Several strawberry transplants are available and have different labor requirements. Workers transplant fresh dug, bare-root plants ("fresh dugs") by hand or with the use of a small tool in annual hill plasticulture systems. Workers need to be trained in order to ensure these plants are set at the appropriate depth. Strawberry plugs can be planted by hand or mechanically with a water wheel. Workers will go back into the field within 1 to 2 weeks to replace unthrifty or dead transplants. With the exception of the owner/operator, workers typically do not re-enter the strawberry plasticulture fields again until the end of the Post-Transplant period (Table 1), during which they may hand weed and remove runners as well as apply winter row covers (spunbonded polyester covers used for winter protection). The next field exposure for workers occurs in the Dormant period during which row covers are removed from fields and dead leaves and runners are hand removed from plants. During the Pre-Harvest period, workers will hand pull branch crowns through the plastic film. At this time, workers will also hand remove any weeds that have emerged in the area of the transplant hole. Both preemergent and postemergent herbicide applications are applied in winter or early spring (row middles) with shielded, tractor mounted spray equipment. About 25% of the industry uses annual ryegrass in the middles for weed suppression, soil conservation, and later for a spring mulch during harvest. Other producers (not using annual ryegrass) keep the row middles weed-free with shielded postemergent sprays of paraquat in the late Post-Plant, Dormant and Pre-Harvest periods. After the Pre-Harvest herbicide application, a backpack sprayer may be used to control escaped weeds in the row middles. There is no hand weeding once harvest is underway. Insecticides and fungicides are applied from early spring and into the harvest period primarily with drop-nozzle field type sprayers delivering 150 to 200 pounds per square inch in 50 to 100 gallons per acre. Virtually all of the strawberry acres are harvested by hand (April to May) for direct marketing (U-pick, Ready-Pick, Farmers’ Markets), although a few larger operations harvest for the wholesale market.

Plasticulture System

The majority of the strawberries produced in North Carolina are grown in an annual hill plasticulture system. Raised beds are formed on four to five foot centers. Black plastic mulch and drip irrigation are used. In conventional production, the soil is usually fumigated in late summer/early fall prior to planting to control a wide range of soil borne pests.  Fields are planted in October with double rows on the raised beds (approximately 17,500 plants per acre). Strawberries are harvested the following spring. Rowcovers and/or over-head irrigation are often needed to protect the flowers/fruit from frost/freeze damage in early spring. Plants are removed after the spring harvest. Some growers will plant another crop on the raised beds to get a second use out of the black plastic and drip irrigation. It is not common for growers to keep plants for more than one year in NC plasticulture systems. Growers interested in improving soil health use summer cover crops and compost as amendments.

Matted Row System

A few North Carolina growers produce strawberries in a matted row system. This perennial system does not use plastic mulch or drip irrigation. The crop is generally not harvested the first year. Matted row plantings are maintained for three to five years.

• In 2014, U.S. produced over 3 billion pounds of strawberries, produced on 59,895 acres, valued at nearly $2.9B
• Fresh markets accounted for 81% of total strawberry production, valued at $2.6B
• In 2014, U.S. harvested strawberries from 59,895 acres located in 10 states: 41,500 acres in CA, 10,900 acres in FL, and the remaining 7,495 acres from OR, NC, WA, NY, MI, PA, WI and OH
• In 2016, North Carolina ranked 3rd at $26,928,000, which is approx. 1% of total value for the U.S.
• Production in NC in 2016 was 1200 acres
• In 2016, average grower price for fresh strawberries was $187/hundredweight
• 100% of the NC crop is marketed fresh

Cultural, biological, and chemical pest management strategies are employed by North Carolina strawberry growers to manage pests. Updated IPM recommendations are provided annually (Louws et al. 2018).

Currently, there are no varieties used in North Carolina that have resistance to common disease problems. ‘Sweet Charlie’ appears tolerant to anthracnose fruit ripe rot but is susceptible to the crown rot phase. Research efforts strive to achieve resistance to anthracnose, caused by Colletotrichum species (a priority issue), but no commercial cultivars are available yet. There are also no cultivars resistant to key arthropod pests of strawberries.

Growers who produce their own transplants should raise them under conditions that will minimize the introduction of pests. Sanitation, isolation of transplants from infested areas, frequent and thorough examination of plants for initial infestations and prompt treatment will favor plant establishment and minimize pest problems in the greenhouse or other plug production facilities. Growers who purchase plants are also encouraged to inspect them carefully for pests such as mites and aphids, and for diseases including anthracnose, Phytophthora crown rot, angular (bacterial) leaf spot, viruses and other less serious disorders. Many growers who use straw mulch will produce the straw on their farm or inspect grain fields prior to harvest to ensure straw is not contaminated with weed seed.

It is advisable to avoid planting strawberries in the same place year after year. Many North Carolina growers rotate strawberries with other crops. Rotation allows for soil building management practices and a reduction in pest pressure. However, much of the acreage committed to strawberry production has been fitted with solid set irrigation or is proximal to easy access for Pick-Your-Own (PYO) or other direct market customers. In such situations, rotation may not be practical or practiced and growers rely fumigants to reduce pest risk.

Appropriate strawberry planting sites are well-drained, with loose soil. Plants should be planted at proper depth when soil temperature and moisture are favorable. Summer cover crops and utilization of composts are becoming more popular with some growers.

There are several reasons why pre-plant soil fumigation is desirable in an annual hill plasticulture system, to control soil-borne pests, pathogens and weeds! Soil fumigants are toxic to humans, other animals, microbial organisms and plants. The strict use of safety measures such as personal protective equipment, no entry signs as well as respecting plant-back dates are essential to ensure the safety of the farmer, the public and the crop.

Fumigation for annual hill plasitculture spring production systems occurs usually in August. Commonly used soil fumigants contain one or more of the following active substances: Chloropicrin, 1,3-Dichloropropen (1,3 D), Methyl Isothiocyanate (Metam-Sodium, Metam Potassium), Dazomet, Allyl Isothiocyanate (AITC). Common fumigant names are: Pic-Clor 60, Pic-Clor 80, Telone 35, Sectagon, Metam, Dominus, etc. All those pesticides have a very wide range of pest control activity. The choice of the correct soil fumigation methods depends, as with every other pesticide, on many factors: The efficacy of soil fumigation highly depends on the chosen fumigant, the structure of the soil, soil moisture, the used plastic mulch and the method of application.

To ensure an effective fumigation, soil should be cultivated about. 2-3 weeks before the application date. Soil should be free of clods and plant residue. Soil temperatures between 45 – 80 F are desirable. The right soil moisture is most critical to ensure an effective soil disinfestation. On the day of fumigation, a soil moisture at 60-70% of field capacity is desired for an effective fumigation. Soil moisture of the field needs to be monitored before fumigation. It is recommended to plan fumigation a week earlier than necessary to have some buffer time, due to August droughts or heavy rain storms. During dry weather some growers will irrigate the field with overhead sprinklers a day or two before bedding and fumigation.

Cultivation is used in the establishment phases for matted row systems and annual strawberry systems. It is also used in the renovation phase of matted row strawberries.

Cultivation is used to control weeds, bury or destroy cover crop residue, or expose soil pests to the elements. Soil cultivation has the potential to disturb arthropod overwintering or oversummering sites, eliminate alternate host plants, bury residue in which pests may persist, and often outright kill soil-inhabiting arthropods.

Non-chemical weed control and sanitation can be accomplished without cultivation. Weeds can be pulled by hand from plant holes. Sanitation also includes the removal and destruction of dead or diseased plants and tissue where practical. Removal of dead or dying leaves prior to first bloom can decrease Botrytis gray mold pressure.

Greenhouse production of strawberry plants can reduce exposure to pests. Yet, even if a grower pays close attention to screening vents and other openings, some may gain entry. Mechanical barriers are most effective when aimed at excluding one or a few pests rather than all pests. Some growers may find it more economical to root their plug-plants outside of a greenhouse structure on gravel beds covered with landscape cloth.

Post-transplant, in field barriers, such as low tunnels or floating row cover, can reduce pest exposure.

Removal and rouging (destruction and burial) of diseased plants or alternate hosts surrounding the field can be used to reduce pest problems. Growers are encouraged to explore border vegetation that may encourage beneficial insects and their relatives while not serving as an alternate host for pests.

Insect traps may be useful in large scale, commercial production as indicators of potential infestations. Yellow sticky traps are used to monitor aphid vectors of plant virus in nursery plant production. Other insect traps that may be employed in strawberries are those for adult spotted wing drosophila (Drosophila suzukii) and sap beetles. However, few commercial strawberry growers in North Carolina use insect traps for pest management purposes.

Efficient commercial traps to monitor for fungal diseases (e.g., spore traps) are not available for strawberries.

The most effective means of determining if arthropod pests require management in strawberries is regular direct plant observation or scouting. For some diseases and soil insect pests it is not possible to forecast outbreaks. Soil insects are generally managed through crop rotation and fumigation and rarely require additional treatment.

Beneficial organisms often occur naturally in fields.  In addition to naturally occurring biological control agents, several beneficial arthropods are available commercially. Predatory mites, described in detail below, are the most commonly used commercially available biological control.

A cover crop is a crop that is planted for the benefits it provides to the soil, but it is not harvested or sold. Most often, after the cover crop has grown and accumulated substantial biomass, it is mowed and the biomass is left on top of the ground or tilled into the soil. Soil incorporation of summer cover crops is preferable for plasticulture strawberry production. Benefits of cover crops can include adding nitrogen to the soil, increasing soil organic matter through crop residues, preventing erosion by covering the soil when the field would otherwise be left fallow, preventing water loss from the soil, reducing soil compaction, and suppressing weeds. Summer cover crops can be fit into a strawberry production system with advanced planning. Specific goals and reasons for including cover crops will determine what type of crop is appropriate. (Refer to https://content.ces.ncsu.edu/sustainable-practices-for-plasticulture-strawberry-production-in-the-southeast)

Composted materials incorporated into the soil can increase organic matter, improve aggregate stability, decrease soil erosion, and promote soil microbial activity. In clayey soils prone to standing water, water infiltration can be increased. In sandy soils that do not hold water well, adding compost can increase water-holding capacity. Organic matter in the soil acts like a sponge that holds water while allowing the excess to drain. In addition, compost can be a slowly available nutrient source for plants, providing nitrogen and micronutrients. Farming systems that include compost have also been investigated as an alternative to fumigation with some positive results, but thus far has not been found to be as effective in controlling soilborne diseases as chemical fumigation. The use of locally produced compost or the production of compost on-farm, when feasible, will increase on-farm nutrient cycling and make applying compost more economical. (Via https://content.ces.ncsu.edu/sustainable-practices-for-plasticulture-strawberry-production-in-the-southeast)

Although most strawberry acreage is grown using conventional methods, there is significant interest in organic strawberry production in North Carolina. Growers who choose sustainable or "organic" methods of control (no synthetic chemicals) must keep in mind several factors. “Organically produced products are not the same as sustainably produced products. In the United States the U.S. Department of Agriculture (USDA) National Organic Program governs which practices can be used for crops to be considered certified organic. Organic production practices include no use of synthetic fertilizers, synthetic pesticides, genetically modified organisms, and sewage sludge. The phrase “sustainable practices” includes many practices that are used by and required of certified organic producers, but the “sustainably produced” designation does not require any verification or certification on the part of the producer. Therefore, producers using the term “sustainable” should explain their use of the term when it is incorporated into marketing language. However, growers who are able to promote their use of sustainable production practices may find it a boon to their marketing strategy, as consumers are becoming increasingly interested in how food is produced. (Refer to https://cintent.ces.ncsu.edu/sustainable-practices-for-plasticulture-strawberry-production-in-the-southeast)

2016 State Agricultural Overview. North Carolina. https://www.nass.usda.gov/Quick_Stats/Ag_Overview/stateOverview.php?state=NORTH%20CAROLINA.

Fruits, Tree nuts and Horticultural Specialties. 2014. United States Department of Agriculture. National Agricultural Statistics Service. https://www.nass.usda.gov/Publications/Ag_Statistics/2015/Chapter05.pdf

Louws (ed.) et al. 2018 Southeast regional strawberry integrated pest management guide for plasticulture production. http://www.smallfruits.org/assets/documents/ipm-guides/StrawberryIPMGuide.pdf.

Louws, F.J. 2018 Strawberry Diseases: Factsheets. https://strawberries.ces.ncsu.edu/strawberries-diseases

McWhirt, A., G. Fernandez, and M. Schroder-Moreno. 2015. Sustainable Practices for Plasticulture Strawberry Production in the Southeast. https://content.ces.ncsu.edu/sustainable-practices-for-plasticulture-strawberry-production-in-the-southeast

North Carolina Agricultural Chemicals Manual. NCSU.

Rysin, O., McWhirt, A., Fernandez, G., Louws, F. J., & Schroeder-Moreno, M. 2015. Economic viability and environmental impact assessment of three different strawberry production systems in the Southeastern United States. HortTechnology, 25(4), 585-594.

Sherrell, E. M., ed. 2002. North Carolina Agricultural Statistics 2002. Publication Number 200. North Carolina Agricultural Statistics, Raleigh. 130 pp.

The Importance of Pesticides and Other Pest Management Practices in U.S. Strawberry Production. North Carolina Cooperative Extension Service.