Strawberry plant with mild winter injury. Photo: Kathy Demchak
Strawberry growth can start out a little slow when the soil is cold, and this can have a number of effects on the plants.
Temperature is a big driver of plant growth, so probably nothing will help growth quite as much as consistent warm temperatures and sunshine. Plants in plasticulture plantings across the state are moving along faster than matted-row ones, as usual, from the combination of plastic mulch warming the soil and the use of row covers which allow in light. Plants in matted-row fields are still struggling to get going since they were covered with straw for a long period. As Marvin Pritts pointed out in a conference call, matted row plants’ carbohydrate reserves were probably depleted to a greater extent than usual this year due to the long winter, resulting in reduced remaining energy reserves to get them going.
In these cases, a light application of nitrogen (10 pounds per acre actual N) as a granular fertilizer or through the drip system should help spur some growth, depending on whether production is in a matted row or plasticulture. Growers of June-bearers in plasticulture will normally be applying about 30 pounds of nitrogen per acre between now and the beginning of harvest, while growers of day-neutrals should be applying 1-2 pounds of nitrogen per acre per week all season, but might want to jump-start with a heavier dose as mentioned to help the plants get going.
There are other potential causes of poor spring growth. One is a rot such botrytis moving in and rotting out the growing point of the crown. This is more likely to occur especially if straw mulch was applied too heavily and conditions were wet. To diagnose, closely examine the growing point and look for a green tissue right in the center of the strawberry crown. If the firm, green tissue is present, the plant is fine. But if the growing point is grayish and mushy, the plant won’t be able to produce new growth from that area. Anthracnose crown rot can cause similar symptoms. An early fungicide spray may be needed to help curb either of these problems.
Winter injury is another potential cause of poor growth and can be diagnosed by cutting the crown lengthwise and looking for tan or brown discoloration towards the base of the crown tissue that would have been last year’s crown growth. Crown tissue that is a mottled red or discolored in a wedge shape from the side, however, is likely an indication of a disease issue. If a disease is suspected, submitting samples to Penn State’s Plant Disease Clinic (growers from states other than PA should check for local services) may be in order for a definitive diagnosis.
Other causes of poor growth can include vole damage or damage from mites such as cyclamen mites or two-spotted spider mites. With vole damage, plants are often chewed off right to the crown. Leaves on plants with cyclamen mites will appear distorted and off-color, but the mites are very tiny and not visible to the naked eye. If two-spotted mites are present, the adults should be visible on the leaf undersides and may appear reddish-orange early in the year. If populations are very high, which may occur under row covers if two-spotted mites multiplied over the winter, leaf stippling from feeding may be present. With either type of mite, a miticide application may need to be made.