Occurrence, Associated Symptoms, and Potential Insect Vectors of the Ash Yellows Phytoplasma In Iowa, U.S.    (View PDF)

Christopher J. Feeley, Elwood R. Hart, Janette R. Thompson, and Thomas C. Harrington

Abstract: The ash yellows (AshY) phytoplasma has been reported widely across the United States as an organism associated with ash decline in urban communities. Prior surveys conducted in Iowa communities indicated that AshY was found in up to 20% of the urban green ash (Fraxinus pennsylvanica Marsh.) when using the DAPI (4' ,6-diamidino-2-pheyIindole'2HCl) staining method. A new survey of trees in nine Iowa communities used polymerase chain reaction (PCR.) to detect the AshY phytoplasma. PCR analyses of tree tissue were positive for AshY in 4% of the 240 trees surveyed. Although 145 of the sampled trees had decline symptoms similar to those exhibited by trees infected with the AshY phytoplasma, the phytoplasma was detected in only 11 trees. Because Homoptera have been shown to vector phytoplasmas, insect populations associated with ash trees in two Iowa communities were also sampled to help determine whether the insects were carrying phytoplasmas. A total of 471 insects, representing 34 species, were collected from green ash trees; of these, 396 were assayed for the presence of phytoplasmas using PCR. Three leafhopper species were found that were reported to vector phytoplasma diseases, but phytoplasmas were not detected in any of the insects assayed.

Keywords: Homoptera vectors; mycoplasmalike organism; polymerase chain reaction.

https://doi.org/10.48044/jauf.2001.037