64 HATCH EXPERIMENT STATION. [Jan. 



account. It must be remembered that each is a definite 

 organism, growing parasitically upon the leaves of the 

 melon, and having its regular course of development. 



Taking up each disease separately, we find the Altemaria 

 less abundant this } r ear than when it first appeared. No in- 

 stances have been found, as was certainly the case in 1898, 

 of this fungus alone being the cause of the trouble. It may 

 be mentioned here, however, that specimens of the melon 

 blight, now so prevalent in the extensive Colorado melon 

 districts about Rocky Ford, sent by Mr. H. H. Griffin of 

 the Colorado Experiment Station, show only a fungus appar- 

 ently identical with our Altemaria. All our experience 

 indicates that trouble from this source alone is not to be 

 looked for until comparatively late in the season, — not, 

 probably, before August 1. 



The anthracnose ( Colletotrichum) causes a well-known leaf 

 blight on greenhouse cucumbers, and has been very com- 

 mon on melons the past season. It is more usual on water- 

 melons than muskmelons, having often been the cause of 

 serious damage to the former. On both species it attacks 

 the fruit as well as the leaves, causing spotting and decay. 

 This fungus is not, apparently, as definite in the time of its 

 appearance upon melons as either of the others, but is liable 

 to come on earlier, and generally does so when abundant. 



The downy mildew has been comparatively unknown in 

 this State up to the present outbreak. It is now abundant on 

 greenhouse cucumbers, and occurred everywhere on musk- 

 melons last summer. Farther south it has been well known 

 on these plants for some time. The appearance of the fungus 

 on melons is not to be looked for here before August 1 and 

 quite commonly it did not become destructive last season 

 until September 1. 



A typical case of the simultaneous occurrence of these 

 three diseases occurred at Mr. A. A. Marshall's place at 

 Fitchburg, Mass., where the growing of muskmelons is made 

 a specialty. Eight acres were grown, all in one field, and 

 all of one variety, the Miller's Cream. At one end of the 

 field the ground was slightly rising, and on this portion the 

 same crop had been grown the preceding year, the rest of 



