|Stenlund, D L - UNIVERSITY OF MINNESOTA|
|Juzwik, J J - US FOREST SERVICE|
Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: October 10, 1997
Publication Date: N/A
Interpretive Summary: Preplant fumigation with methyl bromide is often used in bareroot forest nurseries to control root diseases in north Central United States. Fumigants are needed to replace methyl bromide. Dazomet is a granular fumigant that can replace methyl bromide for root disease control because the active ingredient is environmentally benign and it is relatively easier rto handle. Earlier measurements showed that a spade machine (relatively unknown in USA) gave deeper incorporation and better mixing of the fumigant than the recommended machine. Follow up measures of root disease ratings, and pathogenic fungal populations in the soil confirmed the superior performance of the spade machine. This information will facilitate use of a methyl bromide alternative for fungal root disease control in bareroot forest and other nurseries.
Technical Abstract: Alternative chemicals are needed for soil fumigation to control fungal root diseases in bareroot forest nurseries in the north Central States. The efficacy of dazomet, a granular fumigant, depends on the depth and uniformity of incorporation. A spade machine was superior to rotary tillers for depth and uniformity of application. Four machines were compared at two orates of dazomet application in two nurseries. In the WI nursery the percentage of live pine seedlings was largest at the higher fumigant rate, and the incidence of root rot in one-year old seedlings was highest at the low application rate. In the MI nursery there was little seedling loss due to damping off. Fungal populations of Fusarium and Cylindrocladium were reduced most with the spading machine at both rates of dazomet. The reductions were most consistent throughout the top 30 cm. The spade machine was required when fumigating to control pathogens in the 15 to 30 cm layer, ,when control was needed only in the upper 15 cm all four machines were effective.