I just got back from an all-day workshop about pecan orchard management. The workshop was put on by an Oklahoma non-profit that does an enormous amount of good work and original research in agriculture; the org was founded by a rich oil man back in the dust bowl days who was dismayed at all the soil loss that he could see when flying around in his private plane. I'm not naming the org -- or today's excellent presenter, who does a lot of original research on pecan management issues -- because this thread isn't about shaming them and I don't want this ranty stuff turning up when people Google them. But man, I had a lot of trouble holding my tongue and not smiting my forehead today!
Fundamentally they do conventional ag. So a huge amount of today's workshop was about which chemical fertilizers to put on the trees and which pesticides and fungicides to spray when. On the other hand, they do recommend planting legumes to satisfy the trees' nitrogen needs and there was a lot of information about how to minimize the trees' alternate bearing tendency and how to manage their irrigation, which was more why I was there. There was lots of stuff that would make permaculturalists happy, such as the acknowledgement that the standard management practice of spraying glyphosate to kill grass around the tree could be replaced by mulching, if you have enough mulch. It was a mixed bag, but I knew that going in, and on balance it was a good use of my day.
Here's the part that made me want to smite my forehead. On numerous occasions while running through the list of predominant insect pests, the fundamental solution offered was to monitor for the pest, and then apply the right chemical on the perfect schedule to minimize pesticide application (to save money). But in several cases, the presenter would specially mention that before spraying, you should check the trees for beneficial insects and in some cases hold off on pesticide application if it seemed like there might be enough beneficials present to handle the infestation. Sensible advice. What bothers me is that even when aware of the potential of beneficial insects, the ultimate advice boiled down to spraying insecticide several times a year. How the heck do they ever hope to build a useful population of beneficial insects doing that?
It seems to me that as soon as you have started spraying insecticides, you've locked yourself into doing it year after year, on a much more aggressive schedule. Beneficial insects, being higher on the food chain, take longer to rebuild their populations than the pests do. So once you've killed them all off, you're guaranteed to suffer endless waves of pests that you've "got" -- using the logic we heard today -- to spray, since there's no beneficial population left to deal with them. These are smart scientific people, but somehow they aren't seeing that.