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- Reduced-tillage Pumpkins
Studied in New York
- By Ted Blomgren
Cornell Cooperative Extension
- Pumpkins are produced on 6,000-7,000 acres in the state of New York and are worth $17- $20 million annually. Pumpkin acreage has steadily increased throughout the Northeast because of strong local demand for the crop and increased opportunities to ship pumpkins outside the region.
However, pests of pumpkins are numerous and difficult to control and the strategies that provide the best pest control are relatively costly. Because profit margins are narrow, pumpkin growers are seeking ways to contain costs.
Reduced tillage vegetable systems that utilize cover crops as mulches have been under investigation for many years. These systems have been reported to increase profitability, enhance soil quality and reduce pesticide applications. Nevertheless, New York growers have been reluctant to utilize reduced-tillage systems because of the difficulty of achieving good crop stands in high residue environments, the fear of reduced yields or delays because of cold soils, the lack of appropriate equipment and expertise and the unpredictability of weed control.
Cover crops used as mulches have proven valuable in weed suppression. Mulches function as a physical barrier to weeds, and suppress weed through allelopathic interference. Mulches also suppress weeds by altering the quantity and quality of light reaching the soil surface, and by affecting the soil temperature, moisture and chemical environment. Eliminating tillage also lowers weed pressure, mainly by reducing weed seed germination.
Weed suppression in no-till/cover cropping systems is often short-lived, usually lasting less than four weeks. Winter rye has been shown to suppress weeds in numerous vegetable crops, including no-till pumpkins. Growers have not used this system because they have been unable to achieve satisfactory season-long weed control. More work is needed to develop effective weed control strategies.
Transplants are most often used in vegetable production to facilitate early crop maturation in a short growing season or where weed control when direct seeding is inadequate. Transplanted vegetables are more competitive against weeds than direct-seeded vegetables. A later planting date also allows the soil to warm, providing warm-loving plants with conditions better suited to optimal growth, and provides no-till growers with the opportunity to plant when the cover crop has grown to a more weed-suppressive stage. The later planting afforded by transplanting also provides an opportunity to utilize stale seedbeed weed management techniques.
In no-till pumpkin production, the benefits of superior plant stands, more effective pest management and higher yields may outweigh the costs and inconvenience associated with using transplants.
Objectives
The primary objectives of this research were a) to learn whether a strategy that combines the use of transplants and the creation of a stale seedbed in a reduced tillage system offers improved weed control when compared to direct seeding, and b) to learn whether a stale seedbed/transplanting strategy is more weed suppressive when used in a no-till/cover crop system than when used in a conventional tillage system (i.e, to learn the contribution of the cover crop in suppressing weeds).
Materials and methods
Four treatments were replicated three times in each of the two tillage systems: reduced tillage/rye and conventional tillage. Treatments included: 1) direct-seeded Howden; 2) transplanted Howden; 3) direct-seeded Rocket, and 4) transplanted Rocket. The rye was flail mowed in mid-June and stood about 72” tall. Plots were 30’ long, and contained four rows each on 66” centers. Plants were spaced 24” apart in the row. Rye plots were readied for planting by making a slot with a flutted coulter followed by a narrow shank.
Transplanted Howden treatments were seeded in the greenhouse on 6/1/00 and transplanted on 6/19/00. Direct seeding of Howden also occurred on 6/19/00. Rocket transplants were seeded on 6/8/00 and set in the field on 6/26/00. Field seeding of Rocket also took place on 6/26/00. Weed cover evaluations were made on 8/9/00 and Harvest evaluations were made on 9/26/00.
Results and discussion
Stale seedbed treatments were not used because the cold season delayed the emergence of annual weeds. Weed cover at the time of planting was less than 1% in rye plots. Weeds grew quickly after plant establishment, particularly in the row, where soil disturbance took place. Approximately six weeks after crop establishment, weedcover was evaluated (Table 1). Weed cover was greater in reduced tillage than in conventional tillage, regardless of the method of plant establishment. Conventionally tilled plots were cultivated twice. The rye was only weed-suppressive for a brief period of time. Pumpkin cover (measure of the rate of pumpkin growth) was greater in conventionally tilled plots, and, generally greater in direct-seed plots.
Howden yields were greatest in conventionally tilled plots, regardless of the method of plant establishment. Howden transplanting yielded more pumpkins than direct-seeding, regardless of tillage. Howden, a long-season variety, probably benefited from relatively warmer soils under conventional tillage, and the “jump start” provided by transplanting. Rocket yields, on the other hand, were greatest in reduced-tillage, regardless of the method of establishment, and generally higher when direct-seeded. Rocket, which is a relatively short-season variety, appears well suited to reduced tillage production.
Transplanting may be a better option than direct-seeding when establishing a pumpkin crop in a cold soil, such as that under a rye mulch, or when making an early planting of a long-season variety such as Howden. Future research should include a more detailed investigation of the advantages and disadvantages of transplanting pumpkins, particularly in a no-till environment. Research in no-till pumpkin weed management should focus on the suppression of weed that emerge four to six weeks after crop establishment.
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