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:

For field season 2021, two separate field studies were conducted using sweet corn. Field study A involved the use of different cover cropping systems and field study B  involved investigating the use of an insectary plant to manipulate weeds and/or arthropods in sweet corn plantings.

 

FIELD STUDY A

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.

 

FIELD STUDY B

Experimental design and treatments. A field experiment was conducted at the Central Maryland Research and Education Center in Upper Marlboro, MD during the 2021 field season. The experiment consisted of two treatments: 1) sweet corn bordered by marigold (MG) and 2) a monoculture sweet corn control (C). Treatment plots were replicated four times and each block was placed in a separate site and surrounded on at least three sides by a soybean Glycine max (L.) Merr., field. The total dimension of each block consisting of MG and control treatment was ~ (83 x 14 m); and within individual blocks, MG and control plots were separated by a minimal of 58 m of regularly mowed natural vegetation mostly grasses (Poaceae). Each plot included 16 rows of sweet corn with an intra- and inter-row spacing of ~ 23 and 76 cm, respectively.

Methods. Arthropod numbers were estimated via three methods and was concentrated during corn growth stages just prior to and at the end of corn earworms, Helicoverpa zea (Boddie) oviposition period. Visual counts were performed during the sweet corn pollination stages. One plant was randomly selected from the interior area of each row for a total of 16 plants per plot.

During each sampling event, the entire corn plant was searched and all arthropods found were identified to the lowest possible taxonomic level and recorded.  Aerial arthropods within corn plots and border vegetation (marigold, natural grass) were assessed using yellow sticky cards. One card was placed within the center of a single marigold row and neighboring border vegetation (field border) at a distance of 76 cm from the sweet corn outermost row, between sweet corn rows two and three (crop border area) and between sweet corn rows eight and nine (crop center).  Cards were established to coincide with three growth periods (~ V16/VT, R1, and R2/R3). Collected arthropods were counted and identified to the lowest possible taxonomic level. Vacuum sampling was executed to help compare the arthropod community attracted to the marigold and natural occurring flora and supplement data obtained from sticky card samples during late corn growth stages.

To determine the level of insect damaged sweet corn ears, four ears from each row were removed at harvest. The husk was pulled down about 1/8 the length of the ear and numbers of kernels damaged by corn sap beetles, Carpophilus dimidiatus L., and stink bugs (Pentatomidae) as well as the total area eaten by H. zea were recorded. If H. zea larvae were found within the ear, their numbers and development stage were recorded. Corn ears were randomly sampled from the interior area of each row and grouped according to row number (outer- to inner-most row).

Rationale. For this study, French marigold was chosen to be examined as an insectary plant in sweet corn system partly because prior studies have shown its direct service to natural enemies and benefits when used as a companion or border plant.  Findings from these studies suggest the presence of French marigold may be used to help enhance the number of natural enemies on arable lands and reduce herbivorous arthropods within cropping systems. Consequently, our objectives included: 1) assessing the attractiveness of natural enemies to marigold, 2) determining how marigold buffers would influence beneficial arthropods in adjacent sweet corn plantings, and 3) quantifying the level of herbivore damaged sweet corn ears in plantings bordered by marigold and natural vegetation. We hypothesized that marigold would attract beneficial arthropods (parasitoids and predators) and consequently there would be a greater number of generalist predators in adjacent sweet corn plantings.  However, we were less confident that its present would result in less herbivore damaged sweet corn ears.

Data collection: Data were collected on the number of arthropods (pest and beneficials) on sweet corn plants, community of natural enemies attracted to French marigold and natural vegetation, and the level of insect damaged sweet corn ears.

PictofSAREsweetcorn_plots

Research results and discussion:

Field study A (Relevant findings)

1. The red clover living mulch system suppressed weeds as well as conventional tillage with herbicide sprays

2. The red clover living mulch suppressed weeds equally as well with and without in-row residual herbicides. Specifically, there were no added benefits with respect to weed suppression from adding herbicide sprays to the living mulch system

3. It was anticipated that growing sweet corn in combination with red clover could cause a yield reduction do to competition. However, sweet corn yields were statistically similar among treatments

4. Few differences in insect pest and natural enemies were detected between control and cover crop treatments

5. The no-till (NT) treatment experienced greater corn earworm damage compared to control plots, tentatively due to lower predator abundance and/or delayed corn silking

6. Treatment impacts on corn earworm egg and pre-pupa predation are yet to be analyzed

FIELD STUDY B

Data from field study B is currently being analyzed

Research conclusions:

None at this time

Participation Summary

Education & Outreach Activities and Participation Summary

Educational activities:

7 Webinars / talks / presentations
4 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.

Participation Summary:

150 Farmers participated
7 Number of agricultural educator or service providers reached through education and outreach activities
Outreach description:

Webcast

  1. Title: An Introduction to Integrated Weed Management

      https://umd.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=9654dc81-80c0-4672-8aa0-adf3009afbf5

  1. Title: Prevention and Crop Competitiveness: Tools of Integrated Weed Management

      https://umd.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=b4281525-5d16-4850-9031-adf300a4c176

  1. Title: Crop Rotation: A Cornerstone of An Introduction to Integrated Weed Management

      https://umd.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=ac9a6492-f418-4ff5-8242-adf800a6b0af

  1. Title: Seed Predation and Integrated Weed Management

      https://umd.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=7d9cba9c-1e78-496b-a1a2-ae0c00d2ba3d

 

Other Scientific Presentations:

  1. Hooks, C.R.R., G. Chen, H.M. Kahl, A.W. Leslie and V. Yurchak. 2021. A fortuitous partnership: The tale of winter cover crops and strip tillage crusade against pests. Cornell University New York State Integrated Pest Management Academic Seminar Series. March 18, 2021. Attendance 31
  2. Yurchak, V., and C.R.R. Hooks. 2021. "Creating an ecofriendly pest suppression program in sweet corn" Northeast Integrated Pest Management (IPM) Research Update Conference. Zoom Meeting, Northeast IPM Center. March 21, 2021.

 

Extension Publications:

  1. Hooks, C.R.R.,W. Leslie and V.L. Yurchak. 2020. An introduction to integrated weed management and tools of prevention. Vegetable and Fruit Headline News. Special Alert Edition: Weed Control. March 20, 2020. 4 pgs.
  2. Hooks, C.R.R., A.W. Leslie and V.L. Yurchak. 2020. Using crop competitiveness as a component of integrated weed management. Vegetable and Fruit Headline News. Special Alert Edition: Weed Control. April 07, 2020. 4 pgs.
  3. Hooks, C.R.R., A.W. Leslie, V.L. Yurchak and D. Joseph. 2020. Crop rotation: A cornerstone of integrated weed management. Vegetable and Fruit Headline News. Special Alert Edition: Weed Control. April 13, 2020. 5 pgs.
  4. Hooks, C.R.R., A.W. Leslie and D. Joseph. 2020. Tillage: A well-known tradesman of integrated weed management. Vegetable and Fruit Headline News. Special Alert Edition: Weed Control. April 29, 2020. 6 pgs.
  5. Joseph, D., A.W. Leslie and R.R. Hooks. 2020. Herbicides and integrated weed management. Vegetable and Fruit Headline News. Special Alert Edition: Weed Control. May 18, 2020. pg. 1-8.
  6. Hooks, C.R.R., A.W. Leslie and D. Joseph. 2020. Biological control: An overlooked integrated weed management tool. Vegetable and Fruit Headline News. Special Alert Edition: Weed Control. May 27, 2020. pg. 1-8.
  7. Hooks, C.R.R., A.W. Leslie and D. Joseph. 2021. the critical period of weed control (CPWC): An underutilized concept. Vegetable and Fruit News. Special Alert Edition: Weed Control. May 06, 2021. pg. 1-8.

 

Workshops:

  1. Hooks, C.R, G. Chen, H.M. Kahl, A.W. Leslie and V. Yurchak. 2021. Workshop Title: Beginning Farmers Training Program. Presentation title: Using cover crops and minimum tillage practice to influence insect and weeds pests in vegetables. Zoom meeting, Upper Marlboro, MD April 01, 2021. Attendance 20

 

Field days:

  1. R.R Hooks. 2021. Cover crops and conservation tillage research for managing insects and weeds in vegetable production. Vegetable Production and IPM Twilight Walking Tour. Mechanicsville, MD July 28, 2021. Attendance 100
  2. Yurchak, V. and R.R. Hooks. 2021. Using living and dead cover crops to suppress weeds in sweet corn. Crops Twilight Tour and Ice Cream Social. Upper Marlboro, MD August 04, 2021. Attendance 72
  3. R.R. Hooks and A.W. Leslie. 2021. Using marigold as an insectary plant to enhance natural enemies of stink bugs and other insect pests. Crops Twilight Tour and Ice Cream Social. Upper Marlboro, MD August 04, 2021. Attendance 72

Participants

No participants

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.