Wood Rot (fungus - Ganoderma lucidum): This fungus contributed to the gradual decline and death of trees in a portion of an orchard in the Rio Grande Valley. The decline occurred over a period of several months during the summer. The leaves of affected trees first turned pale to yellow and trees soon lost leaves [Picture]. Eventually, trees were completely defoliated and died [Picture]. Fruiting bodies of the fungus were found on dead and dying trees [Picture]. The above-ground symptoms of the disease resemble Phytophthora root rot. The disease occurred in a portion of the orchard with poor drainage that was subject to waterlogging. The waterlogging led to the death of feeder roots (again, a symptom that resembles Phytophthora root rot) and stressed the trees. This environmental stress allowed the fungus to develop within trees. The fungus infected the trees via wind-blown spores that entered the tree through wounds. There is no chemical control for this pathogen. Encouraging vigorous tree growth by minimizing environmental stresses (e.g. improving soil drainage) will prevent establishment of the fungus in the tree.

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