I recently crafted a seeding shelf, and have been growing basil, and other herbs. They've come along well, however within the past week or so, white blobs have formed on some of the plants.
The only recently changes I can think of are;
1) I switched from 2 bulb 2 foot floresent lights using 1 cool and 1 warm white. To 4 bulb 4 foot floresent lights using 2 warm, and 2 "sunlight" bulbs.
2) I also tried watering from the bottom of the trays about 2 weeks ago, but I think I filled the bottom trays up too much because it took a very long time before the soil dried up.
It was suggested it might be spider mites by my local nursery worker, but I see no signs of them on the bottom of the leaves.