I have hibiscus (rosa-sinensis) seedlings in the ground that are about 6-9 months old. About a month ago one of them started getting yellow leaves and dropping them at an alarming rate. All the affected leaves were all along only one stem. Eventually that stem went yellow and I cut it way back near the base. Then a neighboring stem on same plant did the same thing. Now a THIRD stem is being affected and today I noticed that a seedling growing about 3 feet away is being affected! I am assuming this is either bacterial, viral or fungal. We have had tons of rain for the past couple of months and it's been very hot. What could this be? I am so afraid this will eventually spread and wipe out all my plants (I breed hibiscus). Will try to post pics. Thanks!!