Jimmy Boudreaux, Professor LSU Ag Center School of Plant, Environmental & Soil Sciences-Horticulture, Baton Rouge, La.
Sandra Benjamin, County Agent, LSU AgCenter Cooperative Extension Service, Tangipahoa Parish, Amite, La.
Donald Ferrin, Assistant Professor , LSU Ag Center Department of Plant Pathology, Baton Rouge, La.
Natalie Hummel, Assistant Professor LSU Ag Center Department of Entomology, Baton Rouge, La.

Introduction

Strawberries are grown as an annual in Louisiana and have been an important horticultural crop for many years. They can be grown in all parts of the state. Tangipahoa and Livingston parishes have been the traditional commercial production areas.

Producing strawberries in the home garden is not simple. To be successful, growers must control diseases, insects, weeds and birds. They also must obtain disease-free plants of the right varieties and plant them correctly in a well-prepared site. Harvesting normally begins in mid-March and lasts six to eight weeks.

Varieties

The first step in successful strawberry production is choosing varieties adapted to the areas in which they are to be grown. The varieties used at this time are:

Strawberry Festival -- developed by the University of Florida. Early-maturing, good quality. The predominant variety grown commercially in the Louisiana strawberry industry .

Chandler -- developed by the University of California. High yields fairly early, deep-red berry, somewhat soft, good-to-fair quality, susceptible to the development of misshapen fruit when blooming during times of low temperatures.

Camarosa -- developed by the University of California. A little earlier than Chandler with more firmness, well-shaped fruit with only fair quality.

Sweet Charlie -- developed by the University of Florida. Early-maturing, short fruiting period, light-red berries, good-to-fair quality.

Camino Real -- developed by the University of California. Later than Camarosa, produces large to extra-large berries, firm, good-shaped fruit with good quality.

Source of Plants

Within the last 20 years, the production of strawberry plants in Louisiana has become extremely difficult because of the incidence of crown rot. Few plants are produced in the state. Growers obtain plants from commercial nurseries in California, Michigan and Canada. Plants from each source have unique characteristics and problems.

Quebec and Ontario (Canada) Plants: Large, leafy plants with a good root system and early-season maturity. The most popular source of plants for the Louisiana strawberry industry at this time.

California Plants: Plants without leaves. The maturity of these plants is dependent on the location of the nursery. Plants from nurseries at high elevations have an early maturity while plants from lower elevations have a mid-season maturity.

Nova Scotia (Canada) Plants: Large, leafy plants with a medium early-season maturity. Fruit tends to concentrate at mid-season.

Michigan Plants: Medium-sized plants with a large root system and early-season maturity.

Individuals interested in strawberry plants should check with a county agent for a list of individuals handling plants.

Plug Plants

In the last several years, plug plants from Quebec have become popular. These plants are rooted in small peat pellets. The plug plants have an established root system. They have the advantage of easier transplanting, complete survival and heavy early production.

Site Selection

A site in full sun with deep, sandy soils with good drainage is preferred. A convenient water supply for irrigation is desirable. Often, small plantings (10-25 plants) are not successful because of bird damage. For successful home garden plantings, some type of bird netting is required. Larger plantings (100 to 500 plants) help to spread out the bird damage and allow gardeners to harvest an adequate amount of berries.

Soil Preparation

Soil preparation should begin in mid-August (six to eight weeks before planting in mid-October-early November). A summer cover crop such as cowpeas or soybeans is desirable to maintain the organic matter level in the soil. The cover crop should be turned under in August to allow time for the plant residue to decompose.

Before planting, all old crop residue should be well decomposed and thoroughly mixed with the soil. The most desirable row width is 42 inches to 48 inches. The top of the row is knocked down with a rake to make a row 8 to 10 inches high with a flat surface 18 or 24 inches wide on top of the row. Rows should be prepared several weeks before planting to allow rain to settle the soil.

Fertilization

The soil pH for strawberries should be 5.2-6.0. Gardeners are urged to take soil samples and adjust the soil pH to the desired level several months before transplanting. Strawberries are a long-term plant and require a considerable amount of fertilizer to make a good crop. From 6 to 8 pounds of 8-24-24 or 8 to10 pounds of 13-13-13 per 100 feet of row is sufficient for strawberries. Fertilizer needs to be put down in September, well ahead of planting. To avoid a fertilizer burn, wait for a rain (1 inch to 2 inches) or irrigate before putting out plastic and planting berries.

Strawberries should be sidedressed in January or early February with 1 pound of 34-0-0 or 2 pounds of calcium nitrate per 100 feet of row. Another sidedressing in mid-March or early April may be necessary if the plants are pale green. These sidedressing help to maintain plant vigor and fruit size through the fruiting season. Sidedressing is accomplish on plastic by making a small hole between the plants with a broomstick, 1 ½ -2 inches deep, on the shoulder of the row. Be sure the hole is 6 to 8 inches away from the plants. Placing fertilizer near the plants results in burning. Add 1/2 teaspoon of fertilizer to each hole.

Mulching

To prevent splashing of soil particles on the fruit, mulch strawberries. Pine straw or other natural mulches have been used for years. One bale of pine straw will cover a 25- to 30-foot row (75 to 100 sq. ft.). Apply the mulch in late November and December. Be sure all the mulch is snug against the base of the plant and that the plants are well above the mulch.

Black plastic mulch is used widely. The advantages of plastic mulch are earlier fruiting, prevention of dirt splashing on the fruit and weed control. Plastic 36 to 48 inches wide is most often used in strawberry production. It is important that the plastic mulch be snug to the surface of the row and covered well with soil on both sides of the row. Gardeners are encouraged to have the rows settled and firmed by rainfall or irrigation before putting out plastic. If the soil is firm and moist at the time of transplanting, plants will usually not settle below the plastic, fewer plants will die, and growth and development of the plants will be enhanced.

Transplanting

Transplant only well-developed plants with good root systems. Best yields are usually realized when transplanting is done in October to early November. Use a trowel to make slits to plant the plants. A 3- to 6-inch slit is large enough for the strawberry plant on plastic mulch. The bud and crown of the plant should be above ground and the roots below ground level. Plants set too high will suffer from root injury from exposure. Those set too low will usually suffer from bud or crown injury. Firm the soil around the roots to prevent drying out. After the plot has been planted, water the plants to settle the soil around the roots. Additional watering by sprinkling the plot for two to three hours daily for the next seven to 10 days is helpful in obtaining a good stand.

On single-planted rows, space plants 10 to 12 inches apart in the center of the row. On double-row-planted berries, space the plants 14 to 16 inches apart alternately along the row with a 10-12 inch spacing between parallel rows. Double-set rows usually yield more berries than single-set rows, and single-row plants produce more berries per plant than double-row plants.

Irrigation

The strawberry is a shallow-rooted plant. Anyone growing this crop should have irrigation for watering during establishing and fruiting. Sprinkler irrigation can be used as well as drip irrigation.

Row Covers

Row covers made of light polypropylene fabric can be placed directly on top of the plants to protect the fruit and blooms from frost. The heavier the cover, the more protection provided. Covers between 1 to 2 ounce per square yard are the most popular. They trap heat during the day, pushing plant development and earlier harvest. Covers should put on when you decide to start saving blooms. Remove them during the day to allow pollination and pest control.

It is best to cover berries well before a hard freeze, taking advantage of the building up and trapping of the heat during the day. This trapped heat will help to protect the berries from low temperatures at night. Blooms touching the row cover will be damaged when temperatures dip into the low 20s and teens. See attached picture of row covers.

Growers have started using a wire-hoop-and-string system to keep the row covers off the plants. This prevents the row cover from touching the fruit. A series of wire hoops is place over the row of berries every 10 feet. The hoops are made from heavy wire with a small curl in the corners of the hoop. These curls give the hoop some tension to aide in support of the row cover. A string is run on each side of the hoops, wrapped around the curl and tied to a short stake at the end of the row. The row covers are stretched over the hoops and strings. Sandbags are use to hold the covers down.  See pictures of hoops and row covers in related files.

Disease Control

Several leaf spots and fruit rots attack Louisiana strawberries. Most leaf spots are caused by fungi. Leaf spot, leaf blight and leaf blotch are caused by fungi. These fungi occur early in the growing season and can defoliate the plants or severely restrict their production.

The most common fruit rots of strawberries in the home garden are gray mold and anthracnose. They are also caused by fungi.

Disease in the home garden can best be controlled with a combination of sanitation and fungicidal sprays. The berries should be grown on raised beds with plastic mulch to reduce moisture and contact with the soil. Preventive sprays with captan should be used routinely once the plants bloom and start setting fruit. Thorough coverage of the plants is necessary to control diseases in strawberries.

Insect Control

The two-spotted spider mite and the European red mite are two of the common mite pests normally found during the middle to end of March through the rest of the fruiting season. The two-spotted spider mite does the most damage if not treated early. Look for tiny greenish-yellow or deep red mites under the leaves. A magnifying glass (10X power) is helpful in finding these mites. Watch for webbing and stippling patterns on the leaves.

Insecticidal soaps can be used as soon as you see mites. Thorough coverage of the underneath of the leaves is the key to controlling mites. Insecticidal soaps are fairly safe for the home gardener. Repeat as needed, but rinse the plants with water after the third application of soap. Kelthane (Dicofol) can be used on strawberries to manage mites.

Late-season pests of strawberries include the strawberry sap beetle. As the summer progresses and temperatures increase, adult strawberry sap beetles will fly into your strawberry planting and lay eggs on fruit. The white larval sap beetle will then develop inside the fruit, causing empty holes in the fruit. To minimize damage from strawberry sap beetle, harvest fruit on a regular basis and do not allow rotting fruit to gather around your planting area. Be sure to remove any infested fruit promptly and dispose of it in a closed container away from your strawberry plantings.

Slugs are also pests and can be managed with baits or traps. Place a jar lid in the soil near the plants, fill with beer or 1 teaspoon of baking yeast and 3 ounces of water. The slugs will dive in and drown. They can also be trapped by placing a half a hollowed grapefruit or cantaloupe open side down. Remove it as it fills with slugs. Diatomaceous earth can be spread around the plants. The sharp grains will cut the soft bodies of the slugs. Commercial slug baits can be found in local garden shops.

Dipel (Bacillus thuringiensis) can be used for caterpillars feeding on the berries.

Harvesting

Harvest berries early in the morning when the weather is cool. Fruit for home use is picked fully ripe and totally red. It should be pinched from the plant rather than pulled. Pinching leaves the caps (calyx) on the fruit and also provides a 2-inch stem attached to the fruit to handle the fruit without touching it. A harvest every third day is usually required for maximum yields of high-quality fruit. Rotten, deformed or damaged berries should be removed at each harvest. Remove the discarded berries from the field to prevent the spread of diseases.

Handle fruit gently at all times. Trying to hold too many fruit at one time will result in bruising. Harvested strawberries should be placed, not dropped, in the container. Berries should be refrigerated at 32 degrees to 34 degrees F as soon after harvest as possible.