I think there is the misinformation. An affective application is going to be absorbed rather quickly, within 2-3 days. Once it is absorbed it will take awhile for the weed to succumb to the lethal treatment. There is foliar absorbtion and there is root absorbtion. Foliar is relatively quick. That is why Scotts and other ho products require watering before the product is applied-- to make a wet leaf surface for the dry granule to stick to. The herbicide is often in the small particle thereby more likely to stick while the fert may be a larger particle dropping to the soil zone. Since the fert is almost always going to be a root absorbtion- any herbicide that uses root absorption for effectiveness is going to occur at or near the same rate as the fert application. ***** So I would say as general guideline the herbicide uptake is going to be quicker than the fertilzer uptake. But then I'm no scientist. Purely conjecture on my part from years for applications, reading labels and seeing the effects. ********* As for recommending applying fert and then 2 weeks later applying herbicide.... For a homeowner that may be easy. For an LCO that is cost-prohibitive! NO WAY! Both have to done in one visit to be practical. Otherwise you are selling TWO services and therefore the cost is twice as much. Most of the cost in a fert service is the time to get there, set-up, and the service stuff (invoicing, etc.). ******* Accidental herbicide damage on trees in the applied area, yes that is common. Not a huge deal. Seldom kills a trees, just stuns them a little. NOT good, but just one more likely side-effect of herbicides. Add accidental wind-drift too. Everyone knows all applicators ONLY apply in calm conditions.