Time to renovate strawberries

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Strawberry beds that are to be carried over for another harvest season need to be renovated. Deciding whether to renovate or remove a bed differs with each grower’s circumstances, such as market demand, land availability and production costs. As strawberry fields age, yields and berry size decline, while weeds and some diseases increase. Growers with high market demand but limited available acreage may need to retain beds longer. In the end, an educated decision requires thorough knowledge of your production costs and net returns over the preceding seasons. If you decide to renovate, start as soon as harvest is over. The earlier runner plants develop, the higher they yield the following year, so delaying renovation will reduce yields next year. Also keep in mind that renovated beds need abundant water in July and August. To renovate, follow these steps:

Mow off the leaves just above crown height if the plants are healthy. Mowing may not be desired if the plants are stressed by drought or root diseases because weak plants have difficulty developing new leaves. Also, do not mow the leaves if renovation is delayed for more than a few weeks after the end of harvest.

Narrow the rows
to eight to ten inches by cultivating with a rototiller or disk. Rototillers with tines removed above the row work very well because they toss some soil on top of remaining plants, which encourages additional rooting. However, more than an inch may smother the plants.

Some growers have had success narrowing rows by treating the row middles with directed or shielded sprays of the herbicide Gramoxone (paraquat). Gramoxone is a contact weed killer that is not mobile in plants, so it only kills treated tissues. This method effectively narrows the plant row, and does not expose new weed seeds by disturbing the soil. One potential problem with this approach is that it does not provide a loosely tilled soil which is best for the rooting of runner plants. It also does not throw soil back over crowns.

Herbicides.
Renovation is also a useful time to treat broadleaf weeds with amine forms of 2,4-D, such as Amine or Formula 40. Strawberry plants tolerate 2,4-D after harvest because they are not actively growing. If broadleaf weeds are a problem, apply 2,4-D a few days before mowing. This herbicide must be absorbed by the weed leaves to be effective, so don’t mow off the weed leaves before applying 2,4-D. Sinbar can also be applied at renovation for preemergent weed control. Apply 3-6 oz of Sinbar 80W per acre, using the lowest rates on sandy ground or weaker plant stands. Mow plants first so that Sinbar is applied uniformly to the soil. Irrigate to rinse the herbicide off the plants and into the soil. Michigan has a Section 18 label for the preemergent herbicide Spartan. Spartan is effective on common groundsel, field pansy, mayweed, white campion (white cockle) and pigweeds. Apply 4-8 oz Spartan 4F per acre, after plants have been mowed.

Fertilizing. The last step in renovation is to fertilize. On heavier loamy soils, apply enough fertilizer to supply 50 lb N per acre. On sandy soils, apply 30-40 lb N at renovation and again in early August. Do not neglect irrigation on renovated beds.

Irrigating.
Do not neglect watering at renovation and during the remainder of the summer.Runner plants that develop during July and August need adequate moisture to root. The amount of water available to strawberries is the product of the water holding capacity and the rooting depth, usually considered 8-12 inches (Table 1). Irrigate when about half of the available water has been used. During hot weather, this means strawberries may need irrigation every two to three days (sandy soils) to every four to five days (heavier soils).

Table 1. Available water in a strawberry rootzone as affected by soil texture


Soil texture
Available water (inches)
Per inch of depth
In root zone
(8-12 inch depth)
Loamy sand
.07
.6 - .8
Sandy loam
.13
1.0 – 1.6
Loam
.17
1.4 – 2.0
Silt and clay loams
.18
1.5 – 2.2

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