Little umbrellas of dread

The broadleaf perennial weed known as dollarweed is a taxing problem for many local lawns.  How do we deal with one of the most recognizable turf weeds in our area?  Can we suppress this out of place plant to a level we can live with? 

By nature, dollarweed is very successful as its perennial characteristics allows it to spread around via seeds, underground stems and even tiny tubers.  The green scalloped leaves are a telltale sign that this pernicious weed has invaded your turf.  You may actually be part of the problem.  Dollarweed loves moist to wet areas and overwatering is a great way to provide an environment they like best.  Some of this may be over-irrigation, and some may actually be the nature of the landscape which is simply a site with poor drainage.  Hand-in hand with this cultural management effort, proper mowing can also help turf out-compete dollarweed.  As an example, mow St. Augustine grass so that it is maintained at three and one-half to four inches for best results.  Mowing lower than that can stress the turf and allow weeds to dominate.

Once you have exhausted the noted cultural control options, herbicide control can also be considered.  There are a number of chemicals that can used to manage dollarweed.  A important thing to remember would include the benefit of spot-treating versus a broadcast application.  Often only a certain area of the lawn may be infested, so target just the weedy zones instead of treating the whole, mostly, weed-free area.  At this point in the calendar year, selective, post-emergence control is the most feasible.  This option controls the dollarweed without hurting the grass.  As most people seem to have dollarweed problems in St. Augustine grass, some suggestions will be offered for this grass only.  While atrazine is one of the most commonly used selective, post-emergence materials, there are other herbicides, some combined for extra effectiveness.  It is imperative that you read the label before using any pesticide – it is the law and you need to know all about the ingredients, its uses, limitations and precautions!  If you do not feel qualified to safely apply such materials, either have a properly certified and insured applicator do the work, or stick with the non-chemical options.  Atrazine, and other similar post-emergent herbicides, should not be applied when temperatures exceed eighty-five degrees Fahrenheit. 

The use of “weed-n-feed” products may not be warranted unless dollarweed is infesting  the entire lawn. Again, spot treating with the herbicide only may be the best strategy. 

To wrap up this article on dollarweed, keep in mind that dollarweed’ s other name is actually “pennywort”.  If all else fails, simply change the name of your weed and embrace your newly found pennywort – a weed is just a plant out of place after all!  For more information on all types of landscape and turf weed management ideas, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer.  Don't forget to visit our other County Plant Clinics in the area.  Please check this link for a complete list of site locations, dates and times - http://charlotte.ifas.ufl.edu/horticulture/Plant%20Clinics%20Schedule.pdf .  

Resources:

Trenholm, L. E., Cisar, J. L. and Unruh,  J. B. (2014) St. Augustinegrass for Florida Lawns.  The University of Florida Extension Service, IFAS.

Brecke, B. J., Telenko, D. E. P. Unruh, J. B.  and Leon, R. (2013) Pennywort (Dollarweed) Biology and Management in Turf. The University of Florida Extension Service, IFAS.

Unruh, J. B.,  Leon, R.G., Brecke, B. J., and Trenholm, L. E. (2015)Weed Management Guide for Florida Lawns. The University of Florida Extension Service, IFAS.

Brown, S. H. (2015) Selective Herbicides for Florida’s Lawn Weeds. The University of Florida Extension Service, IFAS – Lee County.