Evaluation of corn gluten meal for preemergence weed management in cranberry

Evaluation of corn gluten meal for preemergence weed management in cranberry

Summary

We evaluated whether corn gluten meal (CGM), a natural product approved for use in organic farming, could be an effective method of preemergence weed control on cranberry farms. We conducted both a greenhouse and a field study. The use of CGM in cranberry is a novel approach, so the greenhouse experiment was used to evaluate potential phytotoxicity of CGM on cranberry plants prior to the establishment of the field study. The field study was established on recently planted organic cranberry farm with assistance from the grower, and aimed to evaluate if CGM suppressed new weeds from establishing. All data have been collected, and are currently being analyzed. Based on visual observations and preliminary data analysis, CGM is not an effective weed control on cranberry beds.

Objectives/Performance Targets

• A granular CGM product formulated for organic agricultural use was obtained from a commercial supplier (McGeary Organics, Inc., Lancaster PA).
• A greenhouse experiment was conducted on potted cranberry plants at the UMass Cranberry Station in East Wareham, MA, to evaluate any potential phytotoxicity of CGM or rate response of CGM on cranberry plants.

o   Baseline measurements were made for each plant (number of stems counted and length of stems measured)

o   Treatments were applied (none, low rate 20 lb/1000 ft², high rate 40 lb/1000 ft²)

o   Plants visually monitored for signs of damage

o   Plants measured and harvested 5 months after treatments

o   Biomass has been dried and weighed, and data is currently being analyzed

• A field study was established on two sites at a farm in Manomet, MA which was planted to evaluate CGM for preemergence weed control on recently planted cranberry beds.

o   Plots 1 m² were marked with flags and handweeded

o   Each plot received one of five treatments: untreated, one application of low CGM, two applications of low CGM spaced four weeks apart, one application of high CGM, or two applications of high CGM spaced four weeks apart.

o   Plots will be visually monitored and photographed. A weed survey documented which weed species were present in each plot, and the percentage of weed and cranberry cover in each plot.

o   Approx. 5 months after the study was initiated, all weeds in each plot were collected and sorted by species. Cranberry biomass was evaluated by harvesting a 1-ft² area of cranberry vines from each plot. In addition, cranberry samples were collected from the grower managed areas outside the plots.

o   Biomass has been dried and weighed, and data is currently being analyzed

• In addition to originally proposed work, sampled were collected for tissue nutrient analysis. It was noted that cranberry plants which received CGM were larger than untreated plants. CGM is also used as a fertilizer, and it may be a good source of nutrition for establishing cranberry beds.A phone survey is being designed, and will be conducted in the spring of 2014.
• We proposed hosting a bogside workshop at the study site. The CGM did not provide any weed control to treated plots. In fact, the CGM served as an additional nitrogen fertilizer and weeds in treated plots were larger and more numerous than untreated areas. We did not host a bogside workshop because we cannot promote CGM as a preemergence weed control.

Accomplishments/Milestones

Proposed – March 1, 2013. Actual – April 1, 2013

• Establish preliminary greenhouse study as described above.

Proposed – Mid-March, 2013. Actual – April 11, 2013

• Bogs for the study identified by the grower and the Cranberry Station staff, and plots will be marked.

Proposed – Late March-early April, 2013. Actual – April 15, 2013

• All plots hand weeded to eliminate present weeds. The first application of CGM applied to plots.

Proposed – Mid-April, 2013: Actual – May 15

• Proposed – Cranberry Station staff will evaluate plots for weed species composition and percent cover, and cranberry cover. Actual – very few weeds were present after hand weeding the previous month. Cranberry coverage was uniform. Plots were photographed instead of a formal survey.
• The second application of CGM will be made to plots selected for that treatment 4 weeks after the first treatment.

Proposed and actual – Mid-May, mid-June, mid-July, and mid-August 2013

• Cranberry Station staff made visual evaluations of all plots, and asked grower for feedback on perceived efficacy of treatments.

Proposed – June 2013. Actual – Spring 2014.

• Identify organic cranberry growers and survey them about pest management needs and priorities, and current weed control methods.

Proposed – August 2013. Actual – September 3, 2013

• Cranberry plants from the greenhouse study were harvested and dried.

Proposed – August 2013.

• Proposed – A bogside workshop, hosted by the grower-cooperator, for organic growers and other interested parties will be held at the experiment site. Actual – CGM failed as a weed control. In light of this result, we opted to not host a workshop.

Proposed – September 2013. Actual – August 15 (site 1) and August 20/22 (site 2), 2013.

• Foot-square areas of cranberry vines harvested, dried and weighed. All weeds harvested from all plots by Cranberry Station staff. Weeds were sorted by species for each plot, dried, and weighed.

Proposed – September – December 2013. Actual- January 2014.

• Data will be statistically analyzed to test for significance between treatments.

Proposed – January 2014.

• Information will be presented at Annual UMass Cranberry Station Research and Extension Update meeting, which is typically attended by 250-300 growers.
• Note: Although not originally proposed, based on the results of vigorous cranberry growth, we are opting to conduct tissue nutrient analysis on treated and untreated cranberry samples (collected in August 2013). Samples will be submitted in January with results forthcoming.

Proposed – February 2014.

• Any relevant information will be included in the 2014 UMass Cranberry Station Chart Book, which is our management guide. It will be available both in hard copy and online. Final report will be prepared for SARE.
• If tissue samples provide interesting results, we will write an article for the UMass Cranberry Station newsletter.

Impacts and Contributions/Outcomes

Preliminary results suggest that CGM is not effective as a preemergence weed control on cranberry beds. Treated plots had more weeds than untreated plots. Corn gluten meal is also known to be a fertilizer, and is approximately 10% nitrogen. The nitrogen in the CGM was likely allowing weeds to flourish, whereas the less fertile conditions in the untreated plots did not allow weeds to thrive.

In addition to supporting weed growth, CGM also supported cranberry growth. Cranberry plants in treated plots were larger than those in untreated plots. Tissue samples have been collected and sent to a laboratory for nutrient analysis.

Although ineffective as a weed control, CGM may be a good fertilizer option for organic growers who want rapid cranberry vine growth to fill in and establish a healthy cranberry canopy in newer plantings.

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