Some strange disease attacked my bonsai elm tree. Please see attached images. Each brown thing is hard on top but soft and white inside. Apparently, it seriously affects the tree as hurt branches start to lose foliage and die.

Could you help me to figure out what it is and how to deal with it?

Thank you in advance.

That looks like mealybugs. As how to treat such pest just go to the menu bar up in this page under the "The Basics -> Bonsai Care -> Pests and Diseases" tab. There you'll find enough info. Or just Google mealybugs and how to treat it.

Alain

alainleon1983 wrote: That looks like mealybugs.

They are however scale insects!

Besides that, the advice stays. Look for treatment online.

If the infestation is small, you can remove them with a toothpick, then spray with generic insecticide. Respray in 10-15 days to catch hatchlings.

If you cannt remove them by hand, use a systemic insecticide.

leatherback wrote: They are however scale insects!

:oops:

Uhmmm... A translation exact match... Mealybugs and scale insects, both are translated the same from english into spanish: "cochinilla".

Alain

Thank you guys! Yes, they look like scale insects richmond.ces.ncsu.edu/2015/02/managing-s...ts-in-the-landscape/ .

alainleon1983 wrote: A translation exact match... Mealybugs and scale insects, both are translated the same from english into spanish: "cochinilla".

And delving even deeper.. Mealybugs are nowadays a subgroup of the scale insects!

However, I was referring to armoured scale insects; Mealybugs are, as far as I know, normally only referred to for the white, wooly specimens.