This week in U Del Weekly Crop Update:
- Remove Weeds Before the Seeds Mature
- Livid Amaranth
Remove Weeds Before the Seeds Mature
Many weeds have started to flower in the past week or two. Weeds, depending on the species, will continue to flower from now until frost. I am often asked how soon after flowering are the seeds mature. We have some ongoing trials looking at this issue, but we have a few preliminary results to share.
First and foremost, seeds are mature shortly after flowering. By this I mean that within two weeks of flowering, the seeds on some plants are capable of germinating and contributing to the weed seedbank. So if you are pulling weeds (or mowing them or spraying them) to stop them from producing seeds, you should physically remove the weeds from the field because they may already have mature seeds.
I have only seen two samples of livid amaranth (also called livid pigweed) in the past 15 years, but both of them came in this year. In neither case was the grower overly concerned about the plant, rather it was more of a curiosity. Livid amaranth is a pigweed that generally is shorter than our redroot pigweeds and often paler in color. It is distinguished from most of the other pigweeds because it has a leaf tip that is noticeably “notched” (see photo below). It has been in the region for a long, long time, so it is not a new species, but it is interesting that I was asked about it twice this summer.
More photos and short description can be found at the Univ. of Massachusetts Weed Herbarium website: