The effect of soil fumigation with D-D on the yields of sugar beet and other crops

An experiment in a field where sugar beet in 1965 had suffered from Docking disorder caused by Longidorus attenuatus tested the effect of fumigating the soil with 3741/ha D-D and two amounts of nitrogen fertilizer on different crop sequences between 1966 and 1969. Although severe Docking disorder did not recur in sugar beet, fumigation increased yield in each of the three following years. Yield of barley was increased for 4 yr and of wheat, potatoes and ryegrass for 1 or 2 yr after treatment. All plant parasitic nematodes were controlled by the first fumigation and the numbers of those in unfumigated plots 3 yr after treatment. Fumigation also largely prevented infection of sugar beet by the fungus Helicobasidium purpureum.