Hopes For Softer Stem Chou

Press, Volume CVIII, Issue 31856, 7 December 1968, Page 9

Hopes For Softer Stem Chou

Plant breeders at the Crop Research Division of the Department of Scientific and Industrial Research at Lincoln are working on the production of a chou moellier that will be better utilised by stock than the present Giant variety.

Mr T. P. Palmer, a plant breeder, told farmers attending a field day organised by the Department of Scientific and Industrial Research this week, that chou moellier was the most productive brassica that could be grown for winter feed under most favourable soil conditions. It was also reasonably resistant to aphides. But under grazing there was a lot of wastage in the woody stems. In Britain he said hybrid types had been developed that had a soft stem. Such a variety of chou moellier was in trials of his division and it certainly had high utilisation. but it also had a lower yield and was fairly susceptible to aphides. Mr Palmer said there had been an attempt to develop a Giant chou moellier that did not have so woody a stem. Needles had been shot into stems of plants of this variety to detect those with softer stems, on the basis that those plants into which the needle penetrated farthest were softer. Last year when a comparison had been made under sheep grazing of the normal Giant chou, the new Giant chou selection and the English material utilisation with the latter two had been high, while with the normal Giant chou variety it was quite low.

Mr Palmer said that there were hopes that this project would proceed successfully and do something to raise the status of chou moellier as a crop. Mr Palmer had been discussing breeding of brassica varieties for resistance to aphis and virus attack. He said the aphides overwintered on seed crops and weeds and then flew into rape crops and in the autumn on to turnips, swedes and chou moellier.

With feed crops, a method of combatting the problem was late planting, as with York Globe turnips, but a disadvantage of this practice was

a lower yield. The other method was to grow a resistant variety. Reasonable crops could be obtained with the turnip variety, Kapai 67, which was resistant to virus. Mr Palmer said that as far as he knew spraying did not give control and he doubted the value of using granules because most of the virus was brought in by aphides from outside and there was not much spread in the crop itself. Aphid Resistant rape, which had been released in 1961, had since grown in importance so that it constituted 90 per cent of the rape grown in the province, A better replacement was now coming out. It was Rangi, with a little more resistance, a somewhat higher yield and more uniformity. Ready for release next year would be Moana, which would have both aphis resistance and club root resistance. It was hoped that this would satisfy the rape requirements of the province but this could be something of a pipe dream. Moana was only resistant to some races of club root, and on the basis of a survey it was felt that it would be satisfactory for any races in Canterbury, but this would not be the case for Southland and a programme was under way to produce a plant that would be resistant to more races of club root than Moana. Mr Palmer said that the year before last quite a few crops of rape had been attacked by aphides and it had been ascertained that the variety had been Aphid Resistant. It had since been shown that there was another race of aphides that had attacked the variety, and this aphis was still about. It had always been thought that this might happen and partly by chance and partly by good management Aphid Resistant rape had been crossed with other resistant rapes that grew along the New Zealand coast From these they had been able to select some that were resistant to the new race of aphis but it would be some time before a new variety would be on the. market. Indeed, by the time that it got out there might have been another change in the aphis.

This had led to a new attitude to testing new varieties, he said. There could not be too much time spent in testing. It was rather like motor-cars —there had to be new models coming on the market frequently or customers did not like it very much.

Mr Palmer said Calder and Sensation swedes had been grown in Canterbury for a long time and were susceptible to the new strain of aphides. But when it came to club root and dry rot there were two varieties—Wye and Rewa—which had been developed by the Department of Agriculture. The Crop Research Division had been breeding for dry rot and club root at Gore but the Department of Agriculture had beaten it to the gun. Alluding to an earlier -eference of Dr H. C. Smith, director of the division,- that a new sub-station of the division was starting brassica breeding at Invermay Agricultural Research Centre, Mr Palmer said the division was taking over the people who had been doing this breeding work and their material, and the division had quite a large amount of material of its own.

Noting that the new aphis had really not done a great deal of damage in rape or even in Calder or Sensation swedes, Mr Palmer said it was not known just how important it was, and as there had not been a bad attack of virus in turnips for a long period this could be due to the effect of using Aphid Resistant rape on a large scale. But in answering a question, he said there was a risk of aphides in any part of Canterbury.