Comparative canopy damage among provenances of baldcypress associated with the presence of Cercosporidium sequoiae (Ellis and Everth.) WA baker and partridge
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Seeds of Taxodium distichum (L.) Rich. were collected, germinated, and grown from native stands ranging from Mexico, Texas, Louisiana, Mississippi, and Alabama. Twenty-two provenance selections were planted in Summer 2004 in College Station, TX, in 36 replicated single-plant replications per block for a total of 792 trees. Below-average midsummer temperatures and above-average number of rainfall events were conducive to the development of a leaf blight associated with the presence of Cercosporidium sequoiae (Ellis and Everh.) W.A. Baker and Partridge. A survey conducted in Oct. 2007 rated differential defoliation responses among provenances. Selections of Taxodium distichum var. mexicanum (Gordon) from Mexico and south Texas showed defoliation rates from 89% to 96%, whereas T. distichum var. distichum from central Texas had defoliation ratings from 79% to 99%. With the exception of one family collected from the Sabinal River in Texas, the central Texas selections had similar defoliation compared with those from south Texas. Selections of T. distichum var. distichum and one selection of T. distichum var. imbricarium (Nutt.) Croom from southeastern regions (Alabama, Louisiana, Mississippi, and east Texas) showed greater tolerance to the presence of the leaf blight with 52% to 80% mean defoliation. A few individuals within these families exhibited little or no symptoms of the leaf blight. In general, those selections from high-rainfall, high-humidity areas had less defoliation associated with the presence of the leaf blight fungus, although defoliation was variable among provenances within all geographical regions. These results suggest that tolerance to defoliation from C. sequoiae could be included in selection criteria when choosing possible germplasm releases from Taxodium distichum.
