24 MASS. EXPERIMENT STATION BULLETIN 327 



several carnation growers in cooperation with the New England Carnation 

 Society. This project will be terminated with these tests. 



Diseases of Herbaceous Ornamental Plants caused by Soil-Infesting 

 Fungi. 1 (W. L. Doran.) Cuttings of Nepeta Mussini rooted as well in dis- 

 infested soil as in sand and with no more damping-off. In similar cases soil 

 may be preferred, for cuttings of this species made about 50 percent more 

 growth in five weeks after insertion in soil than in sand. 



Formaldehyde in quantities safe with seedlings was not safe with some 

 cuttings, and 7 c.c. injured N. Mussini inserted in soil 24 hours after treatment. 



An 18 percent acetic acid dust (of charcoal) did not injure seeds sown within 

 24 hours after soil treatment, improved germination, and prevented most 

 damping-off in naturally infested soil, but not in soil heavily inoculated with 

 Pythium spp. Like formaldehyde, acetic acid is volatile so there may be some 

 reinfestation of soil while seedlings are still susceptible. 



When ethyl alcohol 1:50 was applied 10 days before seeding, there was less 

 damping-off, also better growth, of sweet pea and China aster. It was injurious 

 when applied immediately before seeding. 



Raw pyroligneous acid 4:100 gave fair control of damping-off, but the con- 

 centrated acid at this dilution was not equally effective. 



Antimony and potassium tartrate 8 gms. reduced the severity of damping- 

 off in a naturally infested soil, but not in a soil heavily inoculated with Pythium 

 debaryanum. 



Hollyhock is apparently tolerant of or even benefited by more copper than 

 some other species can stand. Its growth was improved by copper lime dust 

 20 gms. and by metallic copper 9 gms., although the latter injured Ageratum 

 and Petunia. Both of these treatments prevented most damping-off. Copper 

 aceto-arsenite 1 gm., which gave some degree of control of damping-off, and 

 cuprous cyanide 2 gms. were harmless to hollyhock although injurious to 

 Ageratum, Salpiglossis, and cucumber. 



Tannic acid 3 to 15 gms. did not prevent damping-off and caused but little 

 change in soil reaction, but did improve growth of common foxglove. 



Ethylic aldehyde 1:40, 9 days before seeding, did not satisfactorily control 

 damping-off, but did improve the germination of several species, also the 

 growth of sweet pea. 



Salicylic acid 4 to 7 gms. did not affect damping-off, but did improve ger- 

 mination of cress, beet, and cucumber (and also Rhododendron molle). 



Neither potassium permanganate 15 to 30 gms. nor sulfur 6 to 20 gms. satis- 

 factorily controlled damping-off in soil inoculated with Rhizoctonia solani and 

 Pythium debaryanum. 



In the amounts used, the following have been toxic to plants or have failed 

 to prevent infection: acetamide, ammonium persulfate, auramine yellow, beta- 

 naphthol, boric acid, brilliant green, calcium hypochlorite, cerium oxalate, lead 

 acetate, magnesium superoxol, nickel oxide, orthocresol, orthochlornitroben- 

 zene, oxalic acid, oxyquinoline sulfate, and sulfocarbolic acid. 



Damping-Off and Growth of Seedlings and Cuttings of Woody Plants 

 as Affected by Soil Treatments and Modifications of Environment. 



(W. L. Doran.) Softwood cuttings of Cotoneaster divaricata, Enkianthus cam- 

 panulatus, Rhododendron yedoense, Viburnum Carlesii, and V. Opulus nanum 



'In the report on this and the following project, number of grams chemical per square foot of 

 soil is indicated. In the case of solutions, 2 quarts per square foot was used. Soil or other media 

 was 3 inches deep in flats. Soil used was either naturally infested or, after autoclaving, was in- 

 oculated with the fungi. 



