In 2012 the Cornell Vegetable Program was awarded a NESARE grant to evaluate a new use of cover crops, by sowing winter rye between plastic-mulched beds on two cooperating farms, one growing onions and the other tomatoes. After fitting the soil and laying plastic, but before transplanting, both farms sowed winter rye at 3 bushels per acre between plastic as well as establishing herbicide and cultivation plots. Conventional fertilization and drip irrigation was carried out per each grower’s standards. We then collected data on plant height, weed biomass, insects, disease and yield.
While the rye statistically provided as good control of weeds as herbicides or cultivation, it resulted in lower yields which translated to loss income compared to those methods. In onions bulb size was smaller in rye plots, while tomatoes saw increased insect pressure. Yield loss may be attributed to an unusually dry growing season as well as an atypical regional Common Armyworm infestation. Readers are cautioned that this represents one year’s data under dry conditions.
Nonetheless, adopting growers preferred the working environment in the rye covered areas to bare ground, which demonstrates a positive impact in the social realm of sustainability. Also, over time, continued use of a rye ground cover could lead to diminished environmental exposure to herbicides and also help increase water quality by minimizing soil erosion. Thus, improved farmer/farm worker satisfaction; or environmental benefits may justify minor yield losses. Understanding and eliminating these yield decreases are the planned subjects of future work. As weed control and improved harvest conditions in rye plots were excellent the method continues to offer promise for vegetable farmers.
Our work was shared with over 500 growers at 3 field meetings and 7 formal presentations. Articles were published in the Veg Edge Newsletter as well as posts on the Cornell Vegetable Program
Webpage and PI’s Twitter account and submitted to American Vegetable Grower, Country Folks and local newspapers for future publication.
Plasticulture production of vegetables has been widely adopted in the Northeast providing farmers with in-row weed control, soil moisture regulation, season extension and larger bulb size in onions (SARE projects ONE06-062 and ONE09-102). However, the bare row middles of plasticulture systems threaten sustainability by requiring herbicide and/or cultivation inputs which increase environmental impact by impairing water quality, decreasing soil organic matter levels and increasing hand labor inputs.
On conventional farms, herbicide use between plastic rows adds to negative environmental impact, as measured by Environmental Impact Quotients (EIQs). Currently a standard herbicide program on local farms requires up to four materials (metolachlor, pendimethalin, halosulfuron and glyphosate), which could result in a total EIQ of 97.4 per acre. This is a high EIQ rating to begin the season, and does not include later fungicide or pesticide applications. Organic farms do not use the herbicides listed above, instead often cultivating between the rows. Cultivation requires additional fossil fuel to power tractors and high labor inputs to hand-remove weed escapes. Cultivating also reduces soil organic matter, which will decrease soil microbial activity and tilth.
Both herbicides and cultivation strive for ‘clean’ (bare soil) row middles. Tomatoes can be infected with Early Blight, Septoria and bacterial diseases when rain splashes soil from bare row middles onto crop foliage. Onions can be infected with Bacterial Soft Rot and Canker (Erwinia and Burkholderia spp) from soil splashing. These infections further drive fungicide use. Fungicide applications to control diseases such as Septoria Leaf Spot and Early Blight could result in an additional 150 EIQ value per acre, even on certified organic farms.
Thus the use of herbicides and cultivation impairs the environmental sustainability of northeast vegetable farms, while cultivation and hand-weeding impair social and economic sustainability with a high labor requirement. Managing for bare soil reduces organic matter and increases disease risk for multiple vegetables on both conventional and organic farms.
Our project sought to enhance sustainability by using a living cover crop of spring sown rye grain as a growing season alternative to herbicides and/or cultivation for weed control between plastic mulch beds. Spring sown rye was not expected to become overly vigorous since it would not receive the cold temperature cues necessary to produce a seed head.
Project goals were to:
• reduce environmental and health risks in agriculture by decreasing herbicide exposure to the soil micro-environment, applicators, farm workers and consumers
• improve the quality of life for farmers and their employees by replacing chemicals and/or hours of hand weeding with a one-time grain application
• improve worker conditions via ease of harvest by reducing mud
• create an alternative to herbicides known to infiltrate drinking water supplies, and thereby positively impact water quality
1) One of the two cooperating farmers will share their experience with at least 30 other farmers and researchers at a field meeting in the summer of 2012.
Our cooperating onion farm hosted a twilight meeting on August 3, 2012 with over 40 growers observing the trial first-hand. On August 10, 2012 another farm hosted nearly 100 people who learned of the project’s results and observed smaller test plots. In 2013 this method of weed control was shared at an on-farm meeting with over 50 farmers in attendance
2) The project leader will complete at least 50 farm visits to interested vegetable farmers to share research findings.
Over 200 farm visits were made in support of the project by the project leader and team technicians in the growing seasons of 2012-13.
3) Winter presentations at the statewide Empire Fruit and Vegetable Expo, Produce Auction Growers Meeting and others will share the findings with an additional 300 farmers.
Presentations sharing project findings were given to approximately 332 growers via the following presentations/meetings: The Mohawk Valley Produce Auction (Dec. 4, 2012, 40 growers in attendance), Seneca Produce Auction (Jan. 10, 2013 40 growers) 2013 Finger Lakes Produce Auction annual meeting (Jan. 16, 120 growers), the Catskill Regional Agriculture Conference (Jan. 17, 20 growers Empire State Producers Expo (Jan. 24, 62 growers), Allegany Produce Workshop (March 14, 15 growers), Chautauqua Auction (March 15, 35 growers).
4) A reader-friendly summary of the project’s findings will be printed in Veg Edge, a Cornell Vegetable Program newsletter that reaches over 850 people in 28 NY counties as well as the states of MA, MI, NJ, and PA.
A grower-oriented article was published in Veg Edge on June 30, 2012.
5) A newspaper version of our story, with color photos, will be submitted for print to the Finger Lakes Times, Country Folks and Lancaster Farming in the winter of 2012-13.
Published: Lancaster Farming, August 3, 2013 (weekly publication, 60,000 readers)
Country Folks – West Edition, August 5, 2013 (weekly, 4,000 subscriptions, plus
2,000-3,000 distributed the week of Aug. 5, 2013 at Empire Farm Days
Submitted for publishing on July 23, 2013 to: Dundee Observer (weekly, 2,050); The Finger Lakes Times (daily, 14,000 Monday-Sat, 17,000 Sunday).
6) An article will be submitted to American Vegetable Grower, with photos and project highlights.
PI was interviewed by editor on April 24 2013 for potential use in future AVG articles on weed control.
7) Biweekly updates of the project’s progress, including pictures, from 2 cooperating farms will be posted to the Cornell Vegetable Program’s webpage, with social media leads from the program team’s Facebook and Twitter accounts.
A mid-season report was posted on June 30, 2012, with social media feeds from PI’s Twitter and LinkedIn feeds throughout 2012-13.
8) A full Technical Report of the project will be posted to the CVP Webpage
Submitted for posting.
9) A non-technical, farmer oriented summary will also be posted to the CVP webpage with yield, disease, EIQ and labor inputs.
Posted on January 22, 2013, available at: http://cvp.cce.cornell.edu/submission.php?id=111&crumb=pests|pests
10) A link to these results will be posted to the Cornell University Guidelines for Commercial Vegetable Production within the Weed Management, Tomato and Onion pages.
Links to the report were posted to the following online Guidelines pages on Aug. 13. 2013:
Weed Management: http://veg-guidelines.cce.cornell.edu/4frameset.html
Two small-plot, on-farm trials were conducted in Penn Yan, NY on two different farms, one growing onions and one growing tomatoes.
Project Design: The trial was set up as a randomized complete block design with 3 treatments (Rye, Cultivation, and Herbicide) and 4 replications. Each treatment replicate was approximately 10 feet wide by 10 feet long and consisted of two row middles and a plastic raised bed. Onion transplants (Allium cepa, var. Candy) were produced on farm and transplanted by hand on April 16. Onions were planted into reflective silver plastic mulch beds, 4 rows per bed, with 6 inch in-row spacing in a Lima fine sandy loam soil which had received an inch of dairy manure the previous fall and incorporated. The onions received two applications of 10-20-10 fertilizer (Growers Mineral Solutions, Milan, OH), via drip irrigation, prior to bulbing, at 5 gal/A. Herbicide (Prowl H20-pendimethalin) and Rye (3 bu/A) applications were made on either side of the onion beds in the appropriate plots on April 10. A foliar application of Movento (spirotretamat) at label rate for thrips control was made to all plots in early July.
Plant growth: Ten randomly selected plants per replicate were measured for plant height, of the tallest leaf, and number of leaves per plant on May 22, June 12, July 3 and July 24.
Disease & Pest Pressure: Levels of Botrytis Leaf Blight (Botrytis squamosa) and Onion Thrips (Thrips tabaci) were evaluated on June 12. Five randomly selected plants per replicate were evaluated. Botrytis Leaf Blight was evaluated by counting the number of lesions the on outer three leaves and determining how many lesions per leaf. Onion Thrips were counted per plant. Bacterial rot pressure was determined by calculating the percentage of culls in both number of bulbs and weight lost to bacterial rot.
Tissue Analysis: Leaf samples were collected from the newest fully developed leaf of 20 plants per treatment on July 3 and 24. Samples were sent to Waters Agricultural Laboratories, Inc. in Owensboro, KY for foliar nutrient level analysis.
Weed Biomass: Weeds were collected from 4 random 1 square foot sections of row middles per treatment on May 22, June 12, and July 3. Weeds were cut or pulled out at ground level and weighed in grams fresh weight.
Yield and bulb size: Onions were harvested on August 16. All bulbs in 10 feet of bed per block were pulled, topped to 1 inch necks, weighed and sized. Bulb size distribution included colossal (>4”), jumbo (3-4”), medium (2-3”), small (< 2”), culls due to rot and culls due to undersize or other.
Statistics: Statistical differences among treatments were determined by General Analysis of Variance (ANOVA) with mean separation by an LSD test with a p < 0.05.
Project Design: The trial was set up as an in-row complete block design with 3 treatments (Rye, Cultivation, and Herbicide) and 4 replications. Each treatment replicate was two row middles and a plastic raised bed approximately 10 feet wide by 20 feet long. Tomato transplants (Solanum lycopersicum, var. Primo Red) were produced on farm and transplanted by hand on May 15. Tomatoes were transplanted into black plastic mulch beds, 1 row per bed, with 24 inch in-row spacing, the soil a Lima Silt Loam. Tomatoes were staked and woven throughout the season. Rye treatments were seeded between the plastic rows on May 7 (3 bu/A). The herbicide treatment, applied at label rates on May 8, consisted of a tank mix of Sandea, Dual, Prowl, and Roundup (active ingredients: halosulfuron, metolachlor, pendimethalin, and glyphosate, respectively). An application of Admire Pro (imidicloprid) was made on June 18 at label rates for tomato to control common armyworm. Fertility was maintained by the grower, as their standard. The field received 400 pounds/acre 15-15-15 fertilizer on March 15 as well as 2.5 tons/acre chicken manure on March 21. On March 23, Potash (0-0-61) and Phosphorus (11-52-0) were applied to the field at 25 and 30 pounds/acre, respectively. Prior to transplanting plants received 15 oz. of 20-20-20 fertilizer per 100 gallons of water (Miller Chemical, Hanover, PA). At transplant each plant received 2 cups of starter fertilizer solution (8 oz 12-48-8 per 5 gallons of water). Tomatoes received 20-20-20 (9-15-30 was used on July 31 and Aug 16) via drip emitters, weekly, through mid- August.
Plant growth: Three randomly selected plants per replicate were measured for plant height, of the tallest leaf, on July 17, Aug 14, Sept 4 and Sept 25.
Disease Pressure: Early Blight (Alternaria solani) ratings were taken on July 3, Aug 8, Sept 4 and Sept 13. Ratings were done using an ordinal scale of 0-9, with 0 representing no visible disease and 9 representing plant death or near-death.
Tissue Analysis: Leaf samples were collected from the newest fully developed leaf of 20 plants per treatment on July 3 and 8. Samples were sent to Waters Agricultural Laboratories, Inc. in Owensboro, KY for full tissue analysis.
Weed Biomass: Weeds were collected from 4 random 1 square foot sections of row middles per treatment on July 3, Sept 13, and Oct 1. Weeds were cut or pulled out at ground level and weighed in grams of fresh weight. Rye was cut with a string trimmer on June 30 due to manage height. Herbicide plots were hand weeded once, in early August, to remove weed escapes.
Yield: Tomatoes were harvested as they matured from July 19 to Sept 25. All marketable fruit was counted and weighed in pounds.
Statistics: Statistical differences among treatments were determined by General Analysis of Variance (ANOVA) with mean separation an LSD test with p < 0.05.
Plant growth: Onions plots with rye middles were significantly the tallest on 3 out of 4 assessment dates. Cultivation was consistently the shortest treatment. Rye treated plots had the fewest number of leaves.
Disease Pressure: The onions had minor infestations of Onion Thrips (Thrips tabaci) and Botrytis Leaf Blight (Botrytis squamosa). While there were no differences in leaf disease, there was a difference in pest pressure. On June 12, there were significantly less onion thrips in the herbicide plots than in the rye and cultivated plots, with the cultivated plots having the most thrips.
Yield and bulb size: Cultivation and herbicide plots were significantly the highest yielding for marketable bulbs, with 84.26 and 83.5 pounds per 10 feet of bed, respectively. The rye treatment yielded 21% fewer pounds and had half as many colossal sized onions. There were little to no culls from bacterial rot in any plots.
Weed Biomass: The rye treatment had the lowest amount of weeds as measured by fresh weight (g), but was not statistically different from the cultivation and herbicide treatments. Cultivated and herbicide plots had similar weed levels.
Tissue Analysis: Foliar nutrient levels did differ between the treatments. Nitrogen and Potassium were lower in rye treated plots on both sample dates than cultivated and herbicide treated.
Plant growth: Herbicide treated plots were significantly the tallest plants measured on July 17 and Sept 4 and not significantly different on August 14 and Sept 25.
Disease and Insect Pressure: Tomato plots were visibly free of disease until early September when Early Blight (Alternaria solani) developed. On Sept 13 there were significant differences in disease ratings. Herbicide plots had the most amount of disease with an ordinal rating of 7.1, followed by the rye and cultivation plots with 6.3 and 5.9, respectively (Table 5). Although no qualitative data was collected on pest populations, the grower observed slug (Limax and Deroceras spp.) and armyworm (Psuedaletia unipuncta) feeding differences between the treatments. Approximate percentage of fruit grade as affected by pest damage from a single harvest was made on August 30. Culls due to pest pressure were the highest in the rye blocks and lowest in the herbicide treatments.
Tissue Analysis: Potassium was lower in the rye plots on all three sample dates and highest in the cultivated plots. Calcium was higher in the rye plots on all three dates. No other trends are apparent.
Weed Biomass: Weed biomass was collected in grams fresh weight three times throughout the growing season. Rye plot weed biomass was equal to or less than herbicide on the first two dates, with herbicide having the lowest weight late in the season. There were not statistical significant differences between treatments on any date.
Yield: Yield was calculated by mean fruit per plant, mean fruit weight (in pounds) and pounds fruit per plant. The herbicide plots were significantly the highest yielding with 32.55 pounds per plant, followed by cultivation plots with 30.37, both in the same statistical grouping. Rye plots yielded 23.97 pounds per plant. Herbicide plots had the heaviest fruit, 0.67 pound each, while the mean fruit weights in the rye and cultivation plots were the same at 0.62 pounds per fruit; with no significant differences. Cultivation plots had the highest number of fruit per plant with 49.2, followed by herbicide in the same statistical grouping, with 48.9. Rye plots had significantly less with 38.7 fruit per plant.
Rye as an inter-row cover crop presented challenges in this project. The primary effect observed was loss of yield, as measured by fresh weight of product. What is causing this yield loss is not completely understood. Mid-summer rainfall at both farms was scarce, and thus water competition is a possibility. Nutrient competition is also possible, with nitrogen and potassium at times lower in the rye plots, although trends are not clear. Allelopathy from the rye has also been suggested, even though rye roots did not extend underneath the plastic mulch when examined. Pest pressure in the tomato crop did negatively affect yield as common armyworm and slug feeding lead to many unmarketable fruit. The armyworm infestation was a regional phenomenon at abnormally high levels in 2012.
Rye provided very good weed control at both farms. At our onion site it performed as well or better than herbicides and cultivation until harvest. At our tomato site late season weed pressure increased in the rye plots. There was an unexpected disease in the rye, leaf rust, caused by Puccinia recondita tritici at both sites. Although this disease did not impact the vegetable crop it reduced rye stands. For the shorter season crop of onions this did not present a problem. With tomato harvest extending into October the diminished rye stand had diminished capacity to suppress Fall weed growth. Labor associated with managing rye vigor was minimal as both cooperators reported mowing once mid-season.
An inter-row cover crop of rye successfully reduced the environmental impact of vegetable farming in this study by reducing erosion and replacing herbicides. On the cooperating onion farm eliminating an application of pendamethalin reduces the field Environmental Impact Quotient (EIQ) by 33.9 points per acre. At our tomato farm the replacement of 4 herbicides (pendamethalin, halsulfuron, glyphosate, and metalochlor) resulted in an EIQ reduction of 90 points/acre. However, with the increased pest damage in the rye treated plots, some farms may have applied additional insecticides, reducing or eliminating environmental gains made by replacing herbicides. It should be noted that cultivation would also eliminate the EIQ of the herbicides, but with a higher labor input when compared to rye.
The project team notes an unprecedented level of grower interest in this method, with many trialing similar ideas. However, the techniques researched here are still in development stage, and not perfected for wide scale recommendation. Thus true adoption has not been measured, as both the project team and farmers continue to fine tune the system. The adoption of spring sown winter rye for weed control by the two cooperating farms reduces field Environmental Impact Quotient (EIQ) by 33.9 points (onions) and 90 points (tomato) per acre. Adopting growers preferred the working environment in the rye covered areas to bare ground, which demonstrates a positive impact in the social realm of sustainability. Over time, continued use of a rye ground cover could lead to diminished environmental exposure to herbicides and also help increase water quality by minimizing soil erosion.
Education & Outreach Activities and Participation Summary
Outreach efforts were undertaken throughout the project and resulted in the attendance of approximately 522 growers at educational events . Written outreach included articles for Extension newsletters targeting vegetable growers, a summary of the study’s results submitted to 2 newspapers (NY) and 2 farming publications (NY and PA). Additionally, grower-friendly report was made available at http://cvp.cce.cornell.edu/submission.php?id=111&crumb=pests|pests. Other online outreach efforts included social media posts made throughout 2012 and 2013 providing project updates. Oral presentations were given at 7 meetings to 332 growers in the winter of 2012-2013. Finally, over 200 farm visits, extended the project in one-on-one settings.
The yield reduction associated with rye cover did result in a negative economic impact in 2012. Yield reduction in rye treatment tomatoes was over 8.5 pounds of marketable fruit per plant, a value of nearly $13/plant, assuming an average price of $1.50/lb, compared to the herbicide treatment. In onions the loss was over 18 lbs per 10 linear feet of row when compared to cultivation, the highest yielding treatment. Calculating onion economics is difficult as there are price differentials related to grade (bulb size) and market. However, rye treated plots yielded less than half than number of colossal bulbs ( > 4” diameter) of herbicide and cultivation plots. The value of these bulbs is often $ 0.40 more than the next class, representing a loss of over $21 per 10 linear feet of bed.
Readers are cautioned that this represents one year’s data under dry conditions. Improved farmer/farm worker satisfaction; or environmental benefits may justify minor yield losses. The project team is continuing this research in 2013 under separate funding.
Areas needing additional study
Winter rye as an inter-row cover crop provided weed control comparable to cultivation and herbicides. However the yield loss, particularly as caused by pest feeding in tomatoes, prevents promotion of the system at this time. Given the unique pest population in 2012, these may be less in future seasons.
The mechanism in which rye reduced yield, particularly in onions, warrants further attention. Future work will examine other winter grains as inter-row cover crops and higher fertility/irrigation rates for the vegetable crop to eliminate potential competition. In 2013 the project team has incorporated clover into the system, with and without rye and barley. Data is currently being collected.
The project team is also awaiting the decision on a proposal submitted to NRCS for further work on this system; to document erosion control and impact on farming systems.