Effects of Fertilizer, Late Weeding, and Desuckering on Yield and Pest Populations of Taro

Abstract

The effects of fertilization, late weeding, and sucker removal on taro pest populations and yield were compared at two sites with different soils. The first experiment was in an area with shall calcareous soil. Fertilizer increased plant size and yield in this soil. However, in the plots with the lowest levels of iron in the soil, iron deficiency stopped growth of the taro even when fertilizer was applied. All plots showed some symptoms of iron deficiency. Taro planthoppers were more abundant on fertilized plants, but aphids and taro hornworm eggs were not affected by any treatment. The second experiment was planted in a deep clay soil with a more neutral Ph. Fertilizer applications showed no effect on yield in this experiment, in part because of leaching caused by heavy rainfall early in the season. Yield was higher in weeded plots. Pigs consumed signifIcantly more taro in weeded plots than unweeded ones. Insect populations were not affected by the treatments. In both experiments, there was a significant positive association between the number of aphids and taro planthoppers per sample and the size of the plant sampled. The higher numbers of planthoppers on fertilized plants observed in the first experiment was probably due to size differences of plants in fertilized and unfertilized plots.