Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Dutch elm disease - sixth season report, April 1995
From Forest Health News No. 41, April 1995.
Supplementary elm tree location surveys carried out in the 1994-95 season were successful in finding trees missed in the original surveys of Remuera and Pakuranga. Elm tree locations are now slightly in excess of 13,000. During the disease detection surveys in the 1994-95 season, all locations were visited and the trees inspected three times, once before Christmas and twice afterwards. Infected trees were found in 6 locations, 3 in Remuera and one each in Ellerslie, Otahuhu and St Heliers. One hundred pheromone traps were operated throughout the season and 2622 Scolytus multistriatus beetles were caught. Only one of the beetles trapped was contaminated with Ophiostoma novo-ulmi . Pheromone traps were set up at Tamahere, near Hamilton upon the discovery of S. multistriatus there in December 1994. None of the beetles trapped was contaminated with 0. novo-ulmi . Infected trees were found this season in Sturm's Gully, Napier near the group of trees found to be diseased last season. No S. multistriatus have been trapped in this area and there is no sign of beetle activity. Sampling of elm roots in the Gully showed that 0. novo-ulmi is present in the roots and the new infections found this season have almost certainly resulted from transmission of the fungus through root grafts.
(Peter Gadgil)
NZFFA on facebook