Commercial strawberry production in Minnesota
Emily Hoover, Carl Rosen, Jim Luby, and Suzanne Wold-Burkness
Department of Horticulture Science, Department of Soil, Water, and Climate, Department of Entomology
Copyright © 2008 Regents of the University of Minnesota. All rights reserved.
Figure 1. Basic strawberry plant anatomy. (Suzanne Wold-Burkness, U of MN)
Figure 2. Location of flowers and buds on strawberry plants. (Suzanne Wold-Burkness, U of MN)
Strawberries can be successfully grown on a commercial scale throughout much of Minnesota and are also well suited for small small-scale and part-time farming operations. Although the number of acres in Minnesota is relatively small (500 acres grown in 2002, USDA, NASS), the value per acre ($7,000/acre) provides a significant amount of revenue for Minnesota growers. The initial investment is high but is primarily related to the cost of land preparation, planting, and equipment. In addition, factors such as topography, establishment costs, labor, marketing, and water availability need to be considered before an enterprise is started.
The strawberry (Fragaria) is in the family Rosaceae. While there are numerous Fragaria species, the most common commercially grown strawberry is Fragaria × ananassa. Strawberries suited for Minnesota are of two major types, Junebearing and day-neutral. The essential difference between Junebearing and day-neutral strawberry cultivars is the length of the day under which they initiate flower buds. For more information on day-neutral cultivars, please see the publication Day-neutral Strawberry Production in Minnesota for more information.
The strawberry is comprised of a crown (shortened stem), where the leaves and axillary buds are formed. Runners (stolons) arise from the axillary leaf buds, and at the end of the runner a runner, or daughter plant forms (Figure 1). Strawberry flowers develop from buds that arise from a node on the flowering stem (Figure 2). Junebearing strawberry cultivars initiate flower buds in the late summer and early fall of the year prior to fruiting when the length of the day is declining. Junebearing plants produce fruit from early June in southern Minnesota through mid to late July in the northern areas. These plants are usually grown as perennials.
Strawberries are arguably the most popular summer-time fruit. In addition to the wonderful flavor of Junebearing cultivars, they also provide us with many nutritional benefits. They are low in calories and a good source of many vitamins and nutrients that a healthy body needs. Besides vitamin C, strawberries contain folate, potassium and ellagic acid, a nutraceutical that has powerful anti-oxidant and anti-carcinogen properties. As consumers have become more health-conscious, growers can feel good about providing a healthy product to their customers. For more information on the health benefits of strawberries, see the University of Illinois fact sheet, Strawberries and More.
Cultivars should be selected that are adapted to the local climate. New cultivars are introduced each year; however, not all are suitable for Minnesota climatic conditions. New cultivars that do not have a local performance record should be planted on a small scale initially, and limit the number of cultivars to as few as you need to meet market requirements (for example, a pick-your-own operation may need several cultivars to extend the harvest season). Qualities to look for in addition to local adaptability are productivity, season of maturity, berry size, firmness, flavor, freezing ability, color, and disease resistance. Table 1 lists several cultivars recommended for Minnesota growers.Table 1. Characteristics of Junebearing strawberries in Minnesota
|Cultivar||Yield Potential||Hardiness||Vigor||Fruit Size||Attractive-
|Annapolis||Mod.-High||Good||Mod.||Med.-Large||Good||Excel.||V. Good||Good||resist. to red stele|
|Earliglow||Mod.||Fair||Mod.||Medium||Excel.||Excel.||Excel.||Excel.||resist. to red stele|
|Evangeline||Mod.||Good||High||Medium||V. Good||Good||V. Good||V. Good||—|
|Sable||Mod.-High||V. Good||Mod.-High||Small-Med.||Good||Poor||V. Good||Excel.||—|
|Veestar||Mod.-High||Good||High||Medium||Good||Fair||Good||Good||v. susc. to mildew|
|Wendy||Mod.||Good||Mod.||Medium||Excel.||V. Good||V. Good||Good||—|
|Brunswick||High||Good||High||Med.-Large||Excel.||V. Good||V. Good||V. Good||—|
|Honeoye||High||V. Good||High||Med.-Large||Good||V. Good||Good||Good||—|
|Itasca||Mod.-High||V. Good||Mod.-High||Medium||Good||Good||V. Good||Good||resist. to red stele & mildew|
|L'Amour||Mod.||Fair||High||Med.-Large||V. Good||V. Good||V. Good||V. Good||—|
|Allstar||Mod.||Poor||Mod.-High||Large||V. Good||V. Good||V. Good||V. Good||—|
|Cavendish||High||V. Good||Mod.-High||Large||Good||V. Good||V. Good||V. Good||resist. to red stele|
|Glooscap||High||Excel.||High||Med.-Large||V. Good||Good||V. Good||V. Good||—|
|Kent||High||V. Good||Mod.-High||Large||V. Good||Good||V. Good||Good||v. susc. to leaf spot & scorch|
|Lateglow||Mod.-High||Poor||High||Med.-Large||V. Good||V. Good||Excel.||V. Good||—|
|Mesabi||High||Excel.||Mod.||Med.-Large||Excel.||Good||Excel.||Excel.||sensitive to high pH soils|
|Bounty||Mod.-High||Good||Mod.-High||Medium||Good||Fair||V. Good||V. Good||—|
|Gov. Simcoe||Mod.-High||Good||Mod.||Large||V. Good||V. Good||Good||Good||—|
|Micmac||Mod.-High||Good||Mod.||Med.-Large||Excel.||V. Good||Good||V. Good||—|
|Ovation||Mod.||Fair||Mod.||Large||V. Good||V. Good||Good||Good||—|
|Winona||Mod.-High||V. Good||Mod.-High||Large||Fair||Fair||Excel.||Good||resist. to red stele|
Site selection & preparation
Strawberries require full sunlight. The strawberry field should be fairly level with a 2 to 3 percent slope to allow good air circulation and to minimize soil erosion. Cold air will move to low areas, creating frost pockets and damaging flowers during the spring blossoming period. A southern exposure will result in an earlier bloom, while a northern exposure will delay flowering, an advantage in an area of late spring frosts. The site should be near a source of irrigation water.
Strawberries grow well on many different soil types. A well-drained soil is needed to maintain plant vigor and reduce disease potential. Very light and heavy soils are not as desirable as a well-drained loam or sandy loam soil. Avoid muck or peat soils in low-lying sites because they have greater potential for standing water and frost injury.
The previous crop history of a site also must be considered. To reduce the chance of Verticillium wilt disease, we advise waiting at least three years before planting strawberries in fields where potatoes, tomatoes, peppers, or raspberries were grown previously.
In addition, thought must be given to the intended market. A pick-your-own operation must consider population density or proximity and existing production in the area, whereas a wholesale grower must consider transportation costs.
A healthy soil is achieved by increasing soil organic matter, biological activity, and nutrient availability. By increasing soil organic matter through the use of cover crops and crop residues, the soil can provide nutrients to the strawberry plant.
A green manure crop the year before planting will add organic matter to the soil and help maintain desirable soil physical properties. Sow green manure crops such as rape (12.3 lb seed/A), Camelina (4.5 lb/A), rye (63 lb/A), or oats (60.5 lb/A) between April 10 and May 4. Soybean and foxtail millet (75 lb/A and 18 lb/A), soybeans and Japanese millet (75 lb/A and 19 lb/A), and proso millet (38 lb/A) can also be used. Well-rotted barnyard manure worked into the soil will, over time, improve soil physical properties and fertility.
Test soil fertility and acidity (pH) before planting. Strawberries prefer a slightly acid soil (pH 5.3 to 6.5). Soil pH is a key factor in maintaining a favorable root environment. It not only affects root growth but influences availability of many nutrients. If the pH is less than 5.3 you will need to add lime. Follow soil test recommendations for rates of lime to apply. Incorporate the lime thoroughly at least one year prior to planting. Fertilizer suggestions are provided in Tables 2-4.
More information on fertilizer recommendations is included in DG-05886, Nutrient Management for Commercial Fruit and Vegetable Crops.
Table 2. Nitrogen recommendations for Junebearing strawberries.
|Soil Organic Matter (O.M.) Level1||Method/Timing3|
|N to apply (lb/A)|
|Establishment Year||80||70||60||25||Split app.(apply 1/2 before planting, 1/2 in August during runner production)|
|Bearing Year4||80||70||60||25||Immediately after renovation|
|1 Low = less than 3.1% O.M., medium = 3.1-4.5% O.M., high = 4.6-19% O.M.|
|2 Organic soil = greater than 19% O.M.|
|3 Suggested methods of application are a general guide and can be modified when appropriate; if nitrogen is applied in the spring, do not apply more than 15-20 lbs/A.|
|4 Leaf analysis should also be used to help determine nitrogen needs|
|Soil Test P Level (ppm)|
|P2O5 to apply (lb/A) based on test results2|
|1 Application rates listed below test results|
|2 Apply and incorporate before planting. If needed during bearing years, apply immediately after renovation.|
|3 Leaf analysis should also be used to help determine potassium and phosphorous needs|
|Soil Test K Level (ppm)|
|K2O to apply (lb/A) based on test results2|
|1 Application rates listed below test results.|
|2 Apply and incorporate before planting. If needed during bearing years, apply immediately after renovation.|
|3 Leaf analysis should also be used to help determine potassium and phosphorous needs.|
Controlling weeds requires the use of many techniques and strategies to achieve economically acceptable weed control. Since strawberries are generally grown as a perennial crop, weeds must be managed throughout the year. To start, proper field and bed preparation prior to planting is essential for a good weed control program. In particular, a weed eradication program one year prior to planting is recommended if perennial weeds are a problem. This can be accomplished using herbicides, however, consult herbicide labels to avoid potential carry-over problems for the new strawberry planting. In addition to eradication, a pre-plant harrowing of a prepared field will reduce weed populations.
Following planting, the field may be cultivated to remove any newly emerging seedlings. Once the strawberry plants are established, their shade will reduce weed growth within the rows. Hand-weeding, hoeing, cultivation, and spot-treatment of herbicides may be needed throughout the first year. In late fall, an herbicide may be applied to suppress early spring weeds.
More information on weed control is available in the Midwest Small Fruit Management Handbook.
Plant source & planting
Purchase plants from a reputable nursery that are free from insects, viruses, and fungal diseases. Contact the Minnesota Department of Agriculture for a listing of local firms. The plants may be either dormant or spring-dug. Dormant plants can be stored for a few weeks before planting, but spring-dug plants must be planted as soon as possible after arrival. Store dormant plants in a cool, fairly humid area until planted. Soaking plants in water for a few hours prior to planting is beneficial. Trim the roots to 4 to 5 inches immediately before planting.
For the matted row system, planting strawberries in early spring ensures good runner plant development, which leads to higher productivity the following season. Planting after August 1st is not recommended due to insufficient plant growth prior to freezing temperatures. The number of plants needed per acre depends upon the spacing system used (Table 5). Be sure that planter shoes on your transplanting equipment or hand tools penetrate deeply enough to facilitate proper planting. Plants should be set with the middle of the crown level with the top of the soil.
The main planting system used for Junebearing cultivars is the matted row. Set the plants 1½ to 2 feet apart in rows spaced 3 to 4 feet apart. Between row spacing is determined, in part, to equipment width and picker needs. Let the runners develop until the row is 1 to 1½ feet wide. This system allows for good light penetration into the plant canopy which eases weed control, harvest, reduces fruit rot, and foliage diseases.
Table 5. Number of plants required per acre at various spacings.
|Plant Spacing (feet)|
|In row||Between rows||Plants per acre|
New planting and care (see table 6)
To encourage vegetative plant growth, Junebearing strawberry plants should have all flowers removed during the planting year. Strawberry plants are shallow-rooted with most of the root system in the top three to six inches of soil. This necessitates the need for irrigation (see the irrigation section for more information). Proper irrigation will improve fruit quality and yield next year. Effective weed control is essential during the first season to reduce the number of weeds the following year and maintain yield.
Nitrogen, phosphorus, potassium, and other soil nutrients are required for vigorous crown and runner development. Soil tests will identify the nutrient needs (Tables 2-4). In general, phosphorus, potassium, and part of the nitrogen should be applied at or before planting. Apply nitrogen again in August during runner plant production.
Keep in mind, however, that strawberry growers tend to overemphasize the importance of fertilizers and underestimate the importance of water. Yields are more frequently reduced from lack of water, poor soil drainage, and poor soil physical properties than from a lack of fertilizer.
Mulching for winter protection is necessary in Junebearing cultivars to maintain temperatures above 15° F. Apply 4-6 inches of straw mulch after a few hard frosts, usually in early November. Use a mulch that is free of weed and grain seed. Remove all but a thin layer of the mulch in the row in the spring when new leaf growth begins and before foliage starts to turn yellow. Place remaining mulch between rows to control weeds, conserve moisture, and reduce fruit contact with soil.
Table 6. Quick reference guide for timing of activities in Junebearing strawberries
|Prepare site with proper tillage||X||X||X||X|
|Install drip irrigation (if desired)||X||X|
|Assess nutrient needs, fertilize if needed||X||X||X||X|
|Plant dormant transplants||X||X|
|Pre-emergent herbicide application||X||X||X||X|
|Water, as needed||X||X||X||X||X||X||X||X||X||X||X|
|Control weeds (mechanical, hand-weed)||X||X||X||X||X||X||X||X||X||X||X||X|
|Apply fall herbicide if needed||X||X||X||X|
|Apply winter mulch||X||X||X|
|Apply grass herbicide to control volunteer grains /grasses if needed||X|
|Monitor insect pests; apply insecticides if needed||X||X||X||X||X|
|Monitor for diseases||X||X||X||X||X||X||X||X||X||X|
|Apply fungicides at 10% & 50% bloom to control botrytis||X||X||X|
|Water as needed||X||X||X||X||X||X||X||X||X||X||X||X|
|Assess nutrient needs, fertilize if needed||X||X||X||X|
|Apply fall herbicide if needed||X||X|
|Apply winter mulch||X||X||X||X|
Care of June-bearing cultivars during production years
Spring care of Junebearing cultivars begins with mulch removal (mid April – early May). If there was a heavy weed infestation in the fall, and no fall herbicide was applied, a spring herbicide application may be necessary. If so, this must be applied within a few days of mulch removal. Begin scouting for insect pests and disease presence after mulch removal and throughout the fruiting period (see the Insect and Disease Management sections).
Do not apply nitrogen before harvest unless plant vigor is very poor. Nitrogen will promote excessive vegetative growth and reduce fruit quality. Spring nitrogen applications may be used on coarse-textured soils (sands, loamy sands, sandy loams) that are low in organic matter. Please see publication DG-05886, Nutrient Management for Commercial Fruit and Vegetable Crops for more information.
In general, foliar feeding is used as a means of supplying supplemental doses of both minor and major nutrients, plant hormones, stimulants, and other beneficial substances. Foliar feeding began in the 1950's when Michigan scientists H.B. Tukey and S.H. Witter found that foliar feeding of plant nutrients was from 100% to 900% more effective than when the nutrients were applied to the soil. In contrast, in a study conducted by Rosen et al. Minnesota researchers have found no yield benefit by using foliar feeding. In theory, foliar feeding can elicit plant responses ranging from yield increases, to insect and disease resistance, to improved drought tolerance. Foliar applications are often timed to coincide with specific vegetative or fruiting stages of growth, and the fertilizer formula is adjusted accordingly. Foliar feeding is not a substitute for creating a healthy soil environment. Foliar feeding is best used as a supplement.
For more information on foliar feeding, see the section on foliar feeding in Nutrient Management for Commercial Fruit & Vegetable Crops in Minnesota.
Weeds need to be managed throughout the lifetime of the planting. Many of the practices described earlier are applicable here. Hand weeding is important in late spring to clean up any weeds missed by fall and early spring herbicide treatments. Several weeds can become established and flower by late spring which can contribute to weed problems later in the summer. More information on weed control is available in the Midwest Small Fruit Management Handbook.
Management of insect pests begins with proper identification of the egg, larva, and adult stages of both insect pests and beneficial insects. The correct identification of insects will aid in the grower's efforts to prevent economic damage to the crop. Table 7 lists insect pests common in MN strawberry fields. A scouting program with regular monitoring can help determine both the pest pressure and presence of beneficial insects. Beneficial insects such as predators and parasites are important in preventing outbreaks of insect pest populations. To encourage the presence of beneficial insects it is important to increase the plant diversity in an agricultural setting. Generally, crop diversity can be achieved by using crop mixtures, crop rotations, border crops or windbreaks, or plants known to be attractive to beneficial insects. More information on beneficial insects and the benefits of plant diversity can be found in the SARE publication, Manage Insects on Your Farm.
To assess the activity of insect pest and beneficial insects, the use of sticky traps or visual plant samples is needed. Most flying insects are attracted to the yellow or blue color of sticky traps. These traps are sheets coated on both sides with a sticky non-toxic compound. Traps can be used for detecting presence of arthropods or for mass trapping of pests such as aphids and thrips.
More information on insect management can be found in the Midwest Small Fruit Pest Management Handbook, and an online field guide developed by the Minnesota Department of Agriculture.
Table 7. Insects common in MN strawberry fields
|Common Name||Scientific Name|
|Tarnished Plant Bug||Lygus lineolaris|
|Strawberry Bud Weevil||Anthonomus signatus|
|Two-Spotted Spider Mite||Tetranychus urticae|
|Eastern Flower Thrips||Frankliniella tritici|
|White Grubs (June beetle)||Phyllophaga spp.|
|Root Weevils||Otiorhynchus spp.|
Strawberries are affected by several diseases that vary widely in their occurrence and severity; therefore learning to recognize common strawberry disease problems in order to treat them quickly and effectively is important. Soil health and management are a significant component of successfully controlling plant diseases. A soil with adequate organic matter can house numerous organisms such as bacteria, fungi, nematodes, protozoa, arthropods, and earthworms that may suppress soil-borne pathogens. Increasing soil organic matter by incorporating cover crops or adding compost and organic fertilizers will help maintain beneficial organisms.
Rotating strawberries with other crops is critical. The site should be plowed and planted to a crop that is not susceptible to Verticillium wilt for a minimum of two years. Many soil-borne pathogens form specialized survival structures and are capable of surviving for several years in soil, even when strawberries are not present. Crop rotations lasting longer than two years are encouraged, however, crop rotation is not enough to provide adequate control of red stele. Using disease resistant cultivars and improving soil drainage are necessary.
For complete descriptions of the diseases affecting strawberries, consult the Compendium of Strawberry Diseases, available from the American Phytopathological Society (3340 Pilot Knob Road, St. Paul, MN 55121; or order online at http://www.shopapspress.org/41949.html), and the MDA publication, Integrated Pest Management for Minnesota Strawberry Fields, http://www.mda.state.mn.us/plants/pestmanagement/berrymanual.html.
You must time pesticide applications and harvests to observe reentry and pre-harvest intervals stated on the pesticide label. Failure to observe the pre-harvest intervals is illegal, and can result in high levels of pesticide residues in the fruit, and can expose harvesters or customers to unnecessary risks.
Frost protection, irrigation, and cooling
Water is one of the most important elements in the production of small fruits. Supplemental irrigation is a necessary water management practice for small fruit production systems in Minnesota.
Sprinkler irrigation is crucial to prevent frost damage in Junebearing cultivars after the mulch is removed in early spring. Irrigate whenever the air temperature drops below 34° F. Apply 0.1 inch of water per hour with one sprinkler head revolution per minute. Sprinkler irrigation should protect flowers and developing fruit to 20° F. For more information on sprinkler irrigation for frost prevention, see the Alabama Extension publication, Principles of Freeze Protection for Fruit Crops, and the MidWest Plan Service handbook MWPS-30, Sprinkler Irrigation Systems.
Spring frost protection is unnecessary during the planting year in day-neutral strawberries because the flowers are usually removed until the danger of frost is past. Frost protection may, however, be desired in the fall to extend vegetative growth.
Drip irrigation is the slow, even application of low pressure water to soil and plants using plastic tubing placed directly within the rooting zone. Advantages of using drip irrigation include better control of foliar diseases and more efficient water and fertilizer use. Water savings with drip irrigation can amount to as much as 50 percent compared with an overhead sprinkler system. Although drip irrigation has many important benefits, there are a few challenges associated with this method of irrigation. Drip irrigation systems must be carefully designed and installed so that they operate with proper efficiency. The initial expense of drip irrigation systems is expensive, therefore the system should be designed and installed by competent irrigation industry representatives to ensure an operable and cost efficient system. Proper training and management skills are very important to the success of any drip irrigation operation.
Planning your irrigation using daily ET estimates
Water usage will be optimized by keeping track of the crop's daily water use. Daily crop water use, also called evapotranspiration (ET), can be used to help plan irrigation scheduling. This, along with regular monitoring of in-field soil moisture is beneficial in optimizing crop growth while reducing the potential for leaching of compounds like nitrogen into the groundwater. The daily ET values should be recorded in a log like an irrigation checkbook worksheet or computer spreadsheet for quick reference when making irrigation decisions. Irrigation checkbook spreadsheets can be found on University of Minnesota Extension website.
The Minnesota and Wisconsin ET web site (www.soils.wisc.edu/wimnext/) presents daily colored coded maps for the week; and displays a reasonable estimation of the potential ET value across the state based on the actual weather conditions of that day. Potential ET values are very similar to the actual daily crop ET when a crop is at full canopy. The daily values from the web site can also be sent directly to a user by e-mail each day for a given field site within the map area if requested over the web site. These daily ET potential estimations, however, need to be modified by a correction factor when the crop canopy is less than 80 percent coverage or the plant is nearing the end of the season. This correction factor is dependent on plant size and canopy density and will vary from 0.2 at early emergence to 1.0 when the plant has reached full canopy closure. To estimate the daily ET value for a crop before full canopy or near maturity the ET value must be taken times a crop coefficient (Kco) constant that may range from .25 to 1.0 depending on the growth stage of the specific crop. As a crop matures, some crop types will have their actual ET decrease slightly each day as they come to maturity, hence the crop correction factor will go from 1.0 to maybe as low as 0.40 as the leaves senesce. The estimated daily ET for strawberries during the summer months is 0.20. For more information on how to use daily crop ET information contact your local Extension or SWCD office.
For more information on irrigation systems see the Penn State article, Irrigation for Fruit and Vegetable Production.
Proper picking, grading, and packing are as essential as good cultural practices to success. The harvest frequency and duration depend on weather conditions, cultivars, soil factors, and cultural practices. Strawberries are almost entirely hand picked.
As a general rule for wholesale operations, six to nine pickers are needed for each acre. Pickers must be instructed by a competent foreman about proper picking (to prevent plant injury), fruit handling, and sorting (grading) in the field.
The berries must be picked at the proper stage of ripeness (maturity). Harvest only berries that are red. Berries still showing white should be left for the next picking. The fruit is usually harvested every other day unless hot weather makes daily picking necessary.
Quickly place harvested berries in a cool, shady location such as a temporary field shed. Store the berries preferably at 32° F to 35° F and at a 90 to 95 percent relative humidity. Enrichment of the storage atmosphere with carbon dioxide to a 10 to 40 percent level using dry ice will extend the storage life to some extent. Under these conditions berries should remain salable for three to five days and losses during shipping, storage, and marketing will be reduced.
Pint or quart containers are usually filled in the picking fields and covered with plastic film or rigid plastic domes before shipping. The strawberries are then placed in fiberboard trays which hold twelve one- pint baskets to prevent damage. An attractive package with the fruit visible will bring premium prices.
Pick-your-own & road-side enterprises
Pick-your-own (PYO) strawberry farms are the most popular method of direct marketing in Minnesota. PYO farms began when harvesting labor became scarce and increasingly expensive. The advantages of PYO farms include no direct harvest labor and transportation costs, improved quality, increased product availability for consumers, and reduced packing costs. Disadvantages are long hours including weekends (you work when customers can come to your farm), difficult customers, liability costs, parking areas, and damage to plants and equipment. For small farmers, however, operating a popular public picking field is the single most profitable method of strawberry production. Being able to charge higher than wholesale prices while avoiding the high labor costs can be a great combination.
Pick-your-own operations require attention to certain factors for successful harvest and marketing including: sufficient quantity of high quality fruit, proximity to population centers, convenient parking area off the highway, and effective advertising notifying customers of berry availability.
When planning a PYO farm, be sure that you:
- Provide clear instructions for pickers;
- Make sure containers are available before the customers arrive;
- Advertise your product;
- Make sure your insurance will cover your liability;
- Be extremely careful with reentry times for all pesticides;
- Organize your checkout so it runs smoothly.
For more information on marketing, consult the Penn State Agricultural Alternatives Publication: Fruit and Vegetable Marketing for Small-scale and Part-time Growers, available at http://agalternatives.aers.psu.edu/Publications/MarketingFruitAndVeggie.pdf.
Junebearing strawberry plantings should be renovated for many reasons, including, to narrow rows, rejuvenate the canopy, reduce leaf diseases and insect populations, and to stimulate runner production. Renovation should start immediately following the harvest.
Renovation should begin by scouting your fields to assess the weed populations. If you have a heavy broadleaf weed infestation, and you decide that a herbicide is necessary, apply a broadleaf herbicide such as 2,4-D amine after harvest and before August 1st. Approximately one week later, mow off the old leaves, about two inches above the strawberry crowns. This height is recommended in order to prevent damage to the strawberry crown. Next, fertilize the planting with nitrogen, following the recommendations in Tables 2-4. After fertilizing, the strawberry rows should be narrowed using a rototiller, multivator, or other cultivator. The optimum row width at full canopy is between 12-14 inches; therefore the row can be narrowed to as little as 6 inches wide. Narrow rows will give better sunlight penetration, better disease control due to improved air circulation, and better overall fruit quality. Remember that yield is higher on row edges. Continue to cultivate your strawberries to throw soil over the plants. This is important for strong crown development because strawberry crowns continue development at the top, and also for root development because new roots are initiated above old roots on the crown.
Subsoiling may be necessary in plantings that have suffered a great deal of soil compaction. Soil compaction can result from tractor use and picker traffic in the field, especially on heavy, wet soils. Subsoiling between rows will help break up compacted layers and provide better infiltration of water. A fall herbicide application can be made around October 15. Lay down straw mulch in late October or early November before temperatures drop below 20° F. Table 6 summarizes the timing of activities in a commercial Junebearing strawberry operation.
Junebearing cultivars are perennials, but they become less productive after several years. In general, a highly efficient strawberry field will yield around 7,000 lbs./acre. Replace the plants every three to five years to maintain high quality fruit and yields, and to reduce problems with weeds, insects, and diseases. A detailed cost and productivity analysis should be performed to determine whether existing strawberry beds should be renovated or the old plants discarded and the entire field replanted with new plants. An example of an enterprise budget can be found at http://aede.osu.edu/Programs/FarmManagement/Budgets/scrops/strawber.htm.
Strawberries can lend themselves well to both new and existing farms. The attractiveness of adding strawberries to your current farming operation is that they do not require an enormous investment to get started — a few acres, some basic equipment, a love of growing things, and a genuine enjoyment of hard work.