 though the trees are not expected to bear, since the loss of 

 the crop of leaves is as great a drain upon the trees as is the 

 maturing of one half to two thirds of a crop of fruit. 



' Pierce, N. B., U.S. Dept. Agr. Div. Veg. Phys. & Path. Bui. 20, 

 1900. 



