Every time someone talks about Palmer amaranth and how nasty it can be as a weed in your field, they usually get around to talking about how many seeds a single plant can produce. Sometimes they say a million seeds. Sometimes it's 500,000 to a million. Others speak in terms of just several hundred thousand seeds per plant.
According to a Purdue University research student, it is possible for a single plant to produce that many seeds if it is isolated by itself, but that's far more than a normal plant produces. However, he in no way intends to underestimate the veracity of this 'take-over-the-farm' weed.
The number in a normal stand of Palmer amaranth where there are many plants competing is more like 3,500 to 140,000 seeds per plant, Doug Spaunhorst says. He's assisting Purdue University weed control specialists Bill Johnson, Travis Legleiter and Brian Young in plots near Twelve Mile.
While that's a wide range, his work shows that in a thick stand 15,000 seeds per plant may be more normal.
However, he is by no means downplaying the weed's ability to spread, he asserts. It's still a huge amount of seed, he agrees.
The other problem for those wanting to control it is that Palmer amaranth continues to emerge throughout the season from seed. A tillage pass stirs up a new batch, and you can expect a flush of new plants one to two days after tillage, he observes.
Even plants that are two feet tall begin to produce seed, he adds. Seedheads eventually become up to 20 inches long, but even when they are only a few inches long and still growing, they can produce mature seed.
They can also grow from 21 to 42 inches, doubling in size, in about a week during the middle of the summer, he notes.
No matter how many seed it produces, Palmer amaranth is still one tough customer.
In the coffee shop, it is known as Palmer pigweed. In university circles, it is referred to as Palmer amaranth. Whatever you want to call it, this weed is the No. 1 weed to watch. Stay on top of your control plan with our new free report, Palmer Amaranth: Understanding the Profit Siphon in your Field.