WEEDS ON PLAINS

Hauraki Plains Gazette, Volume 58, Issue 4128, 29 April 1949, Page 8

WEEDS ON PLAINS

CAN BE CONTROLLED USE OF HORMONE SPRAY ERADICATION OF BUTTERCUP “ This year has produced the greatest infestation of buttercup and pennyroyal ever known on the Hauraki Plains,” said Mr G. L. Banfield, instructor in agriculture, Thames, in a lecture on hormone weed killers delivered to the members of the Turua branch of Federated Farmers. Several factors had contributed to this. Any operations which bring about the opening up of the pastures will result in infestation, said Mr Banfield. He considered that three dry seasons, the keeping of the herds at high levels, which necessitated hard grazing to carry the herds through the winter, combined with the plague of crickets, had resulted in the opening up, in three successive seasons, of the pastures on a great number of the farms. This meant that the farmers had gone into the winter with very • open pastures which was the best method of weed production. Mr Banfield ventured a forecast that the next season would not be so bad as it would follow a favourable summer. Infestation was due partly to bad management and partly to factors beyond the control of the farmer. On many of the well managed and best farms buttercup and pennyroyal were still beating the fanner. Mr Banfield said he 'wad cbiJ-vlriced that sheep should play a greater part in pasture management than they had done up to the present time. Where sheep were carried in the winter, the farms were in better condition and freer from infestation. Against this however there was the problem of fencing, and that meant that another method of weed control had to be found. Two Classes Considerable attention had been directed ;by him, said Mr Banfield, to the use of hormone weed killers as a means of weed control. Tests had been made and the cost has been considerable. Weedicides, he said, were divided into two main classes:— (1) Plant poisons, such as arsenicals, sodium chlorate, sulphuric acid and oil and tar derivatives. (2) Plant horipones. Plants, so the lecturer explained, have no nervous system similar to that of higher animals. A plant’s activities were controlled by minute doses of chemicals—the so-called “ chemical messengers ” or plant hormones, e.g. rooting hormones, transplanting hormones, fruit sets hormones and weed-killing hormones. With some plants resistance to hormones was developed whilst others were resistant only at certain stages of their growth or under certain conditions. There were two main types of weed killers, said 'Mr Banfield, one type which was referred to as 2-4 D (represented by Weedone, Weedone Concentrate, Weedar and 2-4 D, etc.). All these were of American development. The other type was known as M.C.P., represented by agroxone and Methoxone, etc. These types had been developed in Great Britain. The high cost of spraying plant had always operated against the general use of weed killers .but it was now possible to construct or buy a low volume spraying plant and equipment for between £4O and £5O. Very Good Results It had been found by experiment that weed killing hormones were selective in their action and some have been discovered which were effective against certain types of plants. Some were effective only when the plant was in the seedling stage whilst others require particular climatic conditions before they would work with the desired result. Very good results had been secured by the use of the 2-4 D type of weed killer where land was infested with buttercup and pennyroyal. So far nothing very effective had been found for use on docks. “ The control of buttercup and pennyroyal is near enough to perfect if done at the right time,” said Mr Banfield. ”It should be treated as early as possible in the spring. Spraying after Christmas is not particularly satisfactory. Pennyroyal is then in flower. It is susceptible when young but resistant at a later stage. We do not yet know whether it is better to spray in May or June, but the spraying should be done before December.” Many questions were asked by members of the audience. To one question

as to the frequency of spraying Mr Banfield said that the sparying would be for many years a yearly occurrence on the farm just as top-dressing was part of the routine of farm management. In the course of two or three years of regular spraying infestation would be reduced. The result of the spraying would .be to close up the pastures. “ In the past we had no means of killing pennyroyal but for the first time we now know,” said Mr Banfield, “ that we can kill this weed.” He felt sure that there would be less of it if regular spraying was carried out. Control of Blackberry To a question as to the use of weed killers on blackberry the answer was given that arsenical poison was needed for this and unfortunately there was a danger to stock if it were used. In any case the blackberry grew again. The use of old engine oil as a weed killer w r as not advocated by Mr Banfield, as it killed grass as well as weeds. In reply to a question as to the harmful effects upon pastures resulting from spraying over a period of three or four years Mr Banfield expressed the opinion that if the spraying was carried out early in the spring there would be no harm done to pastures. If done at a later time of the season then the clover would be nearly wiped out. In one experiment in trying to kill pennyroyal, by the use of an increased quantity, the clover was almost wiped out. At the conclusion of his address a very hearty vote of thanks was given to Mr Banfield for his very instructive lecture.