Chemical for stripe rust due today

Press, 13 November 1981, Page 3

Chemical for stripe rust due today

Fresh supplies of chemical for treatment of wheat against stripe rust should be available today. Mr M. S. Moore, advisory and development manager of Bayer New Zealand, Ltd, said that a truck was due in Christchurch this morning with a supply of powder from Germany which had been repacked in Wellington. Supplies of chemical in liquid form were also expected in Christchurch by air last evening. Supplies from both consignments will be' available in Christchurch this morning. With two further consignments of chemical due next week, Mr Moore said supplies should be sufficient for the next three or four weeks. It is expected that the material will be used largely on wheat. Some crops are reported to be heavily infested with the rust, with about half of the plants affected. Mr Moore said that some farmers had sprayed their crops again after only eight days; but this was*wasteful as it would take more than 10 days for the pustules to disappear from the leaves. Where a crop was now severely infected it might be necessary to repeat the treatment after 12 or 13 days instead of three or four weeks. The director of the Crop Research Division of the D.5.1.R., Dr H. C. Smith, said yesterday that the severe infection of Canterbury’s wheat crops by stripe rust disease should not be a cause for despondency. “In spite of assertions to the contrary, more than half of the varieties available to New Zealand farmers are resistant to the disease,” said Dr Smith. The resistance in these varieties was adequate even though some rust might occur on young plants. The

resistant cultivars — Oroua, Karamu, both of which were highly resistant, and Kopara, Arawa, and Konini — were readily available and measures were being taken to ensure that seed supplies were adequate for the 198283 season. Dr Smith said that Oroua was the highest-quality wheat available and if more widely adopted could improve the quality of the national crop. Plant pathologists have advised farmers that the spraying of resistant varieties is unnecessary. The Crop Research Division met yesterday to discuss the effect of the disease on the breeding programme and on seed supplies. Dr Smith said that as a result of the meeting the accelerated increase of several prominent breeding lines would be arranged and material would be sent to Europe in the next

few weeks for further multiplication. “The aim is for all New Zealand wheat varieties to have a high level of resistance to the disease,” said Dr Smith. The D.S.I.R. believed that in spite of the epidemic proportion of the disease, the season would be a good one because about 30 per cent of the crop was sown in resistant cultivars; most farmers growing susceptible cultivars, such as Rongotea, had sprayed to protect their crops; and there were so few other diseases about this year that the crops were looking well. Canterbury grows about 60 per cent of the New Zealand crop. It is the only district affected by rust now because Southland and wheat growing areas in the North Island are spring-growing areas and the wheat crop there has been sown only in the last two weeks. Canterbury’s wheat is sown in the winter.