Imazapyr seed dressings for Striga control on acetolactate synthase target-site resistant maize

High herbicide levels can be localized on or near seed of acetolactate synt hase (ALS) resistant maize (Zea mays). The magnesium salt of imazapyr was o ptimal for seed dressings (drenching, priming, and coating), for preventing field damage from parasitic Striga hermonthica (witchweed) in three season s. Striga emerged on untreated maize from 6 to 12 weeks after planting. The re was almost no Striga emergence for 3 months on imazapyr-dressed homozygo us ALS-R 3245IR maize seeds. Occasional Striga that emerged and flowered fo rmed no seed by harvest. Dust or polyvinylpyrrolidone adhesive coatings wer e safer in maize and as effective in Striga control as priming. Seed dressi ng coupled with pulling Striga escapes reduces infestation and can be used to deplete the Striga seed bank until genetic crop resistance becomes avail able. (C) 2001 Elsevier Science Ltd. All rights reserved.