Effect of post-harvest residue and methods of residue removal on ground inhabiting arthropod predators in sugarcane

Authors: White, William; Viator, Ryan; White, Paul

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2011
Publication Date: 6/1/2011
Citation: White, W.H., Viator, R.P., White Jr, P.M. 2011. Effect of post-harvest residue and methods of residue removal on ground inhabiting arthropod predators in sugarcane. Journal of the American Society of Sugar Cane Technologists. 31:39-50.

Interpretive Summary: Beginning in the mid-1990s, Louisiana sugarcane farmers began to adopt a new harvesting system, the chopper harvester. The biggest impact from adopting the chopper harvester has arisen from the thick trash blanket left over from the removal of cane leaves and shucks. Although research has shown that this trash cover must be removed to avoid losses in yield in subsequent crops its impact on soil-inhabiting beneficial insects has not been determined. We investigated the impact of the harvest trash on ants, earwigs, ground beetles, and spiders – all important predators of sugarcane pests. Predator numbers were monitored by using pitfall traps placed in the top of the sugarcane rows. After four years of sampling we found that the trash cover does not have an adverse effect on these insects, but appears to enhance predator numbers. However, burning to remove the trash does. The impact of relocating the trash blanket by mechanically brushing had an intermediate impact. This is an important finding as it shows that this non-burning approach to trash removal offers a viable alternative to burning the trash blanket. Not burning the residue can have a positive environmental benefit to society while also eliminating a potentially hazardous farming operation for sugarcane growers.

Technical Abstract: The effect of the blanket of post-harvest crop residue generated during green-cane harvesting on ground inhabiting arthropod predators of the sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), was evaluated in two experiments spanning a four year period. Crop residue was either allowed to remain on the field surface or completely removed by burning or repositioned to the row sides by mechanically brushing. In 2007 and 2008, pitfall traps were established in the first- and second-ratoon crops from cane planted in a fine textured clay soil. In 2009 and 2010, pitfall traps were established in the first- and second-ratoon crops from cane planted in a coarser textured soil. When averaged across years and soil types, ants (Hymenoptera: Formicidae) were the most abundant predatory taxa representing approximately 70% of the total predators caught. Ants were more abundant in the fine textured clay soil experiment than in the coarser texture loam soil experiment. Ants and earwigs (Dermaptera) were generally more abundant where the blanket of post-harvest crop residue was not removed or repositioned to the row sides, while burning to remove the residue appeared to have a detrimental impact on their numbers. Brushing the tops of rows to remove crop residue was intermediate in effect. Ground beetles (Coleoptera: Carabidae), spiders (Araneida), and crickets (Orthoptera: Gryllidae) were impacted minimally by the treatments.