Both in a choice and multi-choice laboratory tests, fewer adults of the banana root borer, Cosmopolites sordidus (Germar), settled under the corms of the susceptible banana "Nakyetengu" treated with 5% aqueous extract of neem seed powder or cake or 2.5 and 5% emulsified neem oil than on water-treated corms. Feeding damage by larvae on banana pseudostem discs treated with 5% extract of powdered neem seed, kernel, or cake, or 5% emulsified neem oil was significantly less than on untreated discs. The larvae took much longer to locate feeding sites, initiate feeding and bore into pseudostem discs treated with extract of powdered neem seed or kernel. Few larvae survived when confined for 14 d on neem-treated banana pseudostems; the survivors weighed two to four times less than the larvae developing on untreated pseudostems. Females deposited up to 75% fewer eggs on neem-treated corms. In addition, egg hatching was reduced on neem-treated corms. The higher the concentration of neem materials the more severe the effect.

Ergot is an important disease of sorghum (Sorghum bicolor) in parts of Africa and Asia. Studies were conducted to determine the relationship between flowering biology and ergot infection, and to develop an artificial field‐screening technique to identify ergot resistance in sorghum. Spikelets resisted infection after anthesis, but each day's delay in anthesis after inoculation supported 8‐3% more ergot. The screening technique consisted of three components: trimming of panicles to remove pollinated spikelets before inoculation, a single inoculation of trimmed panicles, and panicle bagging for 7‐10 days. Inoculated panicles were evaluated by a qualitative visual rating method (on a 1‐5 scale) and a quantitative spikelet counting method. Selected accessions from the world collection of sorghum germplasm were screened at Karama Research Station, Rwanda, for two seasons and 12 ergot‐resistant lines were identified. These were also resistant at ICRISAT Centre, India.

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