This project will be conducted over the upcoming 2020 growing season and will address the need for non-chemical insect pest control methods in sweet corn production by investigating the potential for cover crop residues and living mulches to increase insect natural enemy abundance, consequently reducing pest numbers and associated crop damage. Visual assessments, sticky cards and pitfall traps will be used to determine the diversity of natural enemies present, and sentinel corn borer and earworm egg masses will be placed in the field and assessed for predation/parasitism. Additionally, corn earworm pre-pupae will be tethered and exposed to ground predators in all treatments to determine predation mortality. Crop damage and overall yield will also be assessed in each treatment. Results will be presented at on-farm tour events, extension meetings throughout the following fall/winter season and at at least one scientific conference. The impacts on the agricultural community are currently unknown, and will depending on the results obtained this summer.
The overarching project goal is to improve the biological control services provided by ground and foliar inhabiting natural enemies in sweet corn plantings.
My primary research objectives are to assess the effects of growing sweet corn with an interplanted living mulch and cover crop residues on:
1) the number of foliar and epigeal (ground) natural enemies present,
2) rates of predation and/or parasitism of corn earworm and European corn borer egg masses,
3) rates of corn earworm prepupae predation and adult emergence, and
4) crop yield.
The purpose of this project is to investigate the ability of cover crop residues and living mulch to enhance natural enemy abundance to suppress the corn earworm and the European corn borer and reduce ear damage. More specifically, I will investigate effects of red clover living mulch and crimson clover/rye residues on predation and parasitism of the immature stages of the corn earworm and European corn borer, and examine treatment impact on corn earworm adult emergence.
The corn earworm is a polyphagous lepidopteran pest of several field and vegetable crops, and is one of the most devastating and difficult to control insect pests in the United States. Up to 50% losses in sweet corn have been reported as a result of this pest. The European corn borer, though largely controlled in many areas of the United States with genetically modified (GMO) corn varieties, still has the potential to cause significant damage to non-GMO sweet corn cultivars. Thus, organic farmers and others not using GMO sweet corn must depend primarily on insecticide sprays. However, resistance problems may reduce the period that insecticides and GMO cultivars are effective. Additionally, both pests are difficult to control via foliar insecticides due to the short period of vulnerability before they are protected inside the corn plant. This suggests that growers, especially organic producers, can benefit from more sustainable management options.
Living mulches, which are cover crops grown alongside the main crop throughout the growing season, and cover crop residues are increasingly used to suppress weeds in agricultural production. However, limited research has been conducted to evaluate their impact on insects and other arthropods in specialty crops. Previous research investigating the impact of no-till production on corn earworm prepupal search behavior and subsequent site selection for pupation indicates a preference for loose, tilled soils over smooth, compacted surfaces associated with no-till production. Studies determined H. zea pupae spent a significantly greater amount of time and traveled greater distances searching for a suitable pupation location in no-till compared to conventionally tilled fields. This increased search time extends the period that larvae are vulnerable to predation by ground-dwelling arthropods, many of which are more abundant in more diverse habitats. This suggests that integrating cover crops into sweet corn systems should result in greater pre-pupal predation and a subsequent reduction in H. zea adult emergence. This could have important consequences on numbers of adult moths dispersing to other crops later in the growing season.
Foliar searching natural enemies may be greater in living mulch systems, often resulting in reduced insect pest populations. Thus increased mortality due to natural enemies could occur in the foliage and at soil level. However, few studies have investigated the impact of habitat diversification on H. zea infestation rates in sweet corn; and to my knowledge, no studies have examined impacts of cover crop residues on H. zea or O. nubilalis mortality from natural enemies; and how this affects ear damage and yield. Thus, this project will contribute to the sparse body of knowledge related to the impact of habitat diversification on economically important sweet corn pests and provide growers a more sustainable and environmentally friendly option.
Research for this project has not yet begun as it is planned to take place during the 2020 growing season. The only action taken so far has been to plant the various cover crop treatments, which occurred in early September 2019. The four treatments are: NT (no till), CT (conventional till), LMFR (living mulch + forage radish) and LMRye (living mulch + rye). In the NT and CT treatments, a mixture of crimson clover, forage radish and rye cover crops were planted. In the LMFR treatment, alternating rows of red clover and forage radish were planted, and in the LMRye treatment, alternating rows of red clover and rye were planted. All cover crops were planted on September 5, 2020 at 6 inch row spacing. Additional overhead irrigation was required after ~ 2 weeks due to excessively dry conditions.
No results have been obtained yet since the research is to occur this coming growing season. Cover crops appear to have established well, however red clover growth in the fall is difficult to observe and will be monitored more closely in early spring.
No conclusions can be reached yet since the study will take place this coming growing season. They ways in which the proposed methods could impact farming practices will depend on the outcome of the proposed research, and cannot yet be predicted.
Education & Outreach Activities and Participation Summary
No education/outreach has taken place yet since project is for upcoming growing season. However, a twilight tour field event is planned to take place this summer, where progress will be reported and demonstration plots showcased. Additional newsletter posts and extension conference presentations are planned to take place in the fall and winter of 2020, as well as at least one research conference presentation.
We anticipate the proposed research will contribute to agricultural sustainability by identifying non-chemical alternatives for insect pest control in sweet corn via natural enemy enhancement through modification of the typical crop environment. However, since the project has yet to begin, actual outcomes are currently unknown and will be obtained over the 2020 growing season.
As the project has yet to begin, little knowledge has been gained so far. However, we anticipate gaining knowledge regarding the use of cover crops and living mulches in sweet corn production for insect natural enemy enhancement and overall insect biodiversity enhancement, as well as non-chemical methods of pest reduction. Future directions of research are yet to be determined as the outcomes of the current study are still unknown.