Three milliliters of chloropicrin injected 6" deep into moist soil will diffuse a cubic foot of soil volume in sufficient concentration to kill the Verticillium wilt fungus. This information—obtained from laboratory and greenhouse research—has been generally substantiated in commercial fumigation for Verticillium wilt control in chrysanthemums. It applies to soils varying from light sandy loams to moderately heavy clay loams; to soil temperatures of 45°F to 60°F; to soil moisture of a seedbed level extending to the soil surface; and to a completely pulverized soil tilth extending to at least a 9" depth.

The above progress report is based on Research Project No. 981.