Summer 2019
PENOXSULAM
Penoxsulam is a systemic herbicide that moves throughout the plant tissue and prevents plants from producing a necessary enzyme, acetolactate synthase (ALS). Susceptible plants will stop growing soon after treatment and become reddish at the tips of the plant.
Plant death and decomposition will occur gradually over several weeks to months. Penoxsulam should be applied to plants that are actively growing; mature plants require a higher concentration of herbicide and a longer contact time. Penoxsulam was originally designed for use in rice fields and is capable of killing several pest grasses that prefer wet environments.
Penoxsulam is considered slightly toxic to fish – however, I was not able to find much published information.
AGRIDEX
Agridex is a versatile non-ionic surfactant that enhances the effectiveness of range of other products. Agridex is used
on conjunction with other herbicides to improve cuticle penetration, coverage and canopy deposition.
Based on the results of searches of the published literature and the Toxic Substances Control Act Test Submission (TSCATS) database, little data are available regarding the toxicity of the surfactant formulations. Little info is readily available on if, or how, it may affect aquatic toxicity or affects to water chemistry.
Table 2 summarizes the applications of these herbicides in 2016 and 2017. In two years, more than 10,000 gallons and 337,086 lbs. of herbicides were dumped into our State waterways.
Treatment rates have been increasing - it seems like I get an email notification almost every other day all summer long.
If any other private entity would attempt this – it would never happen and they would be rightfully prosecuted to the full extent of the law.
Government programs would not permit it and activist groups would rally against it. You or I could not go down and spray Round-up in the Delta.
Table 2. Summary of treatment area, # sites, and quantities of herbicides
used in 2016 and 2017 per the CA State Parks Aquatic Invasive Plant
Control Program.
Herbicide
Year Area Treated # Sites
(acre)
Total Quantity
Glyphosate
2016 2017
3,347 2,888
224 3,101 gallons 418 2,536 gallons
2,4-D
2016 2017
929 285
-- 929 gallons -- 305 gallons
Imazamox
2016 2017
15 0
-- 3.71 ounces -- 0
Fluridone
2016 2017
2,442 2,940
28 138,976 lbs 47 198,110 lbs
Penoxsulam
2016 2017
5 0
-- 0.22 ounces -- 0
Agridex
2016 2017
-- --
-- 1,995 gallons -- 1,317 gallons
THE LONG AND SHORT
I acknowledge that there is a dire need to control invasive aquatic species – and I am not a staunch opponent, but I think there needs to be further assessment of potential effects to aquatic ecology and a greater focus on mechanical removal, with augmentation with herbicides as needed.
I just hope the end consequences aren’t catastrophic for all species in the Delta. I mean – how much money we spend to research and protect salmonids and Delta smelt – but we literally dump huge quantities of herbicides right back into their habitat.
Hopefully by providing this information – people will realize what, and how much, of these herbicides are being used.
Next issue – I will dive a little further into the results of the programs monitoring. Until next time – don’t drink the water. •
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