Evaluation of Cylindrocladium Root Rot Control By Fumigation

The effectiveness of soil fumigants used for control of Cylindrocladium root rot in Wisconsin state forestry nurseries was evaluated by assays of microsclerotial populations and by outplantings of stock from fumigated transplant beds. Mylone at 200 lb/acre active ingredient almost eliminatedviable microsclerotia, but only to the depth to which it was mixed in the soil. Vorlex left viable microsclerotia near the soil surface; effectivenss of this chemical could be improved by covering the soil with polyethylene sheeting and by injection at a depth of 15 to 18 cm instead of 12cm. Methyl bromide applied in a gel and without a polyethylene cover proved no more effective than Vorlex and also left a residual propagule population in the surface soil. Methyl bromide applied as a gas under a polyethylene cover was effective, but further trials with application rates aredesirable. Mortality of red pine seedlings outplanted from fumigated transplant beds was significantly less than with seedlings from untreated beds, and diameter and height growth were greater. Forest Sci. 17:323-331.