The Pathogens and Pests of Chestnuts

Abstract

The name “chestnut” refers to seven species of deciduous, nut-bearing trees found native and introduced throughout the world. In 1838, a root disease was reported on European chestnut in Portugal, and soon after this “ink disease” was found in several other parts of southern Europe. Ink disease is assumed to have entered the United States in the mid-l800s, and probably accounted for the recession of American chestnut from large areas in the Gulf and Mid-Atlantic states in the United States, and inland to the foothills and mountains of Mississippi, Alabama, Georgia, Tennessee, Maryland, Virginia, and the Carolinas. Chestnut blight, or chestnut bark disease is caused by the fungus Cryphonectria parasitica Barr, formerly called Endothia parasitica And. & And. The fungus enters wounds, grows in and under the bark, and eventually kills the cambium all the way around the twig, branch, or trunk. From 1982 through 1986, the 317 cankers that developed on American chestnut stems in 50 sprout clumps were treated with H strains. European chestnuts (C. sativa) were distributed throughout southern Europe from the Caucasus mountains, and the nuts have become an important food source, both cooked whole and ground into flour. Chestnuts are actually fruits, with shells enclosing cotyledons. Two species of weevils lay eggs in the nuts, and the developing larvae make the nuts unmarketable.