I'm growing 500 odd seedlings for the 5th year now, however I've lost 6 trays to a leaf-curl, wilt, deformation type thing that effects the plants when they are about 6" to 12 " high. It is not variety-related, it hits both potato leaved and reg leaved, it doesn't kill the plant, just causes ugly leaves. I have looked at them with a magnifying glass, no bugs. No webs, nothing on sticky tape. Different sources of potting soil. It didn't spread. I thought that perhaps, given that other stuff was growing in the greenhouse that I had sprayed with a pyrethrum-based spray, that some sort of drift, and under the right circumstances, might have done it.

Now I'm getting it again without spraying. Any thoughts? I can't sell the plants.