The gather page indicates that boosters will be given after 30 days.
This corresponds to neither of the options in the response to comments of the DNA.
As of today, the EPA has not published an update to the pesticide label, so the 90-day interval holds.
RELATED: Buffalo Hills Roundup Ends Early.
UPDATE: The BLM news release reiterates the 30-day interval.
Western Horse Watchers Association 