Creating an Ecofriendly Pest Suppression Program in Sweet Corn

Progress report for LNE20-406R

Project Type: Research Only
Funds awarded in 2020: $100,371.00
Projected End Date: 05/31/2023
Grant Recipient: University of Maryland
Region: Northeast
State: Maryland
Project Leader:
Dr. Cerruti R. R. Hooks
University of Maryland
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Project Information

Summary:

Problem, novel approach and justification. Sweet corn, produced on over 5,400 Northeastern farms1, is the second largest processing crop2. In 2017, its production value in five Northeastern states (DE, MD, NJ, NY, PA) totaled $110 million2. Herbicides and cultivation are used routinely in sweet corn plantings. However, herbicides registered for sweet corn are dwindling because of no-reregistration of older compounds and suspensions over environmental concerns3. Cultivation increases fuel usage, and farmers’ reliance on cultivation and manual weeding increases their production cost. Further, sweet corn is vulnerable to three yield reducing insects (corn earworm, fall armyworm, and European corn borer)4,5,6. Although some GMO sweet corn cultivars are protected from these insects, similar to insecticides, resistance problems reduce their efficacy period6. Thus, there is a need for additional practices that target weeds and insects concomitantly. Reduced tillage with cover cropping can reduce insect and weed pests, and production cost through enhanced natural pest suppression and reduced tillage, pesticide and fuel use. However, farmers are reluctant to adopt this combination partially from fears of inadequate pest suppression7, accompanied with limited knowledge on implementation. Thus, opportunities exist to create and share innovative tactics that lessen farmers’ reliance on tillage and boosts their confidence in implementing novel solutions. Hypothesis and research plan. We hypothesize using reduced-tillage with living and dying cover crop combinations will suppress pests equally or more and at reduced cost than conventional tillage with or without herbicides. This hypothesis will be tested through field studies. Whole plot treatments will include sweet corn grown under: conventional till, no-till with cover crop residue, living mulch + cover crop residue or living mulch + winter killed residue. Subplot factors will include herbicide or no herbicide. We will collect data on insect and weed pests, natural enemy efficacy, time spent manually weeding, input cost, yield and profits. Outreach plan. Methods for disseminating findings and engaging stakeholders include: 1) field day and walking tour events at research and commercial farms, 2) direct farmer participation, 3) uploading information to MD extension and commodity websites, 4) integration of findings into local and regional extension publications and trade journals, 5) presentations at local and regional commodity meetings, and 6) training educators and crop advisors at crop schools and in-service meetings. Project objective. Objectives include generating novel information on the synergistic usage of conservation tillage and winter cover cropping to concurrently manage insect and weed pests. Further goals include using findings to help sweet corn growers reduce their disproportionate reliance on GMO technology, pesticides and/or tillage by generating knowledge on low input practices that provide similar benefits. Potential impacts include similar or enhanced yields at lower operational and environmental cost, which will boost Northeast sweet corn farmers’ confidence, profits and sustainability.

Project Objective:

Objectives include generating novel information on the synergistic usage of conservation tillage and winter cover cropping to concurrently manage insect and weed pests. Further goals include helping sweet corn growers reduce their disproportionate reliance on GMO technology, pesticides and/or tillage by generating knowledge on low input practices that provide similar benefits. Potential impacts include similar or enhanced yields at lower operational and environmental cost, which will boost Northeast sweet corn farmers’ confidence, profits and sustainability.

Cooperators

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Research

Materials and methods:

Experimental design and treatments. Treatments were replicated four times and arranged in a Latin square split plot design. Whole plot treatments included sweet corn grown in: 1) conventional till (CT), 2) no-till with cover crop residue (NT), 3) living mulch + cover crop residue (LM-R) or 4) living mulch + winter killed residue (LM-FR). Subplot treatments were herbicide (H) or no herbicide (N) applications.

 

Methods. During early fall, crimson clover (Trifolium incarnatum), rye (R) (Secale cereale) and forage radish (FR) (Raphanus sativus var. longipinnatus) were combined and planted in CT and NT plots. Red clover (Trifolium pretense) + rye and red clover + FR combinations were planted in alternating rows in LM-R and LM-FR plots, respectively. Rows alternated between two rows of red clover and three rows of rye or FR. During spring, cover crops in CT plots were mowed, plowed and disked. Crimson clover senesces naturally in the spring and the FR winter killed. A roller crimper was used to terminate the rye in NT and LM-R, and temporarily slow red clover growth in LM plots. In mid-May, sweet corn was seeded into each plot. In LM-R and LM-FR plots, corn was seeded within the center rows of the FR or rye residue.

 

Rationale. Cover crops and treatments were selected based on stakeholders’ input and needs, our prior research experiences, success potential and their adaptability to the Northeast. Herbicide subplots in CT received pre- and post-emergent herbicides, and NT, LM-R and LM-FR received only pre-emergent herbicide applications. In CT and NT, herbicides were applied throughout H subplots; and in LM-R and LM-FR treatments, herbicides were banded within crop rows in H subplots.

 

Data collection: Cover crop biomass was estimated in CT and NT plots prior to their termination. Similarly, biomass of rye in LM-R plots was estimated. Weed biomass, density and timed manual weeding data was quantified in each plot. Weeds were identified, counted, and the percentage of area covered by cover crop, weed and bare-ground estimated. Following each survey, entire length of four between- and in-row areas within each subplot was manually weeded and time required for each row and area recorded.

 

To determine treatment impact on weeds in the absent of weeding, two areas within each subplot remain un-weeded the entire season. Percent ground covered by weeds, cover crop, and bare-ground was estimated visually and all weeds within the randomly placed quadrat was counted and identified on each sampling date.

 

Insect pests and natural enemies were estimated via three methods. Visual counts of corn plants, using yellow sticky cards to monitor aerial insects and the use of pitfall traps to monitor soil predators. Natural enemy efficacy was estimated by quantifying the number of European corn borer and corn earworm eggs parasitized or eaten by predators. Pollinators numbers were quantified with the use of bee bowls and direct visual counts

 

Corn development was examined by recording plant vegetative and reproductive stages and height. A spectrophotometer was used to measure leaf greenness as an indicator of N level. At maturity, corn ears in the center four rows of each subplot were harvested, measured, weighed, counted and rated for quality (e.g., insect damage) to determine impact of pests. Corn earworm damage was measured in cm2 of kernels consumed, and according to location (tip, upper, lower). If caterpillars were found, their head capsule size was measured to determine their stage. If sap beetles were found, they were counted and their damage characterized

PictofSAREsweetcorn_plots

Research results and discussion:

Data is still being analyzed

Research conclusions:

None at this time

Participation Summary

Education & Outreach Activities and Participation Summary

Educational activities:

1 Webinars / talks / presentations
1 Workshop field days
1 Other educational activities: Conducted a research presentation on cover cropping and weed management in an undergraduate weed science course. Discussed the NESARE projects and some the preliminary findings to a group of 24 students.

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.