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Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/27/2015 Publication Date: 5/7/2015 Citation: Showler, A. 2015. Effects of compost and chicken litter on soil nutrition, and sugarcane physiochemistry, yield, and injury caused by Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae). Crop Protection Journal. 7:1-11. Interpretive Summary: Mexican rice borer infestations in sugarcane have been shown to be heavily influenced by drought stress on the plants but the effects of soil quality have not been determined. Field plot soil was augmented with two levels of compost, and other plots with chicken litter. Quantities of nitrogen were measured in the compost, and nitrogen was monitored during two consecutive growing seasons in the soil and in the sugarcane plants (as amino acids). The enriched soil was found to be associated with greater amounts of soil nutrients, including nitrogen, and more amino acids and fructose in the sugarcane which have both previously been associated with Mexican rice borer host plant preference. Although higher levels of soil richness increased numbers of sugarcane stalks, this was more than offset by heightened Mexican rice borer infestations. Technical Abstract: Levels of Mexican rice borer, Eoreuma loftini (Dyar), infestation in sugarcane have been shown to be heavily influenced by drought stress on the plants, but the effects of soil quality have not been determined. Soil enrichment with two rates of compost and chicken litter were compared with conventionally fertilized sugarcane, Saccharum spp., in the subtropical Lower Rio Grande Valley of south Texas for two consecutive seasons. The high compost rate resulted in the most consistent increases of soil nutrients, including N, P, K, Ca, Mg, S, Fe, Zn, Mn, and Cu. Analysis of nutrients in sugarcane leaf tissue showed that only N was higher in the high compost treatment, associated with greater abundances of three free amino acids, arginine, histidine, and lysine (each essential to insect growth and development), and of the sugar fructose. Although the high compost treatment yielded the most marketable sugarcane stalks per stool during the first season, this benefit was offset by greater infestations by the Mexican rice borer in terms of numbers of entry and exit holes per stalk, and percentages of injured internodes and stalks. As a result, stalk weight, length, and percentage brix were reduced. During the second season, numbers of stalks per stool were not greater in the high compost treatment, nor was percentage brix less, but the growth parameter measurements were decreased and Mexican rice borer injury was the worst. This study demonstrates that changes in host plant biochemistry from enhancing soil nutritional quality can have substantial negative effects on sugarcane production in the presence of Mexican rice borers. Hence, soil quality should be considered as part of integrated efforts to manage the pest. |
