33 



Fig. 2. — Tomato rot. 



ever, entirely satisfactory iu all cases, partly, no doubt, from the 



fact that a number of clift'erent organisms have been involved iu 



fruit rots, some of which would appear 



to be more difficult to control than others. 



For greenhouse culture we recommend, 



as a partial means of prevention, the 



keeping of moisture from the fruit or 



foliage as much as possible, for in our 



experiments we have found 33 per cent 



less fruit rot where we did not practice 



syringing the plants than where we did syringe. 



There are other troublesome diseases of the tomato, apparently 

 more common in the south than in the noi'th. Among these may 

 be mentioned leaf blights (Septoria, Alternaria) , tomato wilts 

 {Fusarium Bacilhis), etc. There is also a functional disorder 

 occasionally met with in greenhouse tomatoes, known as (Edema 

 or dropsy. This gives rise to a curling and rupturing of the cells 

 of the leaf. (Edema is caused by excessive absorption of water 

 from the soil, brought about by too high soil temperatures. The 

 peculiar crinkling, curling and high coloration of tomato leaves, 

 common to greenhouse culture, especially when grown iu a rich 

 soil and when severe pruning has been practised, must not be con- 

 founded with the dropsy. The latter peculiarity is a form of in- 

 digestion, and the same peculiar curling of leaves may be observed 

 on 3'oung stump shoots of forest trees which have been cut. Un- 

 pruned tomato plants, grown under exactly similar conditions, 

 seldom, if ever, exhibit these peculiar symptoms. 



Cucumbers. 

 The diseases affecting greenhouse cucumbers are referred to 

 more extensively in Bulletin No. 87, issued by the Hatch Experi- 

 <nent Station. 



Dotvny Mildetv (Plasmopara Cubensis, (B. & C.) Humphrey). 

 This mildew can be readily distin- 

 guished by the typical yellowish, angu- 

 lar spots on the leaves (see Fig. 3). 

 It is likely to occur on greenhouse 

 crops from August to November or 

 December. If crops, however, are 

 set in the house as late as October, 

 they are apt to remain free from ' """^^^ 

 mildew during the rest of the year. ^^i'l- a --*- 



Keeping the moisture down in the Fig 3.- Cucumber downy mildew, 

 , , ., . , ., . -1 showiug the characteristic angular 



house, together with ventuation and gpotg. 



