My old plan of attack was 1.5 qts per acre 2,4D Ester (4lb --1qt Lv-6)
mid May to keep them from producing seed and to weaken for a fall followup of 1qt per acre Tordon.
If I have a place I can collect bugs then I will leave an acre un-sprayed and plant bugs.
Plateau is used by many and will knock the spurge down for a period of about 2 years.
My new more effective line of attack is bio control.
I think if you can use bugs that is the most effective way to control and eliminate spurge.
Establishing a stand ( 2 years) and then collecting and moving them to other areas of infestation or to other spots of the same infestation will speed up the elimination.
I do not recommend haying these areas, so as not to disturb the growth of your population or to transfer seed when moving equipment or hay.
I don't even like to use any chemical in infestations./
If the bugs run out of Leafy spurge to chew on they die.
I have not seen any spray that keeps leafy spurge down for longer than two years. So in two years the spurge comes back up but the bugs are already dead. Then what do you have?
PAY SOMEBODY TO DELIVER MORE BUGS
Leave the bugs alone and let them do their work and eliminate the Leafy Spurge there and the new plants that keep coming up from the seed that has been in the ground for many years. If you walk out into a patch that has bugs in it you can see most plants don't have any seeds. The bugs already ate them.
The plant is still there but no seeds, so the bugs have it under control and over the winter will go down into the roots and eat on them
They wont eat on a sprayed plant and when it comes back to life the bugs might be gone.
If your local weed cop pushes you to spray only use 2,4 D Amine. That will keep the plant from seeding yet allow the plant to come back to life sooner so the bug can eat it, yet it shows you are spraying as requested.
You can help the bugs in the fall with a partial application of Tordon. Partial means don't spray all of the spurge in a patch. In the fall when the weather cools the bugs head for the roots. Killing the above ground plant will not hurt the bugs, in the spring (June) they will come back up, they have to have some live plants to lay their eggs on. New seedling from seeds in the ground will also have arrived for them to utilize. If you spray out a leafy Spurge patch in the spring and kill the plant growth, the bugs have no place to lay eggs or raise their young and your population dies off. Then you either have to replace the bugs or spray the Spurge every year for the next 20 years.
It takes Proper Manangement
You should spray your perimeters every fall to keep it from spreading to your neighbors
Updated 9/12/21
Know your bugs and then work with them.
If you have Leafy Spurge in Brule county SD contact me as I relocate bugs for people.
Kenny Konechne
http://www.team.ars.usda.gov/v2/publications/manuals.html#1
By spraying when the bugs have reduced the spurge you are reducing the effectiveness of the bugs. The bugs will never kill all the spurge but if there is a little spurge remaining there will be bugs in that site when all the seeds from the past years germinates. We have seen this when a landowner sprays out the last spurge and then a year is right for germination the spurge comes back and no bugs. We have also seen the same thing when the spurge has not been sprayed out and the bugs increased and cleaned up the spurge.
R.M.