RELATIVE ROLES OF WIND, CROP SEEDS, AND CATTLE IN DISPERSAL OF STRIGA SPP

Parasitic flowering plants of the genus Striga cause extensive damage to cereal and legume crops in Africa, but factors affecting seed dispersal have not been well understood. Petrolatum-coated microscope slides placed at regular intervals from Striga hermonthica plants and suspended at 1-, 2-, and 3-m heights from trees within and around S. hermonthica-infested fields indicated that distribution of seeds by wind was not extensive. The maximum horizontal distance that seeds were caught was 12 m and the maximum vertical distance was 2 m. Samples of local market supplies of cowpea, maize, millet, and sorghum from six areas of Nigeria over 2 yr contained an average of 20.9, 32.4, 24.2, and 27.3 Striga seeds, respectively. Cattle dung was sampled intensively for parasite seeds in and around two S. hermonthica-infested fields and from 45 locations (88 fields) in S. hermonthica-infested areas of Nigeria. Cattle dung was of minor importance in seed dispersal. Implications of dispersal mechanisms in control are discussed.