Aug 8, 2016
Pepper profit potential analyzed in high tunnel trials

New Hampshire farmers looking to grow colored bell peppers in high tunnels received some good news from researchers at the New Hampshire Agricultural Experiment Station in Durham.

Researchers found many varieties produced excellent, high-quality fruit in a research trial conducted in 2015 at the experiment station’s Woodman Horticultural Research Farm.

Becky Sideman, a researcher with the New Hampshire Agricultural Experiment Station and Extension professor of sustainable horticulture production for the University of New Hampshire (UNH); Kaitlyn Orde, graduate student in agricultural sciences; and Talia Levy, undergraduate student in sustainable agriculture and food systems, conducted a colored bell pepper trial to determine the most suitable varieties for production in New Hampshire in an unheated, high tunnel environment.

“The reason that I started this work is that growers are often looking for alternative crops for high tunnel production, and having seen a lot of unheated greenhouse production of peppers in Europe, I wanted to try to figure out whether greenhouse peppers could make economic sense for us in New England,” Sideman said. “I think that the jury is still out on this. We are currently repeating the experiment again, and the peppers will go into the tunnel before mid-May this year, making for an earlier (and hopefully longer) growing season.

“Growing peppers in unheated high tunnels permits the production of very high-quality colored fruit,” Sideman said. “Colored bell peppers have the potential to be a profitable, alternative crop for New Hampshire farmers, although a number of factors such as infrastructure costs, marketable yield and market prices need to be considered.”

Researchers collected information on total yields and marketable yields of 10 varieties of colored bell peppers. The varieties UNH evaluated included Bentley, Felicitas, Orangela, Sympathy, Early Sunsation, Moonset, Karma, Sprinter, Karisma and Orange Blaze.

Sideman and her team obtained yields ranging from 3.5 to 5 pounds of fruit per plant, with total yields ranging from 46,000 to 66,600 pounds per acre. This is more than double typical field pepper yields of 23,000 to 27,000 pounds per acre.

Photos: University of New Hampshire
Photos: University of New Hampshire

The highest yields were produced by Bentley, Felicitas, and Orangela, all classified as “High-Tech Greenhouse Peppers” by Johnny’s Select Seeds. For total weight of marketable fruit, Orange Blaze, a small-fruited type, produced significantly lower yields than both Bentley and Felicita. Otherwise, there were no significant differences, Sideman said.

Researchers found there was a direct relationship between fruit size and number of fruits produced per plant. Orange Blaze (average fruit size of 4.1 ounces) produced significantly more fruit per plant than all other varieties, whereas Karisma (average fruit size of 11.2 ounces) produced the fewest fruits per plant. Both peppers are field peppers by Harris Seeds. The number and percentage of unmarketable fruit was low for all varieties.

The researchers also found that the most common fruit defect was sunscald, which can be difficult to distinguish from blossom end rot in pepper. The other common defect was alternaria fruit rot caused by the fungus Alternaria alternata.

“Successful pepper production in tunnels requires attention to various pests, and it may be possible to increase yields by earlier planting, alternative spacing and pruning systems, or other means,” Sideman said.

Sideman said researchers planted peppers inside a 30- foot by 60-foot high tunnel. Plants were seeded on March 30, 2015, transplanted into 50-cells on April 15, potted up in to 606s on May 13, and transplanted in-ground in the high tunnel on May 28.

“We applied preplant 50 pounds per acre of N and K2O using a mixture of soybean meal (7-2-1), ProGro (5-3-4), and potassium sulfate (0-0-50) with an additional sidedress (at first fruit harvest) of 50 pounds per acre of N using Nature Safe 13-0-0,” Sideman said.

“During transplant production, we used 15-5-15 Cal-Mg at a rate of 300 ppm N, pulse feeding twice per week. Once in the high tunnel, drip irrigation events were managed using tensiometer readings. Irrigation was turned on once the tensiometer read 15-20 centibars, until the meters read 0.”

High-tech greenhouse peppers are recommended for production in conditions with very good environmental control and low-tech greenhouse peppers are recommended for houses with less environmental control, the researchers stated. Spacing and pruning plants were spaced 12 inches apart in single rows on 5-foot centers (6 rows in a 30-foot-wide house).

Each plot contained six plants. Plants were trellised using the Almeria system, where twine was used to corral each plot, looping around vertical supports every six plants. New twines were applied as needed, every 6-12 inches of new growth.

“All fruits that set at the first and second nodes were removed from each plant, to encourage more vigorous plant growth,” Sideman said. “From then on, four leaders were maintained for each plant. All other lateral branches were removed, leaving a single fruit and flag leaf for each. Plants were pruned weekly throughout the summer.”

Sideman said fruits were harvested once they were at least 20 percent colored. In weekly harvests, fruits were weighed and counted after being categorized into marketable or unmarketable due to the following defects: sunscald, alternaria, anthracnose, European Corn Borer (ECB) damage, or other (including rots of unknown reason or misshapen fruit).

“The relatively few ECB-damaged fruit were later categorized as ‘marketable’ for data analysis, under the assumption that growers would have controlled this pest,” Sideman said. “At the end of the experiment, all mature green and immature fruit were harvested and weighed to provide an estimate of overall yield potential.”

Sideman said that shortly after transplanting, a low incidence of aphids was observed on a few plants.

“We effectively controlled the pest through natural colonization of lady beetles plus one inundative release of lacewing larvae in early June,” she said. “Aphid populations remained low throughout the experiment. A single application of Bt (Dipel DF) was made to control hornworm larvae in late August.”

Results and conclusions

“Our first harvest took place on August 14, and continued until October 21,” Sideman said. “Frost killed the growing points of the plants on October 17. We would typically expect to harvest colored bell peppers by August 1 in the field in Durham, so this production was quite late. This is likely for two reasons: 1) plants were not transplanted into the tunnel as early as they could have been, and 2) the earliest fruits were removed from the plants to encourage plant growth, which delayed first fruit production.”

Researchers grew the colored bell peppers in an unheated high tunnel at the experiment station’s Woodman Horticultural Research Farm. Photos: University of New Hampshire
Researchers grew the colored bell peppers in an unheated high tunnel at the experiment station’s Woodman Horticultural Research Farm.

Sideman said the quality of fruit harvested from all varieties was “excellent.” The highest yields were produced by Bentley, Felicitas and Orangela, all classified as “High- Tech Greenhouse Peppers” by the seed supplier.

“Under our conditions, these varieties performed just as well, and possibly a bit better, than those varieties recommended for low-tech greenhouses and field conditions,” Sideman said. “For total weight of marketable fruit, Orange Blaze, a small-fruited type, produced significantly lower yields than both Bentley and Felicita.

“The number and percentage of unmarketable fruit was low for all varieties,” Sideman said. “There were no significant differences between varieties in prevalence of different defects.

“The most common defect was sunscald, which can be difficult to distinguish from blossom end rot in pepper,” Sideman said. “The other common defect was alternaria fruit rot caused by Alternaria alternata.”

Sideman said seed costs vary widely for the varieties evaluated; at the time of writing the report, prices ranged from 11 cents to $1.04 per seed (assuming 250 seed quantities purchased) for the different varieties.

“The profitability of this crop as an alternative enterprise will depend on 1) actual yields in your system and 2) whether your market(s) will pay premium prices for very high quality colored bells,” she said. “Further, it may be possible to increase yields by earlier planting, alternative spacing and pruning systems, or other means.”

More experimentation with the system is required to determine whether yields and earliness may be increased by adjusting planting dates, pruning systems and other management decisions, Sideman said.

Gary Pullano, associate editor





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