Looking around the web, it seems that livestock will avoid the stuff if they have something else to chose from.

At the link is the CSU extension info on leafy spurge. Looks like a system of pasture management to keep healthy grasses on the up while spraying the stuff the article ends up with:

Regardless of the management system used, a combination of methods is essential to return leafy spurge-infested ground to a productive state. The key to control leafy spurge or any creeping perennial is to exhaust the root nutrient stores, causing it to collapse. Persistence is imperative to gain control.

That idea seems to be the case for a lot of noxious, toxic weeds. Here, we have Russian nap weed as well as the spurge. Guys with horses go out and spray every month or so.

Here is a link that might be useful: link

I'd be more concerned with the flea beetles as a control. That'll be fun to control in your veg garden.

There are a number of different species of flea beetles. The 4 that have have been released in the US appear to prefer leafy spurge. What effect might spraying have on those beetles?

The only really remarkable instance I've seen of effective insect control over an invasive plant species is the little fella that eats tamarisk - they've denuded miles and miles of Colorado River tributaries.

I'd be more inclined to carefully spot-spray the weeds with a broad-leaf herbicide, something listed in the linked article, and really work on building up the pasture grasses.

Leafy spurge is one of the worst weeds in the western US. There are beetles that are only for leafy spurge and goats will eat it. The bad part is that the roots can go up to 12 feet and longer and sprout from those roots and the seed explodes if let to go to seed for quite a distance. Keeping it from growing but cutting its leaf source and destroying the cut off part before it goes to seed is a long process to get rid of it. It can take years even with a lot of work on it.

If you want to keep the flea beetles away from your veggies, do a big planting of Asian daikon radish and gourmet lettuces. I've learned over the years that those are their favorites.

I can't imagine anything being worse than Canada thistle.

Hm, clearly I wasn't aware of the specific flea beetles for control. It is very hard to eradicate around these parts, and volunteers are sent out to knock them down before they go to seed. Not the best control, but cheeeep.

They have spent years gathering specific pests for knapweed and leafy spurge. They were growing some at the Western Ag Research Center but the the guy retired so no more there. They have to find ones that do not target anything else in case they would eat someting they don't want to lose. They had 5 insects for knapweed and 2 of those have definitely made a dent in the acres and acres of knapweed here. So sad to go way up in the mountains and see it everywhere where it should be wilderness.

So sad to go way up in the mountains and see it everywhere where it should be wilderness.

I've backpacked all over the west, and yes. Each place has its weeds, some subtle, like California being the "Golden State".

There is nothing at all like going fishing along some of the streams around here - first, wade through a meadow of 4 foot high thistle plants to get to the Russian olives and tamarisk that line the bank, then hop in the water, stepping on invasive crawdads crawling around in whatcha-call-it, that horrible invasive moss.

The browns don't seem to mind.