<PICT:0832391/IV (b)/1> A new antibiotic designated "compound number 616" is produced by cultivating a compound 616-producing strain of streptomyces parvisporogenes, e.g. S. parvisporogenes ATCC 12568 in an aqueous nutrient medium containing a source of carbon and a source of organic nitrogen under submerged aerobic conditions. Specified sources of (a) carbon are sugars such as dextrose, starch and glycerol, (b) nitrogen, are casein, casein hydrolyzate, corn meal, peanut meal, soybean meal, cottonseed meal, wheat gluten, lactalbumin and tryptone. Other components are (a) growth substances, e.g. yeast extract, distillers' solubles and molasses butanol fermentation residues; (b) mineral salts, e.g. sodium chloride, potassium phosphate, sodium nitrate and magnesium sulphate; (c) trace metals such as copper, zinc and iron; (d) buffering agent especially calcium carbonate; and (e) antifoaming agents, e.g. a vegetable oil. Cultivation is at 25 DEG to 35 DEG C., and preferably 28 DEG C., for 1 to 6 days. Compound 616 is recovered from the broth by filtering with a diatomaceous filter aid and then extracting the mycelium cake with an aliphatic alcohol such as methanol, ethanol, propanol, butanol (preferred) or pentanol. The extract is concentrated in vacuo, the precipitated compound 616 resuspended in hexane, filtered and dried. Compound number 616 is an amphoteric polyene compound effective in inhibiting the growth of fungi and containing 62.0% carbon, 7.8% hydrogen, 2.7% nitrogen and 27.5% oxygen; it decomposes at 130-140 DEG C. turning red and then brown; in 0.2% pyridine its specific rotation <FORM:0832391/IV (b)/1> aqueous n-propanol its Rf value is 0.72; it is insoluble in water, acetone, methylisopropylketone, methylethylketone, benzene, chloroform, ethyl acetate and methylcyclohexane; soluble in pyridine, dimethylformamide, methanol, ethanol, n - propanol, n - butanol and dioxane; dissolved in 20% aqueous methanol 0.001 N in sodium hydroxide exhibits the following properties in the ultra-violet E1%1 cm.=467 at 340 mm , E1%1 cm.=692 at 358 mm ; E1%1 cm.=959 at 377 mm ; E1%1 cm.=808 at 397 mm ; exhibits characteristic absorption in the infra-red at 3.01, 3.46, 5.88, 6.15, 6.27, 6.37, 7.11, 8.51, 9.40, 9.65, 10.00, 11.83 and 13.18. Compound number 616 forms salt with (a) acids such as sulphuric, hydrochloric, nitric, hydroiodic, hydrobromic, benzenesulphonic, toluenesulphonic, sulphurous and trichloroacetic acids; (b) inorganic bases such as hydroxides and oxides of the alkali and alkaline earth metals, e.g. the sodium, potassium, barium, lithium and calcium salts. Examples illustrate the preparation of the sodium, triethylamine sulphate, hydrochloride and sulphate salts. Compound 616 tends to isomerize in the presence of strong acids, e.g. H2SO4 and p-toluene sulphonic acid and bases. Compound 616 has low phytototoxicity and is used as a plant fungicide (see Group VI).ALSO:An antifungal antibiotic, designated compound number 616, produced by cultivating Streptomyces parvisporogenes ATCC 12568 (see Group IV (b)), has low phytotoxicity and is used in compositions for the treatment of fungal diseases in plants. It may be used in the crude or pure form as such or in the form of a salt such as the sulphate, hydrochloride, hydrobromide, hydroiodide, benzene sulphonate, toluene sulphonate, trichloroacetate, sodium, potassium, barium, lithium and calcium salts. The crude may be the whole fermentation broth, the concentrated broth, the mycelial cake or the crude obtained on extracting the cake with an alcohol such as butanol. The compositions may be in the form of a spray, emulsion or dusting powder containing 0.01 to 95% of the antibiotic. A suitable spray contains 5% aqueous acetone. A dust may be prepared with pyrophilite, bentonite, talc, kaolin or diatomaceous earth. Optional additions are (a) wetting agents, (b) stabilizers, and (c) buffers. The antibiotic may be dissolved or suspended in waxes or resins. The compositions may be used for the treatment of seeds.