|Juzwik, J J - USDA FOREST SERVICE|
|Gust, K M - UNIVERSITY OF MINNESOTA|
Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: October 10, 1998
Publication Date: N/A
Interpretive Summary: Soil fumigation with methyl bromide is often used to control root diseases in bareroot forest nurseries of the north Central United States. With the pending ban on the use of methyl bromide for soil fumigation, nursery managers must seek out other means of reducing and controlling root diseases. In most cases cost is a significant feature. The location and number of propagules of the Fusarium and Pythium root rots in the soil differed among three nurseries depending on the tillage system used to incorporate crops with a large biomass grown to maintain a critical level of organic matter. The tillage used before tree planting also had an effect on the position of the pathogen propagules. It should now be possible for these nurseries to develop long-term practices to reduce the disease by cultural control and use alternative fumigants only at shallow depths. Such information should have general use in management of nurseries where root disease is a serious problem.
Technical Abstract: The pending ban on methyl bromide for preplant soil fumigation to control conifer root diseases in bareroot nurseries is forcing nursery managers to seek other disease control measures including cultural control. Cone penetrometer measurements were used to describe tillage depths, locate tillage pans, and determine maximum penetration of conifer and cover crop rooting in three white and red pine nurseries in MN, WI, and MI. Profiles of total organic carbon, Ksat, and propagules of Fusarium and Pythium associated with soil strength (measured with cone penetrometer) profiles differed among nurseries. Long-term use of a moldboard plow versus a disk for incorporating a cover crop maintained a larger pool of pathogen propagules deeper in the profile. Use of a rotary tiller for secondary tillage before conifer planting was adverse for conifer rooting as suggested by low Ksat values in the tillage pan. These measurements used collectively as a system can determine what long-term managements have bee used in a nursery and suggest changes to culturally reduce disease and also the need for fumigation.