What is in this article?:
- New glyphosate-resistant pigweed hybrid found in Mississippi.
- From pastures to row crops.
- How did it happen? What are the implications?
A SPINY AMARANTH/Palmer hybrid discovered in a Mississippi cotton field. Notice the flower head with male flowers between zero and 3 inches and fuzzier female flowers between 3 and 5 inches.
Recommendations? Treat it like a normal pigweed?
Molin: “Yes, treat it like you would a normal pigweed. Catch it early — two inches — and follow the recommendations from MSU for control of Palmer. If a grower uses the MSU recommendations for Palmer control, they should be able to control this spiny hybrid.”
How much greenhouse work is left before you have answers to your other questions?
Molin: “We should have those in another couple of months. That should go fairly quickly.
“However, everyone knows our ditch banks are simply loaded with pigweeds. Because we found this on the field’s edge, there’s a real concern that equipment moving in and out of the field can move seed into another field.”
Nandula: “(The spiny hybrid) can act as a back-up to the resistant Palmer already there.”
Has word filtered out on this yet? Are producers already looking for this?
Molin: “That’s part of the purpose for this article. We want growers to be aware this has happened.
“While it was predicted for other species, we didn’t expect it with spiny. A pasture weed is now being found in row crops. It may turn out to act very much like Palmer.
“Spiny amaranth has spines about a centimeter long. It’s a miserable plant to have in a pasture. Some of the spiny that have come out of the row-crop field also have the spines. So, that’s another characteristic that makes this an undesirable plant to have around.”
If farmers find something that looks suspicious do you want them to contact you?
Molin: “They can call me but should also alert the county agent. That would be great so we can identify any new populations and see where it has moved. We need to study this thoroughly.” (William.Molin@ars.usda.gov; email@example.com)
“Obviously, Palmer can hybridize with spiny. But it can also hybridize with waterhemp. If that happens, it would be a really serious development. If producers suspect they’ve got a spiny or waterhemp hybrid, let us know. We would like plant samples, as well.
“Of course, they also need to contact their Extension agents to make sure they have a proper control program in place. We must reduce the impact of these weeds.”
Nandula: “In Mississippi, we have lots of Palmer amaranth resistant to glyphosate. Some is also resistant to Staple, an ALS. However, we haven’t found any PPO resistance.”