Dieback caused by Verticillium dahliae on Blighia sapida

Robert T. McMillan Jr., W. R. Graves, T. F. Wood, R. M. Leahy

Abstract


Akee trees (Blighia sapida K. Koenig) with wilt/dieback symptoms were found in a local south Florida commercial planting during the spring of 1999. A fungus, isolated from the roots onto V-8 agar, was identified as Verticillium dahliae Kleb. by the Division of Plant Industry. Twenty Akee seedlings were transplanted into 3.85 L plastic pots and grown in a greenhouse at 28 C-day/23 C-night temperature. When the plants were approximately 25 cm in height, stabbing a 15 cm long knife, four times into the root zone, severed the roots. A standard plate of uninoculated V-8 Agar was blended with 160 mL of sterile water and 15 mL of this slurry was poured into the disturbed soil of each of 10 control plants. A slurry, made and applied as above, using a 2-week-old culture of V. dahliae onV-8 Agar, was used to infest the soil around the 10 treatment plants. Plants were kept in the greenhouse. After 6.5 weeks, leaves of inoculated plants had symptoms of marginal leaf burn. No symptoms were seen on the control plants. Verticillium dahliae, was isolated from the roots of the inoculated plants.

Keywords


fungus; fungus inoculation; tree dieback

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283