MG, I respect your opinion on this in general. It's good practice.

Luckily instituting an IPM program is not harmful, even as a preventative measure. Predatory nematodes are effective against a wide range of soil pests.

I would not use chemical pesticides just because, say, my leaves were turning colors.

The commercial greenhouse I used to work at had a very aggressive preventative IPM program. I remember the weekly ladybug releases were unbelieveable! You'd get home from work and find the things in the MOST surprising places.