For a little over a decade, weed control in the Mid-South was as easy as 1-2-3. A post application of glyphosate on Roundup Ready crops could protect growers from fast-growing weeds, adverse weather impacts on timing and the high costs of preventative weed control.
But with the onset of resistant weeds, particularly glyphosate-resistant pigweed, growers are having to develop new strategies for weed control and pull some old tools from the closet. The era of post emergent weed control is officially over.
There hasn’t been a pest like glyphosate-resistant pigweed since the late 1800s, when the boll weevil entered Texas and began a devastating march eastward, destroying cotton and forcing producers into developing new strategies, or face crop failures.
Now it appears as though pigweed has undertaken a similar march in the opposite direction. Resistant pigweed first appeared in Georgia in 2005, and with the recent confirmation of glyphosate-resistant pigweed in Louisiana, every state in the Mid-South is now infested.
On a recent trip to Lubbock, Texas, I saw a huge cotton crop being prepared for harvest. (It’s amazing to see so many bolls loaded on such a small plant). I was alarmed, however, to see what appeared to be pigweed thriving along field borders and in some cases, out in the fields.The Texas crop looked very clean for the most part, but those pigweeds looked like an advance patrol looking for a place to attack.
To take back fields, weed scientists say growers need to kick pigweed where it hurts – this being the short longevity of its seed in the soil. Up to 80 percent of pigweed seed die within one year in the soil. After 4.5 years, virtually none of the seed, 99.9 percent, are viable.
Weed scientists believe if growers can systematically reduce the seed bank, or the population of viable seed in the soil, they can slowly start to clean up heavily infested fields. Techniques to accomplish this include tillage and cover cropping, overlapping residuals and hand chopping. The system can also be used to keep pigweed from reaching yield-robbing populations in the first place.
Mid-South growers have faced some big threats over the last 20 years, but glyphosate-resistant pigweed could be their biggest test yet. Pigweed control will prove expensive, but I don’t see growers backing down from the fight.
If you’re looking to arm yourself with the latest techniques on pigweed control, be sure to attend the PigPosium, Nov. 17, at 8:45 a.m., at East Arkansas Community College, Forrest City, Ark. Delta Farm Press and the University of Arkansas Cooperative Extension Service are presenting the one-day seminar of reports and recommendations from a blue ribbon panel of weed scientists and other experts.
Think of it as Round 1 of the fight. Don’t be shy about fighting dirty. Kick pigweed where it hurts.