THE MONTHLY BULLETIN. 483 



may be destroyed by a severe attack of the fungus. Fruits in clusters 

 are more readily injured than where the fruits are single. The disease 

 on the fruit first makes its appearance as a small dark brown decayed 

 spot. This increases in size until the whole fruit is infested. Later on 

 the sunken areas appear and the spore masses of the fungus begin to 

 develop. These break through the skin of the fruit in the form of 

 small tufts, giving the fruit a wart-like appearance. The fruit which 

 is attacked may fall to the ground or hang upon the tree, gradually 

 shrinking until it has a dried, mummified appearance. 



How to Control. — As the mummified fruits are the principal source 

 of infection the following season, they should be removed from the 

 trees or collected from the ground, and either turned under to some 

 depth, or destroyed by burning. 



The Apple Mildew. 



What the Disease Is. — Apple mildew is caused by a fungus, and at- 

 tacks a large number of the rosaceous and other plants, including apples, 

 plums, etc. It has been found by Ballard and Volck* that of the apples 

 grown in the Pajaro Valley the Yellow Newtown and Yellow Bellflower 

 varieties are the most susceptible. The tips of the young branches are 

 diseased and show the grayish mildew covering which is characteristic 

 of the fungus. It has been found that there are two sources of infection 

 in the spring, Avhen the foliage begins to appear: First, in the forma- 

 tion, during the month of July, of irregular dark patches, which contain 

 the wintering spores, and which remain on the twigs until the early 

 spring, when they germinate and start infection ; and second, that known 

 as the dormant bud infection, where the mildew remains dormant under 

 the bud scales during the winter season and becomes active in the spring. 



How to Control. — Pruning off the mildewed tips during the winter 

 season has been found by Ballard and Volck to be valuable in checking 

 the disease. 



Peach Mildew. 



What the Disease Is. — Peach mildew is another disease of fungous 

 nature which often does considerable damage. Like that of the apple, 

 the peach mildew kills the tips of the young twigs. This disease has 

 been very destructive to peach trees in Lake County the past season. 



How to Control. — Control during the winter season consists mainly 

 in removing the diseased twigs, which are then burned. 



*Bul. 120, Bur. Plant Ind., U. S. Dept. Agr. 



