摘要 : Worldwide exchange and trade of propagating material of ornamental crops is still a rapidly growing economic activity. New varieties are developed in all major production regions and can be of value to growers worldwide. To start ... 展开 Worldwide exchange and trade of propagating material of ornamental crops is still a rapidly growing economic activity. New varieties are developed in all major production regions and can be of value to growers worldwide. To start professional propagation and production, the highest quality and plant health is required. Users of plant material must be sure that they receive this material pathogen-free. In line with existing systems, it is proposed to distinguish 3 classes of certified material: prebasis (nuclear stock), basis (propagation stock) and certified stock material. It is concluded that it is up to virologists, mycologists etc. to draw up, in consultation with growers and propagators, standards and max. allowed tolerances for pathogens. Examples are given of certification systems of Dendranthema, Dianthus, Pelargonium and Petunia. 收起