Every now and again something new pops up and surprises me with Bonsai. This week it has been a witches broom of the highest order, a Nimbus 2000 if you will. As is becoming customary at this time of year I find myself fighting the good fight against a never ending sea of satsuki. It is the season for an autumnal prune/removal of unnecessary new growth and also wiring. One tree I worked on today had this growth on it.
A grotesque lump of misshapen and stunted shoots, also known as a witches broom. I personally prefer the Japanese name tengusu byou or "Tengu nest disease". (Careful reading is required here, do not mistake the "u" for an "a"). If you don't know the Tengu is a mythical creature, half devil, half bird of prey in Japanese folklore. He is pretty scary and he obviously likes to make nests in azaleas (not as scary)
Tengu
Aside from the interesting cultural divide over naming deformed plant growth, what caused it? In the case of azaleas, it is almost certainly damage from insects. I have previously seen just very small amount of Tengu Nests in azaleas and The Chief always told me that it was down to Thrips...but there are other culprits which cause it and other damage such as the Clinodiplosis rhododendri (Felt), or it's street name of Rhododendron gall midge which causes damage by eating leaves and shoots. A fearsome beast as you can see...
Other evidence of this little blighter was found
Leaves that had been eaten.
So how to control or prevent? Spray with an insecticide on a regular basis during the growing season for new shoots. They are not difficult to kill off, but timing is key. Once they or their larvae get into the shoots then this can happen
If you have it, cut if off and get rid of it, spray for any remaining bugs and stay on top of it.
Some witches brooms make great new species deal for bonsai, others just look ugly. At least it has a funky name.
Onwards and upwards
