130 DISEASES OF ECONOMIC PLANTS 



was first noted by Pierce,^ and has been fully described by 

 Smith.2 



It consists in dying of the buds of fruiting wood, spotting 

 of green twigs, and dropping or underdevelopment of young 

 leaves and fruit, accompanied by gummy exudate, especially 

 upon the one-j^ear-old fruiting twigs. Leaves opening from 

 buds which survive the disease are marked by small dead 

 areas of tissue, which soon fall out, leaving " shot holes." 

 It is essentially a winter or early spring disease of fruiting 

 tAvigs and one-year-old wood, and the principal damage is 

 from death of buds and twigs before the fruit develops. 

 Infection occurs in winter before new growth begins. 



By pruning, then spraying with the Bordeaux mixture or 

 other cleansing spray, during the early winter (in California 

 between November 1 and December 15), the best results 

 are obtained. 



Crown gall (Pseudomonas tumefaciens E. F. Smith & 

 Townsend). — Crown gall consists in a swelling, a tumor-Hke 

 outgrowth, near the ground line on certain trees and shrubs, 

 particularly upon members of the rose family, pomes, drupes, 

 raspberries, etc. Careful cross inoculations by Hedgcock,^ 

 using fragments of galls, have demonstrated that crown 

 gall of the almond, apricot, blackberry, cherry, peach, plum, 

 prune, chestnut, and walnut are intercommunicable. It 

 has also been demonstrated by Smith and Townsend that 

 crown gall of the peach tree as well as of tomato, po- 

 tato, tobacco, beet, hop, carnation, grape, raspberry, and 



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

 p. 179, 1900, and Sci. n. s. 35, 305, Februarj', 1907. 



2 Smith, R. E., Cal. Agr. Exp. Sta. Bui. 191, p. 93, September, 1907. 

 'Hedgcock, G. G., U.S. Dept. Agr. Bur. Plant Indus. Bui. 131. 



