Leaf spot fungus

Kumaran RS, Muthumary J, Kim EK, Hur BK (2009) Production of taxol from Phyllosticta dioscoreae, a leaf spot fungus isolated from Hibiscus rosa-sinensis. Biotechnol Bioproce 14 76-83. doi 10.1007/sl2257-008-0041-4... 

Light leaf spot Fungus From November onwards,... 

Kinjo, L, K. Yokomizo, Y. Awata, M. Shibata T. Nohara. 1987. Structures of phytotoxins, AV-toxins, C,D, and E produced by zonate leaf spot fungus of mulberry. Tetrahedron Lett. 28 3697-3698. 

Cutler and his group (247) have also isolated cytochalasin H (or paspalin PI) from a parasite fungus, (Phomopsis sp. (Diaporthe is the perfect state of the fungus) which is often associated with leaf spot and diebark conditions of certain plants. This compound showed marked inhibition of growth and floral development of tobacco plants at concentrations of 10 and 10 M. 

Alternaria has been knovm for centuries to cause various plant diseases such as early blight of potato and various leaf spots and fruit rot. Species of this fungus are widely distributed in soil and on aerial plant parts. Because Alternaria requires high moisture levels (28-34%) for growth, infection of seeds occurs when the seed moisture is high, either in early stages of development or after wetting of crops from rain. 

An extreme example of diverse structures which can arise by extensive and varied modifications of a single polyketide-derived metabolite is provided by the phytotoxic spiciferones (28)-(30), spiciferinone (31) and spiciferin (32) produced by the fungus Cochlioholus spicifer responsible for leaf spot disease in... 

Alternaria species are associated with several leaf-spot diseases of plants. Alternaric acid (8.10), produced by A. solani, which is the cause of early blight on potatoes and tomatoes, has a marked phytotoxic activity and may be responsible for many of the symptoms of the plant disease caused by the fungus. It also shows a specific anti-fungal activity. The branched chain structure is biosynthesized from nine acetate units and three Ci units derived from formate. The solanopyrones are another group of phytotoxic metabolites of A. solani. Solanopyrone A (8.11) induced necrotic lesions on the leaves of potatoes typical of this fungal infection. The structures of the solanopyrones were established by... 

Cercospora species are responsible for various leaf-spot diseases. C. rosicola produces small brown lesions surrounded by a red-violet ring on rose leaves. The common black spot is caused by a different fungus, Diplocarpon rosae. A severe Cercospora infection can cause loss of the leaf. The phytotoxic fungus... 

The beticolins (ascertained structures shown, bO, 2,4,6,8,13,1, 3, and 1063-1 70, respectively. Fig. 13.29) are a fascinating fantily of closely related non-host-specific mycotoxins produced by several strains of Cercospora beticola, a fungus responsible for cercosporiosis, a leaf spot disease of sugar beet Beta vulgaris) (680-683). 

Historical and isolation studies of weak spot have given varying results. In some cases those spots were found to be sterile, and in others superficial occurrence of both Colletotrichum and Phoma was demonstrated. In many cases unidentified fungus mycelium could be found in petiole tissue and in leaf tissue clear down into the palisade cells. These may have been, therefore, demonstrations of one of the reasons why leaves dropped prematurely. The problem is still not completely settled, but many workers now consider the good effect from tonic sprays due to control of weak pathogens. 

Leaves with irregular brown spots. Cause Leaf blotch. Caused by a fungus, these spots may spread over leaves and lead to defoliation. Clean up and destroy fallen leaves to remove overwintering spores. 

Stems and leaf undersides with dusty, dark brown spots. Cause Rust. This fungus develops quite rapidly, so leaves must be monitored for initial spotting. Rust-resistant snapdragons are now available and should be used whenever possible. However, they don t eliminate the problem. 

Leaves distorted, orange-yellow spots on leaf undersides. Cause Rust. This fungus produces orange pustules, distorting the leaves and making branch tips swell. Rust usually doesn t harm the tree much, except for detracting from the appearance. Clean up and destroy fallen leaves and branches in autumn. To prevent the spread of mild infections, spray leaves with sulfur early in the season. 

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