Many vegetable and field crop producers grow pumpkins to diversity their operations and provide an alternative source of revenue. The use of cover crops and no-till planting reduces diseased fruit, soil erosion, weed pressure and nutrient loss. However, several concerns have prevented the wide-scale adoption of no-till methods for pumpkin production. These are: concern about carryover seed from the hairy vetch causing a weed problem in subsequent years; weed management in a no-till system; and a potential increase in Fusarium rot. In addition, farmers have requested help identifying cover crops that can be used after the pumpkin harvest.
This three-year project (extended one year) was designed to address research needs expressed by pumpkin growers. We 1) developed two cover crop schemes that maximized profits of pumpkin producers while minimizing disease development, and 2) improved the understanding of how cover crops affect pumpkin disease, fungicide use and the cost of pumpkin crop production. We examined cover crops to precede or follow the pumpkin crop; the effect of the cover crops on yield, fruit quality; incidence and severity of pumpkin diseases; and management options for disease.
Pumpkin growers were active participants in this project through feedback on our research and by conducting on-farm trials and demonstrations. Farmers learned about cover crops and provided us with feedback and suggestions on our project. In 2004 and 2005 replicated experiments, we identified winter wheat and crimson clover cover crops as the best alternatives to hairy vetch or rye. Winter wheat and crimson clover were alternatives for growers that had concerns about carryover seed from hairy vetch, or increased disease. In 2006 and 2007 research, cover crop did not impact yield, fruit weight, handle quality or fruit rot at either location expect in 2007, where pumpkins grown on crimson clover had significantly lower fruit/Ha than pumpkins grown on winter wheat. We never observed differences in disease on different cover crops.
In contrast, yield components and diseases were highly influenced by fungicide spray programs. The seven-day conventional program resulted in the greatest yield (MgHa) and fruit weight and handle quality and lowest fruit rot in 2006 at Salisbury, MD. The seven-day program modified with a biofungicide also performed well and was not significantly different for yield and mean fruit weight and fruit rot. In 2007, the best program also was the conventional seven-day, however, the 14-day program performed better overall and was similar to the seven-day program with one biofungicide substitution. This was probably due to a very dry growing season where disease severity was low overall.
Cover cropping can improve the overall productivity and sustainability of small farms. Past research in Maryland has shown that the use of hairy vetch or rye cover crops can reduce pumpkin fruit diseases and the need for frequent fungicide sprays. However, pumpkin farmers in the mid-Atlantic have not widely adopted cover cropping and no-till methods. One reason is that they are concerned that hairy vetch seed can carry over and cause a weed problem in subsequent years. Another concern is that rye mulch may increase the severity of some diseases, such as Fusarium. A survey conducted at the 2002 Mid-Atlantic Pumpkin School showed that alternative fungicides and cover crops were the two most important research areas for farmers.
Research can help address farmer concerns about cover crop use, thereby increasing adoption. Specifically, farmers need to know 1) the effect of various cover cropping schemes on productivity and profitability 2) the effect of cover crops on disease pressure (increase or decrease), and 3) the implication of cover crops for disease management strategies.
Of the 150 mid-Atlantic pumpkin growers participating in this SARE project, 12 will either initiate cover crop use or improve their cover crop selection and management within three to five years of the start of this project. Alternatively, the research may determine that a particular cover crop/pumpkin production strategy is not profitable and we will demonstrate to 150 growers to not adopt this production practice thus avoiding lost income for these growers.
To help us achieve this goal, we will produce written descriptions of at least two cover crop schemes that maximize the profits of pumpkin producers while minimizing disease development. These descriptions will include information on cover crop management and their effects on pumpkin diseases and management. These products will help farmers adopt new practices even after the project has concluded.
• 75 pumpkin growers will give feedback on cover crop selection and problem identification. In 2003, approximately 75 surveys were distributed and 3 were returned. In 2004, 193 surveys were distributed at 3 meetings. In 2005, 75 surveys were distributed, asking about priority problems to the industry;14 surveys were returned.
• Farmer cooperators will be identified for the on-farm replicated experiments (three or four farms) and of demonstration plantings (at least three farms per year for two years). We exceeded this goal. On-farm experiments were planted in Fall 2003 on three commercial farms (five replications total) to evaluate the success of overseeding legume cover crops into a standing pumpkin crop prior to harvest. Two farms were located in central Maryland, one on the Eastern Shore of Maryland. In addition, five cover crops were planted on the University of Delaware Experiment Station Farm in Newark. New experiments were planted in fall, 2004 on three commercial farms in central Maryland. A total of six blocks were planted. In 2005, three farms provided space for six on-farm trials this year. In 2006, we planted demonstration plots at the University of Delaware Research and Education Center near Georgetown.
• During the three-year period, 150 farmers will learn about using and managing cover crops, including the effect of cover crop selection on pest and disease management. They will learn this by attending one or more meetings that include the topic of cover crop use with pumpkins. We exceeded this goal. In 2004, 223 farmers learned about the experiments, and particularly learned about overseeding clover into standing pumpkins. In 2005, 132 learned about the project, including 33 who visited the experimental site at Queenstown. In 2006, 165 farmers learned about this project including 20 who visited the experimental site during the annual pumpkin twilight at Queenstown.
• Approximately 20 farmers will attend each of the two or three annual meetings that include this topic (calendar years 2003, 2004, 2005). (see above)
• Twelve pumpkin farmers will have either initiated cover crop use or improved their cover crop selection and management within two years of the end of the project. Although the time frame for this objective has not been reached, we know that one farmer has begun to grow pumpkins following a crimson clover cover crop.
1) On-Farm Research and Demonstration;
Three farms assisted with the on-farm overseeding trials in 2004-2005. Crimson clover, hairy vetch, yellow sweet clover, red clover and Dutch clover were spun onto pumpkin fields from September 30, 2005-October 5, 2005. Each trial included a bare-ground treatment, and a total of six full trials were planted. Two trials were chisel-plowed in the early winter, and no cover crop growth was observed. Three trials were planted to rye following the pumpkin harvest. Despite this, 5-80% ground cover was observed in the crimson clover plots on April 7, 2005, while most other cover crop plots showed no growth. The rye rapidly outgrew all cover crops after it was fertilized the remaining trial showed 5-30% ground cover from crimson clover and 5-20% ground cover from hairy vetch on April 7, despite high weed pressure at this location.
2) Evaluation of pumpkin yield on fall or spring planted cover crops or bare ground.
Similar experiments were conducted at the University of Maryland’s Lower Eastern Shore Research and Education Center, Salisbury and the Wye Research and Education Center, Queenstown. Hairy vetch, rye, hairy vetch plus rye, barley, winter wheat, crimson clover, yellow sweet clover and berseem clover were planted in September 2003 and 2004 (Queenstown, and October 2003 and 2004 (Salisbury) except berseem clover, which was planted October 6, 2004 at the Queenstown location. Mustard and spring oats were seeded in March 2004 and March 2005. Treatments, at each location, were arranged as a randomized complete block with four replications. Weed, diseases and insects were managed according to Mid-Atlantic Extension guidelines. Biomass of fall planted cover crops was sampled in May and spring planted cover crops in late May or June. Fertilizer was applied based on estimates of fertilizer contribution of each cover crop in the previous year, and the biomass measured in the current year. Hairy vetch and crimson clover did not receive nitrogen whereas; rye, barley, wheat, spring oats, mustard and bare ground plots received the extension recommendation (WyeREC) or 120 lbs. (LESREC). Yellow sweet clover and Austrian Winter peas received an intermediate amount of nitrogen. In 2005 at Salisbury, berseem clover was winter killed and the plots were disked. Austrian winter pea was then seeded on 10 March. Cover crops were rolled and killed with applications of paraquat or glyphosate, usually in May and June. Additional herbicides (Prefar, Curbit, or Gramoxone) were broadcast applied between the rows to manage weeds.
Pumpkins (cv. Magic Lantern) were direct-seeded in June. Side dress fertilizer was applied in mid- July. Pumpkins were harvested and individually weighed in September. Fruit diseases were evaluated and five fruit/plot placed in storage. Stored fruit were evaluated every two weeks for disease and the final evaluation was in November.
3) An experiment to evaluate the impact of fungicide programs was established in a field of Norfolk “A” loamy sand soil at the University of Maryland’s Lower Eastern Shore Research and Education Center, Salisbury in 2006 and 2007.
Plots were 21 ft long and 11 ft wide. The experiment was conducted as a split-plot design with four replications. Main plots consisted of four fungicide spray regimes: 1) conventional fungicides applied every seven days, 2) conventional fungicides applied every 14 days, 3) modified conventional schedule with biofungicides applied every seven days, and 4) nontreated control (see table).
Subplots consisted of five no-tilled cover crops (crimson clover, hairy vetch, rye, winter wheat, and bareground control). Crimson clover (25 lb/A), hairy vetch (30 lb/A), rye (140 lb/A) and winter wheat (150 lb/a) were seeded in October. Cover crops were killed by spraying with the herbicide Gramoxone Extra 2.5SC (1.5 pt/A) plus Li 700 surfactant (6.4 fl.oz/A). Killed cover crops were flattened with a cultipacker in Jun. Prior to killing cover crops, aboveground cover crop plant biomass was collected in each of three areas (39 by 39 in.) from each plot. Based on nutrient analysis of soil and cover crop biomass, fertilizer was applied to plots. The pumpkin cv. ‘Magic Lantern’ was directly seeded into soil 36 in. apart within rows in June. Fungicides were applied using a tractor-mounted sprayer that delivered 45 gpa at 43 psi. The boom was equipped with four Teejet XR11004 nozzles. Weeds were managed by shielded application of Gramoxone Extra 2.5SC (1.5 pt/A) plus Li 700 surfactant (6.4 fl. oz/A) or manual hoeing throughout the growing season. Plots were overhead irrigated as needed. Percent coverage of ground by cover crop and weeds was assessed in Mar. Powdery mildew severity was evaluated on the upper and lower leaf surface in the middle canopy of three plants per plot during the growing season using the modified Horsfall-Barrat scale. Fruit were counted and weighed in September and the handle quality of 10 fruit per plot was evaluated.
On-farm Overseeding Experiments
In 2003-2004, cover crop treatments of hairy vetch, crimson clover, red clover, Dutch clover, yellow sweet clover, and bare ground were evaluated in on-farm trials. Seeds were broadcast (double the standard seeding rate) into a standing crop of pumpkins in September/October 2004. Individual plot size was 50’ by 50’. Farm 1 (Larriland Farm) hosted two blocks of this experiment. Crimson clover ground cover reached nearly 100 % in the spring, appearing to be a potential overseeded cover crop on this farm. None of the other ground cover treatments showed an acceptable amount of growth. Farm 2 (Baugher Farm) hosted two blocks of this experiment. None of the cover crops showed an acceptable amount of growth. Farm 3 (How Sweet It Is) hosted one block of this experiment. At planting, the research area was noted to have many cool-season weeds. By spring, the weeds had overgrown the plot, and no cover crop plants were observed.
This experiment was repeated in 2004. Farms 1 and 2 hosted three and two replicates, respectively. Farm 4 hosted one replicate.
Research Farm Trials-Effect of Cover Crops on Pumpkin Yield
Replicated cover crop experiments were planted in the fall of 2003 in the following locations: Wye Research and Education Center, Lower Eastern Shore Research and Education Center, and at the University of Delaware research farm in Newark. At each site, treatments were arranged in a randomized complete block design with four replications. Samples of these cover crops were collected in spring, 2004. These were dried and ground and will be analyzed for carbon (C) nitrogen (N). The cover crops were killed by application of herbicide. Pumpkins (cv. Magic Lantern) were planted in the spring. Pumpkins were harvested in September, and individual fruit weights were collected. Foliar and fruit disease incidence was rated, and handle ratings were given. Along with other cultures grown in the lab from some fruit diseases in these experiments, a strain of Fusarium was isolated.
In 2005, pumpkins planted into the fall cover crop of yellow sweet clover or the spring oats cover crop performed well overall. Pumpkins planted into yellow sweet clover performed equal to those planted into hairy vetch, which was the highest ranked fall planted cover crop in ripe fruit weight and good handle quality. Among the spring planted cover crops, spring oats ranked the highest in all assessments. Austrian winter pea, which performed well in 2004, ranked the lowest in mean fruit weight and total yield in 2005.
At the Queenstown location, cover crop type had no effect on ripe fruit yield, number of ripe fruit, or fruit weight yield in either 2004 or 2005.
In 2004 and 2005 we identified winter wheat and crimson clover cover crops as the best alternatives to hairy vetch or rye. Winter wheat and crimson clover were alternatives for growers that had concerns about carry over seed from hairy vetch, or increased disease. Experiments to determine the optimum fungicide disease management program for each of the five systems (pumpkins produced on bare ground, winter wheat, rye, crimson clover, or hairy vetch) were conducted at two locations in Maryland. The disease management programs were conventional fungicides applied every seven days, conventional fungicides applied every 14 days, a program where the biofungicide Serenade was alternated with conventional fungicides, or no fungicide was applied (nontreated). Powdery mildew was the most severe disease at both locations and Plectosporium blight (aka Microdochium blight) was present at UM Lower Eastern Shore Research and Education in Salisbury.
Unlike previous research, cover crop did not impact yield, fruit weight, handle quality or fruit rot at either location. We never observed differences in disease on different cover crops. However, yield and diseases were highly influenced by fungicide spray programs. The seven-day conventional program resulted in the greatest yield (MgHa). The seven-day program modified with a biofungicide ranked second in performance, followed by the 14-day program.
Delaware Vegetable Growers Meeting, Vine Crops Session “Pumpkin Round Table” at Harrington, DE (January 7, 2004; attendance approximately 30). Included brief summary of project.
Central Maryland Vegetable Growers’ Conference (January 23, 2004; attendance approximately 100). Included preliminary information about the overseeding experiment in cover crop presentations. Provided a brief summary about the project (from the proceedings of the Pumpkin Twilight Tour). Surveyed attendees, solicited names for pumpkin mailing list.
Southern Maryland Vegetable Growers’ Conference (February 4, 2004; attendance 68). Include preliminary information about the overseeding experiment in cover crop presentations. Provided a brief summary about the project (from the proceedings of the Pumpkin Twilight Tour). Surveyed attendees, solicited names for pumpkin mailing list.
2004 Pumpkin and Sweet Corn Twilight Tour at the Wye Research and Education Center, Queenstown, MD, on September 29 (attendance: 25). Reported observations from research in MD and DE. Provided written summary (attached). Received few surveys-too dark. Will follow up in Feb.-Mar. 2005.
Presented a poster describing this work at the Northeast SARE conference in Burlington, VT. (Fitzgerald, C., K. Everts, B. Butler, L Romaneo, L. Lynch, A. Collins. (2004) Optimization of Cover Crop Strategies for Pumpkin Production in the Mid-Atlantic. Setting the Table. Northeast Sustainable Agriculture Research and Education Program.)
Thirty-three farmers and Extension personnel visited the SARE research plots as part of the 2005 Pumpkin and Sweet Corn Twilight Tour. In 2005, 93% of attendees rated the twilight as “excellent” or “very good”, and 100% said that attending the twilight was valuable for their businesses. Surveys in 2002 and 2005 showed that farmers anticipated using the following information: 86-100% variety selection; 86-100% disease management.
One hundred and ninety-nine farmers and pesticide applicators learned about pumpkin production and were introduced to this project through four invited presentations in 2005. These were the Delaware Vegetable Growers’ Meeting, Marketing for Success: A Short Course for Growers and Market Managers (West Virginia), Maryland Commercial Pesticide Applicator Recertification, and the Caroline-Dorchester Vegetable Conference (Maryland).
The 2006 Pumpkin Twilight Tour was held September 27, 2006 at the Wye Research and Education Center. Several conclusions from Alyssa A. Collins’ dissertation (University of Delaware, July 2006) were presented.
Central Maryland Vegetable Growers Meeting, “Vegetable Crop Disease Issues – Late Season Fruit Rot in Pumpkins.” Upperco, MD.
Wye Research and Education Center Pumpkin Twilight meeting. “Cover crops and pumpkin disease management.” Queenstown, MD
Additional Project Outcomes
Impacts of Results/Outcomes
In 2004 yields were higher at the Queenstown location than at Salisbury. Hairy vetch had the highest yield at Salisbury, and legume cover crops performed better than small grains at that location. Pumpkins planted into yellow sweet clover and crimson clover performed equal to those planted into hairy vetch, which was the highest ranked fall planted cover crop in ripe fruit weight, fruit number and total yield. Among the spring planted cover crops, Austrian winter pea ranked the highest in all assessments. Yields in hairy vetch plots also ranked the highest at Queenstown, but were not significantly higher than other cover crop treatments. In addition, yields in the small grain plots were good at the Queenstown location. Irregular plant growth was observed in the experiment July 2005, at Queenstown. This effect was due either to irregular seeding depth or possible herbicide effect. It appeared that the bare ground treatment had fewer small plants than the other treatments. These effects were not noticeable later in the season.
In Salisbury in 2005, there were large differences in vigor of pumpkin plants on 7 September. A hairy vetch (HV) cover crop alone or in combination with rye, rye alone and yellow sweet clover produced the most vigorous plants, significantly better than pumpkins grown on Austrian winter pea (Table 2). Pumpkins grown on bare ground and mustard were less vigorous than those grown on HV or HV plus rye. Pumpkins grown on barley, crimson clover, spring oats and winter wheat were intermediate in vigor. Incidence of Plectosporium blight on fruit was high in 2005 (10 to 34%). Fruit grown on a spring oat cover crop had significantly lower incidence of Plectosporium blight on fruit than did fruit grown on crimson clover. There were no significant differences in the number of fruit per acre or total fruit weight among the different cover crops. However, the mean fruit weight was more on bare ground, HV, HV plus rye and yellow sweet clover plots compared to Austrian winter pea plots. Handle (peduncle) quality was significantly better in pumpkins grown on HV, HV plus rye, crimson clover, spring oats and yellow sweet clover than in pumpkins grown on mustard, barley, Austrian winter peas or bare ground.
In experiments to evaluate fungicide programs on the cover crop alternatives winter wheat and crimson clover, cover crop did not impact yield, fruit weight, handle quality or fruit rot at Salisbury expect in 2007 when pumpkins grown on crimson clover had significantly lower fruit/Ha than pumpkins grown on winter wheat. However, there was no difference in total yield between the two cover crop treatments. We never observed differences in disease on different cover crops.
In contrast, yield components and diseases were highly influenced by fungicide spray programs. The seven-day conventional program resulted in the greatest yield (MgHa) and fruit weight and handle quality and lowest fruit rot in 2006 although the seven-day program modified with a biofungicide also performed well and was not significantly different for yield and mean fruit weight and fruit rot. In 2007, the best program also was the conventional seven-day, however, the 14-day program performed better overall and was similar to the seven-day program with one biofungicide substitution. This was probably due to a very dry growing season where disease severity was low overall.
Economic Analysis is ongoing.
Although the tim frame for this objective has not been reached, we know that one farmer has begun to grow pumpkins following a crimson clover cover crop.