Gymnosporangium sabinae

Pear rust in October

The pear rust ( Gymnosporangium fuscum syn. Gymnosporangium sabinae ) is the order of the rust fungi ( Uredinales ) scoring, economic changing, plant pathogenic fungus.

Life cycle

The pear rust attacks lasting several juniper species, where it causes nodular thickening of the branches. The spore deposits are visible as orange, rubber - to gelatinous growths in the spring. They swell and shrink depending on humidity and precipitation.

The basidiospores formed here are transmitted every spring by wind on the leaves of pear trees. The infection of the leaves is carried forth from the leaf surface and is visible in the initial stage by orange - red spots, which enlarge with time. Here is the fungal spores summer, which in turn only the leaves of the pear trees infected. Perhaps the eye-catching color and excreted " nectar ", flies and wasps helps to attract, assist in the dissemination of spores. In this way and in favorable weather conditions, the fungus can spread explosively within a short time. In late summer, the fungus grows through the leaf and forms on the underside of leaves brownish, up to 1.5 cm long, irregularly oval growths. In these Aecidiosporenlagern the winter spores are formed. With the Sporenreife the growths tear on grid-like and put the dark brown winter spores free, the back can now infect juniper.

In some years, the infestation reaches almost all the leaves of a tree. Young pear trees can seriously damage the fungus, in older plants it is usually just another stress factor.

Combat

The pear rust is to fight as an economic varying fungus in two places:

Treatment of winter spores bearing on juniper (mostly Chinese juniper (Juniperus chinensis) and juniper (Juniperus sabina ) ):

• Removal of affected trees and shrubs
• Removal of affected spots on trees and shrubs
• Replace with robust (Juniperus hetzii ) or better resistant species (eg Juniperus communis)

Treatment of the host summer pear ( rare: Quince ):

• Treatment of pear with fungicides, for example, myclobutanil (best seen in the spore phase of flight to infested juniper control )

The spores can be transported many miles with the wind before they settle on a host. The prophylactic removal of trees in the vicinity is therefore usually only moderately effective. Experience has shown that treated you prone to infestation pear trees prophylactically already at appearance of the first flower buds by spraying with triazole at two-week intervals. The foliage of infested pear trees can be composted.

Confusion

Orange ( orange or gray ) thickening of the leaves are also caused by the pear leaf blister mite.

Pear rust on Juniperus pfitzeriana

Swellings on the bark, orange to brown spore deposits that are slimy with time, the time of the attack: the beginning of May

Gallery

Lower leaf surface in July

Upper leaf surface in October

Lower leaf surface in October

Lower leaf surface in October

Pear rust

Pear rust on Nashibirne