Documented evidence has revealed that damage by stem borers Chilo partellus and Busseolafusca in maize accounts for 18-53% of yield losses in the field. All available varieties grown by the farmers are susceptible to these borers and most of the methods used to reduce damage are either ineffective or not cost effective. Since 1997, efforts have been made towards identifying new sources of resistance for use in the mid-altitude breeding programme. Germplasm consisting of inbred lines, synthetics and lines extracted from populations like P531, P391, ITSI (Intermediate Tropical lines) and MIRT (Multiple Insect Resistance Tropical) has continuously been obtained from CIMMYT, Mexico and Harare and systematically screened over years under an artificial infestation technique. Results have indicated that in terms of foliar damage on a scale of 1-9 and stem tunneling, some lines and populations have been found to possess tolerance either to C. partellus or B. fusca, with a mean foliar score of 4 and below. However, these materials were not well adapted to the local environment as evidenced by their yield levels. Breeding work in progress is to introgress borer resistance to local breeding germplasm Emap la and 2a using the identified tolerant lines. Some crosses developed with some of the lines have already been made and evaluated. Development of synthetics in the long term and extraction of inbred lines in the short term is envisaged.

English

0409|AGRIS 0401|AL-Maize Program

Juan Carlos Mendieta

CIMMYT Staff Publications Collection