Comparison of pathogenicity with cerato-ulmin production in isolates of Ċeratocystis ulmi.
| Pathogenicity | |||
|---|---|---|---|
| Exp. no. and isolates | Crown symptoms (%) after 6 wk | Crown dieback (%) after 12 wk | Cerato-ulmin production indexa |
| Experiment l:b | |||
| ALd | — | — | 637 x |
| MA 2 | 9 ze | 12 z | 186 yz |
| MA4 | 88 x | 85 x | 330 y |
| TN4 | 40 y | 50 y | 210 y |
| TN5 | 1 z | 4 z | 60 z |
| Experiment ll:c | |||
| ALd | — | — | 628 x |
| NDd | — | — | 865 w |
| TN1 | 27 z | 16 z | 3 z |
| TN 2 | 60 y | 46 y | 87 z |
| TN3 | 62 y | 49 y | 299 y |
↵a Cerato-ulmìn production index = A400 × 1000.
↵b Eight 5-year-old American elm trees were inoculated June 1979.
↵c Twelve 3-year-old American elm trees were inoculated June 1979.
↵d Highly pathogenic isolates AL and ND (5) were included for comparison.
↵e Within the same column and experiment, values followed by different letters are significantly different by Duncan s multiple range lest (P=0.05).