- Author: Vonny M. Barlow
The blue alfalfa aphid, Acyrthosiphon kondoi Shinji, was first identified by entomologists in the spring of 1975 in the Imperial Valley of California. Since then it has become widespread throughout the state and has become established in Arizona, Nevada, New Mexico, and as far east as Kansas and Oklahoma. Both adults and nymphs feed on photosynthetic fluids from the leaves and stems of the alfalfa plant. Low to moderate populations of blue alfalfa aphid may cause little to no visible yellowing of plants. Blue alfalfa aphid feed in the new growth, at the tips and young leaves. After prolonged feeding, leaves will eventually turn yellow, starting at the veins, leaves will curl and wilt, and turn necrotic (dead). ...
- Author: Peter B Goodell
As reported in this blog by Dr. Godfrey, the Blue Alfalfa Aphid has been reported at high levels. Entomologists with UCCE continue to monitor the situation with Pest Control Advisors and IPM Professionals. Here is a summary of observations in the San Joaquin Valley in past two weeks.
Extent of Outbreaks
While populations are widely noted, the heaviest densities have been very localized. In the Buttonwillow area of Kern County, populations exceed the threshold of 40-50 aphids per stem for hay prior to cutting. There are reports of alfalfa being...
- Author: Daniel H Putnam
Yes, Virginia, there is a Free Lunch. Thanks to CA Crop Improvement!
All are welcome to attend the field day at UC Davis to see research plots on alfalfa, small grains, corn/sorghum, and canola/camelina/castor as biofuels. This is a great opportunity to meet others, learn about new varieties, pest management, IPM, and irrigation management.
California Crop Improvement offers a barbeque lunch for attendees. Many thanks to CCIA for providing...
- Author: Rachael Freeman Long
There have been several alfalfa fields in the Northern Sacramento Valley area that have been deficient in molybdenum (Mo or moly), which is unusual, but not unheard of for the Sacramento Valley. Symptoms of molybdenum deficiency are like those of nitrogen and sulfur deficiency: light green or yellow, stunted plants, caused by a lack of moly that is essential for nitrogen fixation by the rhizobium bacteria that live on alfalfa roots. There may be a region just south of Sacramento that may have alfalfa with somewhat low concentrations of Mo but as you go further south, Mo toxicity begins. Some low copper—high molybdenum soils have been documented in the Modesto and south areas.
Plant tissue testing is the only way to confirm...
- Author: Larry Godfrey
Spring is the optimal time for aphids to flourish. The cool weather is perfect for many aphid species to build-up high numbers. Some aphid species prefer hot conditions but as a general rule cool weather and aphids go “hand-in-hand”. Cole crops, roses, other ornamentals, etc. are stressed by aphids in the spring. Four species of aphids infest alfalfa with the pea aphid and blue alfalfa aphid being favored by the cooler conditions. The spotted alfalfa aphid prefers hot weather and the fourth species, the cowpea aphid, appears to also like hot conditions but populations have also been found at other times of the year.
How do you tell these species apart? A pictorial key is...