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Effects of Five Acids that Occur in Pine Needles on Fusarium chlamydospore Germination in Nonsterile Soil. Freddi Hammerschlag, Plant Pathologist, Ornamentals Laboratory, Plant Genetics and Germplasm Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705; R. G. Linderman, Plant Pathologist, Ornamental Plants Research Laboratory, Oregon State University, Corvallis 97330. Phytopathology 65:1120-1124. Accepted for publication 28 April 1975. DOI: 10.1094/Phyto-65-1120.

Five acids that occur in pine needles, shikimic, quinic, malic, citric, and phosphoric, both separately and in combination stimulated chlamydospore germination of two isolates of Fusarium oxysporum f. sp. lilii (HF and 319) in nonsterile soil. Germination in the presence of the five acids was followed by germ-tube lysis without formation of replacement chlamydospores. Germination of the HF isolate in the five acids at pH 2.8, 4.5, 6.5, and 8.0 was 54, 81, 41, and 37%, respectively. Germination of the 319 isolate was 70, 70, 59, and 46%, respectively. A tenfold dilution series of the five acids revealed that germination was proportional to the concentration of the total acids. When combinations of acids were tested, shikimic and quinic proved to be the most important germination stimulants. The presence of these acids in pine forest soil (pH 4.0 5.5) may be partly responsible for the absence of Fusarium spp. from these soils.

Additional keywords: weak organic acids, phenolic acids, secondary chlamydospore formation.