My dragon fruit (Hylocereus sp.) has some weird yellow spots. anyone know what they are?
I know the plant is in really rough shape, all the calloused parts are from two summers ago, so i don't really think that has anything to do with it. The light green/yellow patches just started appearing about 2 weeks ago. I did have a very small aphid infestation about 2 months ago, is it possible this is just damage showing up late from that? Or is it just in need of some fertilizer? I did notice it sending up a really big new branch in the last couple of weeks.
Hello Tom2643,
I believe, that these bleached areas (spots) are the result of insect feeding. I have looked at and examined many cacti over the years, but I have yet to encounter aphids or thrips on them, although that should be possible. Usually I do see mealybugs, scale insects, mites, and true bugs. All these will cause an effect similar to the one shown on your image. The tissue underneath the epidermis has collapsed by the feeding and the chlorophyll has disappeared. Fertilization will not re-green these spots. However, as your plant adds stem tissue, the cosmetic damage will seem to diminish. You should be carefully watching, whether or not you really got rid of all the pest insects. I do not know how you removed the aphids. Because in a lot of cases there are adults, they also may have left some tiny eggs behind which could restart the infestation.
In summary, if the spots are not increasing in size or numbers and you do not have any evidence of insect presence, you are OK. Other agents that can cause a splotchy effect are plant viruses and early stages of some plant pathogens like fungi or bacteria.
However, your mentioning of the aphid infestation leads me away from a diagnosis other than "insect feeding damage".
Yeah, I do know it had aphids. I sprayed them off with insecticidal soap because i've never been too sure of the sensitivity to more harsh insecticides. I guess I'll just keep a closer watch on it for now then.
