CLEAN SEED DESIRABLE OBJECTIVE

Press, Volume CIX, Issue 32068, 16 August 1969, Page 9

CLEAN SEED DESIRABLE OBJECTIVE

The vital importance of producing a sample of herbage seed that was as free as possible from weed contamination was emphasised repeatedly during a session on pure seed production at this week's conference of the New Zealand Weed and Pest Control Society.

To sow clean seed and keep 1 the resultant crop clean—that 1 was a fundamental principle i in producing good seed and simplified the task of hand- 1 ling the seed at other stages, i said Mr A. V. Lithgow, super- i intendant of the seed Indus-1 try for the Department of i Agriculture, who presided 1 over the session. i In presenting a paper for Mr N. L. Shillito, a farm ad-1 visory officer (seed produc- 1 tion) of the Department of i Agriculture in Christchurch, i who is at present overseas, 1 Mr Lithgow said the farmer would be forced to produce a reasonably clean sample. On the basis of overseas trends ' higher prices could not be expected—hence the need for greater efficiency. With machine dressing charges representing a major cost, if all lines of seed going into store were of a satisfactory standard dressing charges would probably be reduced. he said. Mr J. R. Hartley, of Wright Stephenson and Company, whose contribution to the discussions was on seed cleaning, said that undoubtedly the place to remove weeds was before seed was planted and then in the paddock. A seed grower, Mr J. R. Cocks, of Eiffelton, Mid-Can-terbury, echoed these sentiments when he said a fundamental fart, which bore repetition, was that the easiest way to remove many impurities was never to sow them in the first place. It was possible, he said, that a substantial premium paid for very ' high purity, or for such a factor as freedom from goose grass, could give a producer an Incentive to do this. Mr F. C. Allen, of the research division of the Department of Agriculture, however raised.the issue that so long as there wai T market in New Zealand for Htlines of seed, other than those containing nauella, monetary losses as a result of weed contamination were of degree and not absolute as could be the case if buyers were more discriminating. The question was what return was obtained for producing a clean line. An urgent need and aid to clean seed production envisaged by Mr Lithgow was a chemical that would effectively destroy seeds in the

top layer of the soil so ensuring a clean seed bed before sowing a crop. Mr Cocks emphasised that the whole problem of seed production was one of economics and the best way of achieving economic production was where this was skilfully integrated with a mixed farming system. There were good prospects for expanding the export trade in seeds now running at a value of about s3m annually, be said, but seed quality and low production costs were vital factors in such an expansion. In the past too little attention had been paid to problems affecting herbage seed production and it was pleasing to note the recommendations of the agriculture committee of the National Development Conference that considerable expansion in research in this direction should be undertaken.

The problem was a real one as the economics of seed production had reached a stage where growing dirty or low yielding crop* did not pay.

Looking at the main problems which made it difficult to produce clean seed, Mr Cocks said there was the ingress of particularly other grasses in producing ryegrass, timothy and cocksfoot seed, and of suckling clover and sorrel in white clover seed. Goose grass, hair grass and Yorkshire fog were among the most common grass weeds. Chemical weed control provided no answer to this probi lem. Good husbandry was the only means of control. Grass weeda constituted by far the greatest problem and after 100 years of seed growing science had still to provide ,gn answer. In fact, modern methods of harvesting only intensified the problem as a large proportion of seeds such as hairgraaa and Yorkshire fog were blown out the back of the harvester on to the paddock during harvestlog. As seed production was done on mainly arable areas there was also a build-up during the arable rotation of wild oats and weeds which were difficult to kill like stinking mayweed, rayless chamomile and ox-eye daisy.

With other weeds the scientist had done an outstanding job and chemical methods had largely provided a satisfactory means of control. The main problem of the seed producer was rising costs. Partly as a result of devaluation there had recently been a substantial increase in the cost of harvesting and cultivation machinery and increases in certification, seed handling, labour, and transport costs.

Clean seed had to be grown if New Zealand was to grow it cheaply enough to compete on highly competitive world markets. Skilful integration of seed production with intensive mixed farming was the best method of achieving this and in such a S7Stem weed control was vital at every stage of the rotation. Looking at what seed producers could do to ensure the production of cleaner seed, Mr Cocks listed the following: sow clean seed; sow after a summer fallow (ideal but often impractical); grow a series of arable crops between seed crops; never allow seed heads of injurious grasses to appear in the subsequent life of a seed stand (this is not easy); take full advantage of modern methods oi chemical weed control; hand rogueing has a valuable place; exercise care in threshing; epray fence lines, drain banks and irrigation supply races and similar areas to prevent ingress of injurious species; ex- '■ ercise extreme care in feed- ■ ing seed residues; arrange rotations and pay close atten- ■ tion to manurial practices to try to combat weeds such as sorrel, which is a menace in . white clover production. On a national basis, Mr Cocks said, it was of vital 1m- : portance that weeds such as i nodding thistle were completely controlled to prevent - their spread to hill country and marginal land where coni trol would be difficult or im- ; possible. Present arrangei meats for rejection at field • inspection of crops contaln- : ing nodding thistle should ensure that this was the case. To prevent the spread of wild oats crops of grain intended for seed multiplication i should be field inspected and • rejected if they contained wild oats. Rejection of herbage seed crops at field in- : spection which contained wild oats was not practicable at i present. Continued research was needed into the chemical conI trol of some weeds which i were very difficult to kill, and ! much more research was i heeded into many aspects of herbage seed production.

A noxious weeds inspector, Mr H. W. Fawcett, said he believed it was common practice in Canterbury for farmer A to buy seed from farmer B without the seed ever going near a seed dressing plant. The fields superintendent of the Department of Agriculture (Mr A. R. Dingwall) said there was a certain amount of trade across the fence but he thought it would be of mainly machine dressed seed.

Mr Hartley said this did happen to a certain extent and he thought it was where seed was dressed by a portable plant, which could make a relatively good Job so long as tiie field dressed sample was not badly affected by undesirable seeds.