248 EXPERIMENT STATION RECORD. 



whether this fungus is specialized on particular species or varieties of cucurbita- 

 ceous plants. 



In the course of the experiments 23 varieties of common cultivated cucurbits 

 were, used, which represented 5 different species and 3 genera. Each of the 

 types was readily infected when inoculated with the conidia taken from any 

 other. Young plants were used in all the experiments, and the great suscepti- 

 bility of young i)lants to the disease was questioned. In this connection several 

 vines of squashes and ornamental gourds grew to maturity in the greenhouse 

 and the mildew spread over all of them. At first the spread was slow on the 

 gourds, but later they were covered with white patches of mycelium and 

 produced immense quantities of conidia. 



As a result of the experiments there appears to be no indication of specializa- 

 tion of this mildew on any genus or species of cucurbits. 



The same species of mildew is reported as occurring on golden-rod and asters. 

 The author transferred conidia from squashes to these plants, without causing 

 any infection. This line of investigation is being continued. 



A brief bibliography is appended to the article. 



The cross-inoculation of fruit trees and shrubs with crown-gall, G. G. 

 Hedgcock (U. S. Dept. Agr., Bur. Plant Indus. Bui. 131, pp. 21-23).— An ac- 

 count is given of experiments with apple and pear seedlings, in which the 

 author attempted to determine the susceptibility of these plants to infection 

 by the soft and hard gall forms from other host plants. Three series of experi- 

 ment's have been carried on, involving several thousand seedlings, and as a 

 result of these and other investigations the author has arrived at the following 

 conclusions : 



" The soft galls from the almond, apricot, blackberry, cherry, peach, plum, 

 prune, and raspberry have been transferred easily to seedlings of the almond, 

 apricot, peach, and raspberry ; less readily to those of the blackberry, cherry, 

 plum, prune, and pear; and with great difficulty to seedlings of the apple, 

 chestnut, walnut, and rose. 



" The soft galls of the apple, chestnut, walnut, rose, and pear, as a rule, have 

 not been transferred readily to any of the plants mentioned. Evidence has been 

 obtained of a wide range of susceptibility in different varieties of the same 

 plant. This has been noted in varieties' of the apple, blackberry, cherry, chest- 

 nut, peai-, and rose." 



A new cherry disease, E. S. Salmon (Gard. Chron., 3. ser., 43 (1908), No. 

 1110, pp. 209, 210, figs. 3). — During 1907 a fungus disease of cultivated sweet 

 cherries was observed which, according to the author, does not appear to have 

 been hitherto recorded in England. 



The general appearance of the affected branches shows the leaves curled and 

 of a pinkish-red color. Soon a delicate whitish bloom becomes visible, spread- 

 ing over the greater part of the under surface of the leaf. The leaves then 

 turn brown, blacken, and decay. Frequently only a single leaf on a branch 

 shows the disease, in other cases 2 or 3 scattered here and there are affected, 

 while in rare cases most of the leaves on a branch are attacked. In large old 

 trees seldom more than a few branches ai"e attacked, but young trees may 

 become seriously infested. 



The disease is due to the fungus Exoascus minor. It is said to be closely 

 allied to E. deformans, which causes the leaf curl of peaches, etc., and also to 

 E. cerasi, the cause of the witches' brooms of cherry. 



As the fungus is perennial, the mycelium living from year to year in the 

 buds and young wood, the affected branches should be pruned and destroyed. 

 The pruning should be followed by thorough spraying with Bordeaux mixture. 



