In the last couple of years, wild cucumber vines grew prolifically to cover windbreak trees by late summer. By the time vines reach this stage, it is too late for control measures other than pulling vines off trees.
If wild cucumber control is needed, May is the month to apply a pre-emergence (PRE) herbicide. These types of herbicides need to be in the soil just before weed seed germinates. PREs then kill weed seedlings.
If hoeing, hand-pulling or mowing is the control method used, late May into June is the time to begin. These methods are best used when plants are young and prior to seed production. Preventing the soil from becoming a seed bank will aid control over the long run.
Wild cucumbers are warm season annual plants. As an annual, the entire vine dies at the end of each season and new plants grow from seed each year. Hence, pre-emergence herbicides are most effective and safer for trees and other plants growing nearby. Hoeing or hand-pulling is very effective as well.
As a warm season plant, seeds begin to germinate sometime in May after soil temperatures have warmed to at last 55 degrees and usually much warmer. Applying a PRE from early to mid-May is the best timing. Simazine can be used in shelterbelts to kill weed seedlings as seed germinates.
Wild cucumber seed can germinate throughout the season, especially after rainfall. During a rainy summer, a second application may be needed six to eight weeks after the first was applied.
If wild cucumber vines are to be controlled by hoeing or hand-pulling, scout the area throughout the season for young plants. Hand-pull plants before they bloom and produce inedible fruit with seeds. In large areas, mowing may be effective.
The low growing purple weed that has been blooming this spring is henbit. Henbit is also an annual weed that can be controlled with pre-emergence herbicides.
However, henbit is a winter annual or cool season plant. The majority of seed germinated last fall. Young seedlings overwintered to grow and bloom this spring.
Since the plant is already growing, it is too late to apply a PRE product. After blooming and setting seed, the plants will die naturally.
Henbit is a good, early season nectar plant for pollinators. If control is not essential, leave henbit to feed the pollinators.
Where control is desired, homeowners should hand-pull and destroy weeds to reduce the amount of seed placed into the soil seed bank.
In lawns, applications of a post-emergence herbicide for broadleaf winter annuals can be used to kill henbit quicker than it will die naturally. This may allow turfgrass to fill in the area and compete with henbit.
The most effective time to use an herbicide is in early September. Apply a PRE product just before seed germination begins in fall.
The most effective control of henbit in lawns is to determine why the grass is not competing with this winter annual. Change lawn care practices to increase turfgrass density and competition.