That early, you can use pyrethrins. they have a 12 hour half-life.
but, nothing is 100% certain to be safe in flower. even if it says 'safe for veges 2 weeks before harvest" because inahaling is different than eating.
this stuff kills on contact. if you want 2 weeks, it's .5^28 *100 = X% remaining after 14 days. it's some .000000 %. That doesn't gauarantee safety as toxicity of any 1 molecules is different than another... sometimes 1part per billion is dangerous or even less concentrated.
nothing is "safe" in flower, technically. Teh best bet is something with a short half-life and non-systemic. The last pert just means it doesn't easily enter and stay in the plant - plants have no excretion so once it is in there, it's staying there until it biodegrades (hence, uses of half-life).
pot growers used to be big on Eagle20 fungicide.. it's systemic and theose people did damage to anyone they sold their nasty weed to. all for the sake of greater profits and less lost to fungi.