Damage by Asphondylia sesame Felt (Diptera:Cecidomyiidae) to Sesame (Sesamum indicum L.) as Influenced by Variety and Planting Date at Lafia, Nasarawa State, Nigeria.

Varietal and planting date effects on damage by the gall midge, Asphondylia sesame, to sesame was investigated in small plot tests conducted at Lafia, Nigeria, in 2007 and 2008. Three dates of planting, July 26, August 3 and August 10, as main plot treatments, and an early-maturing variety [90 days] variety of sesame, E-8, and a late-maturing one [120 days] Yandev-55, as subplot treatments, were replicated four times in randomized complete block design. Over the two years, incidence of galling ranged from 4.2-17.5% (mean = 11.54%) and it explained 66.6% of the variation in seed yield. The earliest- planted plots were the most productive in terms of number of pods (mean = 789.8/5 plants), seed yield (mean = 175.0 kglha), and were the least damaged (4.25% galling incidence). One to two weeks delay in planting caused 22.1-34.1 % reduction in podding, 39.1-45.1 % reduction in seed yield, and it increased galling incidence by 171.8-305.9%. Varietal differences were significant (P<O.OOl) for days to 50% flowering and podding, galling incidence, and seed yield but not significant for pod production (P>0.05). Galling incidence was >2-fold lower and seed yield 1.8-fold higher on Variety E-8 than on Yandev-45. Early planting of E-8 is recommended as a sustainable way of mitigating gall midge damage to sesame.