An integrated approach to developing a day neutral strawberry production industry

An integrated approach to developing a day neutral strawberry production industry

Summary

Strawberry producers in the eastern United States primarily use spring bearing cultivars, which produce a crop for a relatively short period of time. Harvest is finished by the end of June; however, with large urban populations nearby, the demand for fresh strawberries is strong throughout the summer. Until recently the small size and poor quality of day neutral strawberry cultivars have prohibited day neutral strawberry production from filling a portion of this market. Many growers are looking for ways to produce fruit during the summer months to meet the demand by the consumers.

This project will introduce farmers to new varieties of day neutral strawberries, which have the potential to produce heavy yields of fruit with very desirable flavors. Potential producers will be invited to yearly field days, have the opportunity to attend a strawberry short course, and participate in monthly field walks during the growing season.

As a result of this project, growers will have information on the best nitrogen fertilization levels, plant propagation methods, growing techniques and variety selection. During the first year of the project organic nitrogen (compost) and nitrogen levels will be evaluated to determine which level will produce the highest marketable yields and healthiest plants. In the second year of the project, growers will evaluate the best method of propagating day neutral strawberry plants. In the final year of the project, growers will evaluate new varieties in variety trial plots.

Potential producers will be invited to attend annual field days held during each of the three years of the project. Of the 200 potential producers that will attend a field day, 100 will attend a strawberry short course or field walk to further their knowledge of growing day neutral strawberries and 20 will plant day neutral strawberries utilizing new varieties and production techniques. Surveys will be conducted to determine that milestones have been reached.

Objectives/Performance Targets

The primary outcome of this project will be to establish a day neutral strawberry production system in the cool climate areas of the northeast. Information gained through this project will be presented through field days, yearly strawberry short courses, and field walks held during the growing season.

Two hundred farmers will attend field days on growing day neutral strawberries. Farmers who have interest in producing fruit will be invited to attend a yearly strawberry short course or field walks. One hundred farmers will attend a second educational event such as a strawberry short course or field walk. Of the farmers that attend the field walks or strawberry short courses, 20 will add day neutral strawberries growing new varieties utilizing advanced growing techniques to their farming operation. All participants of the short courses and field days will be surveyed to determine who has added day neutral strawberries to their farming enterprises.

Accomplishments/Milestones

During 2008, the project completed two separate research projects. The first project was a cultivar trial of day neutral strawberries. The cultivar trial was conducted at two locations: Penn State’s Horticulture Farm at Rock Springs, PA and at the farm of Harry Swartz near Oakland, MD.
The cultivar trial was done as an annual day neutral planting. The main plant source used was plug plants which were grown in Maryland, originating as dormant plants that were trimmed and grown in plug plant trays for 2 to 3 months prior to planting. With the cultivar Evie 2 in the PA trial, dormant plants were also planted for comparison to plug plants. Due to wet soil conditions, plants in Pennsylvania were planted on June 6, 2008 which is late relative to a normal or desirable planting date, though the MD planting date of May 7 was more typical In PA, plants were planted into a field that was amended with compost applied at a rate that was calculated to provide 60 lb of nitrogen per acre for the first year assuming a 10% mineralization rate. This rate also provided 190 lb/a of P2O5 and 270 lb/a of K2O, which exceeded the recommended amounts by 140 and 160 lb/a, respectively as based on soil test results. No additional fertigation of nutrients was used. In MD, plants were fertilized with MicroStart60 Pelleted Poultry Litter to provide 60 lb/a of N, 40 lbs P2O5 and 60 lbs of K2O and were also fertigated with 20-20-20 to provide 1 lb of N/acre/week. Plants were planted into raised beds mulched with black plastic. Plants were grown in staggered double rows with 12” between rows within each bed and between plants. Yields are given as pounds per plant, but can be converted to lbs per acre, assuming beds on 6’ centers by multiplying by 14,520. In PA, blossoms were removed from the plants until July 3 and in Maryland no blossoms were removed.

The cultivar used as the standard was ‘Seascape’ in both states, with ‘Tristar’ also included in Maryland. Other named cultivars tested were ones which have been tried on only a limited basis. Several advanced selections from 5 Aces Breeding, one from the USDA, and one from North Carolina State University were included. The three “FAB” selections have Fragaria moschata in their background, which imparts a wide range of flavors to the fruit.

Yields in general were a bit low, which in PA could have been in part due to the late planting date, very hot temperatures soon after planting, and a somewhat shortened fall harvest season compared to previous years. In Maryland, the cold wet weather following planting also delayed peak production. Seascape yields, for instance, were only about half as high as has been obtained on average during 3 other years at both sites. Growing the plants on aluminized plastic rather than black also might have increased yields. Even so, considerable information was obtained on relative yield potential, fruit size and soluble solids, a measurement of sugar levels.

The three varieties with the highest marketable yield in the Pennsylvania trial were Everest (1.16 lbs per plant), Evie 3 (1.01 lbs per plant) and Albion (.68 lbs per plant). The three varieties with the highest marketable yield in Maryland were Seascape (.59 lbs per plant), EMF-f3 (.43 lbs per plant) and Evie 2 (.41 lbs per plant). Data was also collected on plant growth characteristics and disease and insect susceptibilities. Below is a description of each of the varieties in the trial.

Seascape: The current standard cultivar for day-neutral production in the eastern U.S. and Canada. Seascape is typically very productive, and produces medium-sized medium-red fruit with notable sweetness, but yields were low in this trial. Powdery mildew has been a problem in grower fields in some years.

Albion: Performed better in PA than in MD. Berries were quite firm and large – averaging 15.3 g over the season and over locations, reich resulted in a higher percentage of marketable fruit. If you’re familiar with the cultivars Camarosa or Diamante, you have an idea of what this berry is like. Similar to Camarosa in firmness, or just slightly softer. Perfect red color, with acceptably good, but not great, flavor when fully ripe. Despite vigorous plants, the size and fast picking of this berry makes it worth a try at least in small quantities. One potential problem is production of large numbers of runners.

Everest: Produced very high yields in PA but low yields in MD. The main problems with this berry are a smaller size, and it can be soft and lack flavor in warmer weather. Color is a bit light. In the cooler climates of western MD it fruit has acceptable firmness and flavor. Flavor also improved during cool fall conditions, and some growers have the quality to be acceptable. Produced the lowest number of runners of all cultivars and selections.

Evie 2: Improved berry size and flavor compared to Everest, but low yields in MD. Other characteristics (softness, shape, and light color) were very similar to those of Everest.
Evie 3: Produced high yields in PA similar to Everest. Quality was nearly identical to Everest, except slightly sweeter, but still soft with fairly small berries.

Tristar: Only grown in MD trial. Yields were average and berries were small. Excellent flavor but the fruit is very soft.

FAB series: The soluble solids (sugar) readings for all of these selections were the highest of all cultivars in both PA and MD (data not presented for MD). Their unique flavors made them favorites for some taste testers, but also made them unacceptable to others. Insects also seemed to have a preference for FAB14 and FAB25. Of these selections, only FAB26 in PA produced yields that would be high enough to be commercially acceptable. FAB26 had a somewhat flattened shape.

EMF-F3: This cultivar produced large berries, but the yields were fairly low. Flavor and sweetness were below average.

USDA EB: Trialed only in MD. This cultivar had good shape, color, flavor and size. Large size and good flavor. Would like to see this one again for more data or possibly in tunnels to extend the late season.

NCL 05-87: Plants were extremely vigorous but, remained vegetative and produced numerous runners well into the fall.

The second research project involved comparing day neutral strawberry size and yield on three different colors (black, aluminized, and white) of plastic. Black plastic mulches have been shown to increase soil temperatures around 50F. Black plastic mulches would be favorable for plant establishment during cool spring weather but may reduce production during hot summer weather. Aluminized reflective mulch has been shown to decrease soil temperatures by 2-4oF at 2-3 inch deep soil levels. White plastic has also been shown to reduce soil temperature. During hot summer days, the cooler soil temperatures would be desirable for strawberry production. In Garrett County where the springs are often very cool and the summer temperatures are milder than most other strawberry production areas, it is questionable if strawberries produced on aluminized or white plastic will out yield strawberries grown on black plastic. Aluminized plastic has a higher cost to the producer of about $400.00 per acre.

We established two research plots to compare fruit production of annual plug planted day neutral strawberries on three different colors of plastic mulch. The plants were planted in a typical 12 inch double row raised bed plasticulture system. Three twenty plant blocks were randomly selected in each of the different plastic color rows. Soil temperatures were taken with a probe at 3” deep during each harvest time. The variety for the research was ‘Evie 2’ and the planting date was May 14th.

Data collection from one of the sites was interrupted during the summer, therefore the data is only being presented from one site which did not allow for statistical analysis of the research. At the remaining site, however, increased production was observed on the aluminized plastic. The production per plant on aluminized plastic was 792 grams with an average berry size of 13.7 grams. Production per plant on white plastic was 743 g with an average berry size of 13.3 grams. The plants on the black plastic produced 689g per plant with an average berry size of 13.2 grams. Soil temperatures under the black plastic averaged 71.5oF which was lower than expected. This might be explained by the fact that the plastic was not tight to the bed due to rocky soil conditions.

Average soil temperature on the white plastic was 73.3oF and on the aluminized was 69.7oF. Early fruit production was slightly higher on black plastic during the later part of June and early July, however in mid summer, production on the aluminized plastic was greater.

The important question would be whether, the additional cost of the aluminized plastic would be covered by higher yields as compared to black plastic. At a plant population of 15,000 plants per acre, an average marketability of 70%, and a value of $3.00 per pound, the value of an acre of strawberries planted on aluminized plastic would be $7,119.00 higher than that produced on black plastic and $3,385.00 higher than that produced on white plastic. From our observations the extra cost per acre of aluminized plastic ($400.00 per acre) would be a profitable investment. The disadvantage to growers of small plots is that they would have a higher initial investment in a roll of aluminized plastic that may be used for several years and that the aluminized plastic may not be available from local suppliers.

Two outreach events were held in 2008. The first was the Appalachia Strawberry Field Day held at the site of the Oakland, Maryland variety trial on September 18th. The second event was the Pennsylvania Day Neutral Strawberry Workshop held on October 16th. This workshop was held at the Penn State Horticulture Farm which was the location of the Pennsylvania variety trial. Participants were able to view the variety trials and heard about various aspects of the research from those involved with the project. The events were attended by 60 people.

Fall and spring producer meetings were also held in Garrett County, Maryland. The meetings gave the producers a chance to discuss successes and challenges with growing day neutral strawberries. The group also discussed marketing strategies. Each of the meetings was attended by 16 producers.

Impacts and Contributions/Outcomes

To assist those interested in growing day neutral strawberries, the Garrett County Extension office worked with a local greenhouse to prepare and grow plug plants for spring planting. Twenty-one farms planted over 20,000 day neutral strawberry plants in 2008.
At the fall strawberry producer meeting, a survey was conducted to evaluate the effectiveness of the education and outreach of the SARE grant. Of the producers surveyed (n=14) 86% had not produced strawberries before the start of the SARE grant. These producers now have an average of 2.2 years of experience producing day neutral strawberries. The producers were asked to rate on a scale of 1 to 5 (1 equals very important and 5 equals little importance) the impact that six education/outreach type activities had on the success of their operation. The average rating was a 1.65, indicating that the participants felt the outreach activities were important to the success of their operations. The two education/outreach activities with the highest ratings were “education programs sponsored by the grant” and “technical assistance provided by extension”. Producers were also asked to rank their knowledge and skills with producing strawberries based on three questions before becoming involved with the grant and the same three questions after becoming involved with the grant. On a scale of one to five (1 equal to very knowledgeable and 5 having limited knowledge), the producers ranked themselves an average of 3.7 before and 1.9 after. The producers were also asked to report the number of plants producing fruit in 2008. The 14 produces indicated they produced fruit on 16,500 plants. Eleven of these producers estimated their gross sales from strawberries were $18,863. While this is less than $2,000 gross income per producer, the average number of plants per producer was only 1,200 which is less than 1/10th of an acre. About 80% of the producers indicated that they would stay about the same size or increase production in 2008.

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