Eye on Extension: Managing spring weeds is crucial


VALLEY — The first weeds of the year seem to be a rite of passage into spring. Some of the weeds this year are going quite well. There are some annual weeds and some perennial weeds that show up with the first green up in the spring. Controlling these weeds early and all year long is important.

The annual weeds can often be controlled with time and perseverance. Kochia and dandelions are two of the first weeds to show up. While hand digging isn’t a viable option for managing these weeds in small areas, mowing, grazing and herbicides can improve control when used together. Mowing and grazing can be done as soon as the plants are tall enough to be mowed or grazed. Repeated mowing and grazing may be necessary. This can provide feed for livestock in seasons when normal feed is short, or just be used a weed control. 

Herbicides can be used to control annual spring weeds. 2,4-D is one of the most common. However, some of the weeds have developed resistance to 2,4-D. To avoid resistance to herbicides we need to alternate classes of herbicides. When purchasing herbicides look for different active ingredients. 

Some of the perennial weeds are the most difficult to control. One of these is Hoary Cress, or Short White Top. White Top is often found along ditches, roadsides and other areas where the ground is disturbed. It also likes alkaline soils, which we have a lot of in the San Luis Valley. Once it becomes established it can spread quickly.  Before you know it you have a carpet of white flowers that you don’t want. Revegetation after eradication is necessary.

One of the options for controlling White Top is to keep good vegetation along areas it might grow. Proper grazing can help keep good grass cover and not allow White Top to start growing. Cut the plant so it doesn’t go to seed. Mowing can create more vegetative growth but continued mowing can help control the weed. Small patches can be hand pulled, hoed or tilled.

In areas where you can’t mow or graze as desired, herbicides may be in order. 2,4-D can provide fair control. Telar or Escort can be used in non-cropland areas. There are no biological controls for White Top. Sheep and goats can graze it. Burning is not effective.

This time of year other weeds are also growing. Perennial Pepperweed, or Tall White Top, is growing and now is a good time to spray it. There are a number of herbicides that can be used. Banvel, Roundup and 2,4-D are some herbicide options. Mowing and burning early might give some limited control. It can be grazed but animals must become accustomed to it. Reseeding is needed to provide competition to the plant and take away places for it to grow.

There are other weeds that can be controlled now as well. If you aren’t familiar with them, have them identified. This way you will be able to provide the best control methods possible. It will also save you money.

Weed control is a growing season activity. Starting in the spring when weeds are young will help with controls throughout the growing season. It is necessary to use a multitude of different control methods on the toughest weeds to reduce resistance and insure the best control possible.

If you have questions, you can also call the Colorado State University Extension, San Luis Valley Area Office at 719-852-7381 or your county weed director.

Extension programs are available to all without discrimination. Colorado State University Extension, U.S. Department of Agriculture and Colorado counties cooperating.

Marvin Reynolds is the SLV Area Extension Director

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