- Author: Lynn M. Sosnoskie
- Author: Brad Hanson
Prior to the latter half of the 20th century, weed control in agriculture was achieved almost exclusively through mechanical means (e.g. plowing, cultivating, disking, hoeing, and hand-pulling) (Timmons 1970). The earliest (mid-1800’s to mid-1900’s) investigations into chemical weed management focused, primarily, on the use of inorganic compounds such as sodium chloride, sulfuric acid, sodium arsenite, and copper- and iron-sulfate (Appleby 2005; Timmons 1970). Although some products provided an acceptable level of weed control efficacy, the extensive adoption of these chemicals was decidedly limited (Appleby 2005; Timmons 1970).
The successful debut of 2,4-D (1946), an auxinic compound...
- Author: Brad Hanson
Earlier this year, Lynn posted an explanation of herbicide modes of action and what that means for herbicide resistance management in orchards and vineyards.
I thought to myself "Self, we should put this in a table so it would be easy to understand". Then I remembered that we actually did this already in one of the four glyphosate resistance publications that I mentioned in an August posting.
Here's an excerpted table from ANR Publication 8501 "Preventing and Managing Glyphosate-Resistant Weeds in...
- Author: Brad Hanson
In the past couple of years, I've gotten a lot of questions about goosegrass in orchard production systems, particularly about suspected glyphosate-resistant biotypes.
From a California orchard standpoint, we have two main goosegrasses (Eleusine spp) to deal with; these are goosegrass (Eleusine indica) and threespike goosegrass (Eleusine tristachya). These species are fairly similar but have quite different flowers (see the photo below).
According to the Weeds of California and Other Western States, goosegrass is a summer annual (or occassionally a short-lived perennial) while threespike goosegrass is a perennial (or sometimes...
- Author: Marie Jasieniuk
Horseweed and hairy fleabane are closely related annual weeds that are widespread in Central Valley orchards and vineyards where many populations have evolved resistance to glyphosate. Interestingly, however, the geographic distribution of glyphosate resistance differs markedly between the two weeds.
A survey of 42 horseweed populations across the Central Valley in 2010 showed that glyphosate-resistant plants were abundant across the southern part of the Valley but that horseweed in the northern part of the Valley was still largely susceptible. In contrast, a survey (unpublished) of 35 hairy fleabane populations in the same general...
- Author: Brad Hanson
A followup today on a post from last October about a series of glyphosate-resistant weed extension publications that were "about to be finalized". These four paper finally wound their way through the review and publication process and were posted on the UC ANR Catalog last week.
Brad
Selection pressure, shifting populations, and herbicide resistance and tolerance. Hanson, B., A. Fisher, A. Shrestha, M. Jasieniuk, E. Peachey, R. Boydston, T. Miller, K. Al-Khatib. 2013. University of California, Division of...