The Dry Root-Rot of the Bean 1029 



tion of the seed injured, but over 95 per cent of the plants showed 

 severe infections of the dry root-rot. Later in the summer these rows 

 were torn up and again planted to beans. It was thought that by that 

 time the sulfur might have had an effect on the pathogene. Practically 

 all the plants became infected. No further experiments with sulfur 

 were conducted. 



A volatile chemical which would kill the pathogene and then evaporate 

 would be the ideal substance to apply. The use of formaldehyde possibly 

 furnishes the closest approach to this condition. Calcium hypochlorite 

 is another substance which would break down and leave no injurious 

 substances. In the winter of 1915-16 preliminary tests were conducted 

 with these two substances. One of the beds in the greenhouse was 

 thoroughly contaminated with Fusarium martii phaseoli. It was then 

 divided into three plots, each containing 12 square feet, and planted to 

 beans. Plot 1 was treated with calcium hypochlorite applied at the 

 rate of 200 pounds to the acre and drilled in with the seed; plot 2 was 

 left as a check; plot 3 was treated with a formaldehyde drip similar to 

 that used in onion smut treatment. The strength of the formaldehyde 

 solution used was 1:100 and it was applied at the rate of 400 gallons to 

 the acre. The germination of the seed was not injured by the formal- 

 dehyde, but injury to the extent of 75 per cent was observed on the 

 plot treated with calcium hypochlorite. In both plots all plants were as 

 severely infected as those in the check plot. 



Further experiments with calcium hypochlorite and formaldehyde were 

 conducted in the field in the season of 1916. A bean field near Perry, 

 known to be contaminated with F. martii phaseoli, was used for the pur- 

 pose. In each plot the beans were planted in four rows 28 inches apart, each 

 row containing about 100 plants. Some of these were destroyed by the 

 seed-corn maggot and by slugs. Plot 1 was treated with calcium hypo- 

 chlorite at the rate of 200 pounds to the acre, the treatment being made 

 ten days before planting; plot 2 was treated with the same substance 

 at the rate of 100 pounds to the acre, and the chemical was drilled in 

 at the time of planting; plot 3 was treated with formaldehyde, 1:100, 

 which was applied as a drip at the time of planting at the rate of 400 

 gallons to the acre (this plot was repeated three times); in plot 4 the 

 strength of the formaldehyde was doubled. Only in the last plot was 

 any injury to the germination of the seed observed. No beneficial effects 



