Research results demonstrate that fall-sown rye, rye + hairy vetch and spring-sown oat can be successfully incorporated into pumpkin production in Ohio although integration and success will depend on fall-planting date, lbs/A planted, spring kill date, and method of pumpkin planting. A strip tillage production system may allow for easier pumpkin planting as well as offer some leeway in the window of opportunity for spring cover crop kill. Too much production of fall-sown rye biomass and successful kill of hairy vetch has often been a problem incountered by pumpkin growers. Spring-oat when planted at a high rate (110 lb/A) can also be successfully incorporated into a strip-tillage pumpkin production system. Planting a cover crop such as oat in the spring alleviates some of the problems of a fall-sown cover crop such as having a field free for planting and helps to avoid some of the weather contingencies necessary for a successful cover crop. Although oat will not produce as much biomass as a fall-sown rye, its growth habit makes it much easier to kill with herbicides, as well as, having a much greater window of opportunity for kill. Although cover crops such as rye can provide season long ground coverage, herbicide applications will be necessary. An herbicide over mulch (HOM) study will be under taken in 2003. Spring-sown annual medics when left as living mulches in a strip-tillage system with drip irrigation cause reduced yields. Competition for water and available N and allelopathy may all play a role, future work still needs to be done. Fruit cleanliness and pumpkin yield loss due to FFR was lowest in fall-sown rye and rye + HV plots suggesting that these cover crops provided an excellent physical barrier between pumpkin fruit and the soil.
Cover crops have been used in high-input agronomic and vegetable production systems to help reduce soil erosion, fungicide use, plant disease, and weed pressure. Cover crops have also been shown to increase soil organic matter, nitrogen availability, and moisture. Traditional cover crops, such as hairy vetch (Vicia villosa) and winter rye (Secale cereale), which are killed and left on the soil surface, have been used in pumpkin (Cucurbita pepo) production with limited success. These traditional fall-sown cover crops can be killed by herbicide applications or mowing prior to pumpkin planting. Fusarium fruit rot (FFR) is a major soil-borne disease in pumpkin production. Current recommendations for control of FFR are crop rotations of four years or more. In small roadside farm operations where pumpkin rotations are grown continuously or rotated every one or two years, FFR can cause serious yield loss. Because control of FFR with fungicides does not work, there is a need for an alternative production system that allow for shortened pumpkin rotations. Cover crops killed and left on the soil surface may play an important role in alternative pumpkin production systems, as well as help reduce FFR.
1.Selection of spring-sown living, fall-sown (herbicide) killed, and spring-sown (herbicide) killed cover crop mulches for use in commercial pumpkin production.
2.Determine the effects of these cover crop mulch systems on pumpkin yield and aesthetic fruit quality.
3.Determine the effects of cover crop mulches on soil-borne fungal diseases such as fruit rot of pumpkin caused by Fusarium spp.
4.Introduce these cover crop systems to growers for use in commercial pumpkin production.
In Oct. 2000, fall-sown cover crop treatments of winter rye “Wheeler” (90 lb/A and 50 lb/A) were established at research branches in Columbus, Fremont, South Charleston, and Wooster, OH. In early May 2001, spring-sown cover crop treatments of spring oat “Armor” (110 lb/A) and annual medic “Sephi” and “Polygraze” at 40 lb/A were established at same sites. In Sept. 2001, fall-sown cover crop treatments of winter rye “Wheeler” (90 lb/A and 50 lb/A), hairy vetch (50 lb/A), hairy vetch and rye (50 lb/A each) were established at research branches in Fremont, South Charleston, and Wooster, OH. In late April 2002, spring-sown cover crop treatments of spring oat “Armor” (110 lb/A) and annual medic varieties “Sephi,” “Parabinga,” and “Polygraze” at 40 lb/A were established at same sites. Plot sizes were 25’ by 25’. In late May of 2001 and 2002, fall-sown rye plots were killed with Roundup® at 4 pt/A. In hairy vetch plots 2,4D (Lo Vol) at 2 pt/A was added. Planting strips (22” wide) on 10’ centers were prepared in each treatment by spraying Roundup® (5%) with a backpack sprayer. Fall-sown rye and spring-sown oat were laid down with a 2’ wide walk-behind roller in June. In mid to late June, Poast Plus® (2 pt/A) + 24DB (2 pt/A) were sprayed on annual medic plots to control broadleaf weeds. Prior to pumpkin planting, planting strips were tilled with a roto-tiller. Pumpkin cv. “Magic Lantern” was seeded into the cover crop treatments in early July by hand. Two seeds were planted every two feet. to approximate standard production practices. Seeds were established with 8 oz. water with (10-52-10) and Admire® at 2.2 oz/1000 ft. Plots were maintained with rotated applications of Bravo Ultrex® at 2.7 lb/A and Quadris® at 12.3 oz/A beginning in August. Nova 40WP® at 3.0 oz/A or Benlate® 1 lb/A was also added to the spray program to help control powdery mildew. Sulfur-coated urea (39-0-0) was broadcasted @ 50 lb/A over entire plots at planting and banded at 50 lb/A at vine-tip. Pumpkins were watered with 1” drip irrigation tape throughout the growing season when necessary. At harvest all fruit from each treatment were graded according to color (orange, green) and weighed. Percentages of marketable (orange) and clean fruit were also calculated. Pumpkins were harvested during the first three weeks of October.
Establishment, cover crop biomass, and percent ground cover production.
In general, fall-sown rye (90 lb/A and 50 lb/A) produced enough biomass to provide season-long ground cover. Early establishment (prior to hard freezes) in the fall is critical to the success of winter rye and hairy vetch as cover crop mulches. Fall-sown oat and annual medic (winter-killed) do not produce enough biomass to last the following season. However, spring-sown oat at 110 lb/A planted in late April to early May provided excellent early- to mid-season ground cover. Oat tends to breakdown much quicker than fall-sown rye and its ability to provide ground cover, suppress weeds, and conserve soil moisture decreased much quicker than rye during the growing season. Annual medics established well when planted in late April to early May. Spring-sown annual medic “Sephi” provided excellent season long ground cover, whereas “Parabinga” and “Polygraze” provided early, but failed to provide season-long ground cover due to early senescence from summer heat, spider mites, and powdery mildew.
Pumpkin yield and fruit quality.
In 2001 and 2002 marketable yield (orange fruit) on fall-sown winter rye (90 and 50 lb/A), hairy vetch (50 lb/A), winter rye (50 lb/A each) and spring-sown oat (110 lb/a) were comparable to slightly higher than bare soil. In both years, yield of pumpkins grown in spring-sown living annual medic cover crops were reduced. In both years, fruit cleanliness was highest on fall-sown winter rye. Spring-sown oat and fall-sown hairy vetch provided intermediate fruit cleanliness. Fruit cleanliness in annual medic cover crops ranged from poor to excellent depending on variety and year.
Cover crop effect on development of Fusarium fruit rot.
In 2002, research plots in Fremont, South Charleston and Wooster, OH were artificially inoculated with Fusarium fruit rot (FFR) by three different methods. Method of inoculation affected severity of FFR. In Wooster, 2002, average percent yield loss (PYL), based on weight, was highest in bare soil plots (43%). PYL in spring-sown annual medic ranged from 21% to 37%, based on variety. In hairy vetch (50 lb/A) PYL was 27% and spring-sown oat PYL was 22%. PYL was lowest in fall-sown cover crops. PYL was 9% in rye (50 lb/A), 5% in rye (90 lb/A) and 4% in rye and hairy vetch (50 lb/A ea).
In this study, the effects of fall- and spring-sown cover crop mulches were evaluated for their effects on pumpkin yield, fruit cleanliness, and control of Fusarium fruit rot. Research demonstrates that fall-sown winter rye and winter rye and hairy vetch cover crop mulches that are desiccated and allowed to lay on the soil surface during the production season can improve fruit cleanliness and reduce the incidence of Fusarium fruit rot in pumpkins. Although spring-sown oat may be used as an alternative for fall-sown cover crops, like winter rye and winter rye and hairy vetch, its ability to improve fruit cleanliness and control of Fusarium fruit rot is limited. Fall-sown hairy vetch alone did not provide adequate ground cover and control of Fusarium fruit rot. Spring-sown annual medic, when left as a living cover crop mulch during the production season, reduced pumpkin yield, making it unsuitable as a living cover crop mulch in pumpkin production. The strip tillage cover crop production method used in this study may help improve pumpkin seeding and germination.
This study should provide pumpkin growers with general information on the methods and benefits of incorporating cover crops mulches in pumpkin production.
Educational & Outreach Activities
“Update on the use of cover crop mulches in pumpkin production.” Ohio Small Fruit and Vegetable Congress – Toledo, OH. February 2001 – In proc.
Amish Vegetable Pumpkin School – Richland Co., OH,
Amish Vegetable Growers Twi-light Tour, Holmes Co., OH, July 2001.
Vegetable Field Day. Vegetable Research Branch (OARDC). Fremont, OH, August 2001.
“Update on the use of cover crop mulches in pumpkin production.” Ohio Small Fruit and Vegetable Congress – Toledo, OH, February 2002 – In proc.
“Update on the use of cover crop mulches in pumpkin production” Tri-State Vegetable Meeting. Angola, IN, March 2002.
“Evaluation of annual medics (Medicago spp.) as living cover crop mulches in vegetable production systems in the Midwest (OH).” North American Alfalfa Improvement Conference – Sacramento, CA, July 2002 – In proc.
Vegetable Field Day. Vegetable Research Branch (OARDC). Fremont, OH, August 2002.
Pumpkin Production School, Western Branch (OARDC), South Charleston, OH, August 2002.
“Cover crop mulches in pumpkin production.”
Great Lakes Expo. Grand Rapids, MI. December 10, 2002, – In proc.
“Use of cover crop mulches in pumpkin production”
Vegetable Growers Co-op, Paris, KY, December 2002.
“Update on the use of cover crop mulches in pumpkin production.” Ohio Small Fruit and Vegetable Congress – Toledo, OH, January 2003 – In proc.
“Evaluating spring-sown oat (dead) and annual medic (living) cover crop mulches in two different commercial pumpkin production systems in Ohio.” Ohio Innovative Farmers Forum. Mt. Vernon, OH, January 2003.
“Cover crops for disease control in pumpkins.”
Mid-American Vegetable Trade Show. Hershey, PA, February 2003 – In proc.
“Control of Fusarium fruit rot with cover crop mulches.” Tri-State Vegetable Meeting. Angola, IN, March 2003.
“Implementing cover crop mulches into commercial pumpkin production.” The Vegetable Growers News. Sept. 2002.
“Cover crop mulches for control of Fusarium fruit rot in pumpkin production” – in prep.
Areas needing additional study
Spring-sown annual medics, when left as living mulches in a strip-tillage system with drip irrigation, cause reduced yields. Competition for water and available N and allelopathy may all play a role, and future work still needs to be done.
Herbicides will still need to be used with cover crops mulches to improve weed control. The use of herbicides and application methods over cover crop mulches needs to be studied.
Although cover crop mulches, such as winter rye and winter rye and hairy vetch, greatly reduced the incidence of Fusarium fruit rot in pumpkins. The effects of cover crop mulches on soil-borne fungal populations in pumpkin soil need to be examined further.