128 THIRTEENTH ANNUAL REPORT 



grayisli mold growing in little cushion-like masses or tufts. Ex- 

 amined under the microscope these tufts are found to consist of 

 chains of oval spores produced in countless numbers. The spores 

 are ready to germinate at once and infect other plums. This 

 takes place by contact, owing to the thick clustering of the fruit, or 

 by wind-carried spores. Possessed of such abundant means of re- 

 production, and occurring at a time when the weather conditions 

 are especially favorable to the development of fungi in general, 

 this disease spreads with great rapidity, and does a large amount 

 of damage. Once started it is a difficult disease to remedy. 



Spring infection is believed to come chiefly from the diseased 

 plums of the previous year which fall to the ground or may remain 

 on the tree. Hence one of the most important measures of treat- 

 ment is tlie destruction of all diseased plums as soon as possible. 

 These should be gathered and burned or securely buried. The 

 trees should be disinfected by a thorough spraying with Bordeaux 

 mixture before the buds open ; a second spraying should be given 

 soon after the fruit has set. As ripening time approaches the 

 spraying should be repeated at intervals of a w^eek or ten days, 

 using the solution of copper carbonate instead of Bordeaux to 

 avoid staining the fruit. 



Peach Rot. — The peach is affected by tlie same disease as the 

 plum, and may be treated in the same way. 



Doivny Mildew of the Grape. — This disease developed to an 

 unusual extent in the Station vineyard during the season of 1901. 

 There are numerous species of downy mildew which attack differ- 

 ent cultivated plants ; they are characterized by the production of 

 whitish downy or mold-like patches on the affected part. The 

 " mold " consists of the fruiting part — spores and spore stalks — of 

 the fungus which is growing in the deeper tissues. The downy 

 mildew of the grape appears first as yellow spots on the leaves, 

 which soon develop on their under surface the characteristic downy 

 growth. The diseased leaves die and drop off. This disease also 

 attacks the stems and fruit on which it produces brown spots which 

 later become grayish from the development of the spores and 

 spore stalks, hence the disease when affecting the fruit is spoken 

 of as the brown or gray rot. The treatment which has been found 

 successful consists in spraying with Bordeaux mixture just before 

 the blossoms ojien, again after the fruit has set, and a third time 



