Effect of the fumigant dazomet on the development of mycorrhizae and growth of nursery stock

Abstract

The harmful effect of the fumigant Dazomet (DMTT, Mylone 50 D) on the development of mycorrhiza-forming fungi and accompanying growth of nursery stock is usually due to an inadequate pre-seeding detoxification period and/or a prolonged occurrence during this period of temperatures below 10°C. The eradication of the symbionts is occasionally caused by the lateral movement of water causing local high concentrations of the toxic chemical. A low supply of soil organic matter greatly aggravates the vulnerability of the mycorrhiza-formers to damages by the eradicant. During the past many years, a critical demycorrhization of stock in Wisconsin nurseries was observed predominantly in soils with organic matter content of less than 1.5% in the 15-cm surface layer.