" Any pests that survive the pesticide now have the evolutionary advantage and so might future generations they breed."
"Any pests that survive the pesticide now have the evolutionary advantage" this part is true.
"and so might future generations they breed." This part is not necessarily true. If there are non-resistant individuals around for them to breed with and the resistance is not a dominant trait, then their offspring are not necessarily resistant. And the fewer resistant individuals there are as a percent of the population, then the less likely the resistance is to spread through the population.
Actually, since the resistance is not something we are putting in them, it is just that by treating the plants we are selecting for the strongest, most resistant individuals, it is more accurate to say that the less chronic and widespread the treatment, the less likely we are to be left with only/ mainly the resistant individuals who will then be able to pass along the resistance and who will have less competition for resources.
Interesting discussion though. I like it when people are willing to delve deeply into an issue like this.
wiki has a nice article on resistance: https://en.wikipedia.org/wiki/Pesticide_resistance
It shows this:
Left column is before pesticide application; right column is after. Top row is first generation; bottom row is later generations.
"Pesticide application can artificially select for resistant pests. In this diagram, the first generation happens to have an insect with a heightened resistance to a pesticide (red). After pesticide application, its descendants represent a larger proportion of the population because sensitive pests (white) have been selectively killed. After repeated applications, resistant pests may comprise the majority of the population."
If there are not repeated applications and if there remain non resistant individuals to breed with, then the population does not become resistant.
Here's another article: https://jenny.tfrec.wsu.edu/opm/displays ... php?pn=-70
It notes that the longer time between repeat applications, the less likely for increasing resistance in the population.