Field observations on the biocontrol of Dutch elm disease with Trichoderma virie pellets

Fifteen elm trees ranging in DBH from 25 to 40 cm were inoculated with ca. 8 mm diameter pellets containing propagules of Trichoderma viride IMI 206039 and IMI 2006040 besides nutrients. These pellets were inserted in the trunks every 10 cm around the circumference. Dead elms present upwind and downwind from the 15 treated elms remained standing during the four year duration of the experiment. No progress in the disease occurred during three growing seasons after the original treatment. During the fourth growing season (1982) 4 elms died and 11 survived, though one was severely damaged. These 11 surviving trees were retreated in September 1982.