WILT OF CUCURBITS. 297 
So far as known to the writer, no one has studied carefully the relative resistance of 
different varieties of melons, cucumbers, squashes, etc., to this disease. Possibly careful 
field work covering a number of seasons and many varieties would develop some interest- 
ing differences which might be turned to practical account in the production of resistant 
varieties by cross-breeding and selection. ; 
To recapitulate—Prompt removal of diseased plants and wholesale destruction of cucur- 
bitaceous insects are the best available means for holding this disease in check. 
PECUNIARY LOSSES. 
This disease has proved an extremely vexatious one to a great many growers, but the 
writer has no means of knowing the full extent of the losses. Numerous complaints have 
reached the Department of Agriculture. The disease is particularly bad in some regions 
where cucumbers are cultivated extensively for pickles. The writer has seen entire fields 
Fig. 97.* 
of cucumbers, of cantaloupes, and of winter-squashes destroyed by it in the vincinity of 
Washington, and knows from personal observations in other places (Delaware, New York, 
Michigan, etc.) that it is capable of doing serious damage over a large region of country. 
According to Sturgis (1899) a destructive muskmelon disease in Connecticut is caused 
by B. tracheiphilus. ‘That this is actually the disease which, for the past five years at 
least, has destroyed a large percentage of the melon vines in Southern Connecticut there 
can be no doubt. Continuous observation in the field, in three separate localities, during 
the past season, convinced me that the chief source of trouble was the bacterial organism 
above mentioned.” 
*Fic. 97.—Petri-dish poured-plate of nutrient gelatin densely sown with Bacillus tracheiphilus, covered with 
impervious paper except central star-shaped part which was cut away, and then exposed to sunlight for 3 hours at 15° 
C. Therewas prompt growth of the bacteria in the form of a white clouded mass in covered part, and almost no growth 
in part exposed to light, 7. e., only about 1 colony in 1,000 survived as shown by a count on the seventh day. The 
figure also illustrates a bit of badtechnic. A moldspore germinated at x, and threatened to swampthe plate. When 
the cover was removed to cut it out the dish was exposed to a draft of air, the result being the entrance and growth 
of 30 or 40 other organisms so that when the plate was old enough to photograph (4th day) these also were visible. 
