Three antibiotics were isolated from a CH2Cl2 extract of the liquid culture of Pseudomonas fluorescens strain PFM2. Two of the antibiotics were identified as 2,4-diacetylphloroglucinol and pyoluterin. The structure elucidation, absolute stereochemistry, synthesis, and biological activities of the new antibiotic (+)-(S)- dihydroaeruginoic acid [1] are reported.

Pseudomonas fluorescens strain PFM2, antagonistic to Septoria tritici, also inhibited growth of several other phytopathogenic bacteria and fungi in vitro. Three inhibitory compounds were extracted from liquid glycerol‐peptone‐phosphate medium in which strain PFM2 was grown for 4 weeks. The compound recovered in greatest quantity (70 mg/1) was identified as 2,4‐diacetylphloroglucinol. The other two antibiotics, which were produced in small amounts (< 5 mg/l), were not identified. A similar pattern of inhibition against the different bacteria and fungi was exhibited by both 2,4‐diacetylphloroglucinol and strain PFM2 when grown in a medium of the same composition as that in which the antibiotic was produced.

It has also been reported from Wisconsin, Georgia, Tennessee, Illinois, Delaware, and West Virginia. 2. Blackpatch has caused considerable losses during some years to the red clover seed crop in eastern West Virginia. 3. The symptoms of blackpatch on leaves are spreading, zonate lesions which may kill an entire leaf within a few hours. Individual lesions are usually connected by strands of superficial dark mycelium. Stems may show similar zonate lesions or may be encased in a web of superficial mycelium. Flower parts show necrotic lesions from which the mycelium may spread over the entire flower head. Greater damage is done to seed when the head is infected at the early stages of flowering. 4. The fungus causing blackpatch has never been observed to form spores and has remained unnamed. Under some laboratory conditions sclerotia are formed. The name Rhizoctonia leguminicola sp. nov., is proposed for the blackpatch fungus. 5. Many factors may influence sclerotia production; nutritional factors seem to be of major importance. The production of sclerotia by R. leguminicola was favored when the following nitrogen sources were added to a glucose agar medium: asparagine (Difco), peptone (Difco), DL-beta-phenylalanine and potassium nitrate. No sclerotia formed when casein hydrolysate, urea, casamino acids (Difco), ammonium sulfate, ammonium tartrate or ammonium nitrate were used. Over the range of concentrations tried, 0.05 per cent asparagine induced most active production of sclerotia. Numerous sclerotia formed when the sugars D-glucose, D-mannose, D-fructose, maltose and sucrose were used as single carbon sources but few developed in media where D-galactose, D-xylose or lactose were used. Temperatures favoring growth (25°-29°C.) also favored the production of sclerotia. Sclerotia formed best at a pH ranging initially between 5.9 and 7.5. 6. The blackpatch disease has been reported only on legiuninous hosts. In addition to its occurrence on red clover and a number of other common hosts, it has been found in this region on black medick (Medicagu lupulina L.) and Korean lespedeza (Lespedeza stipulacea Maxim). Inoculations have resulted in infections on bush beans (Phaseoliis vulgaris var. humilis) under some greenhouse conditions.

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