Silicon supplementation: effects on chrysanthemum growth, leafminer populations, and parasitism

Abstract: With increasing regulation of pesticide use and a growing number of independent sustainable agricultural certification services fueled by the general public’s desire for less pesticides, alternative pest management strategies are needed. It is well known that nutrient management can influence pest populations. The purpose of this study was to assess the effect of silicate (Si) supplementation on chrysanthemum (mum) growth and Liriomyza trifolii population development compared to standard fertilization. The impact on successful parasitism by Diglyphus begini (Hymenoptera; Eulophidae) was also investigated. Si treated mum plants received 500 ppm of Si in the form of liquid potassium silicate with every irrigation. A control for potassium was provided using an equivalent potassium sulfate solution. Liriomyza trifolii and the D. begini were present in the greenhouse throughout the trial. Mum stem caliper was found to be the same across all treatments. Plant height was reduced in Si treated plants by 10%. In Si treated plants there was a mean reduction of 54% in mining. The number of parasitoids was too low for a meaningful evaluation. This will be repeated with the inundative releases of parasitoids into the greenhouse.