Fall Pre-emergent Time is Here

I know it’s been hot. I know it’s still hot. But it’s time to apply pre-emergent weedkiller granules to prevent germination of winter weeds, especially grasses. They’re set to start sprouting. It’s better to be a week too early with the preventive treatment than one day too late.

Annual bluegrass (Poa annua) invades even healthy turf. It seeds prolifically and for many months. Prevent it now!

Henbit germinates in September and becomes unsightly from early January on through March.

Facts you need to know…
Weeds controlled: winter weeds that germinate in fall, grow over the winter, and become unsightly from late winter through spring.

Grassy winter annual weeds: annual bluegrass, rescuegrass and ryegrass. For these weeds, pre-emergent control is your only hope. There is no treatment once the grassy weeds are up and growing.

Broadleafed (non-grassy) annual winter weeds: dandelions, clover, chickweed and henbit. There are post-emergent broadleafed weedkiller sprays you can apply in November should any of these weeds still appear.

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Products to use for grassy weeds: Halts (available from national chains); Dimension or Balan (available at local independent retail garden centers, hardware stores, feed stores).

Product to use for broadleafed weeds: Gallery (available from local independent retail garden centers, hardware stores).

You must make two passes over the lawn, one with each type of pre-emergent. (That assumes you decide to use both types.) Do not try to mix them before application. Granule size variations will prevent uniform mixing.

Sequence of fall lawn care…
1. Mow grass.
2. Fertilize with an all-nitrogen lawn food that has a significant percentage of its nitrogen in slow-release form.
3. Water deeply.
4. Wait two days.
5. Apply pre-emergent weedkiller(s).
6. Water lightly to disperse herbicide(s) across surface of soil.

You must not use pre-emergent weedkillers if you intend to overseed your lawn with ryegrass. Do one or the other.

Do not apply pre-emergent weedkillers where you intend to sow wildflower seeds.

Do not apply pre-emergent granules if lawn is less than four months old. It will inhibit good rooting of new sod and seed.

Pre-emergent weedkillers are safe around trees and shrubs when used according to label directions.

Dandelions and other non-grassy and grassy winter weeds can look this bad within the next two months if you don’t make an effort to stop them.

Posted by Neil Sperry
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