Keeping out disease may not be so important to N.Z.

Press, 29 August 1980, Page 17

Keeping out disease may not be so important to N.Z.

Tn his _■ presidential address -.to the. 26th meeting' of" the New. Zealand Genetical. Society in Auckland this week, Mr T. P. Palmer, of the Crop Research Division of the Department of Sc-.entific and. Industrial Research at Lincoln, had some- interesting views about the introduction of animal and. plant material front; overseas and.disease control. He does not see the in-’ traduction of disease being by any means all bad or harmful and indeed some advantages may flow from it.

“If we are to breed for resistance to disease, and this is a surer long term bet for disease control than attempting to isolate ourselves from it, then there is a risk of introducing the disease,”he said. “But if we do not breed for resistance or inoculate against the disease, once it enters it will move unhindered through the local susceptible population.”

“To combat a disease an isolationist would not consider introducing plants or animals from areas where the disease in endemic. A breeder would not import from anywhere else . . .”

Mr Palmer said that one of the main reasons advanced for restricting im-

ports was to prevent the introductioninto New Zealand of dread animal and plant diseases, which would ruin 'the economy .. . That the ' diseases might not be ail that bad, =that the 'risks of introducing’ them should be scientifically assessed and that there were, costs associated with . the present policy were heretical thoughts

But some of the dread diseases were, not intrinsically very harmful. They had been made so by definition, regulation or scare mongering. Potato cyst nematode was a case in . point; scrapie in sheep w T as another. These diseases did not cause significant losses in countries where they were endemic,

but New Zealanders feared that they might ; restrict trade to other countries.

It was important that restrictions should' be based on facts and not on unjustified fears. There seemed to be little evidence that animal products from this country’s disease-free flocks and land sold at premiums on world markets. In fact, quite the contrary ’in developed countries, while customers ■in the developing markets of the Middle East were more interested' in “sanctity” than the sanitary aspects of meat production (Processes.

As, with animal diseases there were many plant pests which New Zealand had not got and did not want, and restrictions on the entry of seeds and plants were designed to prevent them getting here.

Some of these diseases were innocuous and restrictions to

keep them out could 0n1y... hinder production in New Zealand. Pea seed-borne mosaic or barlev stripe mosaic were examples..

Some diseases, ’ though serious, turned out to confer benefits as well as -having costs. Attempts to keep them out could be counter-productive.

Restrictions on the importation of lucerne - seed, designed to prevent the entry into New Zealand of bacteria! wilt, of . lucerne, had aggravated the effects of the disease when it was discovered to be here. Because. of tire restrictions, very few resistant varieties had been tested here and now 10 years later the supply of seed of resistant varieties was not adequate to meet the demand.

The history of the disease in the United States was instructive. It was probably introduced to the United States in undressed lucerne seed from Turkestan. This was imported in large quantities in the

early years of the century following Hansen’s expeditions to Siberia and the realisation that these lucernes were winter hardy enough to extend lucerne growing into the Great Plains of the United States and Canada.

They had a high degree of resistance to bacterial wilt and when it spread from them to susceptible varieties in other zones they were used to breed resistant lucerne varieties with a wide range of adaptation. The importations from Turkestan thus brought into the United States the cure as well as the disease and stimulated lucerne breeders to 'produce varieties' which were better in many other respects than being resistant to bacterial wilt.

Similarly in New Zealand varieties such as Saranac, with a high degree of resistance to wilt, or Rere with aphid resistance, were being grown primarily for their wilt or aphid resistance, but were also conferring the advantages of resistance to leaf diseases or extra winter production. The New Zealand consumer might be introduced to the pleasures of eating yellow-flesh potatoes because -.-a yellow-flesh, nematode resistant variety had been bred at the Crop Research Division. A yel-low-flesh potato, without the strong selling point of nematode resistance, would not have been

acceptable to the conservative potato growing and marketing industry.

"The introduction of quite serious pests and diseases need not be an unmitigated disaster,” said Mr Palmer. “If there is a positive reaction to them they may result in gains and not losses.” He said that breeders of crop plants, with some exceptions, . had . reasonable access to world plant resources. For animal breeders the situation was quite different Gene sources had been limited historically, and now legislatively, to a small part of Europe. Techniques for sale introduction and rapid multiplication now existed. They should be developed and used to overcome unreasonable quarantine barriers. Unreasonable barriers, which had been erected from fear or prejudice and were not based on facts, should be examined and dismantled. The impetus for this must come from animal breeders. They should know, or find out, what the introduction of exotic genes offered the animal industry. It could not be expected from the present

breed societies. It must come from professional animal geneticists in university, Government or producer board employ.

Mr Palmer said that introduction of plant breeders’ rights had brought New Zealand plant breeding into the mainstream of world plant breeding and given New Zealand, farmers access to the best the world could offer.

• Animal breeding needed a nudge from its present isolationist position. If New Zealand farmers did not have access to the best breeds of animals and varieties of crops which the world could offer, they would be competing with a continually worsening handicap on world markets.

New Zealand agriculture needed a more open policy, particularly towards animal breeding. Who was to be the advocate for this policy? The breed societies had vested interests opposing it, the universities had shown no inclination to take up the challenge and Government departments were constrained from doing so. It was one of the duties of the Genetical Society to do this.