I agree, good post. Not sure thou that it is the cost of imazapyr as to why it isn't used, imazapyr is probably the most cost effective chemical for killing trees. Triclopyr is not soil active, imazapyr is. More might be better with glyphosate or triclopyr but not with imazapyr, I try to keep track of about every drop of that stuff and I have had some colateral damage.
G
You're right George, Imazapyr is the most powerful chemical in the group that starts with the name Imaz. Here's a simple breakdown on this confusing family of herbicides (I have only ever used Imazethapyr):
Imazapyr,
Imazethapyr, and
Imazapic are all Imidazolinone herbicides in the same family. They all work by inhibiting the enzyme "acetolactate synthase".
Imazapyr kills more weeds than Imazethapyr and is more persistent (up to 2 yrs), used for pre- and post-emergent control of a broad range of weeds, including woody species and aquatic weeds. Imazapyr can persist in soil for extended periods, potentially harming nearby desirable plants. Imazapyr is generally considered to be relatively safe for fish, so it is often used for aquatic treatment. Imazapyr is not safe for legumes. Imazapyr is considered a high leaching hazard after terrestrial applications, moving along with water. Trade names include Arsenal, Chopper, Stalker, TVC Total Vegetation Control, Assault, and Habitat.
Imazethapyr is less persistent (up to 1 yr) and is also used for pre- and post-emergent weed control, often in soybeans and other legumes. Imazethapyr is safe for legumes. Imazethapyr also has a high leaching hazard. Trade names include Thunder, Pursuit, Hammer, Overtop, Passport, Pivot, Resolve, Contour, Praxis, Pemex, Zepher Max, Cheetah, and Willowood.
Imazapic is more persistent in soil than imazethapyr. Imazapic is primarily used for controlling grasses and broadleaf weeds in wildlife areas, pastures, and rangeland. There are Imazapic herbicide tolerant native wildflower mixes available that make Imazapic popular for prairie restorations. Imazapic is considered an environmental hazard due to its potential harm to aquatic life. Trade names are Plateau, Panoramic, Propose, and Cadre.