Survival of the nuclear polyhedrosis virus of Heliothis armigera on crops and in soil in Botswana

Experiments are described that record the change in activity of the nuclear polyhedrosis virus of Heliothis armigera on cotton and sorghum in the short-term and long-term survival of the virus on sorghum and in soil. Virus activity was lost rapidly on cotton but remained at a high level for up to 30 days on sorghum. Activity was still detectable on harvested sorghum more than 80 days after spraying and on the soil below, but soil activity fell to less than one-third of its original level during the winter.