- Author: Eric T. Natwick
Growers in the Imperial Valley, CA increasingly planted alfalfa during the 1980’s in heavier soils on raised beds as the field became more available due to diminishing cotton acreage. Growing alfalfa on raised beds with furrow irrigation helped growers to better manage alfalfa planted in heavier soils. Furrow irrigation of alfalfa on raised beds also provided ideal conditions for survival of cutworms, creating chronic cutworm pest problem by mid- to late-1980’s persisting until today. In this low desert alfalfa, the granulate cutworm, Agrotis subterranea (Fabricius) became predominant cutworm replacing the variegated cutworm, Peridroma sausia (Hübner). The increase in cutworm moth activity also caused...
- Author: Tunyalee Martin
It’s that time of year again when hot weather fuels the creation of ozone, or smog. Some pesticides emit volatile organic compounds (VOCs) that contribute to ozone formation. Using pesticides that release VOCs may be restricted in certain California locations between May 1 and October 31.
If you plan to apply a pesticide, use the Department of Pesticide Regulation’s VOC calculators to determine emissions from fumigant and nonfumigant pesticides. Get there by clicking on the Air Quality button at the top of each treatment table in the UC IPM Pest...
- Author: Carol A Frate
It’s not that I am unpatriotic, but in this context “flags” refer to isolated dead alfalfa stems with dead leaves still attached that are surrounded by healthy stems. The “flags” are usually light colored and the tips are often curled over like a shepherd’s crook or staff.
“Flagged” stems can be caused by several pathogens but when they appear in summer, are light tan in color and have the characteristic crook at the top, it is probably because the stem is infected with the fungus Colletotrichum trifolii (Figure 1). The disease this fungus causes is called anthracnose (it has also been called southern anthracnose). The most obvious symptoms...
- Author: Michelle Leinfelder-Miles
I recently received a call from a PCA who had questions about nematodes that infect alfalfa. He had observed stunted crop regrowth after the first cutting and had reason to think that nematodes could be the cause.
There are three nematodes that tend to be the most problematic in alfalfa. Stem nematode (Ditylenchus dipsaci) is a nematode that feeds on above-ground plant parts, unlike most plant-parasitic nematodes that feed on roots. To recap a blog by Rachael Long and Dan Putnam, stem nematode symptoms include stunting, shortened internodes, and even plant death when infections are severe. It is a fairly easy pest to diagnose if...
- Author: Rachael Freeman Long
- Author: Daniel H Putnam
- Author: Rollie Meyer
When is nitrogen fertilization of alfalfa beneficial? Almost never!
Nitrogen (N) fertilizer is generally not required for alfalfa production since alfalfa can obtain its own N from N-fixing nodules (Figure 1). Alfalfa fixes most (70-90%) of its N needs from the air through Rhizobium bacteria residing in alfalfa root nodules (Figure 1). Since 78% of our air consists of nitrogen gas, this supply of ‘free fertilizer' is inexhaustible. A recent unpublished UC Davis-CSU Fresno study showed 90% of N in alfalfa originated from the atmosphere -- but less when soil N levels were high, for example, in manured fields.
Although there have been some reports of yield and forage quality...
