bad biologist ???

Obviously you've never read the label or used it, prickly pear is one of the several dozen plants Sendero is labeled for use on.

It is in Table 5; Mesquite and associated woody plant control, directly under Mesquite.

Biggest problem with 98% of people that use herbicides, they never read & follow the label.

Sendero + surmount (or tordon22k/triumph22k/picloram22k)+ surfactant + water + dye = dead pear.

Surmount on its own mixed and used per label in a pump up sprayer will kill every cactus it touches. think I mixed it 4 oz surmount 1 oz surfactant and fill up 2 gallon sprayer to the line. then take off. I tried the dye, but just made a mess with it and couldn't tell where I had been. walk in a grid pattern like your looking for a dove. Good luck.

That's all. No water.

Tordon 22k or surmount either one will work mixed with water and a surfactant (not dish soap) and die if you are doing ipt with a hand sprayer. It with take two three years to completely kill it. You can burn the pasture and wait until new pads get the size of a silver dollar then spray using a reduced rate and get a quicker kill you must do this within five months of a burn. I like to mix it with cimmaron Max to kill broadleaf weeds and use a 60 foot boom sprayer or a helicopter myself . Cows will eat pear no matter what . Once you have them started on it the only way to make them stop is to move them where there is no pear. Fire is the best tool for reducing cactus and cedar plus it promotes grass and forbe growth for wildlife and cattle. Mesquite is the devil but Sendero will keep it in check . You could always use spike in the fall and kill everything known to man and have a great grass pasture and not much else. Remember the label is the law.

What I've been using for years. Spray in the Spring, it needs a rain on it to soak it in the roots.

picloram is the key ingredient for killing pear tordon, surmount and vista have it in it, not sure about sendero. straight diesel, diesel and remedy, and others will make you think you have killed it but it seems to come back unless it contains picloram. diesel and spray are not cost effective.