WEEDS IN CROP LAND

Press, Volume LXXXVI, Issue 26201, 26 August 1950, Page 5

WEEDS IN CROP LAND

Cultivation Is Main Control

FARMERS’ EXPERIENCES DETAILED

After a day of almost purely scientific discussion of chemical weed control, interest in the second day of the Weeds Conference was considerably broadened by the presentation of four papers, based on the practical experience of the speakers, which examined the farm management aspect of the control of weeds. Each of- these papers, of course, dealt with chemical weedkillers, but stressed that chemicals were not more than very useful and specialised complements to well-estab-lished and well-understood farm practices.

Professor A. H. Flay, who is in of the farm management department at Lincoln and has wide practical experience, was followed by three farmers, Messrs R. G. Allan, of Southbridge, A. Amos, of Wakanui, and L. B. Scott, of Woodend, and as usual when practical farmers speak at such conferences, there was intense interest in what they had to say.

Professor Flay described control of weeds in mixed cropping farm practice by cultivation and other means, and emphasised that these means frequently controlled weeds at the same time as they prepared the land for the normal cropping rotation. Such means were therefore cheap, and were efficient.

“Unless chemical control is less costly than established husbandry methods, it is unlikely that it will replace presentday husbandry methods,” he said. “The point to note -about the husbandry methods is that they are often necessarily carried out for reasons other than weed control, and to control weeds against which chemicals are not effective, for instance, twitch. Chemical weedkillers will be used on arable farms only if they can achieve success where husbandry methods are not practicable.” Husbandry methods fell short, he considered, in growing crops, except row crops, after the crop was three to six inches high; they could not control or check weeds in a pasture or cocksfoot area closed up for seed; they could not control weeds in a live fence or places inaccessible to the plough or mpwer; and they could weaken but not eradicate Californian* thistle.

Expect Too Much “Perhaps we have come to expect too much of. chemical control on mixed farms,” he said, “and have tended to forget the wide range of effective and cheap husbandry methods we already have at our disposal. The whole slant of my thought has been to minimise the use of chemical control, not to maximise it. I have done this purposely—perhaps at the risk of being considered a little old-fashioned. But I think this is the crux of the matter—on mixed farms good husbandry can with some few exceptions control weeds more cheaply than, and as effectively as, chemicals. The good farmer will tend to use chemicals as an adjunct to husbandry control, not as a substitute for it. I look upon chemical weed control as a useful aid to good management, not as a cover-up for bad farming.” The first of the farmers to speak was Mr Allan, who farms 340 acres at Southbridge. He took the farm over 12A years ago when it was showing signs of eight years of neglect, and found it heavily weed-infested, mainly with wild turnip, Californian thistle, wild tares, fat hen, twitch and wild oats. Wild turnips was probably his worst weed, he said, and was particularly bad in his own locality, specially in crops of garden peas. The method for controlling it was to deep plough in the winter, cultivate throughout the spring with cultivatons shallower eacn time to avoid bringing up fresh seed. The spring crop got up to four harrowings while it was young.

“I had only one patch of Californian, and that covered the whole farm,” said Mr Allen. “It is certainly a difficult weed to handle in crops at harvest time, but Calis can be killed in one year. The method is to cultivate them at all possible times. If after three or four years of cropping, Calls begin to increase, I give the paddock a summer fallow after ploughing and then grubbing with 11-inch points. Grubbing is done whenever the thistle appears above the ground, and I endeavour to do one paddock each summer. This method of control also kills many strikes of other small seeds as the killing of the thistles proceeds. I have several paddocks free of thistles. Lucerne is also a sure kill for thistles. Another good smother crop is cocksfoot for seed.”

Wild tares had caused him some loss of sleep in a wet summer, and the only method of controlling them appeared to be to germinate them before the crop was sown. Twitch could be killed by cultivating when the ground was dry to bring it to the surface. Where a paddock was very bad with wild oats, it should be ploughed and put into greenfeed for three years running, and the greenfeed fed off before the oats came into ear. Ploughings should be successively shallower. Mr Allan said that after one season’s experience with hormone weedkillers, he was convinced that the cost of a spray outfit and materials would be repaid by its control of wild turnip alone. Chemicals could also be used successfully to control Californian thistles, though not to kill them. They could be sprayed in growing crop so that they were put down and did not interfere with the harvest. For control of spring weeds also, chemicals were a great help with peas, and he could now sow peas and expect a good crop where he had never been able to sow them before.

“Farmers must not expect spraying ! to give good yields unless they do their part in respect of the tillage of the < soil,” he concluded. ‘ Mr Amos described his farm at ■ Wakanui as having “every weed bar ‘ seaweed.” “Most of them can be , handled by good husbandry,” he said, ' ] “but there are others that, especially j in springtime, can be handled with sprays. Spraying outfits are easily operated and cheap, but a mechanically- j minded farmer can make his own at , about half the cost of the commercial article, and you must have your own outfit if you are growing much cron. You must not be dependant on contractors.” Spring Sown Crops He found the greatest benefit from sprays was in spring-sown crops. He hated sowing spring crops because of i weeds, but now spraying allowed him to sow spring crops with confidence. I His most successful experience, he be- 1 lieved, was in a crop of barley over- : sown with cocksfoot and white clover I which became infested with fat hen, 1 wild turnip and Californian thistles. , He sprayed at the rate of gib of 2,4-D ; when the crop was about nine inches high and in the shot blade, and the weeds were beginning to show ud above the crop. He considered now that he had sprayed about a fortnight , late. The spray killed the turnips, and stopped the fat hen growing, and put the thistles down out of the way. On an unsprayed part of the paddock he i got 14 bushels of barley, but where it was sprayed the yield was 41 bushels. ' and the cocksfoot and white clover ’ were not damaged. “Chemical control can be an eco- ! nomic proposition to the agricultural i farmer,’’ said Mr Amos. “One man j can do a big acreage in a day, and an | advantage is that the work requires doing at a time when there is not much other pressing work to do. Why should you harvest crops of rubbish when one man, with a machine it is a pleasure to use, can control the . weeds?” Mr Scott described the experience of a farmer on. say, 200 acres of good arable land whose main interest was cropping. The rotation would be grass to peas to wheat to barley, and perhaps a third grain crop before going back into certified grasses and

clovers after a fallow. Fallow meant keeping the soil continually stirred from the beginning of October to the end of January. “Such farms can produce large and profitable crops, but there is one problem that can hold up the cropping programme—the weed problem.” said Mr Scott. “No matter what care the farmer takes, the header broadcasts some weed seeds, and there are the wind-borne seeds, particulary the thistles. Fallowing will clean the ground: but in my district the third year finds the Californian thistle well established. This means we must try to grow crops, and at the same time check the weeds, and so we have turned to the use of honmone sprays. Even if hormones do not completely eradicate the weeds, but enable us to , harvest our crops satisfactorily, surely that is worth while. I know of no other means bv which I coulfi have got eaual results.” I Mr Scott gave details of his experi- ' ences. which were mainly with Californian thistles in the crops, and in gorse hedges, and in his kitchen garI den. and said that most were satis- ! factory. He might not have obtained complete kills, but checked the thistles satisfactorily. “I had my failures, of course,” he said, “for there seemed to be too little information obtainable. I tried to find out the time of year to spray, the type of day, and the time of day, but this was not something common to all weeds, and so few peonle seemed to know. There is a need for some information service, not only to set up proper investigations. but to keen the farmers advised of any new developments. It is an improvident policy whereby each farmer has to find out for himself, so much by trial and error.**