Follow These Steps for Strawberry Renovation

Author: Annie Klodd, Extension Educator - Fruit and Vegetable Production

Strawberry growers throughout Minnesota are at or near their final harvest days for the season. After the final harvest, the field is renovated in order to restore the health of the plants and prepare them for the following season.

This process involves: Weed control, mowing, row narrowing, cultivation, fertilization, and irrigation.

Step 1: Herbicide application (if using)

If applying herbicides for weed control, a burndown herbicide can be applied before mowing. 2,4-D is frequently recommended for this purpose. While it may feel counter-intuitive to apply 2,4-D to strawberries, Michigan State University states that it is unlikely to hurt the plants at this point in time because the plants are not actively growing. However, it is critical to follow the rate and instructions on the label to prevent unintended damage.

Should you apply 2,4-D before or after mowing? If there are lots of weeds in the field, apply 2,4-D prior to mowing. If there are not many weeds, you can mow first, and then apply 2,4-D with a pre-emergent (more information below in Step 5). Mark Longstroth at Michigan State University says "if the weeds are above the strawberries, spray 2,4-D before mowing. If the strawberries are above the weeds, mow and then spray."

Step 2: Mowing

For organic or non-chemical strawberry growers, mowing is the first step in renovation. For growers using herbicides, mowing should occur 3-5 days after post-emergence herbicide application.

Healthy plants should be mowed just above crown height. If the field is an uneven height, then adjust the mower height up in order to avoid hitting the crowns (base of the plants).

If mature weeds are present that have already produced flowers or seeds, such as nutsedge, these should be hand-pulled and removed from the field prior to mowing. This prevents the seeds from spreading and increasing weed pressure in the field.

Cautions about mowing:

• If the plants are drought stressed or have root diseases, mowing may further damage them because the stressed plants have reduced ability to produce new leaves. If you farm in a drought stressed area of the state and have not been irrigating regularly, either consider skipping the mowing, or irrigate a couple of times prior to mowing to reduce stress on the plants.
• Do not delay renovation. If renovation is delayed by more than a few weeks after harvest, mowing is no longer advised.

Step 3: Apply fertilizer

After mowing, broadcast apply 25-60 lbs/acre of nitrogen, or an N-P-K fertilizer if phosphorus and potassium are also needed. Split applications of N are beneficial, particularly on sandier soils. University of Massachusetts Extension recommends applying part of the total N now, and the second part 4-6 weeks later. 

Determining fertilizer type and rate: Sandier soils require higher N application rates, while heavier soils (clay, clay loam, etc.) retain more N and require smaller rates. 

If a foliar test was done last season or earlier in the season, that will help in determining the rate and nutrient concentrations of fertilizer to use. In the absence of a foliar test, consider the most recent soil test as well as soil type. You may limit fertilizer application to just nitrogen at this time, and hold off on applying P and K until a foliar test is done. A balanced N-P-K fertilizer such as a 20-20-20 can be used, but be cautious not to over apply P and K if the soil is already high in these nutrients; this emphasizes the importance of regular foliar testing.

Soil and foliar nutrient testing are a central part of fruit production. If you have not taken a foliar test this year, or a soil test in the last 5 years, prioritize these activities in the weeks following renovation once mature leaves are present and before plant senescence. 

Step 4: Tillage

Tilling or cultivating between the rows serves to narrow the rows, incorporate fertilizer, incorporate straw, and remove small weeds between the rows. The rows should be narrowed to 12-18 inches. More fruit is produced along the sides of the rows compared to the centers, so narrower rows are more productive.

Step 5: Pre-emergence and post-emergent herbicide (if using)

If using herbicides, a pre-emergent herbicide after tilling will help suppress weed emergence in the late summer and early fall. A post-emergent herbicide labeled for safe use on post-renovation strawberries may be added to the tank mix if emerged weeds have persisted after the last herbicide application. 

This recent article from Michigan State University gives greater detail about herbicide options for renovation, including product names: https://www.canr.msu.edu/news/it-is-renovation-time-in-perennial-strawberry

Additionally, refer to the Midwest Fruit Pest Management Guide for a list of herbicides labeled for strawberries during renovation.

Step 6: Irrigation

The plants need water at this point to re-establish leaves, access the fertilizer that was applied, and to activate herbicides. Emphasize irrigation after renovation particularly if conditions have been dry and the near-term forecast does not call for much rain.