Palmer Amaranth – a Dangerous Weed

What is one of the fastest spreading weeds in the Corn Belt? This weed is a cousin of pigweed, called Palmer Amaranth. Beware, it is a dangerous weed, spreading fast and unless stopped in its tracks it could cause serious economic losses. Some of the facts about this weed are given below:

• Palmer Amaranth is an annual broad leaf weed which is related to other Amaranth species like, Waterhemp and Redroot Pigweed .
• This weed grows faster than other pigweed species. It can grow 2-3 inches per day. Some studies in the south have reported it can reduce corn and soybean yields from 70-80 percent if not controlled.
• Palmer Amaranth has already caused a lot of problems in the Southern United States and is marching north and east, spreading into Illinois, Indiana, Michigan and Ohio.
• In Nature, the Species that can produce a lot of seeds can spread fast and quickly colonize large areas. Each plant of Palmer Amaranth can produce up to one million seeds. The heads containing the seed can be more than 20 inches long and each plant can produce multiple heads.
• We need an aggressive management approach to control the spread of this weed to protect our crops. Prevention is much better than control of this dangerous weed.
• Now that most of the crops are finally in the ground, we must pay attention to weed control, especially if Palmer Amaranth is suspected. As with all weeds, it is easier to kill them when they are small. For me, the only good weed is a dead weed.
• Most of the Palmer Amaranth populations are resistant to glyphosate and ALS herbicides, although some atrazine resistant populations have been found.
• Glyphosate and ALS resistant populations of Palmer Amaranth are going to be tough to control.

Some of the strategies recommended by Purdue scientists are:
1. Use of suitable herbicides
2. Crop rotation
3. Deep tillage to bury the seeds of Palmer Amaranth.
4. Use Crimpled cereal rye grass as cover crop.
5. Keep the drainage ditches and field borders free of Palmer Amaranth