- Author: Lynn M. Sosnoskie
Recently I was asked to help identify prostrate knotweed (Polygonum aviculare) that was collected from an alfalfa field. Admittedly, the tough and wire-like specimen that was submitted to me at the end of autumn didn't much resemble the succulent seedlings that I have often observed emerging in tree and vine systems in early spring. Consequently, I dug out my 'Weeds of the West' and 'Weeds of California and Other Western States' books and double-checked with colleagues to ensure that my ID was accurate. This post is meant to build on that effort and describe the morphological traits that are characteristic of prostrate knotweed and how to differentiate the species from a similar-looking weed, spotted spurge (Euphorbia...
- 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: Pratap Devkota
I visited an onion field where I saw this interesting emergence pattern with annual bluegrass (Poa annua L.). Onion beds are listed in east-west orientation (as seen in pictures). We can see annual bluegrass emergence only on the south facing slopes and none on bed-tops or north facing slopes. These pictures were taken around noon, the exact time was 12:44 PM. I assume that cultural and irrigation practices are same throughout the field. The only difference I observed was north facing slopes were shaded, but the bed tops and south facing slopes had ample light. With this situation, I am wondering what could be the possible reason for annual bluegrass to emerge on the south facing slopes but not on the bed-tops and north facing...
- Author: Guy B Kyser
This is only somewhat weed-related... just an excuse to post some photos of fossil tomatillos, from the days when Africa and South America formed the single continent Gondwanaland. If you have lanceleaved groundcherry (Physalis lancifolia) or one of the other Physalis species, this is where it came from.
- Author: Lynn M. Sosnoskie
This is the abstract and a poster from a presentation that I made at the 2016 Weed Science Society of America meeting in San Juan, PR. The results were generated from one run of each of the experiments. At this time, all of the studies have been replicated, the data is being analyzed and the manuscripts are in preparation.
JUNGLERICE (ECHINOCHLOA COLONA) GROWTH AND DEVELOPMENT IN RESPONSE TO TEMPERATURE AND SHADE.