Reducing Common Groundsel in Strawberry Fields

Common groundsel is an annual weed that continues to cause problems for strawberry and vegetable growers. It is a fairly short weed, with slightly fleshy leaves similar to dandelion. Like its cousins in the Composite family, groundsel has a distinctive composite flower with many florets. Look for the cluster of small yellow flowers that quickly shed an abundance of seeds, flying away on the wind.

The problem is that groundsel can germinate, flower and shed seed in a very short time, especially under warm conditions. We often find very tiny plants with flowers and seeds shortly after mowing. These seeds continue the cycle, as they are not dormant and germinate almost immediately after hitting the ground. Usually 50% of the seeds germinate immediately after dispersal.

Common groundsel is a particular problem for strawberry growers because our common strawberry herbicides - Treflan, Sinbar, and 2,4-D - do not control it well. So growers who notice a few small plants in the spring may find their field totally covered in common groundsel by the fall, and many strawberry fields have been removed a year or two early because of common groundsel.

Fortunately, Devrinol herbicide will prevent groundsel germination. Our strategy in strawberries has been to target Devrinol in early September for winter annuals.

Recent research in Ohio has shown that groundsel that germinates in the fall produce seeds with a longer dormancy that will persist in the seedbank. This study also showed that 94% of groundsel seed that is buried will either germinate or die within 24 months. This indicates that a focused effort for 2 years can practically eliminate groundsel, especially if control efforts are focused in the fall.

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Several approaches will be needed to reduce common groundsel:

• Frequent cultivation in the year of planting are needed. Groundsel seedlings are most susceptible to cultivation before the first true leaf, and can easily re-root if cultivation is delayed until weeds are larger.
  
• Application of Devrinol at Labour Day (followed by irrigation if ½" of rain does not fall) will prevent establishment of winter annual forms that produce dormant seed.
  
• Using Lontrel in your renovation program will reduce groundsel, although weeds that have already formed seeds will continue to shed them.
  
• Using Sinbar regularly also reduces groundsel to some extent.
  
• Hand weeding of groundsel escapes will be important, especially on new fields, and during the early fall.
  

Where groundsel has become a severe problem, growers have had success in switching to a reduced-till system using chemical renovation (ie. narrowing rows with Gramoxone, with no soil tillage). By the 2nd year, groundsel problems have been drastically reduced, especially if weed escapes are removed as well.

We know that several approaches are needed to manage common groundsel, and focusing efforts to eliminate the fall population will help reduce long-term problems. Another example where knowledge of the weed's biology can help us achieve the control level we need.

Common groundsel (Senecio vulgaris) can be significantly reduced with diligent prevention efforts
over 2 years

Dandelion and other broadleaf weeds can be controlled with post-harvest applications of 2,4-D in orchards and after renovation in strawberries

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