ANTHRACNOSE OF CUCURBITS. 



55 



tiveness and safety was used. This consisted of immersion in mercuric 

 chlorid, 1 to 1,000, for 5 minutes, followed by 15 minutes' washing in 

 running water. This bulk seed treatment, involving the handling of 

 400 pounds of seed, was done at Madison. By this cooperative 

 method very large amounts of seed were tested in separate districts 

 under a variety of conditions. As in the tests at Madison, these tests 

 aimed not only at a proof of the theory of the seed carriage of disease 

 but at the same time aimed at disease control, as will be noted later. 

 In Michigan anthracnose occurred in neither the 34 fields planted 

 with untreated seed nor the 42 planted with treated seed, so it is ob- 

 vious that there was no anthracnose in the Iowa seed. The results 

 obtained in Indiana and Wisconsin are briefly summarized in Table 

 VIII. It is to be noted that due allowance has been made for the 

 complicating factor of possible overwintering in the soil. 



Table VIII. — Effect of seed treatment upon the occurrence of cucumber anthracnose, as 

 shown by cooperative field tests in Indiana and Wisconsin, season of 1917. 





Effect of seed treatment . 



Overwintering. 



State 



Seed. 



Num- 

 ber of 

 fields. 



Diseased 

 plants. 



Anthracnose 



not due to 1916 



crop. 1 



1916 crop, same 

 soil. 



Anthracnose 



due to 1916 



crop. 2 





Num- 

 ber. 



Per- 

 cent- 

 age. 



Num- 

 ber. 



Per- 

 cent- 

 age. 



Num- 

 ber. 



Per- 

 cent- 

 age of 



dis- 

 eased 

 fields. 



Num- 

 ber. 



Per- 

 cent- 

 age 

 of dis- 

 eased 

 fields. 



Indiana 



Wisconsin 



Total . . 



/Untreated 



\Treated .... 



/Untreated 



\Treated 



/Untreated 



\Treated . 



30 



42 



43 

 33 



73 



75 



15 



7 



2 



4 



17 

 11 



50 

 16.6 



4.7 

 12.1 



23.3 

 14.6 



4 

 



1 

 1 



5 

 1 



13.3 

 .0 



2.3 

 3.3 



6.8 

 1.3 



9 



4 





 2 



9 

 6 



60 

 57.1 





 50 



52.9 

 54.5 



11 



7 



1 



3 



12 

 10 



73.3 

 100 



50 



75 



70.6 

 90.9 





8.7 



5.5 





due to 

 treat- 

 ment. 











1 1916 crop not on same or neighboring held. 



2 1916 crop on same or neighboring field. 



The results show that there was apparently very little anthracnose 

 in the Ohio seed, since most of the cases of anthracnose occurrence 

 may be attributed to overwintering. Among the very few cases in 

 which anthracnose could not be due to the previous crop, the Wisconsin 

 trials are inconclusive, while the Indiana tests indicate that anthrac- 

 nose may have been introduced with the seed. 



From the standpoint of the introduction of the disease with the 

 seed, all of these seed-disinfection tests, while inconclusive, indicate 

 that anthracnose may be carried with the seed, and they show the 

 need of further tests of this nature. 



