I have used Grazon for many years.
We have hired a guy to apply Grazon to our pastures and pens once/twice a year. Last year, I took the state's pesticide applicator's course, and I now have a license to buy and apply the herbicide myself. (Plus I can buy all sorts of other restricted pesticides and such). I have not yet bought Grazon myself and applied it, but I am planning on doing it myself this year.
We bought some bad hay that was full of weeds about 7 years back. That hay gave my pastures "hog weeds" everywhere it had been. These "hog weeds" took OVER and NOTHING will kill them. Except Grazon.
We tried Roundup but that just made them grow bigger. We tried mowing, but that made them thicker. We tried hand-pulling them, but that didn't work either. The ONLY herbicide that will kill the "hog weeds" is one that is restricted to licensed applicators. I had help from my county extension agent on identifying the weeds, and how to treat. Also, getting into the course.
So these "hog weeds" have big thorns on them! And they get up to about 3 feet tall, and have an underground root system that chokes out all of the grass. A baby hogweed can go from 2" tall to 3 feet tall in about 2 weeks! And they absolutely thrive in drought conditions.
Compounding the problem, is the issue of my smaller pens being "overgrazed". We could have Grazon applied to the large pasture, and get great results. But in the smaller pens, where horses were constantly trafficking on the soil, the grazon would kill the "hog weeds" and there was no grass coming in to replace where the hog weeds have been. These "hog weeds" have millions of seeds on each plant, and the seeds can stay in the soil for YEARS.
So, another big key to success with Grazon is RESTING the pasture. I could accomplish that in the big pasture, so it survived well, but the small corrals were full of the horses that had been taken out of the big pasture!
So now we have 15 pens that measure approximately 10 x 12, each with its own loafing shed. I have to pull EVERYONE off the pastures and we tore down the corrals we had and made them into small pastures. The horses are not given free access to graze during the time period that we are reconditioning the pastures.
We are also going to fertilize this year, which will help the grass to return. If the grass has a good hold on the soil, the hogweed can't come back. Its when the horses strip the grass down, and then their hooves turn up the hogweed seeds when they walk/trot the barren areas, that the hog weed comes back.
I experienced absolutely no problems due to the application of grazon. We have applied it with horses grazing in the pasture, pregnant mares, and breeding stallions, and no problems.
However, again, the best scenario FOR THE GRASS is to pull the horses off of the pasture.
Grazon WILL KILL all broadleaf weeds, and brush, and even young trees and domestic plants. It won't kill the grass or your livestock. But if you get some of the spray onto your flower beds, yard bushes, and such, they will be dead.
We had planted 30 bradford pear trees going up the driveway. A tiny bit of overspray from the Grazon and you have DEAD trees. It can hit the trunk, but not the leaves. So if there is any wind, it will drift into your other "good" plants and kill them. Every year we have lost 2 or 3 of the bradford pears, after Grazon was applied. So that has been disappointing.
The guy I hired would only use his tractor to spray the Grazon. His nozzles were not properly set to keep the drift down. Also, in my small pens, he could not control the drift as he maneuvered the cumbersome tractor in the small spaces. That is why I now have a spray rig that I can pull behind the lawnmower, and I will take the time to apply it by hand, to keep it off my trees.
Charlotte: Make sure that Grazon is what you need (there are also varieties of Grazon, mind was P-D). Get your extension agent to identify the weeds giving you problems. IF Grazon is the only thing that will kill them, then that is the way to go. However, there might be another product sold over the counter that would suffice...
Either way, RESTING the pen to allow the grass to come in (and thus choke out the weed), FERTILIZING the area to balance the soil's pH in such a way that weeds can't grow as easily, and REPEATED applications during the growth phase of that weed, are crucial. ...you have to hit them when they are 3" tall or less, to really be effective. IF they get big enough to produce seed, you'll kill the plant, but the seeds will start a whole new wave of weeds.
Your mares will be safe with Grazon. Mine did fine. I even got confirmation from my vet that it would be safe for the horses. But the weeds will come back if you don't remove them from the pens for as long as it takes for the grass to get a good hold. And your money spent on Grazon will be wasted.
Lauralee
