Three-Way Cross Maize Hybrids Show Herbicide Resistance and Tolerance to Striga Hermonthica (Del.) Benth with Herbicide Seed Treatment Under Artificial Infestation.

Members of the genus Striga are vascular root parasites of cereals and legumes, and a main constraint to maize production in the savanna region of Africa. Although Acetolactate synthase (ALS) inhibiting class of herbicides may control Striga, they are naturally phytotoxic to maize plants. Successful use of low doses of ALS inhibiting herbicides for seed coating depends on maize cultivars that possess resistance to this group of herbicides. To test the herbicide seed coating potentials of maize hybrids initially bred for imazapyr resistance (IR), there is need to challenge the hybrids with ALS inhibiting herbicides under artificial Striga infestation to determine their resistance to these herbicides and by extension, tolerance to Striga. Multi-locational field trials conducted to evaluate the performance of three-way cross maize hybrids developed for imazapyr (IMP) resistance with herbicide coating, reveal that in addition to resistance to IMP, seeds also showed resistance to metsulphoron methyl (MSM). At the concentrations tested, MSM and IMP showed similar results. When compared to commercial varieties used as checks, hybrids showed lower emerged Striga plants, Striga damage rating and higher grain yield. Coating seeds with IMP or MSM herbicide provides better option to indiscriminate use of herbicides. This study suggests seed coating IR maize hybrids with metsulphoron methyl is as effective as imazapyr for Striga control.