What these translucent formations exactly on central veins of rainbow eucalyptus can be? Trees are 6 weeks old, growing in a greenhouse with +25..35°C temperature and 90-100% humidity. Burrs look and feel somewhat like inside of cucumber - springy and light. It's almost like leave's flesh is bulging out. I tried to cut them (they're small), but didn't see anything inside.
Other than that, plants look healthy and have no alarming symptoms.

this may be wooly aphids which can be exterminated with a few weekly sprays of a basic insecticidal soap. or this could be a disease your trees a carrying in this case not much can be done except to fertilize and water regularly.

hope this helped.

Don know what it is but that are certainly not woolly aphids.

This is typically cause by sucking insects. Thrips come to.mind, but also gall mytes. They trigger the plants growth instincts causing bulges.
Check whether you find thrips. If not, treat for.mites.

totempoleguy wrote:

hope this helped.

not really.