As above really i have seen loads of these over the years and i was wondering what they are and what causes them?
Can any one tell me what this is growing on oak?
- Thread starter Man of Tanith
- Start date
Gall wasps. It starts out as an acorn until a gall wasp comes along and stings it, and lays an egg. That actually changes the DNA of the acorn and it turns into a gall, solely for the purpose of raising and protecting the young wasp grub. Amazing.
It looks like a gall ... usually caused by either a fungus or insect larvae .... there are quite a few different types of them.
Ed
Ed
Knopper galls look a little like a lump of popcorn. When they first form in August, they're a reddish colour, and sticky to the touch. Later they turn brown and woody. They're caused by the tiny gall wasp Andricus quercuscalicis, which lays its eggs in the acorn.
Knopper galls have rapidly become widespread in Britain since they first appeared about 1960. Some years they have a bad effect on the acorn crop. The trees most affected are generally in close proximity to Turkey Oak trees.
Knopper galls have rapidly become widespread in Britain since they first appeared about 1960. Some years they have a bad effect on the acorn crop. The trees most affected are generally in close proximity to Turkey Oak trees.
Turkey Oak (Quercus cerris L.)was introduced into Britain in 1735, and is required for the completion of the life cycle of the gall. The Knopper is a recent introduction to the British Isles, first arriving in the 1960s and now found throughout England, Wales and as far north as Scotland; first occurring for example in 2007 at Eglington country park in North Ayrshire.
