MSU Extension

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

In July 2006, plum pox virus (PPV) was detected in a plum tree sampled at the Southwest Michigan Research and Extension Center (SWMREC) in Benton Harbor, Michigan. The Michigan Department of Agriculture (MDA) has worked very intensively since that time to test the Prunus trees at risk at this and other Michigan locations. After testing more than 50,000 samples in late summer, no new “positives” were found in Michigan.

PPV is a serious disease of stone fruit that can cause significant yield and quality loss. PPV has been the most significant disease of stone fruit in Europe for many decades and was detected for the first time in Pennsylvania in 1999 and Ontario in 2000 and in New York and Michigan in 2006.

In August of 2006, the USDA issued an Emergency Action Notification (EAN) to all landowners with commercial orchards identified within one mile of the infected tree. The EAN notified landowners that they may not move propagative materials from PPV susceptible plants off their properties.

On March 12, 2007, the MDA issued a PPV Quarantine, signed by MDA director Mitch Irwin, which extends beyond the scope of the EAN. Under the provisions of the PPV Quarantine, all plant material such as nursery stock trees, seedlings, rootstocks, scions, budwood, branches, twigs and leaves, except for the seeds and fruit of Prunus species susceptible to PPV Dideron strain (strain D), are “regulated articles.” Movement and sale of fruit free of any leaves and branches is exempt from the quarantine regulations.

Prunus species susceptible to PPV-D strain include types grown for fruit production and for ornamental uses. Fruit-bearing species susceptible to PPV-D include peaches, nectarines, all species of plums: European (P. domestica), American wild plum (P. americana), Japanese plum (P. salicina), Myrobalan or cherry plum (P. cerasifera), apricot and almond.

Ornamental species susceptible to PPV-D include flowering almond (P. glandulosa), Myrobalan plum/cherry plum (P. cerasifera), purple-leaf plum (P. cerasifera “Atropurpurea), black thorn, sloe (P. spinosa), flowering plum (P. triloba), flowering peach, purple-leaf peach (P. persica), sand cherry (P. pumila), Japanese flowering cherry, Kwanzan cherry (P. serrulata), Nanking cherry, Hansen’s bush cherry (P. tomentosa), and purple-leaf sand cherry (P.x cistena).

The quarantine consists of an inner quarantine zone of approximately two-mile radius (see below for description) and a larger nursery stock regulated area of 7.15 mile (11.5 km) radius around the positive PPV-site. Movement of restricted Prunus material within or to outside the quarantine zone is prohibited. Regulated material may not be planted in the Quarantine area. Regulated species of nursery stock originating from or growing within the quarantine zone or nursery stock regulated area cannot be used as a source of propagative material (either rootstock or scion or seed) unless it is grown under a compliance agreement issued by the Director of the MDA.

The quarantine may be cancelled when sampling of all susceptible fruit bearing and ornamental trees in the quarantine zone is negative for PPV for three consecutive years.

Neither the EAN nor the MDA quarantine will hinder the harvest and sale of fruit in this area since PPV is not transmitted through the fruit or the seed. The plum pox virus poses no human health risk. The MDA plans to resample all regulated varieties in the 7.15 radius zone and additional targeted locations in 2007.

PPV Quarantine area boundary (see map)
The current PPV quarantine area is in Berrien County in southwest Michigan. It includes parts of Benton, Bainbridge, Sodus and Pipestone townships. It is outlined starting at the intersection of Britain Avenue and Benton Center Road in Benton Twp.; south side along the Benton Center Road to Meadowbrook Road; continuing west to Yore Avenue; than south on Yore Avenue to Snyder Road in Sodus Twp.; than east along a line formed by Snyder and Union Roads to Britain Avenue; than west to the starting point.