- Author: Rachael Long
- Author: Daniel H Putnam
This is the time of year that alfalfa fields provide a lush green carpet, outgrowing the damage from 4 months of cold and frost in California’s Central Valley. But not all fields are emerald green-some show the ugly, patchy, stunted evidence of a nasty little invader: stem nematode.
Of course you can’t see the nematodes (ugly or not) with the naked eye but they sure make the alfalfa look ugly.
Stem nematodes (Ditylenchus dipsaci) are causing significant damage to alfalfa fields again this year in the Sacramento and San Joaquin Valleys. These microscopic worm-like pests primarily move through fields in water and infect the above ground portion of the plants (crowns and stems)....
- Author: Rachael Freeman Long
It’s that time of year again when we need to start thinking about controlling weevils in alfalfa hay production. Egyptian alfalfa weevils are the most damaging insect pests of alfalfa in California, as the larvae feed on the foliage, causing yield and quality losses if left untreated.
The life cycle of the Egyptian alfalfa weevil is predictable. Adults spend the summer outside fields in protected areas, such as behind tree bark (for example, eucalyptus trees) and in crevices. In late fall or early winter, adults emerge and migrate into alfalfa stands. Soon after entering fields, they begin laying eggs in new and old or dead alfalfa stems. Hatching larvae make their way to the terminal buds and feed on the developing...
- Author: Steve Orloff
Dodder is a troublesome annual parasitic weed that infests alfalfa fields. Initial infestations are usually caused by sowing dodder infested seed (a good reason to purchase Certified seed) and by “sheeping off” fields with sheep that came from an infested field. Perhaps no weed problem is worse than an alfalfa field heavily infested with dodder. As a parasite, it lives at the expense of the alfalfa plant and literally sucks the vigor and life out of the plant. If left uncontrolled it can actually kill the alfalfa plant. It emerges as a rootless shoot and must attach itself to a suitable host within a few days or it dies. After it embeds its sucker-like structures (called...
- Author: Eric T. Natwick
The UC Statewide IPM Pest Management Guidelines lists many insecticides as effective for Alfalfa (http://www.ipm.ucdavis.edu/PMG/r1300511.html). However, these are not the only insecticides registered for control of Egyptian alfalfa weevil on alfalfa grown for hay in California. Some newer products have been evaluated for Egyptian alfalfa weevil control and are mentioned in this report. Most of those newly registered insecticides are formulations of two different insecticides in the same container and are referred to as ‘in-the-can-mixtures’. An important question that PCA’s and alfalfa growers should be asking is: “What are the potential benefits and/or...
- Author: Vonny M. Barlow
The alfalfa weevil complex, comprised of the Egyptian alfalfa weevil, Hypera brunneipennis, and alfalfa weevil, Hypera postica, is the most damaging arthropod complex in California alfalfa (Medicago sativa). If populations of alfalfa weevil are left unchecked, the larvae can cause severe defoliation, significantly reducing yields. Repeated use of insecticides such as organophosphates and carbamates has resulted in these insecticides being detected in surface waters, providing incentives to find alternative means to manage this pest. The alfalfa weevil is susceptible to the biological control agent Bathyplectes curculionis in many alfalfa-growing regions in the United States. Work...