30 BULLETIN 127, U. S. DEPARTMENT OF AGRICULTURE. 



On July 26 a second center was found in the experimental field 

 with secondary infection present. The rains of July 17, 19, and 21 

 probably account for this secondary infection, as well as that noted 

 about the centers in the neighboring private field. An inspection 

 of all of the 217 plats in the experimental field on July 28 resulted 

 in the discovery of the disease in only two other plats. One week 

 later scattered anthracnose lesions were noted in five more plats. 

 It is of interest to note that up to this time all the anthracnose infec- 

 tion in this field was confined to one area consisting of 15 adjacent 

 plats. 



A careful inspection of all the plats on August 9 and 10 revealed 

 anthracnose in five more plats in the area mentioned above and 

 tertiary infection was noted about the old centers. Due probably 

 to the rains of August 1 to 5, there followed a very rapid spread of the 

 disease. An inspection of the field on August 17 and 18 revealed 

 anthracnose in 45 plats outside of the diseased areas already alluded 

 to. In two of these cases the infection was in apparent original 

 centers. Thus, the most rapid spread in 1915 seems to have occurred 

 prior to the middle of August, and it will be remembered that wet 

 weather prevailed the first five days of that month. A frost killed 

 the vines on August 28. 



DEVELOPMENT IN 1916. 



In the summer of 1916 the cucumber experimental work was lo- 

 cated at Madison. With five rather scattered experimental fields, 

 numerous small garden patches, and two private fields under con- 

 stant observation during the early part of the summer, anthracnose 

 was found only in the five experimental fields. 



A diagram showing the weather conditions during this season is 

 presented (fig. 12), to which reference may be made in connection with 

 the discussion of the progress of the disease. 



The disease was first noted on July 19, in field 1, planted five 

 weeks previously. This center consisted of infection on two adjacent 

 plants. As in 1915 the first infection was not found until after the 

 rows had been thinned. All of the lesions were less than 1 cm. in 

 diameter. On July 20 another center of two infected plants was 

 found in field 1, and three centers of infection were found in field 2. 

 On July 21a third center was found in field 1 and a center was found 

 in field 3. On July 22 anthracnose was found on one plant in 

 field 4 and a center of two infected plants was found in field 5. 



Rather thorough inspection of fields 1 and 2 made on July 26 and 

 27 revealed 12 additional centers in field 1 and two in field 2. On 

 August 1 eight more centers were found in field 2 and the following 

 day five more were found in field 1. The relation of this rather sud- 

 den increase in the number of new centers of infection to weather 



