ABSTRACT
The Delta and Pinelands cotton cultivars, NuCOTN 37B and NuCOTN 35B, containing Monsanto’s patented Bollgard® Bt-gene technology was performance tested under irrigated, rainfed and small scale conditions in all cotton producing regions of South Africa (approximately 25 trials). A minimum of 1ha of the transgenic cultivar was planted adjacent to its non-transgenic parent, and the co-operating farmer managed each cultivar as an extension of his own cotton. The only exception was with respect to insect control. The non-transgenic block was sprayed according to the farmers own system, while the Bollgard block was only sprayed when a threshold of 5 larvae per 24 plants was equalled or exceeded. Each block was assessed for larvae of Helicoverpa armigera, Diparopsis castanea and Earias spp. at weekly intervals. Presented results summarize the larval infestations on each of the cultivars, the number of sprays on each of the cultivars as well as the yields and fiber qualities. Under both irrigated and rainfed production, the larval threshold was regularly exceeded in non-transgenic blocks, whereas it was very rarely exceeded in transgenic blocks (only once in three of the trials). Under commercial irrigated conditions the reduction in the number of sprays varied between 4 and 7, whereas under commercial dryland conditions the saving varied between 4-6. Under small-scale production (dryland), one producer saved 9 sprays. In general the transgenic cultivars out-yielded their non-transgenic parents by 5-20%. The implications of genetically modified Bt cotton for emerging small scale farmers in Africa is also discussed. The main advantages are huge labour and timesaving as well as increased yields. Technology of this nature should make a significant contribution to cotton production in Africa.

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