The purpose of this pocket symptoms guide is to help stone fruit growers identify plum pox virus (PPV) and differentiate its symptoms from those of other diseases. The guide contains photographs of PPV symptoms on peach, plum, and apricot fruit, flowers, and leaves. (The strain-D PPV currently found in North America does not infect cherries.)

Several other diseases of stone fruit resemble PPV. The guide also includes photographs of diseases such as scab, leaf curl, and rust, as well as symptoms of nutrient deficiency, herbicide damage, and insect/mechanical damage. The guide is cross-referenced so you can compare similar-looking symptoms.

Because of the impact of this virus on the stone fruit industry, it is important that growers continue to scout their orchards for symptoms. It was an observant grower who first found plum pox virus symptoms in Pennsylvania.

The disease referred to as plum pox was first reported in 1915 in Bulgarian plums. It has spread steadily throughout Europe since then and is considered the most devastating disease of stone fruits there, infecting over 100 million trees. Plum pox continues to spread eastward in Eurasia and southward along the Mediterranean coast of Africa. In 1992, plum pox symptoms were first detected in the Western Hemisphere, in Chile.

Late in 1999, plum pox was identified in North America for the first time in a small number of orchards in Adams County, Pennsylvania. Because of the localized nature of this infection, it is hoped that eradication may be successful in eliminating this pocket of PPV in the United States. PPV was found in several stone fruit orchards in Canada during the 2000 growing season.

The strain of PPV that was found in Pennsylvania not only infects plums but also most (not cherry) other economically important cultivated stone fruit species including peach, nectarine, and apricot. Researchers at Penn State University are currently surveying wild Prunus plants and common weeds for PPV. So far, PPV has only been found in commercial stone fruit orchards.