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These cone-shaped growth, totally dry and brown were spotted on a branch of a healthy tea tree. The "cone" appeared to have a dense core but another one on a nearby tree (pic 4 & 5) was more open exposing what looked like a branch with highly shortened internodes. Only the "cones" appeared dry and dead.
Spotted on a coastal tea tree like the one in http://www.projectnoah.org/spottings/869... Leptospermum laevigatum
Witches-brooms are caused by any of a number of organisms - fungi, nematodes, bacterial parasite, pathogens, insects or viruses. These interfere with the plant hormones that regulate growth at the apices - keeping overgrowth in check. The interference causes the apices to grow abnormally forming clusters of shoots from a single point. these eventually die away looking like brooms.
"Witches' brooms are of wide ecological importance. They generally tend to be inhabited by a wide variety of organisms apart from the causative organisms. Some of the invading organisms, such as some species of moths, are specific to particular types of witches' brooms, relying on them for food and shelter for their larvae. Various larger animals nest in them, including the northern flying squirrel." - Wikipedia
I am not sure what causes these on a Leptospermum but will keep looking...
2 Comments
Thanks Pam. I wish we had someone to help us with galls..
Lovely photo Leuba, and interesting information...