Expert: C.L. Fornari - 6/6/2006

Question
Middle Georgia.

My petunas feel sticky and then seem to dry up and die. I have sprayed them but not sure what is best to spry them with. Any suggestions? Is this a fungus, bugs, or what?

Answer
CD,
Sometimes petunia foliage can naturally feel sticky, but if they dry up and die, it could be an insect, fertilizer burn or it could be the watering.  I hope the following will help:
1. Plants that "dry up and die" can be suffering from too much water, too little watering or from too much fertilizer or fertilizer that is applied to a dry plant.  (Always water a plant first, then a couple of hours later apply fertilizer.)  The general rule of thumb is not to water if the soil feels wet, but to water well before the plant wilts.  Water the plant when the soil is dry, wait a few minutes and then water again to be sure the soil is fully saturated, but then don't water again until the soil is completely dry.
2. Insects that suck plant juices excrete the excess, and this makes the plant sticky.  Common "sucking insects" include aphids, whitefly, scale and mealy bug.  Most common on petunias are aphids and whitefly.  (if you shake these plants do small white insects fly out?  That's whitefly.)  Spray with any insecticide labeled for these pests, or use horticultural oil or insecticidal soap.  Do not spray if the plant will be in the hot sun afterwards, because most insecticides will make the plants die if they are used and then the hot sun shines on the plant.

Let me know if you have other questions,
C.L.