Farm Forestry New Zealand

PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND

Dutch elm disease 1992 - 1993

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Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.

From Forest Health News No. 20, May 1993.

DED - another season ended
Trees infected by Dutch elm disease were found in 21 locations. The infected area now includes part of North Shore (Chatswood), Western Springs, Ponsonby, Remuera, Pakuranga, Howick, Mt Wellington and East Tamaki. By the end of the season (April 1993), 3170 Scolytus multistriatus beetles were caught on 74 traps. Twelve of these (0.4%) were contaminated with Ophiostoma novo-ulmi.

(Peter Gadgil )

1993 DED snippets

1. One of the earliest calls responded to. A lady has three elms on her property, one with severe dieback, the others not too bad and an urgent check is needed. Hello, "elms" turn out to be Lombardy poplars.
2. Urgent call from property owner via city council staff. Massive dieback and defoliation occurring. Drop everything and race to check. Oops, silver poplar this time.
3. Urgent call of elm dying. In the middle of infected elm pickup and not far from one infected site. Better get there fast. Enter fortress, large front gate, large golden elm on left, large tortured willow on right with dieback. You guessed it. Willow was the dying "elm".
4. Golden elm with dieback. Bit more casual this time, but must respond. Front door open; knock, knock. Rapid appearance of owner defending herself with large biro pen. "It was all I could find in a hurry!". Inspection over, tree safe, write that off to experience!

(Chris Scott)

DED - plans for 1993-94
Details for the 1993-94 Dutch Elm Disease central programme are being considered. A complete survey of the listed 3800 elms before Christmas and again afterwards is planned. Subject to approval it is planned to release the D2 factor virus to lower the potential of the fungus. In the season just completed there were 91 elms felled in 19 locations. A number of the locations were elms that had been infected at the tail end of the previous season.

(Dave Kershaw)

Dutch elm disease - latest position
From Forest Health News No. 16, January 1993

Special intensive surveys were carried out in January 1993 to identify the sources of beetles contaminated by Ophiostoma novo-ulmi which were being caught by pheromone traps in Remuera, Howik and East Tamaki. Three teams took part, two from FRI (John Bain and Lindsay Bulman; Mark Self and Roger Crabtree) and one made up of FHOs (Chris Scott and Brent Rogan). The surveys were successful in finding what well could be the sources of these contaminated beetles - a gully in Remuera with lots of elms, some infected, a couple of trees in Howick seething with beetles and a number of trees on a stud farm in East Tamaki. The Remuera and Howick trees were in quite inaccessible places, completely hidden from the road. A lot of potential breeding material, including a retaining wall built of unpeeled green elm rounds (since demolished), was uncovered during the surveys. Remuera is an area known to be infected since 1990 but the Howick and East Tamaki infestations, which were at least a year old, had gone undetected so far. A lot of new elm locations were added to the list through the special surveys. There are now some 3000 of these and the task of keeping them all under surveillance will be a hard one. Just one FHO can hardly be expected to do this job on his own and more help will have to be sought - FRI staff are still doing some special surveys based on trap catches but no new infection centres have been found since the January surveys. The eradication campaign certainly could still succeed but it could be in difficulties if more staff for the work are not forthcoming.

(Peter Gadgil)

From Forest Health News No. 15, November 1992
Dutch elm disease update
It's that time of year again. Dutch elm disease season. Work is continuing on much the same basis as last year, all known elms in the Auckland area are being routinely inspected and pheromone traps are being used to check the distribution of Scolytus multistriatus and to obtain information on the number of the beetles carrying the fungus. So far very few beetles have been trapped but one diseased tree has been found in Western Park - at the bottom end, opposite Auckland Girl's Grammar. This was almost certainly a tree that was infected right at the end of last season but no symptoms appeared before leaf fall.

(John Bain)

Dutch Elm Disease
From Forest Health News No. 13, September 1992
At a meeting of the Dutch Elm Disease Advisory Committee, held on 1 October 1992, the following work was agreed upon.
Surveys: One Forest Health Officer (Chris Scott) will be responsible for a continuous survey of all known elms in the greater Auckland area. The survey will begin when elms come in leaf, about the end of October or the beginning of November 1992 and continue until the end of the beetle flight season (March/ April 1993). With the changes in the Ministry of Forestry regional structure, Peter Tate will now be responsible for seeing that felling, fumigation and disposal of infected trees is properly done. It is essential that one person be responsible for arranging and supervising the disposal of infected trees. It was agreed that the local authorities will bear the cost of felling of infected trees on public land and the Ministry of Forestry that of trees on private land. Fumigation and disposal remain the responsibility of the Ministry.
Pheromone trapping: Pheromone traps will be set up and isolations from trapped beetles will be made by FRI. About the same number of traps as in 1991-92 will be used. Attempts to trap living beetles using window traps will also be made.
Publicity: It will be necessary to give wide publicity to (a) the need to report suspected infected trees to MOF and (b) the danger associated with the storage of elm firewood (a policy of how to deal with this problem needs to be developed).

(Peter Gadgil)

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