Fall Armyworm-Tolerant Maize Varieties Exhibit Lower Leaf Damage under Farmer Management

Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) is now a major threat to maize production in Africa since its invasion in 2016. Chemical control remains the dominant farmer's response to FAW. However, increasing concerns over insecticide resistance, environmental risks, and costs have increased interest in exploring host plant tolerance as a sustainable management strategy. This study evaluated the performance of a newly released FAW-tolerant maize hybrid (FAWTH) under smallholder farmer management conditions across three agroecological regions of Zambia during the 2024/2025 growing season. A sample of 127 farms with complete non-FAWTH and FAWTH plot pairs were analysed, using a standardized scoring scale approximately 60 days after planting. Results showed that the FAWTH variety consistently exhibited significantly lower FAW leaf damage than the farmer-selected hybrids grown alongside them on the same farms, with mean damage scores about 1.2 points lower on the 1-9 scale (roughly a one-third reduction). Foliar damage reduction was most pronounced in the low-altitude, low-rainfall agroecological region I and in the medium rainfall (∼800mm per annum) region II, and not observed in the high-altitude high-rainfall (>1200mm/annum) region III. Intercropping FAWTH with legumes (predominantly soybean, cowpea, and groundnuts) provided no statistically significant additional benefit. FAWTH varieties can be promoted for smallholder farmers as part of integrated FAW pest management, especially in areas highly susceptible to FAW.