Expert Discusses District Weed Problems

Chronicle (Levin), 16 August 1949, Page 4

Expert Discusses District Weed Problems

"The main weed problems in this district shourd be fairly simp.y overcome," said Mr, J. Forrester Brown, of New Plymouth, an authority on the use of plant1 hormones, who is at present visit-' ing .this district and discussing problems with local authorities. When discussing weed prob ems, Mr. Brown said that apparently the main weed in this district. as f ar as pastures are concerned are Californian thistle, Scotch thistle, variegated • thistle, luphi and fiat weeds, all of which had been con.rolled in spraying operations covering thousan'ds. of acres that have been carried out in N.Z. dur.ng^the last year. This work had shown that Scotch thistle, variegated thistle and winged thistle shouid all be spray ed during the rosette stage, i.e., during the next „wo months, when a very high percentage of control would be obcained, It was during the spring that these wee'ds, were growlng most actively. The sap movement at-.this time wss rapld, so that ch, action.of .he hormones wou-d ' bt much more effective. When these wec'as had reached the howermt stage they became hard an.t woody, and had been found moi\ difficult to contro-. Flat weedt might be treated au any time o, the year, but the ume taken fo. the weed to die depended on the time of the year, the spring beinr the time when most rapid contro. would be obtaine'd. Californian thistle on. the otfc.ei hand shonld not be sprayed untii it had reached the bud stage. Mr. Brown explained that before thh stage was reached. the main flov of sap was from the roots to the p ant and if spraying was carried out at this time the top of the thistle only would be controlled: This, he said, might be desirable when the farmer wished to take off a clean erop of hay or a clean cereal crop, but the majority of farmers wanted to deal with the large root system attached to these thistles. "When the bud stage is reached, the main flow of sap is down to the roots, where food is being' stored away for the winter months; If sprayed then the hormone will be carried through the roots and a good control should resul't. Unfortunately, all Californian thistles do not come into bud at the same time, so that if the majority are spraye'd when in bud there are still many that have not reached this stage. These latter thistles wiL probably come again the following year, but if the farmer waits again until the bud stage is reached a good control should result." Lupins, he said, were proving to be fairly simple to control provided they were sprayed during spring and early summer. When asked how it was that these 2, 4-D sprays did not #£E.ect grasses and clover, Mr. Brown ' explained that the growing points of these species were hid'den away either in sheaf or below the ground. The grasses, too, had uprighfc shiny leaves, which normally caused the spray to run off. He then explained that these chemicals were not poisonous. Mr. Brown explained that the oil based forms of 2, 4-D might be used in any weather and had been found very effective. The water based formulation, which was just as' effective ori dommon pasture weeds, should not be used during rain. When asked about the progress of .. work on the more' resistant weeds such' as ^blackberry and gorse, Mr. Brown said that very encouraging results were being obtained with a new chemical known as 2, 4, 5-T. Blackberry treated with the later formulation of this chemical sprayed at the rate of one gallon per acre with suffrcien. water to wet the stems had given very encouraging results. The stems and roots were now white and britt'e and the general impression gained by all those who had viewed the area sprayed near

«ew jfiymouui was that the blackberry was really dead. Mr: Brown described various other hormones for the treatmeni of tomatoes, fruit trees, potatoes, onions and most other vegetables. "In fact," he concluded, "now that We have at our disposal the various hormones that regulate the plants' gfowth we seem to be able to do anything to a plant." Mr. Brown lectured to I^vin farmers yesterday. On Wednesday he will lecture to OLaki farmers In the afternoon and Otaki market gardeners in the evening. Finally, on Thursday he will be studying the weed problems in .the Waikanae district and will lecture to farmers there on Thursday afternoon. „