Saturday, 7 September 2019

botany - What are these white spots on a dracena


I have a Dracaena Marginata which started to have some white spots. They turn out to be some kind of "mold"


enter image description here



enter image description here


which can be removed when swapping the leaf and then leaves some discolored spots


enter image description here


They usually appear when the leafs get yellow (because of it, or because I have forgotten to water for too long) and seem to be more present at the base of the leaf.


What is this?


And more importantly: is it a problem for the plant? (minor issue, though it is a gift from my children) or for me? (major issue, and death sentence for the plant)



Answer



These are plant pathogens commonly known as scale insect (Coccoidea). Among the genera mentioned to infect Dracaena marginata here and here the most likely candidate is Pinnaspis.


They are close relatives of aphids and psyllids (and more distantly -- also to true bugs). Cochineal is probably the most famous representative of the superfamily. Scale insects suck host's sap and can be quite dangerous to the plant. Adult females are immobile and the spreading is performed by nymphs and (when present) males.


As far as I know they are harmless to humans. When digested (products of) at least cochineal can cause allergic reaction in some persons.



No comments:

Post a Comment

evolution - Are there any multicellular forms of life which exist without consuming other forms of life in some manner?

The title is the question. If additional specificity is needed I will add clarification here. Are there any multicellular forms of life whic...