DEPARTMENT OF BACTERIOLOGY 129 



a fortnight later. Our ex])eriments indicate that the earlier spray- 

 ings are especially desirable. 



Another disease, sometimes very destructive to the grape, was 

 observed in a large vineyard in the southern ])art of the state ; this 

 was the black rot. Tliis affects both the leaves and the fruit, but 

 more especially the latter. The grapes turn brown and finally 

 black, become dry and shriveled with sharp angular ridges and 

 roughened with minute pimples vvhidi contain the spores. This 

 disease, as far as our observation goes, is not so likely to do seri- 

 ous damage in New Hampshire as in other grape-growing locali- 

 ties. It may be successfully treated by spraying with Bordeaux 

 mixture before the buds open, again before flower buds open, again 

 after fruit has set, a fourth time two weeks later. 



Downy Mildew of the Cucumber and Muskmelon. — The 

 cucumber crop in some localities in this section was almost a com- 

 plete failure. Just after the vines had reached a productive stage 

 they rapidly took on a diseased appearance and soon died. The 

 trouble was caused by a fungus similar to one of the above men- 

 tioned grape diseases, viz., a downy mildew. At the outset of the 

 disease in the cucumber, yellowish spots appear on the leaves ; 

 these mark the points where the mycelium of the fungus is devel- 

 oping in the tissues of the leaf. After this has reached a certain 

 stage the spore-bearing branches are developed and push their way 

 out through the epidermis of the leaf, forming the mold-like patches 

 on the under side. Tlie whole leaf turns yellow, dies and becomes 

 brown and dry. Soon after the disease was noticed in the Station 

 garden, the cucumbers were sprayed with Bordeaux mixture, but 

 with little if any good effect. This is not surprising, for we know 

 that in case of many of the fungous diseases, perhaps in case of 

 most, after the disease has reached a stage when it becomes notice- 

 able, it is too late to remedy it. Hence it is of the greatest im- 

 portance to know in case of each disease when infection is likely 

 to take place, in order that it may be forestalled. The cucumber 

 mildew usually makes its apjiearance sometime in August. The 

 vines should be sprayed with Bordeaux mixture by the last of 

 July, and the spraying repeated two or three times at intervals of 

 about ten days. 



The muskmelon crop also suffered from the attacks of the 



