Mite to help control gorse

Press, 2 December 1987, Page 33

Mite to help control gorse

A new mite to help control gorse biologically may be imported and released by the D.S.I.R. The aim is to suppress gorse to a level where it no longer causes damage. Biological control should reduce the vigour and abundance of gorse but cannot eradicate it. Once suppressed, gorse will remain in balance with introduced natural enemies. Permission to import the mite has been sought from the Ministry of Agriculture and Fisheries supported by a detailed 350page environmental impact assessment. This assessment concluded there were no compelling environmental or economic reasons why the mite should not be

introduced and that big benefits would ensue if gorse were successfully controlled in New Zealand. The E.I.A. has been lodged in 27 public and university libraries, and public submissions on the proposal are now invited. These should be sent by January 21, 1988, to Dr A. F. Rainbow, MAFQuaI, P.O. Box 41, Auckland. Although gorse is New Zealand’s most costly weed, some regard it as a valuable plant and oppose the proposal to control it biologically. The E.I.A. is a synthesis of the wide-ranging scientific and public consultation which the Entomology Division of the D.S.I.R. has promoted since 1982. It incorporates

several major publications which have already been issued on this subject. The director of the •D.S.I.R. Entomology Division, Mr John Longworth, says the introduction of biological control agents to suppress gorse would be in the public interest. Gorse flowers are valued as a source of pollen for the beekeeping industry. Mr Longworth said that the amount of gorse in New Zealand would need to decline by well over 50 per cent before significant losses were felt by the industry. Pollen substitutes could be used to feed bees, and, in the long term, alternative pollen-bearing plants could be established. Gorse could be used as a fodder for goats, but

was not essential to the' viability of that industry, said Mr Longworth. On the other hand, biological control of gorse would be extremely valuable to the much bigger sheep industry. Some concern had been expressed that regeneration of native forests would be adversely affected, but Mr Longworth said there was no evidence of this. Biological control of gorse would have little Impact on soil erosion either. Mr Longworth said the: successful control of gorse would lead to a reduction in the use of herbicides' for this purpose. A decision on whether this proposal will go ahead is expected in February.