| abstract |
Macrocyclic compounds of the formula I <IMAGE> in which either R is methyl and a double bond exists in the 9,10-position, or in which R is hydrogen and a single bond exists in the 9,10-position, can be obtained by a microbiological route by cultivation of Sorangium cellulosum "So ce 26" (NCIB 12 411). They represent active substances for controlling plant diseases and can be used in customary formulations. |