Germinated rust spore

Figure 8. Germinated rust spore that has developed an appresso-rium above a stoma. (Reproduced with permission from Ref. 6. Copyright 1982 Pflanzenschutz-Nachrichten Bayer.)...

The most thorough studies of promotion of fungal development by volatiles was done by French and co-workers (4-6) who showed that volatile compounds in solution or their vapors were effective promotors of rust spore germination. Rusts are diseases found on many species including crop plants such as wheat, corn, beans and others. They are caused by fungi whose life cycle includes multiple development steps with the formation of rust colored uredospores in... 

Compound identifications were based on comparison of mass spectral data and co-chromatography of plant components with standards as reported (8,9). A sample of 3,6-nonadien-l-ol was isolated from melon (10) whereas 8,11—heptadecadienal and 8,11,14-heptadecatrienal were obtained from cucumber fruit (11). Of primary interest in the present study is the identification of Cg aldehydes and alcohols including nonanal and nonanol which are effective promotors of wheat rust spore germination. The unsaturated Cg compounds have not been evaluated for activity but their close structural relationships to nonanal and nonanol make them candidates for germination promotors. 

An epimeric mixture of sclareol (29) and n-epi-sclareol (33) has been shown to inhibit germination of spores of several rust diseases on tobacco, broad bean, dwarf bean, and wheat plants at 100 ppm (Wain, 1977). 

Spore germination and appressoria formation during the pathogenesis of rust fungi is affected to a very low extent. The interference with haustorial formation is the most important effect. Colonized cells undergo a hypersensitivity reaction finally they become necrotic. Further development of the obligate parasite is therefore stopped. 

Mildew, scab, rust mites, pear pox mites Preventive against fungi, kills the germinating spores... 

Copper salts Inorganic Prevents spore germination nonsystemic Control of powdery mildew, blights, and rust —... 

Volatile compounds have been reported to stimulate germination, in vitro and in vivo, of spores of the fungal pathogens which cause wheat rust diseases. 

Methyl Z-ferulate is a powerful inhibitor of uredospore germination in a range of rust fungi (Friend, 1979). This and related compounds occur in the fungi themselves. They are gradually leached from the spores on the host surface. This process must take place before germination of the spores occurs. 

Compound released from roots of Parthenium argentatum causing self inhibition of growth Inhibitor of spore germination in rusts (Puccinia, Uromyces)... 

French, R.C. 1992. Volatile chemical germination stimulators of rust and other fungal spores. Mycologia 84 277-288. 

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