30 MASS. EXPERIMENT STATION BULLETIN 355 



root at all without treatment. Where growth substances proved beneficial, 

 indolebutyric acid generally produced more improvement than potassium naph- 

 thaleneacetate or naphthaleneacetic acid, and the latter seemed more likely to 

 cause injury. Indolebutyric acid was beneficial to more species than was any of 

 the other substances used. 



Response of cuttings to growth substances may be afifected by both the rooting 

 medium and the time when cuttings are taken. Cuttings sometimes rooted 

 so well and so rapidly without treatment that they rooted no better with it. 

 Although indolebutyric acid hastened the rooting of cuttings of some species 

 when taken on certain dates, it made no difference in the number which ultimately 

 rooted. As more becomes known about the optimum time for taking cuttings of 

 various species and the factors which affect it, there may be less need for treat- 

 ment with growth substances, but they will continue to be useful when it is nec- 

 essary to take cuttings at other times. 



The rooting of softwood cuttings of a number of species was not improved by 

 potassium permanganate or by sucrose. Treatment of hardwood cuttings of 

 conifers with acetic acid or with formic acid was equally ineffective. A hot water 

 treatment which apparently somewhat hastened the rooting of cuttings of one 

 species was without efTect on another. 



Chemical Soil Surface Treatments in Hotbeds for Controlling Damping-Off 

 of Early Forcing Vegetables. (VV. L. Doran and E. F. Cuba, VValtham.) Formalde- 

 hyde, diluted sothat 1 quart of the solution per square foot supplied from 3 to 5 cc, 

 was applied to the surface of soil after seeding. Pepper and beet were not injured 

 by 5 cc, and 4 cc. was harmless to celery and onion and to some, but not all, orna- 

 mentals. Cress was injured by 3 cc, and 4.9 cc. (one teaspoonful) interfered with 

 the germination of the seeds of all crucifers used, but did not hurt lettuce and beet. 

 Germination and final stands of all species not chemically injured were much 

 improved by 3 to 5 cc, and damping-of? was well controlled by 3.7 cc. (three- 

 fourths of a teaspoonful). None of these treatments injured growth of anything 

 but crucifers. When the pots or flats of soil were tightly covered with glass or 

 wet paper after treatment, there was a little more injury to the germination of 

 some species than when the soil was not covered. 



Vinegar, 215 cc. in 1 quart of water per square foot of soil surface, applied after 

 seeding, did not injure germination of beet, lettuce, or eggplant and prevented 

 most damping-off ; but 230 cc. similarly applied was less safe. 



Pyroligneous acid, 140 or 160 cc. in 1 quart of water per square foot, applied 

 to soil after seeding, improved germination and final stands of lettuce, pepper, 

 and cress; and 175 cc. markedly improved germination and final stands of tomato 

 and cauliflower without injury to their growth. 



The dry chemical seed treatments — red copper oxide, Semesan, and zinc 

 oxide — insure good control of the pre-emergence phase of damping-off, but 

 serious incidence of the disease in the post-emergence phases of growth of the 

 seedlings is frequent. 



Solutions of formaldehyde 1:200 to 1:600, acetic acid 1:300 to 1:500, Seidorin 

 1:800 and 1:1000, and Larvacide 1:800 to 1:1200 were applied, after seeding, to 

 soil in ground beds at the rate of 1 gallon to 5 square feet. Seidorin and Larvacide 

 emulsions, which contain 45 and 70 percent chloropicrin respectively, caused so 

 much discomfort to workers that they may not be considered practical although 

 they showed fungicidal value. Acetic acid 1 :400 gave better results than formalde- 

 hyde 1:400 with beet, chicory, eggplant, lettuce, pepper, and radish, and equally 

 good results with cabbage and tomato. 



