Role of herbicide (metalachlor) and fertilizer application in integrated management of Striga asiatica in maize in Malawi
Keywords:
Witchweed, Zea mays L., metalachlor, on-farm fertilizer responses.Abstract
The parasitic weed species Striga asiatica (L.) Kuntze is one of the major constraints in maize production in Malawi.
The effects of metalachlor (as DualTM Magnum 960 EC), a pre- emergence herbicide, with 69N:21:P2O5:4S kg ha-1 and
without fertilizer application, on maize growth and Striga suppression, were investigated at 5 sites in 2000/’01 season
and 6 sites in 2001/’02. The use of metalachlor at 2.2 kg ha-1 gave no considerable phytotoxic effects on maize plants.
Application of metalachlor significantly suppressed Striga emergence across all sites in 200/’01 and not in 2001/’02.
Metalachlor application increased yields from 1448 to 1793 kg ha-1 in 2000/’01, and from 1677 to 2077 kg ha-1 in
2001/’02. On the overall, the use of fertilizer was superior to herbicide use in increasing maize yields. Yields were
generally low as, in most cases, sites with Striga are low in productivity. Due to this association between poor site
productivity and Striga, an integrated approach which tackles both problems is suggested. For example, rotation with
legumes is strongly recommended not only to reduce Striga seeds in the soil, but to improve fertility. The increased
productivity in subsequent years would then allow sufficient yields to cover other inputs such as herbicides, fertilizer
and improved seed.
