12 MASS. EXPERIMENT STATION BULLETIN 394 



Table 9. — Results of Applying Soil Disinfestants to Pea Seed in the 

 Row at Time of Planting 



Relative Number 

 Treatment of Plants 



Which Lived 



Soil Treatments 



Liquid Treatments' 



Water only (check) lOO 



Acetic Acid 1:300 113 



Formaldehyde 1 :200 136 



1 -.300 134 



1:400 140 



Larvacide 1 :500 136 



1:700 , 129 



1 :1000 141 



Dry Treatments 



No treatment (check) 1 00 



Formaldehyde, 6-percent dust, 0.25 pound to 30 feet of row 138 



0.33 pound to 30 feet of row 141 



Seed Treatments 



Semesan 215 



Red cuprous oxide 203 



'Liquids were applied at the rate of 1 gallon to 30 feet of row. 



Stands of beet, spinach, Swiss chard, and onion were improved by an applica- 

 tion of 1.5 to 2.5 cc; those of eggplant, tomato, pepper, celery, and celeriac by 

 2.0 or 2.5 cc. per square foot; and 1.5 or 2.0 cc. was effective with chicor>^ dande- 

 lion, endive, and lettuce. Lettuce is more likely to be injured by formaldehyde 

 than are beet and spinach but it is less susceptible to such injury than are the 

 crucifers. 



Stands of cabbage and Brussels sprouts were sometimes improved by formalde- 

 hyde 1.25 to 2.0 cc, those of kohlrabi by 1.5 cc. per square foot; but formalde- 

 hyde did not give good results with collards, cauliflower, and water cress. Cruci- 

 fers are more susceptible to injury by formaldehj-de (also by acetic acid, salicylic 

 acid, pyroligneous acid, and o.xyquinoline sulfate) than are most other vegetables; 

 and it is safer to protect crucifers by seed treatment with Semesan or zinc oxide 

 than by soil treatment with formaldehyde. 



Cucurbits, on the other hand, are relatively tolerant of fomialdehyde, and 

 stands of summer squash, cucumber, and muskmelon were much improved by 

 formaldehyde, 1.5 or 2.0 cc. per square foot. 



Table 11, based on these and other experiments, contains suggested rates of 

 application for most of the vegetables other than crucifers, 1 fluid ounce (2 table- 

 spoonfuls) of formaldehyde in 2.5 to 3.5 gallons water being enough to cover 12 

 to 17 square feet of seedbed. 



Rates of application suggested in Table 11 are based rather more on what is 

 safe with different vegetables than on what is required to kill the fungi which 

 cause damping-off. They are to be considered more as maximum rates of appli- 

 cation than as absolute minima; although, in heavily infested soil, it would not 

 be wise to go far below them. 



