| Code | Definition | Number of Accessions |
| 2 | invasion of the stem past the site of inoculation but not to the first node | 13 |
| 3 | invasion of the stem to the first node | 92 |
| 4 | invasion of the internode slightly past the first node | 205 |
| 5 | invasion to the middle of the internode | 172 |
| 6 | invasion to the second node | 22 |
| 7 | invasion slightly past the second node | 6 |