Tuesday, April 19, 2011
It’s now fall and you thought you did everything right for your lawn; why are there so many weeds this year? There seemed to be an awful lot of nut sedge, crabgrass and weeds including clover.
Let’s assume that you followed the Jonathan Green Annual Lawn Care Program that included Crabgrass Preventer plus Green-Up Lawn Fertilizer in the spring and Jonathan Green Weed & Feed Lawn Fertilizer for broadleaf weeds in late spring to summer. A good, healthy growing lawn is the best defense against weeds. Bare spots and open areas that do no contain grass are going to naturally fill in. What do you think would happen if you took a sod cutter and cut a one-foot swath across the front of your lawn? Do you think it would stay as bare dirt forever? Of course not, there are thousand of seeds in the soil. These weed seeds are able to survive for years and when the proper conditions arrive they will germinate. All they need is to be near the surface and to get some sunlight and moisture; they are off to the races!
Another reason for excessive weeds would be if there was a mild winter. Cooler temperatures help to keep weed populations in check to a great extent. Clover is especially affected by the cold winter. We saw a fair amount of clover this year. Weeds go through their life cycle trying to survive and produce the next generation, just as the human race does. Crabgrass and dandelions set their seed this year and then wait in the soil until next year. They have a remarkable ability to survive in many parts of the world.
Crabgrass is coarse-bladed, light-colored and just plain ugly when it is present in a well- groomed lawn. The cool-wet spring season delayed the germination of crabgrass seeds in the soil until later in the spring. Many of the crabgrass preventers that were applied ran out of gas and did not do as good a job as hoped. The hot-dry summer then favors the growth of crabgrass, as desirable lawn grasses tend to shut down and go dormant under heat and drought stress.
Crabgrass also will thrive along driveways and sidewalk edges where heat builds up in the soil. These same areas also are affected by salt damage and traffic from kids and dogs. Once foot traffic, digging or hard raking has broken the barrier of the control, crabgrass seeds have a better chance of breaking through on your lawn. In these areas that crabgrass always seems to show up, apply a second round of Jonathan Green Crabgrass Preventer plus Green-Up Lawn Fertilizer 6-8 weeks after the first application or apply at the heavier rate in these areas in the spring. There are a few products available to control crabgrass during summer months. Follow label directions, do not over-apply or apply to a stressed lawn.
Nut sedge is a unique lawn weed that superficially resembles grasses but is true sedge. Their leaves are thicker and stiffer than traditional lawn grasses. They are arranged in sets of three at the base while lawn grass blades are opposites in sets of two. Nut sedge grows from tubers or ‘nutlets’ that are in the top foot of the soil. Buds on the tubers sprout and grow to from new plants. Patches of nut sedge to up ten feet can form. The ‘nutlets’ live in the soil for 1-3 years and the leaves do not necessarily appear above ground every year; it’s very mysterious weed.
The stem of the leaf is triangular in the cross-section. If you pinch the leaf off correctly you can see this ‘triangle’, making nut sedge identification easy. In summer, after you mow your lawn, if there are light-green leaves growing 2 to 3 days after you mow, it is usually nut sedge. Nut sedge favors soils that are water logged and poorly drained. It can also do quite well in stressed areas, once it is established. The best way to control a small number of plants is to pull them gently in order to get as much of the blades and ‘nutlet’ out of the ground. This reduces the energy level needed for the buds to grow. There are controls available in stores; however, non-selective herbicides such as glyphosate do not really completely kill nut sedge. They provide only suppression since the chemical does not translocate down to the soil ‘nutlet’.
Let’s hope this helps for next years weed wars!Back