TG2407 : Hollyhock rust (Puccinia malvacearum)

taken 11 days ago, near to Trowse Newton, Norfolk, Great Britain

Hollyhock rust  (Puccinia malvacearum)
Hollyhock rust (Puccinia malvacearum)
This rust fungus affects Hollyhock (Althaea rosea) and other Malva species > LinkExternal link causing yellow or orange spots on the upper leaf surface > LinkExternal link and reddish-brown pustules (depicted here) on the lower, extracting nutrients from the plant's cells; heavy attacks can cause tissues to collapse and die prematurely. The reddish-orange pustules on the leaf undersides contain numerous spores that remain embedded within the leaf and which under humid conditions germinate to produce a second spore type, causing the pustules to turn an ash-grey colour. These spores are then carried in air currents to create new infections when they land on other plants in the Malvaceae family.
Plant galls
Galls are abnormal growths, swellings, pustules or discolourations produced by a plant or other host under the influence of another organism, involving the enlargement and/or proliferation of host cells and the provision of both shelter and food or nutrients for the invading organism. Galls provide a home for the larvae or grubs of certain invertebrates, where they can feed and develop, and each type of gall-producer or causer is specific to a particular kind of plant. Galls come in many shapes including spheres, knobs, lumps, warts or blisters, each being characteristic of the causal organism, and can have a range of colours. Galls can be found on the stems, leaves, flowers, fruits, seeds and roots of plants. Although many varieties of plants can be affected, oaks and willows are particularly rich in galls. Oaks are said to be host to more than 500 different types of galls. Weather, plant susceptibility, and pest populations affect the occurrence of plant galls.

Certain galls are documented to have been used in the production of ink since at least the time of the Roman Empire, and iron gall ink was the main medium used for writing in the Western World from the Middle Ages to the early 20th century. Oak marble galls > LinkExternal link for instance, were introduced in the early 19th century in an attempt to grow our own supply of galls for making ink. In Chinese medicine, oak galls are used as a remedy called moshizi, which is used for treating dysentery, ulcers and hemorrhoids among other things. Native Americans used poultices of ground gall nuts on sores, cuts and burns. The high content of tannic acid also makes oak galls a good source for tanning and dyeing.

Galls cause little permanent injury and rarely kill the infested plant.

For more detailed information go to the British Plant Gall Society's website at LinkExternal link
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TG2407, 524 images   (more nearby )
Photographer
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Date Taken
Thursday, 6 June, 2019   (more nearby)
Submitted
Friday, 7 June, 2019
Geographical Context
Suburb, Urban fringe  Wild Animals, Plants and Mushrooms 
Subject Location
OSGB36: geotagged! TG 2487 0718 [10m precision]
WGS84: 52:36.9481N 1:19.2178E
Camera Location
OSGB36: geotagged! TG 2487 0718
View Direction
West-northwest (about 292 degrees)
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