30 MASS. EXPERIMENT STATION BULLETIN 378 



Rooting of September cuttings of Daphne Cr.corum was improved 

 by treatment with 50 mg./l., 5 hr., or 12.5 or 25 mg./l., 20 hr. November 

 cuttings of Gardenia rooted so well untreated that the only benefit of 

 treatment (indolebutyric acid 25 mg./l., 24 hr., gave best results) was to 

 hasten rooting a little. November cuttings of Berheris candidula rooted 

 more than 80 percent without treatment, no better with treatment. De- 

 cember cuttings of Pfitzer juniper rooted 50 percent without treatment, 

 100 percent after treatment with indolebutyric acid 50 mg./l, 20 hr. 



Study of Diseases of Ornamental Herbaceous Plants Caused by Soil- 

 Infesting Organisms, with Particular Attention to Control Measures. (W. 



L. Doran.) L'ntil better and cheaper soil disinfestants are found, it is 

 important that more be learned about how best to use the old ones. Since 

 damping-oflf is important and also convenient to work with, its control was 

 here used as a measure of effectiveness, for Avhat is learned in this way 

 can be useful in efforts to control othei and similar diseases caused by 

 soil-infesting fungi. 



In order to learn how the efficacy of certain soil disinfestants is affected 

 by soil reaction, pH values of soil were adjusted with sulfur or with hy- 

 drated lime before soil treatment. 



Formaldehyde was equally effective in soil with a pH value of 7.0 and 

 in acid soils with pH values of 6.0 to 5.6. 



Calcium cyanamide, 1000 pounds per acre, applied to soil two weeks 

 before seeding, gave better control of damping-off and of a root-rot of 

 sweet pea seedlings in soils with a pH value of 7.0 or higher than it did 

 in a more acid soil with a pH value of 5.9. Sweet peas usually grow best, 

 if they escape root-rot, in a soil which is not very acid and it was in such 

 soil that calcium cyanamide was more effective. 



Applications of acetic acid in the form of vinegar (about 200 cc. vinegar 

 per square foot) which gave good control of damping-off in more acid 

 soils at pH 5.7 to 6.0, gave poorer control in soils with pH values of 7.0 

 or higher. More vinegar is needed for good control in less acid soils and 

 it was observed that a given quantity of vinegar can be used with greater 

 safety in less acid soils than in those with a lower pH value. Growth of 

 a few species was somewhat injured by vinegar applied to the more acid 

 soils, but the growth of seedlings of all species used was unaft'ected or 

 improved by vinegar applied to soil with a relatively high pH value. 

 Growth of sweet peas was also improved by vinegar in the more acid 

 :-oils for in such soils the control of root-rot was best. In soils with 

 more lime, such as are usually used for sweet peas, vinegar would prob- 

 ably not, however, be the preferred soil disinfestant. 



Aqua ammonia (containing 27 percent NH3) prevented damping-off 

 equally well in soils with pH values of 6.9 and 7.2 and in acid soils with 

 pH values of 5.7 and 5.3. Aqua ammonia, 8, 16, or 24 cc. per square foot, 

 gave good results; but 24 cc. per square foot applied 7 or 10 days before 

 seeding injured some species, and 16 cc. but not 12 cc, interfered with the 

 germination of beets sowed immediately after soil treatment. 



Soil treatments with ammonium sulfate and ammonium phosphate were 

 without fungicidal effect in acid soil (pH 5.4 to 5.9), but ammonium sul- 

 fate had some fungicidal effect in soil recently limed. Heavy applications 

 of ammonium sulfate which were harmless to germination in acid soil 

 were decidedly injurious in the limed soil. This is probably due to the 



