- Author: Carol A Frate
We may begin to see symptoms (stem wilting) and signs (white fungal mycelium growing on stems) of Sclerotinia stem and crown rot now that there has been some rain and fog. Although the fungus infects mature plants, we are most concerned when the disease infects fall planted fields because seedlings and young plants are more easily killed by Sclerotinia than established alfalfa plants.
The disease begins in the late fall/early winter when spore bearing structures (apothecia) are produced by the fungus on the soil surface. Apothecia production is triggered by cold, wet soil. We have had some cold weather and in many places in the Central Valley there has been sufficient rain to promote apothecia production. Spores,...
- Author: Larry Godfrey
As the weather turns cool, how will insects cope with this? Have you ever pondered what keeps insects from perishing in unfavorable environmental conditions; they obviously survive successfully and annually compete with us for crops. This may have not “been on your mind” as much as the last 49ers football game or the stock market ups and downs but nevertheless it is important. With the millions of species of insects in the U.S., there are also numerous strategies for dealing with poor weather. Depending on the species and geographic location, some species must deal with cold weather, some with hot conditions, some with extremely dry conditions, etc. In terms of cold and hot weather, the key difference...
- Author: Michelle Leinfelder-Miles
This blog is an outreach tool for alfalfa and forage information. We hope you will find it convenient and the information relevant and timely. From time to time, however, we may stray from posts on production and management to bring you other interesting information, as related to alfalfa and forages. In that vein, I would like to take this opportunity to tell you about AgVenture in San Joaquin County, which took place last Wednesday.
AgVenture is a field trip where third graders learn about the importance of agriculture in their county and in their daily lives. Modeled after a Monterey County program which began in 1992, AgVenture in San Joaquin County started in 2007 with 1,500 participants and has grown to over 11,000...
- Author: Carol A. Frate
In the second week of October, we had a one-to-three trifoliate seedling alfalfa field in Tulare County with plants dying on the north end. The surviving seedlings had leaves with holes and ragged edges. No insects were observed on what remained of the foliage and none could be found in the soil. Returning to the field in the warm afternoon, we walked further into the field where there was less damage. This time as we walked we observed small, dark insects moving quickly on and off the plants. However, when we stopped to look closely we couldn’t see them on the plants. Then we used a sweep net to sweep in front of us as we walked and collected dozens of pale striped flea beetles in the net. The adults are just 3/16 inch in length...
- Author: Vonny M. Barlow
Verticillium wilt disease of alfalfa is relatively new to California, having first been found in isolated fields in Humboldt and Monterey counties in 1985. Verticillium wilt is a disease caused by Verticillium albo-atrum alfalfa strain. Verticillium wilt is the most serious disease problem of alfalfa in the north-temperate areas of the United States, Canada, and Europe. In southern California the V. albo-atrum alfalfa strain was found in 28 of 52 fields sampled in Riverside and San Bernardino counties. Verticillium albo-atrum has a limited host range. The most important hosts of this pathogen include hops, alfalfa and cotton.
Symptoms of...
