Horticulture Hotline 08/08/21
Bill Lamson-Scribner
On my way to the radio show on Saturday, I was talking with one of the guys I work with at Possum’s (Nathan), and he said he was carrying out a bag of 15-00-15 Dimension to a customer’s car. Since I don’t have young children going back to school, Nathan’s statement hit me like a ton of bricks. Summer is over! Cool weather is on the way! Football! Fall fishing! Deer Hunting! Shrimping! Golfing! Volleyball! Pickleball? Time to put out your fall application of preemergent herbicide!
Before giving you a product name and time to put it out, I want to explain a little bit about the life cycle of the weeds you are trying to control and how preemergent products work.
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, you usually will not have to mow your grass until later. 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.
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.
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). There is an organic product, Corn Gluten that received rave reviews from the people that tried it. Various fertilizers such as; 15-00-15, 15-00-05 and 23-00-08 combined with preemergent 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 in 6-10 weeks depending on the products you use and the weather conditions. If you plan to plant ryegrass, make sure you understand about the rates to use and timing.
Always read, understand and follow product labels.
