Monday, August 27, 2018

Kill the Weeds you See in the Spring Now!

Horticulture Hotline 08/27/18
By Bill Lamson-Scribner

When the temperature is so hot, winter weeds are probably the last thing on your mind. Just like football, deer hunting, volleyball, and shrimp baiting season, the time to control winter weeds is here. If you have read this column over the past 29 years, you have probably read a column or two about preventing winter weeds; however, as you know, many new people move to the Charleston area every day.

What you are targeting now are small seeded winter annual weeds.  These are weeds that germinate from seeds late summer, grow into plants during the winter, then flower and produce seed for the following year in early spring.  The seeds lay dormant over the summer, and then germinate late summer to begin another life cycle. 

Some examples of the most common winter annual weeds are annual bluegrass (Poa annua), chickweed, Carolina geranium, and Henbit.  The weed that we get the most complaints about is annual bluegrass.  It is the grassy weed with the white seed head in late March, early April.  If you control your winter weeds now with a preemergent herbicide, you usually will not have to mow your grass until later in the spring.  All of these weeds are very visible in a brown dormant grass. These weeds also compete with your existing turf when it tries to come out of dormancy in April. 

A couple of weeds that are not annual weeds that are visible at the same time are Dollar weed and Florida Betony (rattlesnake or artichoke weed).  These weeds require different control methods since they are not coming up from seed.

Many customers of ours at Possum’s have reported a drastic reduction in Florida Betony by using the higher rate of Dimension right now. I have done research for the manufacturer (Dow AgroSciences) and have shown great results in all my test plots.  Technically, since Dow did not pay the EPA the money to add this application to the label because this weed is not significant enough in their eyes to recoup the money paid to the EPA, I cannot recommend this application. If you have Florida Betony and are going to use a preemergent product for annual bluegrass, you might want to give a product containing Dimension a try and see if your results are as good as mine and other landscapers. Casaron is also labeled for beds only around certain plants for the control of Florida Betony.

Dimension comes in many strengths, so be sure you purchase the correct one. We see many national companies (and some local companies) selling the lower active ingredient product (0.10%, 0.13%, and 0.15%) and not advising the customer about the higher use rates required in the Coastal South for this product.
Preemergent products do what their name implies.  These products kill the weeds seed before it can emerge from the ground.  By killing the weed before it emerges from the ground, you are making your life a lot easier.  Killing weeds after they emerge (post-emergent) is much harder on you and your grass. Post-emergent weed control involves checking the weather (for temperatures and rain), applying a product, mowing at the right time and following the label.

Be careful to read and follow product labels so that you do not over-apply products.  Since a lot of people put out preemergent products as a granular, be careful not to overlap too much or you can damage your turf. 

Now is the time to put out preemergent products (two weeks before the soil temperatures are ready for winter weeds to germinate).  Various fertilizers such as; 15-00-05, 15-00-15, and 23-00-08 combined with preemergent control products and will give your lawn and shrubs (don’t forget the shrubs!) one last feeding of nitrogen for the year while controlling the weeds.  Usually you will want to come back with another preemergent (a 00-00-07) in 6-10 weeks depending on the products you use, the rate, and the weather conditions. 

Many leaves, of trees that lose their leaves for the winter, have started losing their chlorophyll and developing spots on the leaves. You should not have to treat these leaves with a fungicide for leaf spot because they are getting ready to fall off anyway; however, you might want to check and see if there is a cultural reason (wet area, dry area, herbicide applied in area, tree in full sun that should be in shade, improper fertility  …) that is causing these leaves to drop early.

Mosquitoes, Army worms, the Nasty Rascal, the Chinch Bug, Web Worms and mole crickets are out in full force. Thatch management in zoysia grass has become very important. An application of BGK 7500 should help reduce the thatch with regular applications. BGK 7500 is a powerhouse of microorganisms that eat the material that causes thatch. Be warned.

Always read, understand and follow product label. The product label is a Federal Law.