Mulching

Fall mulching with straw or wood chips is recommended for Interior strawberry plantings, especially where snow protection is not reliable. In these areas, mulching has many benefits. Freezing and thawing soil can lift plants and damage the roots. Mulching keeps soil temperatures more uniform and reduces the risk of frost heave. Mulching also reduces low temperature injury to roots and crowns. By delaying removal of the mulch, blooming can be delayed to reduce frost injury.

Apply the mulch after the plants have been hardened by several frosts but before the temperatures drop below -7°C. Cover the plants with a 5 to 8 cm (2 to 3 in) layer of straw or wood waste (wood chips) using about 4.5 to 6.5 t/ha (2 to 3 tons/acre). To ease spreading, the mulch should be dry and not frozen.

Remove the mulch when new plant growth starts in the spring. If delayed too long, the new growth will be yellow and spindly, and crowns may be damaged when the mulch is taken off the plants. The mulch can be incorporated into the soil but additional nitrogen should be applied. Additional mulch can be applied to improve the conditions in the rows for U-pick operations.

Mulching is not recommended in coastal areas as it can increase disease and insect problems.

Nutrition

Soil Analysis

Soil analysis is the most accurate guide to nutrient requirements with the exception of nitrogen and a few micro-nutrients. The best time to take soil samples is immediately following harvest. Soil test results can then be used to plan fertilizer requirements for late summer application. Soil testing may also be done in the fall and used to plan spring fertilizer or manure applications.

Take soil samples from within the matted crop row for June bearing varieties and between plants in the row for Dayneutral varieties. Sample from 0 to15 cm (0 to 6 in) depth. Up to 90% of strawberry roots are within this depth. When sampling prior to planting, take samples to a depth of 30 cm (12 in). Refer to the BCAGRI factsheet, “Soil Sampling”, or contact the private laboratory that will test the soil, (see factsheet, “Resources for Berry Growers”) for more information on sampling procedures.

Leaf Analysis

Leaf analysis is a tool to monitor the uptake of nutrients by the plant. It is an alternative to soil testing or can be used if a nutrient deficiency is suspected. Sample only the youngest mature leaves. Details on sampling for tissue testing are available from private tissue testing laboratories.

Table 3 gives an indication of the range of plant tissue nutrient levels that should be present in healthy plants.

Fertilizers

This section gives general fertilizer recommendations only. Nutrient requirements may vary with varieties and soil type. A standard blend of fertilizer may be available to meet the crop needs. However, soil test analysis is the best way to determine the nutrient requirements. Also monitor fertilizer applications, soil nutrient levels and crop yield over time. A custom blend of fertilizer may be necessary to provide the required nutrients for a particular field.

Table 4 is the approximate macro-nutrient requirements for established plantings in coastal areas.

Consider the following when applying nitrogen:

Total application of nitrogen should not exceed 75 kg/ha (30 kg/acre) per year.

Apply fertilizer in bands as close as possible to the sides of the matted row and 7 cm below the soil surface. Fertilizer mayalso be broadcast over the top of the rows. To avoid plant injury, broadcast when the plants are dry.

Research has shown that spring applied nitrogen has little benefit in increasing yield. In addition, excessive nitrogen before flowering can cause vigourous leaf growth. The leaves may cover flowers and interfere with pollination. Heavy growth can also increase fruit rot.

Nitrogen at renovation is key to revitalizing the plant, obtaining good flower bud initiation, and providing nutrient reserves in the plant for the next year’s crop. Apply the second application of nitrogen as soon as possible after mowing.

Late applications of nitrogen can make plants more susceptible to winter injury.

In coastal areas, late nitrogen applications can leach and will not be available to the crop in the spring. In the Interior, late nitrogen applications will be available in the spring and should be accounted for in the fertilizer program.

Foliar Feeding

Fertilizers can be applied as sprays to the leaves but this method of application is supplemental to soil applications. Plants respond much more quickly to foliar fertilizer applications. However, the effects do not last as long as with soil-applied fertilizers because the rates are lower. The two main uses for foliar feeding are:

To give a boost to frost-damaged or weakly growing plants; and

To apply additional nitrogen, boron, magnesium or other elements during the growing season.

Nutrient sprays should not be applied during very hot weather as leaf-burning may occur. The plants generally respond better to foliar feeding during the earlier portion of the growing season when the leaves are younger and less waxy.

Nutrient Deficiencies

Leaf and soil testing can determine deficiencies of some micro-nutrients. Use Table 3 to help interpret leaf analysis results. Also refer to the Table 5 below and the Table, “Foliar Symptoms of Nutrient Deficiencies and Corrective Treatments” in the Nutrient Management Section.

Boron, magnesium and calcium are frequently at low levels on light, coarse, sandy soils. Soil analysis can be used to determine the amount available to the plant. Foliar sprays of these micro-nutrients can be applied during the growing season if nutrient deficiency symptoms appear.

Renovation

Renovation – or after-harvest care – allows plantings to be kept for two, three, or more harvests. The yield, fruit size, and quality of the third crop is typically less than the first and second crops. It is often not profitable to take a third harvest.

Renovation is most successful on vigourous plantings with reasonable control of perennial weeds. Growth in strawberry plants slows down considerably towards the end of harvest. Renovation begun shortly after harvest, stimulates new growth.

Successful renovation includes the following activities. The order may differ between plantings:

If perennial weeds such as clover or thistle are present, apply Lontrel before mowing.

Mow plant tops to 2 to 5 cm (1 – 2 in) above the crowns – take care not to damage crowns. Do not mow dayneutral varieties.

Thin plants. This may be needed to keep plants about 15 cm (6 in) apart. Rake unrooted or poorly rooted runners into the alleys. They will then be removed when the rows are narrowed. Hand thinning is not usually economical.

Narrow rows to desired width. This removes excess runners and incorporates the leaf trash. Do not throw soil up on the plants in the row.

Apply the remaining fertilizer – band or broadcast over row (see Table 4).

Apply recommended herbicides (see “Weed Control” below).

Irrigate if rainfall does not occur within a few days.

Remove weeds by hand, if necessary.

Watch for aphids on the new leaves, and control as necessary to reduce the spread of viruses.