The Animal and Plant Health Inspection Service of the US Department of Agriculture (APHIS-USDA) developed rules for permitting the importation of artificially dwarfed or “penjing” plants from China, in pots containing growth media rather than bare-rooted (USDA/APHIS, 2003). Buxus sinica (Chinese boxwood), a host for P. buxi (Zhang et al., 1997), was among the plants governed by the rule. Requirements for production of plants for export that relate to the exclusion of P. buxi include that the plants should be developed from clean inspected “mother” stock, that they should be rooted and grown in approved media in an active condition for at least 4 months before export, and during that time, they are kept in a greenhouse practicing sanitary procedures, including inspections, to exclude pests and pathogens (USDA/APHIS, 2003).
After this rust was reported from a nursery in Pennsylvania, USA, a quarantine was placed on rooted cuttings and plants resulting from a shipment of Buxus material from Greece to a nursery in Maryland in the USA (NAPPO, 2006).
Fungicide sprays should be prohibited during such post-entry quarantine of Buxus plants because the fungicides can suppress development of the fungus and disease symptoms. The distribution or sale of asymptomatic plants could spread the fungus to other areas (NAPPO, 2006).
Cultural Control and Sanitary Measures
Planting for sun and air circulation, as well as thinning and pruning for control of other fungal diseases (Batdorf, 1995), may create conditions that retard the growth and spread of P. buxi. The removal of any shed leaves will reduce available inoculum. As Durrieu (2001) indicates, pruning may remove susceptible and/or infected leaves.