- Author: Rachael Freeman Long
- Author: Ian Grettenberger
Painted lady butterflies (Vanessa cardui) are dazzling us with color, but surprising us with sporadic finds of caterpillars on crops this year, including alfalfa, pistachio, walnuts, artichokes, and hybrid sunflower (see IPM Advisor Emily Symmes blog: What's that Caterpillar on my Weeds?).
Painted lady caterpillars primarily feed on weedy hosts such as Malva (cheeseweed), plantago, cocklebur, star thistle, and some legumes, especially lupines, but NOT alfalfa or close relatives. They do not breed on alfalfa or tree crops, so while one may find larvae in these crops, they should not cause any...
It is both a blessing and a curse that alfalfa in California's Central Valley essentially grows all winter long. Although we can get very high early yields, if conditions are too wet, the fields look pretty ragged after a winter which saw rains in excess of 130% of normal.
However, alfalfa is a resilient crop and can likely recover from disease infestations.
Here comes the sun. Warmer, drier weather in the coming weeks is just what we need to dry out water-logged alfalfa fields and get them growing. Rainy, cold weather is a double blow for plants, especially in saturated soils where the crop is growing slowly, so it is more susceptible to diseases favored by moisture. This includes foliar diseases,...
There is little doubt that the heavy late rains we've seen in spring, 2019 in the northern part of California will reduce yields and quality for many alfalfa growers.
How much depends upon soil type and the flooding risk of individual fields and the health of the plants during this stress period.
Roots are often damaged during extensive wet periods, and the remaining roots need mostly time to recover as the weather improves.
When alfalfa is dormant and not growing, it's fairly tolerant of saturated soil conditions. When it begins to break dormancy, and it's cold and wet, plants will start growing, but slowly, making us wonder if there's going to be a reasonable first cutting.
However, when soils begin to...
Have you seen this crop injury in your Roundup-Ready Field or conventionl field? If so, we want to hear from you.
We are asking alfalfa growers everywhere to look for the following symptoms (below) of injury in Roundup-Ready (or RR-HarvXtra) alfalfa or even in conventional fields. It's unusual, but we've observed it under specific conditions, usually after glyphosate applications in the spring.
Figure 1. Stunting of alfalfa after applications of glyphosate (Roundup) under controlled conditions, Northern California.
Have you seen these symptoms in your field? If so, please fill our our survey. Here, we are trying to understand the conditions that may...
- Author: Rachael Freeman Long
- Author: Dan Putnam
In a period when we've had high rains, it's very difficult to manage excessive winter growth in a Mediterranean climate.
We're familiar with the term 'sheeping-off' for describing the use of sheep to graze alfalfa fields during the wintertime to remove thatch, weeds, and help with weevil control (see ‘Sheeping off' alfalfa is a win-win for all!).
But how about 'goating-off'? Doesn't sound quite right, but close winter grazing by goats is likewise an effective pest management practice, just like sheep. When grazing with sheep or goats, timing is important. Watch for excessive soil compaction when rainy and wet and do...