Experiments using cultivars with differing degrees of striga
resistance were conducted at two sites at
Kamboinse in 1988 and at two locations (Kamboinse and Kouare) in 1989 in
the
Sudan-Savannah
region of Burkina Faso. At each site, striga-free (SFP) and striga-infested
plots (SIP) were selected.
Two factors, location and genotype, were found to be associated additively
with yield losses in soils
infested by striga. The location effect was probably due to lower soil
fertility in the SIP than the SFP
plots under farming conditions. Yield losses in SIP relative to SFP ranged
from 3·1%, at the
experimental station, to 44·2% under farmers' field conditions.
The genotype effect was evident at all
locations. Depending on the susceptibility of the cultivars, it varied
from
3·1 to 36·5% of the mean
yield of SFP with an average of 31·4% in susceptible cultivars.
The location effect was evident only
at Kouare, where SIP plots were under continuous cultivation without
appropriate soil fertility
maintenance and/or restoration measures. This amounted to c.
19·4% of the mean yield in the SFP.
To reduce yield losses in soils infested by striga, it appears to be
necessary to grow high yielding,
striga-resistant cultivars using agronomic practices which are known
to improve soil fertility.