Kali Zammit, Schmit, Rene G. | 3/21/2013 7:53:55 PM
A common weed found to infest most home lawns during early spring is dollar weed. This major weed pest, also known as pennywort, thrives in wet soils, and vegetates from rhizomes that grow below the soil surface. Each rhizome produces multiple nodes that grow into an individual leaf with roots. These roots produce new rhizomes that again produce new leaf plants. This cycle continues over and over and is why dollar weed can spread fast and quickly dominate large areas of the lawn.
Mowing can provide some control but often generates limited results. This is due to taller plants that are removed while plants below the mower blade escape untouched. The surviving plants then have the opportunity to continue multiplying. A quick and more effective method to removing dollar weed is to use of a pump or hose end sprayer and conduct spot-treatments with a post-emergence herbicide. Recommended herbicides that offer good post-emergence control include atrazine, or tri-mec formulated products such as Weed-B-Gone MAX, or Fertilome Weed Free Zone.
As atrazine can be used safely on St. Augustine and Centipede lawns it is not safe for use on Bermuda grass lawns. Atrazine can be applied at any time of the day but should never be applied near shade, nut or fruit tree roots. Tri-mec formula products are safe for all southern lawns including Bermuda grass, but should be applied only in the early morning hours and preferably when the grass is still wet with dew. Note that each of these products are for use in lawns only and should never be applied to landscape beds. For controlling dollar weed in landscape beds, use herbicides such as Image (Imaziquin) or Round Up or Kilzall (glyphosate). Whether controlling dollar weed in the home lawn or landscape beds, keep in mind that more than one application may be needed at a 12 to 14 day interval between spray applications, to achieve desired results.
Granular weed and feed products can be an alternative to using liquid applications of atrazine or tri-mec formula products. It is important to know the herbicide product that is contained in the weed & feed since the same precautions must be considered as for liquid applications. However, since most weed & feeds supply high nitrogen for feeding, applications should be made around early to mid-April to avoid possible occurrence of Brown Patch Disease. Weed and feed applications would be more applicable to lawns with light infestations of dollar weed where chemicals, including weed & feed would be more applicable for control of heavy infestations.
Whether choosing to mow or apply a liquid or granular herbicide, or use all in combination, attacking dollar weed when it first emerges will go a long way in restricting its ability to multiply and spread.Rene’ Schmit is the LSU AgCenter county Agent for St. Charles Parish. He can be reached at 985-785-4473.