Did you spray it, or did you use it as a root drench? If as a spray, you could literally wash it off. If as a root drench then you would need to flush, but I wouldn't recommend flushing with just water, I would use a mild nutrient solution so as to not shock the plant too hard.
How do the plants look? That's the most important thing right now.
And, btw, thanks for making your thread title make sense in context with the actual question. Thanks for not posting just the word "HELP!" or something similarly useless.
This is an odd product to be using on weed... older one that was used to suppress root rot & just learned they treat potatoes with it (post harvest) to ward off forms of blight... essentially phosphorous acid that has been bonded.
What were you using it for? They say that crops treated with this are resistant for years... like it doesn't exactly go away...???
Yeah, MIW, now I'm a bit confused. I thought this was a Tx for fungul diseases (mostly PM). But based on this...? It sounds like he's Txing for spider mites.
Been reading a bit more on it... and Exel LG isn't overly effective for Powdery Mildew. It's really known for fighting off water borne pathogens... water molds, e.g., Downy Mildew... totally different than PM. You might have some continued problems.