Sowing date or transplanting as components for integrated Striga hermonthica control in grain-cereal crops?

Abstract

A study on the effect of sowing date on Striga hermonthica infestation of maize and sorghum indicated a linear relationship. When sowing was delayed for 30 days crops were 3.5–5 times less infested than after early sowing. This effect of delayed sowing cannot be explained by a change in the root distribution of the host plants. It may be caused by a combined effect of a dying-off process of the seeds and excess soil moisture. It may not be related to the occurrence of secondary dormancy. Although measurements of soil moisture content did not show measurable differences in the course of the rainy season, it may be assumed that this resulted in leaching of host root exudates following heavy showers, which would reduce Striga germination. Despite a higher infestation, early sowing gave higher crop yields compared to late sowing. Therefore, delayed sowing does not seem to be a practical control method for farmers in Bénin. However, transplanting after cultivation in a Striga-free nursery for 4–6 weeks, which may be comparable to late sowing is a better alternative as it combines the respective beneficial effects of early sowing and the effects on Striga of delayed planting.