Selecting herbicides for spring application in fruit crops

Photo: Reading the Midwest Fruit Pest Management Guide to find the right herbicide for a new strawberry field.

 

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

 

I received a good question in my email inbox this week. The grower asked (I am paraphrasing): 

What herbicides can I spray before planting strawberries this spring? And how long before planting should I spray them?

This grower is planting three acres and is aware that the field already has a large weed population. With that large of a space, they cannot only rely on hand- or mechanical weeding without risking significant weed competition with the plants. Therefore herbicides are the most economically sustainable solution in this case. 

To answer questions about pesticide recommendations, I always direct Minnesota growers to the Midwest Fruit Pest Management Guide. It includes herbicide recommendation tables for strawberries (and the other major fruit crops of the Midwest). We like this resource for a few reasons: 

• The recommendations are based on current research
• Every two years it is thoroughly reviewed by a team of experts and then updated based on any new research or products
  
• The authors have no commercial interests
• It is written with Midwest fruit growers in mind, by people who work with this audience. The herbicide recommendations are relevant to the weeds of the Midwest, our climate, and to the systems in which we grow fruit crops.

To access the guide, you can either download a free PDF copy, or purchase a hard copy for $15. Personally, I like to have a hard copy so that I can flip freely between pages as I work.

The guide is easy to use. For example, here is how I would use it to approach the question above: 

1) Download or purchase a hard copy of the Midwest Fruit Pest Management Guide.

2) Find the chapter on Chemical Weed Management (in the 2023-24 version, this is page 251)

3) Flip to the page where the "Herbicide Recommendations for Strawberry" section begins (270)

4) Decide if you need a preemergent, postemergent, or both.

5) Decide which weeds you need to target - broadleaves, grasses, or both? Are there specific problem weeds in your field, like lambsquarters or nutsedge? (page 273 has an efficacy table, but you will need to refer to the strawberry table to make sure the product you want is labeled for strawberries)

6) Find your options: Let's say you want to spray a preemergent herbicide before planting strawberries. Use the table on page 270 to narrow your search. Only write down products that can legally and safely be sprayed before planting. These include Chateau, Goal 2XL, and Spartan. The guide states that Dacthal and Sinbar can be applied at/immediately after planting, respectfully.

7) Narrow your shortlist further: Look each option up in the "Relative Effectiveness of Herbicides for Fruit Crops" table on page 273. See if they are effective on the weeds you have in your field. For example: If your problem is nutsedge, then Sinbar and Spartan (listed as: Zeus XC, Spartan) are the only products from your shortlist that have any activity on it.

8) Once you've selected the product(s) you want to use, look up the labels to make sure the information in the guide is consistent with the label. It should be; but the label is the law, so always refer to it to make sure.

The most important goals with herbicide selection are to 1) select herbicides that are effective on the weeds you need to control, and 2) are safe and legal to apply when you want to apply them. 3) Save money when possible.

Avoid the following mistakes: 

• Buying an herbicide that will injure the strawberry plants (i.e. buying off label)
  
• Buying an expensive herbicide that does not control your problem weeds
• Buying a post-emergent herbicide when you really meant to prevent weed emergence (need a preemergent)
• Buying an herbicide that may be effective on your weeds, but is not labeled for use in the crop you have or for the timing you wish to apply it
  

By using this guide, reading the labels, and contacting your local Agriculture Extension Educator, you will be on track to find a weed management plan that works for you. 

CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Be sure that the plant you wish to treat is listed on the label of the pesticide you intend to use. And observe the number of days between pesticide application and when you can harvest your crop. Remember, the label is the law.