Monday 18 June 2018

A pest on grapes

Uncinula necator or powdery mildew, a basidiomycete, is a pest on grapes. Its septate hyphae forms a mycelium on the surface of the leaves similar to a spider web. Special hyphal branches, the haustoria, penetrate the host cells to absorb food substances, thereby weakening the grape and reducing the harvest.

Wednesday 6 June 2018

A medicinal parasite

Mistletoe (Viscum album), sinkers in host tissue, longitudinal.

The evergreen, spherical shrub of about 1 m in diameter grows on different trees. As a semi-parasite the mistletoe assimilates with its leaf green. The sinkers of the mistletoe penetrate deep into the wood body of the host plants and withdraw only water and mineral salts from the host, but this causes the part above the infestation site to suffer. The opposite, oblong-ovate leaves evaporate only a little water due to their leathery texture.