Control of farley fly delia, flavibasis stein (diptera: Anthomyiidae) with resistant varieties and insecticides

Abstract

Control of barley fly Dolia fla7ibasis Stein (Diptera: Anthomyiidae) with resistant varieties and insecticides. Field experiment awere carried out to determine the effects of infestation of D. flavibasis on growth and yield of barley. The effects of the attack on the malting quality and commercial value of harvested barley crop was also assessed. Attacked plans suffered a check in their growth and were observed to compensate by recovery growth. The slow rate of development and compensatory growth delayed ripening. In attacked barley, the shoots developed unevenly and the ears did not ripen evenly. D. flavibasis infestation caused high yield losses. Highest yield losses occurred in varieties Proctor, Tumaini, K. Research and MP'IT 169 - 2Y. The lowest yield loss occurred in Can B35/2. However, E. flavibasis attack did not affect the grain quality, hence no effect on the malting quality of barley. The pest incidence did not reduce the commercial value of the harvested barley crop. Five barley varieties viz Procter, K. Research, Tumaini, MP"J.'"T 169 - 2Y and Can B35/2 were tested in the field to compare their resistance to D.flavibasis. Despite variation in results, Can B35/2 be identified as moderately resistant variety useful for reference in further work. The barley varieties were observed to recover their growth after the infestation. Although it was difficult to identify the mechanism of resistance, visual growth recover scores in the field experiments suggested some form of tolerance. However, observed grain yield differences between varieties indicated resistance could be due to many unknown factors such as environmental or varietal yield potential. The response of barley varieties to attack by flavibasis was studied in the greenhouse. The effects of infestation were quantified. 'Barley plants infested with D. flavibasis larvae at 11 - 12 growth stages were virtually killed, while plants infested at 13th growth stage survived. Infested plants suffered. a check in their growth and development but were later observed to recover their growth. Also in response to attack proportionately more tillers were produced by infested plants. This suggested tolerance as the mechanism of resistance. Field experiments carried out on the chemical control of barley fly Q. flavibasis showed carbofuran 5c granules as an outstanding preventive seed-dress treatment, with 4Kg a.i/Ha giving lCC%control to D. flavibasis larvae. Aldrin 4CDk wettable powder was the second effective seed-dress treatment. Phosphamidon 5 S.C.w. and trichlorphon 95 S .P. were the most promising foliar sn.ray insecticides evaluated for control of D. flavibasis larvae on barley. Applications of seed-dressings of both carbofuran granules and aldrin 40J.t wettable powder for control of D. flavibasis larvae significantly improved grain yield.