| In addition, weeds left uncontrolled may harbor insects and diseases and produce seed or rootstocks which infest the field and affect future crops. |
| A few fruit grower associations and progressive orchardists have already started importing virus-free nursery rootstocks. |
| Plants that form rootstocks can be spurred to regrowth after several years through tillage. |
| Vegetative propagation through budding, grafting, tubers, rootstocks and tissue culture are major industries. |
| We know that even the use of clonal rootstocks does not entirely eliminate variability. |
| Nearly five per cent of all vines grow on their own roots, without having been grafted on to resistant rootstocks. |
