The growth of Norway spruce seedlings with fungal infection. (A) The primary root length of seedlings. (B) Effect of fungal infection on the growth of Norway spruce seedlings. (C) Fungal isolation from the infected seedlings. Pa: non-inoculated seedlings control; PaPs: P. sphaeroides-inoculated seedlings; PaHp: H. parviporum-infected seedlings; PaPsHp: H. parviporum-infected seedlings in the presence of P. sphaeroides (coinfection).