Sphaeropsis tip blight development in Austrian pines mulched with heat-treated or fresh needles and shoot tips collected from diseased trees. Means represent the average of 15 trees. Values with different lowercase letters indicate a significant difference (P ≤ 0.01) among treatments in a given year.
| Mulch treatment | Average percentage of blighted tips (Average # blighted tips per tree) | |
|---|---|---|
| Year 1 | Year 4 | |
| Heat-treated | 3.8% (1.0) a | 6.8% (5.4) a |
| Fresh | 9.6% (1.6) a | 15.1% (12.0) b |