Strawberry Renovation Revisited

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

As strawberry season winds down in June, it will be time to consider renovation options depending on the production system

Matted Row Systems
In matted row strawberries, the goals in renovation are to reduce plant numbers by narrowing the rows, remove old foliage (reduces diseases), control weeds, reduce insect and mite pests, and promote new runner development (production of daughter plants). After renovation, regular irrigation and weed control are essential. High yields next year depend on having large, healthy, vigorous plants when fruit buds are initiated in late summer.

With matted rows, renovation starts with an application of 2,4-D amine herbicide (Weedar 64) after the last harvest. If grasses are a problem a sequential application of sethoxydim (Poast) or clethodim (Select) may be necessary (do not tank mix with the 2, 4-D). After the last herbicide application, wait 3-5 days and then mow off the strawberries to just above the crown (do not damage the crown). Apply nitrogen fertilizer (25-60 lbs N/acre) at this time. Using a split N application half at renovation and half 4 weeks later is preferable. If other nutrients were low or deficient (as indicated by tissue tests prior to fruiting) then apply at this time. Subsoil fields with compaction from equipment or heavy foot traffic between the rows (U-pick plantings for example).

Next, narrow the rows with a cultivator, coulters/discs, a rotary tiller/multivator or other devices to 12-18 inches at the base. Matted row strawberries are edge bearers and benefit greatly from this narrowing. Strawberries produce new roots higher on crowns each year so try to throw about 1/2 -1 inch of soil over the row (without covering the crowns). This will also help new daughter plants root (runners produced from mother plants).

After narrowing the rows apply preemergence residual herbicides. Apply 2-4 ounces of terbacil (Sinbar). This is one half the annual rate. Sinbar can injure some varieties and attention should be paid so as not to have overlaps. If Sinbar is not used, DCPA (Dacthal) may be applied at this time. This material requires adequate rainfall or overhead irrigation for activation. Dacthal benefits from being lightly incorporated (possible in row middles). During the summer, cultivate between rows to remove weeds and to sweep runners into the row. From late summer on, cut off any additional runners during cultivation (discs or coulters work best).

Weeds in the rows must be controlled throughout the summer. Sethoxydim (Poast) or clethodim (Select) may be sprayed over the top to control grass weeds. Clopyralid 0.12-0.25 lb (Stinger 0.33-0.67 pt/A) has a 24c label for use in MD, NJ, VA, and PA for over the top control of some broadleaf weeds. Hand hoeing will be necessary for removal of remaining weeds.

Irrigate strawberries so that they receive 1.5 inches of water (combined rainfall and irrigation) each week during the summer. Irrigation during late July and August are very critical to produce large plants as flower buds will be initiated starting in August. Continue irrigation (at reduced rates) through the fall until dormancy. Strawberries may benefit from low amounts of additional nitrogen fertilizer (25 lbs of N/acre) later in summer depending on the vigor.

Plasticulture Systems
With the high cost of establishing strawberries planted on plastic mulch, many growers choose to carry them over for another year. First, evaluate the disease pressure on the planting. If anthracnose was a major problem, you should not carry the planting over. If disease pressure was low, then renovation can proceed.

The goals in renovating plasticulture strawberries are to remove old foliage, remove any runners formed, remove diseased plant material from the field, control weeds, reduce insect and mite pests, and reduce crown size of very large plants.

Mow the strawberries as close to the crowns as possible without damaging them. Remove any diseased plant material from the field. Plants with more than 5 branch crowns will benefit from thinning. Using an asparagus knife, remove one half of the crown. Apply weed control measures between plastic beds (herbicides, cultivation, or combination) being careful not to apply herbicides over the plastic beds. Irrigate strawberries so that they receive 1.5-2 inches of water each week during the summer. Fertigate with 40 to 60 pounds of nitrogen per acre in late August and add any additional nutrients as suggested by tissue tests. Continue irrigation as needed throughout the fall.

The key for carryover strawberries on plastic is not to have too many crowns going into the fall. Excessive crown numbers will reduce berry size greatly. Carry over beds should not be row covered until winter to avoid excessive growth and may not need row covers in mild winters until the frost protection period in March and April during flowering.

Day Neutral (Repeat Blooming Types) Renovation on Plastic
The decision on when and how to renovate day neutral plasticulture strawberries differs from June bearing types in that production can continue into the summer, picking up again in the fall.

With fall planted day neutrals consider renovation in July when production slows. Mow the strawberries as close to the crowns as possible without damaging them. Remove any diseased plant material from the field. Plants with more than 5 branch crowns will benefit from thinning. Using an asparagus knife, remove one half of the crown. Apply weed control measures between plastic beds (herbicides, cultivation, or combination) being careful not to apply herbicides over the plastic beds. Irrigate strawberries so that they receive 1.5-2 inches of water each week during the summer. Fertigate with 40 lbs/a N at the July renovation and fertigate again with 20-40 lbs/a N and 40 lbs/a K when first bloom appears in the fall.

With spring planted day neutral strawberries, remove runners throughout the season. If production stops, maintain plant health by regular irrigation and disease, mite and insect management. In mid-August, fertigate with 40 lbs/a N and fertigate again with 20-40 lbs/a N and 40 lbs/a K when first bloom appears in the fall.