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Proceedings of the First Symposium on Marsupials in New Zealand

Research Objectives

Research Objectives

There are three approaches by which research can improve protection of the poles: the development of less palatable tree types, protection of the poles by physical barriers and the improvement of possum control techniques.

Research so far has been concentrated on breeding less palatable clones of poplars and willows. The Plant Materials Centre of the Ministry of Works and Development has had some success with willow breeding (Hathaway 1974). However, a vigorous, unpalatable, tree willow has yet to be produced (van Kraayenoord 1975). The arrival of the Melampsora spp. poplar leaf rusts have largely nullified the efforts with poplar breeding (van Kraayenoord 1975). All of the unpalatable clones in common use were susceptible to one or both rust species.

page 208

Development of less palatable, rust resistant clones is being attempted by the Plant Materials Centre.

Physical barriers in the form of sleeves can be attached around the trunks of the poles. The sleeve design must allow for expansion of the trunk over the critical first 4–5 years of the pole's life. They must also be designed to be recovered and re-used or to break away when their maximum diameter is reached. It is believed that metal sleeves are unsuitable because of the excessive heat transferred to the trunk of the young tree but formal trials are lacking. Several designs of both plastic and metal sleeves will be tested as barriers to possums and for any deleterious effects on the poles.

Research is also required to try to produce possum control techniques that avoid the expensive practice of blanket poisoning large areas. Highly palatable bait trees or crops dispersed amongst plantings will be assessed as lures where the possums can be subsequently poisoned in confined areas. A variety of methods of presenting the poison, such as bait stations or poison in gel form, will also be tested. There is also a need for research on poisons other than 1080 which are safer in farm land conditions, particularly in the presence of farm dogs. A lure in the form of highly palatable poles is suitable for systemic poisoning.

It is likely that only a combination of all three approaches will result in greatly reduced damage.