Control of Witchweed, Striga hermonthica Benth., in the Sudan Gezira

Abstract

RECENT work¹ has shown that the phanerogamic root parasite Striga hermonthica Benth. (witchweed), which causes considerable crop losses to sorghum (Sorghum vulgare Pers.) in the Sudan and elsewhere, can be controlled by spraying the young crop with hormone weed-killers of 2,4-D type two to three weeks after sowing. Although such measures often result in substantial increases in yield, there are several difficulties which at present preclude their general adoption in the Sudan Gezira. One is the extreme sensitivity of certain crops, notably cotton, to even minute traces of hormone weed-killers, together with the fact that such spraying has to be carried out at about the time of cotton sowing in the Gezira. Furthermore, spraying must be carefully timed and performed to avoid injuring the young sorghum plants, and involves the use of relatively costly and complicated spraying apparatus with which most Gezira cultivators are unfamiliar—the initial cost and subsequent maintenance of such apparatus discourage many cultivators from using this method of witch-weed control.