No abstract

The American chestnut (Castanea dentata [Marsh.] Borkh.) became susceptible to a blight fungus, Cryphonectria parasitica [Murr.] Bar, in the 1870s. This was imported on seedings from Asia, and American chestnut had no resistance to it. Since then, all attempts to eradicate or control the disease have met with very limited success or failure. This paper briefly reviews the history of the biocontrol of chestnut blight, from the use of 'hypovirulent' strains of C. parasitica to the use of a bacterium of Castanea spp. that are (I) antagonistic to C. parasitica and (2) can survive for an extensive time period on the bark of C. dentata. The study reveals that some Bacillus megaterium isolates from C. dentata bark may have potential in biological control. The results also provide an explanation for the success of mud packs in 'healing' cankers.