NOXIOUS WEEDS

Te Awamutu Courier, Volume 56, Issue 4042, 2 May 1938, Page 5

NOXIOUS WEEDS

CHEMICAL PREPARATIONS ANALYSED. FIFTEEN VARIETIES UNDER TEST. The Waipa County Council, at Wednesday’s meeting evinced a keen interest in the following report on chemical weed killers published in the British Trade Journal, and the opinion was voiced that farmers might with advantage study the report: “A Canadian scientific journal has recently been discussing the toxic effect of fifteen varieties of chemical weed killers on couch grass and thistle, based on the experiments ot Cook, Mason and Garron. The observation of the action of the various compounds was extended to a period of one year after applications, which is considered essential for correct valuation, as it was found that many substances, although producing a very rapid immediate effect in killing weeds, nevertheless do not appear to affect the roots, so a new growth may appear. “Of the fifteen substances examined only five were found to have any useful toxicity. These were sodium and barium chlorates, arsenic pentoxide ammonium thiocyanate and sodium arsenite. A characteristic of all these compounds was a rather slow killing action which, however, extended to the roots, as was shown by the poorness of the next year’s crop—non-ex-istent in the case of the chlorates, the effect of the other compounds falling oii' in the order named. “The quantities of each substance required to produce theoptimum effect were found to be 6001bs per acre for sodium chlorate, 900 lbs per acre for barium chlorate and arsenic pentoxide, and more than 1200 lbs per acre for ammonium thiocyanate and sodium arsenite. “Among the rejected compounds were several, such as sodium cyanide and dichromate, and phenol, which produced much more rapid killing of weeds than any of the five selected compounds, but which were shown to be valueless, by the. appearance of a new growth, in as little as three weeks after treatment. These substances are detoxified by the soil, so that they cannot attack the roots. A PRACTICAL DEMONSTRATION. TREATING BLACKBERRY. A very interesting demonstration of weed killing was given on Thursday afternoon last, in the presence of several Waipa County Councillors and farmers of the neighbourhood on Jary’s Road. Blackberry was the pest attacked, and the demonstration was conducted by Mr Hall of Hamilton, and Mr Montgomery, of Auckland, to demonstrate a new device evolved for the purpose of expeditiously and economically treating blackberry with such compounds as sodium chlorate and atlaside.

A small pump of special construction, attached to a two man hand platform, with two leads of 100 ft of hose, was used to spray the blackberry growth, which at the point selected was about eight feet high and from 20to 30 feet in thickness. The pump, operated by petrol, is estimated to run for eight to ten hours on one gallon of petrol, delivering a fine spray from two nozzles. The patch of blackberry on the roadside treated was dealt with in 35 minutes, and the length was approximately 200 feet. One side of the road was treated with sodium chlorate and the other side with atlaside. The strength on the first section was 5 per cent solution, and alongside a per cent solution was used.

The weather was not ideal for the demonstration, for soon after starting a light rain commenced and continued throughout the period of the test. Arrangements were made by which the County Council, which has been recommended to buy a plant for dealing with blackberry growing on the roadside, is to carry on further experiments, and when the results are noted a decision will be reached whether to purchase the apparatus or not.