When you go to the store to look at chemicals peel open the back panel and scan for your fruit. Also look at the preharvest interval (PHI) some are pretty high and even though the fruit is listed it leaves you too long without protection on early varieties. I know Triazicide has plums listed.

Normal growth on your plant.

I've grown in coir based medium for several seasons, to trial it out for my g'house operation. I liked it, but it isn't for all types of plants without some major cultural changes to accomodate it. You can get fungus gnats on sterile media! To think you can't is like thinking you can buy a bug free plant from me in April and come September if you find aphids on it, thinking it has to have come with the plant. Hey, fungus gnat adults are winged. They fly. Ditto drain flies. The thing with planting media and gnats is that it isn't overwatering in how much water you put on a plant. Mature plants in pots should be watered until it runs out the drain holes to prevent salts build-ups if you fertilise. But it's how frequently you water. Soil on most plants should not remain consistantly moist. You will get fungus gnats or worse, you can get rots. Now, about the damage fungus gnats do. At low numbers, most plant inspectors will turn their heads the other ways. But, as the population pressure builds, they stop eating the fungus on the soil and start eating soil roots. Not a good thing. You can also find them INSIDE the stems of hollow stemmed plants. Also not a good thing. Bt Israelienses will kill the larvae. It's the stuff in mosquito dunks. It's a naturally occuring organism and I'd call it pretty organic. But, actually I most infestations will stop by themselves if you just allow the pot to dry out and resume watering properly. Help it along by providing good air movement and you can even take a kitchen fork and "fluff" up the surface of the soil to a shallow depth, and that'll expose the larvae and cocoons and they perish in dryness. Good luck.

as suggested on your other thread, mostly likely leafhoppers http://forums.gardenweb.com/forums/load/pests/msg1014442011985.html?9 Here is a link that might be useful: other thread