Aphid Populations on Oats Grown in Various Nutrient Solutions1

Abstract

Plant nutrient availability to Garry oats (Avena sativa L.) Var. Garry was controlled by nutrient solutions in the greenhouse. The plants were infested by apple grain aphids, Rhopalosiphum fitchii (Sand.), according to their preference for individual plants and allowed to feed and reproduce thereon for a period of 14 days. The data indicated that there' as a significantly greater population increase potential where nitrogen was available to the plants. Elimination of nitrogen from the nutrient solutions resulted in lower aphid populations and adversely affected the plants, as indicated by decreased plant height, yellowish coloration, and spindly growth. Aphid population on all treatments correlated with plant height to a highly significant degree. Whether population differences reported here were due primarily to nutrient media or plant height (leaf area) has not been determined.