Slides Contributed by Sandra Anagnostakis
CHESTNUT  BLIGHT

1. American chestnut trees at Poplar Cove, Joyce Kilmer Memorial Forest, NC
    Photo S.V. Streeter, January 15, 1910

2. American chestnut tree 23 inches dbh, 83 feet tall; Scotland, Connecticut, 1905

3. Chestnut blight (Cryphonectria parasitica [Murr.] Barr) on American chestnut
    tree (Castanea dentata [Marsh] Borkh.)
    Fungus probably entered at broken branch stub on left of trunk; orange stromata
    have broken through the lenticels to the surface; concentric ridges of callose are
    tree's defense, which fails.

4. American chestnut tree killed by blight canker at base has sprouted from root collar

5. American chestnut sprout against old chestnut fence in forest (good picture of leaf form)

6. Three virulent (V) strains of Cryphonectria parasitica (top) and their
    hypovirulent (H) converts (bottom)
    Each H strain is directly under its V progenitor and has the same nuclear
    genotype. Difference in morphology is caused by cytoplasmic genes from
    Italian H strains. [PDA (Difco), 12 hrs white fluorescent light, 28 C (12 hr)]

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