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.
