Therapeutic Treatment of Mature, Living Douglas-Fir with Chloropicrin, Methylisothiocyanate, or Vorlex Reduces Root Colonization by the Pathogen Phellinus weirii : Root and Butt Rots

Uppsala

International Union of Forest Research Organizations, Swedish University of Agricultural Sciences

1994

S. 736-741

10 Lit. Ang.

Bandaufführung

13462

73863

In 1982, 135 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees were segregated into three infection classes based on signs and symptoms of Phellinus weirii (Murr.) Gilb. infection. Eight fumigation treatments and one control treatment were applied to five replicate trees within each established class. Stumps of trees killed before 1991 and stumps of all remaining live trees harvested in 1991 were excavated and their roots dissected and sampled for viable Phellinus weirii. Twenty-four of the 30 trees treated with the two highest doses of chloropicrin were killed, presumably by the fumigant. None of the 45 trees treated with methylisothiocyanate (MITC) and only 3 of the 15 trees treated with Vorlex died (as did 3 of the 15 untreated controls). Volume of stained and decayed roots occupied by viable Phellinus weirii was reduced 80 to 90% by MITC or Vorlex. This compares with reductions of 52 to 66% by chloropicrin at the two lower, less phytotoxic doses and 9% for untreated controls.