- Author: Sharon Lawler
- Author: Maribel Portilla
- Posted by: Guy B Kyser
Mosquito research by Maribel Portilla and Sharon Lawler recently included an experiment on how Egeria, or Brazilian water weed, affects mosquito populations. Egeria is a submersed aquatic weed that can cause problems in channels and irrigation waterways. Mosquitoes also breed in stagnant waters, but, we asked, is this because of the weeds?
We used large cattle-watering tanks to simulate stagnant, back-water areas with and without infestations of Egeria (Figure 1). Five tanks had no weeds, five had healthy Egeria, and five had Egeria that was sprayed with the herbicide fluridone. We added zooplankton and insects colonized naturally.
Interestingly, there were fewer...
- Author: Amber C. Vinchesi
We are a little over a month into the processing tomato season. I have received a couple of farm calls regarding herbicide damage or symptoms originally thought to be diseases. The first was trifluralin injury to young tomato plants. These samples were brought in to confirm that it was in fact trifluralin injury and not corky root rot. Corky root rot in tomato presents as corky bands on the roots with brown lesions leading to cracking of the cortex on larger roots. The tips of older roots may be pinched off. Small roots may be decayed and the tomato plants may be stunted. Trifluralin injury to tomatoes presents as root stunting, callused stems, swollen crowns, leaf distortion, stunted plants. It can look very...
- Author: Chris McDonald
Ralph Waldo Emerson, called a weed a plant whose virtues that have not yet been discovered. I disagree, and yet generally speaking he is correct, what we call a weed is in the eye of the beholder, a plant that it is not helpful, useful or wanted.
An invasive plant by definition in Executive Order 13112 (Feb. 3, 1999) is a plant whose introduction will likely cause economic or environmental harm, or endangers human health. The same EO also defines alien weed. Generally speaking this is the best agreed upon definition for invasive weeds (causing economic, environmental or human harm). Not everyone uses or knows about this definition, and I hope I am consistent in using it too.
Noxious weeds are generally those that are...
Automated lettuce thinners that use a spray mechanism to remove unwanted lettuce plants and weeds have been widely adopted in the Salinas Valley and desert production districts. The machines utilize a camera to capture images of the lettuce plants in the seedline, calculate plants that need to be removed and those that will be kept (keepers) and then it activates a spray mechanism treat the unwanted plants. The spray mechanism has advantages over mechanical devices (e.g. swinging or spinning blades) because they do not disturb the soil or cut roots, and in addition, they have less inertia and can be quicker in responding to a signal from the computer. However, spray mechanisms can potentially drift or wafting control materials onto the...
- 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.