Location: Crop Genetics and Breeding ResearchTitle: Impact of applying edible oils to silk channels on ear pests of sweet corn Author
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2011
Publication Date: 6/1/2011
Citation: Ni, X., Sparks, A.N., Riley, D.G., Li, X. 2011. Impact of applying edible oils to silk channels on ear pests of sweet corn. Journal of Economic Entomology. 104:956-964. Interpretive Summary: Corn earworm damage has been considered one of the most important impediments in sweet corn production in the southeast coastal plain region. The key management strategy for corn earworm is relying on frequent insecticide sprayings. Many alternative environmental-friendly pest management tactics have been examined in recent years to reduce the number of insecticide sprayings for sweet corn production. In addition, the recent increasing demand for organic sweet corn production requires no chemical insecticide application. To identify alternative management strategies without using any insecticides, six vegetable oils (that is, canola, corn, olive, peanut, sesame, and soybean oils) were examined for their efficacy in reducing corn earworm damage in sweet corn production. In addition, two insecticides (that is, neem and mineral oils) and water were used as controls for comparison in the experiment. Among the vegetable oils used in the experiment, the applications of 0.5 ml of corn and sesame oils at post-pollination in 2007 reduced corn earworm damage. In contrast, the peanut oil treatment at post-pollination attracted more sap beetle adults in 2006, and attracted more sap beetle larvae in 2007. In addition, the sesame oil significantly increased smut infection rate in 2006. The mineral oil application consistently increased the rate of smutted corn ears in both 2006 and 2007, although the mineral oil was effective in general in reducing corn earworm damage and sap beetle population. Ramifications of utilizing vegetable oils in a practical ear pest management program need to be further examined.
Technical Abstract: The impact of applying vegetable oils to corn silks on ear-feeding insects in sweet corn production was evaluated in 2006 and 2007. Six vegetable oils used in this experiment were canola, corn, olive, peanut, sesame, and soybean. Water and two commercial insecticidal oils (Neemix' neem oil and Sun-Spray' mineral oil) were used as the controls for the experiment. Six parameters evaluated in this experiment were corn earworm [Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)] damage rating, the number of sap beetle [Carpophilus spp. (Coleoptera: Nitidulidae)] adults and larvae, the number of corn silk fly (or picture-winged fly) (Diptera: Ulidiidae) larvae, common smut [Ustilago maydis (D.C.) Corda] infection rate, and corn husk coverage. Neem oil reduced corn earworm damage and husk coverage in at both pre- and post-pollination treatments in 2006. Only mineral oil reduced the number of sap beetle adults at post-pollination application in 2006, while peanut oil attracted sap beetle adults in 2006. In 2007, the oil treatments at pre-pollination showed no reduction of corn earworm damage and sap beetle adult population, whereas the applications of corn, sesame, and mineral oils at post-pollination reduced corn earworm damage. Neem and olive oils significantly reduced husk coverage compared to the water control. In addition, the neem oil application at post-pollination attracted the most sap beetle adults in 2007. The number of sap beetle larvae in neem and peanut oil-treated ears was greater than the control at pre- and post-pollination in 2007, respectively. Applying neem, sesame, and mineral oils significantly increased smut infection rate in 2006, but in 2007, only mineral oil application increased the rate of smutted ears. Ramifications of utilizing oils in a practical ear pest management program were also discussed.