Thoughtful weed management is essential to maintaining high yields and fruit quality in a blueberry operation. It also serves to reduce other pest issues. Growers continue to face challenges associated with weed management, including the development of herbicide resistance and challenges associated with climate change.  

Below is a brief overview of managing weeds in blueberries, with a special emphasis on pre-emergent materials. 

Preplant Measures (one-two seasons prior) 

Preplant weed management should primarily be focused on the reduction of perennial weeds. These will be the most challenging weeds to get rid of, and it may take more than one year to effectively reduce the population. To accomplish this, utilize various materials and methods, including: 

Chemical: There are plenty of options for chemical control including organic and non-organic materials. Thoughtful selection of materials requires knowledge of the target species. Rotation is required. 

Cultural: Addressing weed populations prior to planting allows for more freedom in the cultural management strategies employed. When the crop is not yet in place, the use of grazing animals, stale seedbed method, mechanical cultivation, and cover cropping are more viable options. The soil environment’s disturbance should also be kept to a minimum during planting. 

First Year 

The first year is the most critical time for control. The goal during the first year of blueberry planting is to minimize competition as much as possible to allow for adequate establishment of the crop.  

Materials specifically labeled for first-year blueberries must be used, to avoid injuring the crop. All materials must be rotated. Utilize the pre-emergent herbicide charts below for quick reference (Table 1) and see the New England Small Fruit Management Guide for rate and further information. 

First Year and Beyond 

After the first year, post-emergent herbicides should be used to burn down winter annuals and perennials. Pre-emergent materials should be applied before budbreak each year. Pre-emergent materials can be applied again five to eight weeks later.  

Be aware of the pre harvest intervals of all materials. Post-emergent materials can be used on an as-needed basis, but extreme care needs to be taken to not hit any new shoot growth with these materials. Again, rotation is required.  

Other methods including mechanical cultivation, flame weeding, and hand cultivation should be utilized as needed. See Table 2 below for pre-emergent materials for established plantings. 

Notes – It is highly recommended to mix two materials of varying modes of action or from two HRAC groups to avoid herbicide resistance. One-half inch of rainfall or irrigation is required within seven days of pre-emergent application, to move materials down into the soil. 

Table 1. Pre-emergent herbicides registered for blueberries in the planting year. 

Table 2. Pre-emergent herbicides registered for established blueberry plantings. 

Other Considerations: 

• Maintain grass cover between rows; 

• Wood chips/mulch for sandy/dry/well-drained sites; 

• Care should be taken with manures and/or compost as low-quality materials may contain viable weed seeds; 

• Read labels, as each material may have different target species, PHI, etc.; 

• Check spray equipment for adequate/even spray applications. Calibrate at the beginning of every season and periodically during the season; 

• Consult the New England Small Fruit Management Guide for further information, including materials and rates for post-emergent control. 

Resources

MSU Extension – Blueberry Weed Control 

https://www.canr.msu.edu/news/better_blueberry_weed_control_for_2015  

Rutgers – Highbush Weed Control 

https://plant-pest-advisory.rutgers.edu/2023-update-on-weed-control-with-residual-herbicides-for-new-jersey-highbush-blueberry/  

University of Maryland Extension – Stale Seedbed Method 

https://extension.umd.edu/resource/stale-seedbed-technique-relatively-underused-alternative-weed-management-tactic-vegetable-production  

The information in this document is for educational purposes only.  The recommendations contained are based on the best available knowledge at the time of publication.  Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended.  UConn Extension does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.  The University of Connecticut, UConn Extension, College of Agriculture, Health and Natural Resources is an equal opportunity program provider and employer.