- Author: Lynn M. Sosnoskie
A drive around parts of the San Joaquin Valley revealed some fields with Palmer amaranth (Amaranthus palmeri) rising above the crop canopy (See image below).
A male Palmer amaranth in a corn field in Merced County
Palmer amaranth is a tall (growing up to 10 feet in height), dioecious (male and female flowers develop on separate plants), summer annual that grows rapidly and produces significant amounts of seed (upwards of 400,000-1,000,000 per female plant). The species is extremely competitive with many crops, including corn and cotton. In the United States, Palmer...
- Author: Cheryl A. Wilen
One point I always make is that the sooner you control annual weeds, the better. The reduces crop-weed competition, along with a host of other issues caused by weeds (we'll save that for another blog). But the real key to forward-looking weed management is to kill the weed before it produces seeds. Once seeds are produced, they contribute to the seed bank, pretty much ensuring that the weed population will be a continual problem.
But suppose you miss some weeds that are starting to flower but the flowers aren't open yet? I think most growers will just pull or cut the weed and leave it in or near the field.
I want to show you a time-lapse video I took. I cut the flowering stem off of an...
- Author: Lynn M. Sosnoskie
- Author: Brad Hanson
- Author: Ted Webster
- Author: Stanley Culpepper
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Talking Points:
Weed control failures can and do occur.
Weed control failures occur for many reasons, including improper treatment applications and plant size and development at the time of treatment.
Plants that aren't completely controlled can produce viable seed and re-infest fields.
Insufficient control of herbicide-resistant weeds could facilitate the establishment and spread of undesirable traits.
Introduction:
Weed pressure, and the resulting competition for water and nutrients, can significantly impact crop establishment, growth, yield and harvest. Furthermore, there is some concern among growers that non-managed weeds may support...