Q.Black powdery on my Hibiscus buds
The outside green of the buds on my Hibiscus tree have a black powder like mildew on them. I have used a magnifying glass to see if there are bugs in the black and do not see any bugs. My buds are opening wide and are beautiful and measure about 6″ across. My flowers only last about 12-18 hours and then start closing up and the bloom falls off in a matter of hours. I have been told Hibiscus closing of the flower is normal in a matter of a day and they fall off, is this true? Can you please tell me what the black like powder is on my buds could be. Also, I read somewhere not to remove the outside of the empty bloom as another bloom will appear. I can see what looks like a new bloom forming but the bud falls off in a day or two after appearing. Any help or information would be greatly appreciated. I have taken a picture of the black on the buds but can not get it to transfer on this site.
The black substance is likely to be "sooty mold" which grows on the sweet honeydew droppings from sucking insects like aphids or scale. You won't see bugs in the mold, but if that is in fact what is happening, the insect pests will be higher up, above where the mold is growing. Look on the under side of leaves and on the petioles (leaf stalk) and small green twigs.
In your climate, the feeding adult aphids or scales will be gone soon. The sooty mold stays longer. So you may need to concentrate your pest control program on dormant spraying for overwintering eggs and nymphs, and spring - summer pest management.
