Most well-known example: Annual Bluegrass (Poa Annua)
Other examples: Shotweed, Chickweed, Mustards.
Life Cycle: 1 year – Germinate in fall. Flower and produce seed quickly, then die in spring.
Pre-emergent timing: Late summer/early fall (rule of thumb is by September 15th)
Principle #1: Pre-emergent herbicides are designed to control germinating weed seeds.
Are there cultural practices that could help reduce the presence of the weeds?
How Pre-Emergent Herbicide Works
Remember, pre-emergent herbicide can affect desirable plants. That includes turf. Caution must be taken if you’re applying pre-emergent and seeding the turf in the same season. Seed first, then apply pre-emergent at least 6 weeks later to allow for lawn establishment. Or seed at least 3 months after the pre-emergent has been applied.
What desired plants are on the property, and are the herbicides you’re considering safe/labeled for those plants?
Pre-emergent herbicide is an important tool in an effective weed management program, but properly timing the application can be tricky. In this article, we’ll look at key principles in developing a weed control strategy, what pre-emergent herbicide can and cannot accomplish within a management program, and when to apply pre-emergent to different classifications of weeds.
The weed will only be killed when it begins to sprout from the seed and hits the herbicide barrier. It is possible for seeds to remain dormant and not be harmed by the pre-emergent herbicide application. This is why weed control is a constant process. There will always be seeds under the surface and a portion will germinate each season. Annual applications must be made to significantly reduce large infestations.
The best time for broadleaf weed applications is when weeds are young, actively growing, and soil moisture is adequate. Normally a single application is sufficient to control broadleaf weeds in these conditions. Two applications may be necessary for hard-to-control weeds, dense infestations of perennial weeds, for adverse/extreme environmental conditions, or for hardened-off and mature weeds.
IMAGE Southern Lawn Weed Killer for St. Augustinegrass and Centipedegrass Concentrate contains multiple active ingredients to provide excellent broadleaf weed control in established warm-season and cool-season grasses. Weeds controlled include dandelion, chickweed, clover, dollar weed and spurge. Weed injury symptoms are normally noticed within a few days of application.
How to Apply Hand-Operated Tank Sprayers:
For hand-operated sprayers (backpack, knapsack, tank-type or pump-up):