Witch's broom

A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest.

Diseases with symptoms of witches' broom, caused by phytoplasmas or basidiomycetes, are economically important in a number of crop plants, including the cocoa tree Theobroma cacao,[1] jujube (Ziziphus jujuba)[2] and the timber tree Melia azedarach.

[3] A tree's characteristic shape, or habit, is in part the product of auxins, hormones which control the growth of secondary apices.

In cases of witch's broom, the normal hierarchy of buds is interrupted, and apices grow indiscriminately.

The phenomenon can also be caused by other organisms, including fungi, oomycetes, insects, mites, nematodes, phytoplasmas, and viruses.