Bean grate
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Uromyces appendiculatus |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Uromyces appendiculatus | ||||||||||||
| ( Persoon ) Unger |
The bean rust ( Uromyces appendiculatus ) is a stand fungal art from the order of the rust fungi (Pucciniales). The fungus is an endoparasite of the legume genera Phaseolus and Strophostyles . Symptoms of the infestation by the species are rust spots and pustules on the leaf surfaces of the host plants. It is common worldwide and is a major disease in bean growing.
features
Macroscopic features
Uromyces appendiculatus can only be recognized with the naked eye by means of the spore beds protruding on the surface of the host. They grow in nests that appear as yellowish to brown spots and pustules on the leaf surfaces.
Microscopic features
The mycelium of Uromyces appendiculatus grows as with all Uromyces TYPES intercellular and forms Saugfäden that grow into the storage tissue of the host. Your spermogonia grow on the underside of the host leaves. The aecia of the species growing underneath the leaves are whitish. Their hyaline aeciospores are 20–28 × 18–20 µm in size, angular, spherical to long ellipsoidal and warty. The uredia growing on both sides of the mushroom are cinnamon brown. The golden to cinnamon-brown uredospores are 24–30 × 20–27 µm in size, ovate to broadly ellipsoidal and spiky. The parts of the species growing on both sides around the uredia are black-brown, powdery and uncovered. The chestnut-brown teliospores are unicellular, usually spherical to broadly ellipsoidal, warty and mostly 28–32 × 22–27 µm in size. Their stem is colorless and up to 45 µm long.
distribution
The known distribution area of the bean grate includes all cultivation areas of haricot beans .
ecology
The host plants of Uromyces appendiculatus are various Phaseolus and Strophostyles species. The fungus feeds on the nutrients present in the storage tissue of the plants, its spore beds later break through the leaf surface and release spores. The species goes through a macrocyclical development cycle with Spermogonia, Aecien, Telien and Uredien. As an auto-ecologic parasite, it does not change host . In principle, the fungus needs a high level of humidity. There are a number of varieties and breeds that differ in their virulence and pathogenicity .
Economic importance and control
The bean rust is one of the most important diseases of the kidney bean and can even lead to a total loss of the harvest. Practically all areas where the bean is grown are affected, with the disease being exacerbated in areas with high humidity. Damage is not only caused by a reduction in seeds, but also by a reduction in quality and the production of smaller beans. There is a high correlation between disease infestation (measured in pustules per cm 2 ) and crop failure. A wide variety of fungicides are used to combat this , such as various sulfur preparations , dithiocarbamates or chlorothalonil . But the most successful and inexpensive are the cultivation and breeding of resistant bean varieties. The biological control of the bean rust has so far only been little studied. The use of the bacterial antagonist Bacillus subtilis or the fungus Verticillium lecanii is documented . The use of the bacteria Pantoea agglomerans and Stenotrophomonas maltophilia also had an effect comparable to that of a contact fungicide.
literature
- George Baker Cummins : Rust Fungi on Legumes and Composites in North America . University of Arizona Press, Tucson 1978, ISBN 0-8165-0653-1 .
Individual evidence
- ↑ a b c d Liebenberg, MM; Pretorius, ZA: Common Bean Rust: Pathology and Control . In: Horticultural Reviews . tape 37 , 2010, p. 100 , doi : 10.1002 / 9780470543672.ch1 ( Online [PDF; 350 kB ]).
