Insecticide resistance in alfalfa weevils is spreading across California
JUST HOW DRY IS IT?
It really doesn't look good out there for many western alfalfa growers. Most parts of the West are currently under 'severe, extreme, or exceptional' drought.
One would think that NOAA and USDA would run out of superlatives! (how about 'excruciating'?).
Figure 1. Drought status, April 28, 2022 (Drought Monitor, USDA, NOAA).
Normally our wettest months, the first four months of 2022 were some of the driest on record for California, which does not bode well alfalfa and other crops. Many of our...
During the 2021 season, we conducted an insecticide trial evaluating a new insecticide being developed for a range of crops. It could be a very good fit for alfalfa weevil given the efficacy we saw as well as the critical need for novel modes of action for alfalfa weevil management. The need for more modes of action comes from the growing issue with pyrethroid resistance in alfalfa weevils. Across the US (an in California), there are now populations of pyrethroid-resistant alfalfa weevils. We are addressing this in a separate project, focusing primarily on resistance to lambda-cyhalothrin. New modes of action could allow for rotation, something that is very difficult given that currently, effective options are mainly limited to...
DIAGNOSING A FIELD PROBLEM
Can applications of Calcium (Ca) fertilizers improve plant nutrient uptake or improve soil properties in alfalfa fields?
These questions were presented to us by an alfalfa grower in the Sacramento Valley of California where low soil Ca levels were observed.
Soil samples were taken from 9 different alfalfa fields in Yolo County in the fall of 2021 to assess nutrient needs. This farmer had done an excellent job of maintaining P and K levels, but calcium levels were often low: ranging from 1.0 - 4.0 meq/l. Anything less than 4.0 meq/l calcium is considered very low. Were these calcium levels too low...
- Author: Apurba Barman
- Author: John Palumbo
- Author: Michael Rethwisch
A new caterpillar pest was found infesting alfalfa fields in Imperial County.
It was first observed in mid-September when pest control advisers brought it to our attention (Apurba Barman and Jon Palumbo). This pest has not been previously observed in low desert. Based on the photo of the larvae Michael Rethwisch (UC Cooperative Extension-Riverside County) identified this pest as alfalfa leaftier, Dichomeris acuminatus (Staudinger, 1876). John Palumbo also found alfalfa fields infested by this pest in Yuma, Arizona area. Subsequently, larvae and adults from a laboratory reared colony were sent out to California Department of Food and Agriculture in Sacramento, and expert there confirmed our initial...