Measuring the impact of Collybia fusipes on the root system of oak trees

This work describes the aetiology of Collybia fusipes root rot and the impa ct of the parasite on the structure of mature oak root systems. The collar roots were examined and rated for C. fusipes infection at the base of 26 Qu ercus robur and 20 Q. rubra trees. Trees were then felled and their root sy stems were up-rooted with a mechanical shovel. Number and infection status of the roots present were recorded at 40, 60 and 80 cm from the trunk base. C. fusipes drastically reduced the number of living roots. At 80 cm from t he trunk base, on cylinder 3, Q. robur rated as lightly and heavily damaged had only 52 and 25 %, respectively, the frequency of living roots of undam aged trees; the values were 72 and 25 %, respectively, for lightly and heav ily damaged Q. rubra trees. C. fusipes impacted especially the vertical roo ts just under the collar. ((C) Inra/Elsevier, Paris.).