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September: Time for Pre-Emergent

What Turf Scientists Say

University and turf scientists agree: timing is everything. Pre-emergent herbicides don’t stop seeds from sprouting, they block the tiny seedling from establishing roots and shoots right after germination. That’s why timing matters so much.

  • Soil temperature is the key. Texas A&M recommends applying fall pre-emergent when soil temps fall to 70°F and trending downward, which usually happens in September here in San Angelo.

  • Target weeds now. A fall application is designed to stop winter annuals like annual bluegrass (Poa annua), burweed, chickweed, and henbit.

  • Avoid late fertilizer push. Turf specialists caution against heavy nitrogen late in the season, it can encourage growth that freezes back. That’s why we stick to balanced, slow-release nutrition this time of year.

  • Three applications per year give the best coverage. once in the fall for winter weeds, in the spring for summer weeds like crabgrass, and in late summer for late-germinating weeds, provides the best overall weed coverage. Fall applications control winter annuals, while spring applications target annual grasses such as crabgrass and goosegrass. A late-summer application can control weeds that germinate later in the season.

Is Pre-Emergent Right for Every Yard?

Not always.

  • New lawns or repair zones: Pre-emergents can inhibit rooting and stolon spread, so wait until grass is well established.

  • Overseeding rye? Certain chemistries will also block your desired seed. Always check the label.

  • Activation matters: Almost all products need watering-in within 1- 2 days to work properly.

Turf Types in Our Area

  • Hybrid Bermudagrass (TifTuf, Tif 419): Handles pre-emergents well once established. Avoid when turf is thin or recovering.

  • St. Augustinegrass: More sensitive. Atrazine is often used here for winter weed suppression, never on Bermuda.

  • Zoysiagrass: Similar tolerance to Bermuda; follow label rates and reseeding intervals.

Winter Annual Grasses

  • Annual Bluegrass (Poa annua) the #1 problem in turf, bright green clumps in spring.

  • Rescuegrass (Bromus catharticus) coarse, upright, early spring seedheads.

  • Ryegrass (Lolium spp.) usually intentional, but can volunteer and compete. 

Winter Annual Broadleaves

  • Burweed (Soliva sessilis) makes those painful “stickers” in spring.

  • Henbit (Lamium amplexicaule) purple flowers, common in thin turf.

  • Chickweed (Stellaria media) mat-forming, thrives in cool moist spots.

  • Shepherd’s Purse (Capsella bursa-pastoris) rosettes with tiny heart-shaped seed pods.

  • Wild Geranium (Geranium carolinianum) lobed leaves, pink/purple flowers in spring.

Chemistry Options Explained

“Yellow Herbicides” (Prodiamine, Pendimethalin, Oryzalin)

  • Called “yellows” because of their orange/yellow color.

  • Mode of action: Stop root and shoot growth by disrupting cell division in germinating weeds.

  • Long residual, great baseline defense in established turf.

Dithiopyr (Dimension)

  • Adds early post-emergent activity on very young crabgrass seedlings.

  • Good for a little forgiveness if timing is slightly off.

Indaziflam (Specticle)

  • Very long residual at very low use rates.

  • Must watch label restrictions, especially on St. Augustine.

Isoxaben (Gallery)

  • Strong broadleaf weed prevention, best as a tank-mix partner.

Atrazine/Simazine

  • Only for St. Augustine and centipede. Effective on poa annua and certain broadleaves.

  • Never use on Bermuda.

BES-TEX Product Lineup

Dry / Fertilizer + Pre-Emergent

  • Anderson’s 11-3-11 with 0.86% Pendimethalin (50 lbs)

    • Balanced fertilizer plus pendimethalin for broad winter weed control.

    • Great choice for established hybrid bermuda and zoysia.

  • 6-3-12 with 0.73% Prodiamine (Houactinite filler)

    • Same slow-release filler we use in our branded 16-8-8 and 21-7-14.

    • Excellent long-term barrier against annual grasses.

Benefits of Dry:

  • Fertilizer + weed control in one pass.

  • Steady feeding plus long-lasting weed suppression.

Liquid Pre-Emergent

  • Apply with a sprayer at 3 - 5 gallons of spray solution per 1,000 sq. ft.

  • Irrigate right after to activate the barrier in the root zone.

Benefits of Liquid:

  • Immediate activation.

  • Flexible for spot-treating and tank mixes.

  • Contractors and pros often prefer for precision.

Application Pointers That Matter

  1. Soil temps, not calendar. Wait until 70°F and dropping.

  2. Always water in. Label usually requires irrigation within 24–48 hours.

  3. Established turf only. PREs can slow stolon spread in thin lawns.

  4. Split apps where possible. Fall + spring = season-long protection.

Bottom Line

Turf scientists are clear: September is the window to stop winter weeds before they become a headache. With both dry fertilizer + pre-emergent combos and liquid options available, you can choose the route that fits your lawn best.

These two products are just part of the BES-TEX lineup. We carry many others, and we’d be glad to help you decide which pre-emergent is right for your yard. Stop by, let’s talk it over, and we’ll match the product to your grass and your goals.

BES-TEX Supply • 4512 Adobe Dr., San Angelo, TX 76903 • 325.653.1300