Control of Basal Rot of Cuttings of Chrysanthemum and Other Ornamentals

Abstract

Basal rot is a serious disease of cuttings of chrysanthemum (Chrysanthem orn morifolium Ram.) in clothhouse cutting benches in San Mateo and Salnta Clara counties, California. A similar rot affects cuttings of other orniamiiental plants in cutting benches in lathhouses and greenhouses in the samiie areas. The purpose of this paper is to report studies on the cause and conitrol of this disease on cuttings of chrysanthemum and other ornamental planits. Review of Literature. There are a number of reports on the rotting of planit cuttings, but few deal with the causal agents and the use of Ferbam,2 Ziram,3 and Spergon (tetrachloroquinone) as protective fungicides. Dietz (1944) has enumerated many different types of diseases affecting cultivated plalnts in the United States and successfully controlled by using Ferbam (Fermiiate) either as a dust or as a spray. MeCallan (1946) has discussed control of certain diseases of fruit trees, vegetables, tobacco, and miscellaneous cuttings by applications of Ferbam. Inl a preliminary note, Tompkins (1944) directed attention to a basal rot of soft-green cuttings of florists' chrysanthemum (Chrysanthemum hortorumi Hort.), oceurring each year, from January to April, in clothhouse cuttinog benches in San Mateo County, California. Three soil-inhabiting fullgi, Ftsarium sp., Pythium sp., and Sclerotinia sclerotiorum (Lib.) de Bary, were isolated from infected cuttings. Field tests indicated that the disease could be controlled by dusting the basal ends of the cuttings with Ferbam or a mixture of Ferbam and Celite 505 (a diotomaceous earth), Stoutemyer (1938) having suggested earlier that tale, a similar material is anl excellent carrier of root-inducing substances used for dusting of cut-