We talk about herbicide resistance all of the time in California rice, but how does it evolve in a field? Understanding how herbicide management selects for resistant populations is an important part of preventing the problem from occurring in your fields.

We have many weed species in CA rice that are confirmed to be herbicide resistant. The major herbicide-resistant species are late watergrass, early watergrass, barnyardgrass, smallflower umbrella sedge, ricefield bulrush (roughseed), sprangletop, and redstem. For this illustration of how herbicide resistance evolves in a field, we use redstem as our example. 

Year 1, Beginning of season: A population of redstem is found in a...

Annual bluegrass is a common winter growing grass in agricultural and urban environments. It is a well-known weed of turfgrass systems but its ability to grow in a range of environments makes it an increasing problem for other agricultural systems. Annual bluegrass has a short life cycle which may range from annual to perennial, seeds can germinate rapidly and multiple times in a growing season and has a high degree of survival when defoliated or trampled (Galera, Chwedorzewska et al., 2015).

All of these traits make chemical control an attractive and primary mode of management for annual bluegrass. This is true for turfgrass systems where managers use regular applications of PRE and POST herbicides and orchard systems where...

Here's something from the Aquatic Plant Management Society blog :: posted Feb. 2017
(Original source: East County Today)

DBW Begins Herbicide Treatment in the Delta for Water Hyacinth and Egeria...

In June 2016 the Madsen team revisited the site of our 2015 surfactant study to establish a more extensive test of aquatic herbicides for controlling waterhyacinth in the Delta.

Recall that in summer 2015 we established a preliminary trial to evaluate waterhyacinth response to different aquatic surfactants with glyphosate, using our famous floating quadrats with color-coded swim noodles (Figure 1).

By season's end, the crawdads had chewed up most of the swim noodles, so this year the quadrats underwent a slight redesign. We used thinwall 2” PVC, no noodles, and no fencing (Figure 2). (Calculating the enclosed volume and the weight per linear foot, we figured we had 8 to 10 pounds of ‘float' per...