Plastic sheets may control lakeweed

Press, Volume CXVI, Issue 34132, 20 April 1976, Page 14

Plastic sheets may control lakeweed

I (N.Z. Press Association) HAMILTON. A new method of con- ! trolling weed growth {will go on trial at Lake {Karapiro. I The experimental method, jin which malthoid, sisalation j paper. PVC and polythene; i will be laid on different; areas of the lake bottom to! prevent weeds from taking {root, is expected to prove I economical and environmen- ! tally acceptable in con-; { trolling weeds in small areas; ! of waterways. The trial, to be made by a I Ruakura Agricultural Research Centre scientist, Dr B. T. Coffey, with the help; of the Electricity Depart-! ment, will start in about a; month. The materials will be laid in a swimming and recrea-i

tion area where weed is aes-l thetically unpleasant and; possibly dangerous, and assessed to find which pro-! vides the best weed control. About half an acre would be used in the experiment,! and results should be known) in about a year, Dr Coffey; said. Recommendations could; then be made to the depart-! ment on which materials to] use io spread in the Waik-! ato R ver to solve weed con-: otamination problems at hydro-power stations. The materials could have, a use in recreation water-; ways controlled by the Lands and Survey Department, and could even be; used by individual farmers, he said. At this stage it was ex-‘ pected the use of materials; woui-i be much less costly! than the use of herbicides to control weeds.

A trial on a more limited scale had been held in Lake Rotoiti, but the Karapiro experiment was the most comprehensive yet undertaken. The method was originally advocated in the United States, where similar materials had been used before weed growth was a problem, Dr Coffey said. It was similar to mulching crops t< protect them from weed regrowth. “Once the weed has been cleared and the lining laid, detached plant fragments will ne unable to re-establish in the bottom mud. “If this method works, the use in recreational waters of heroicides and even more drastic measures, such as lake lowering, could be avoided. “The linings will be mom , tored over a five-year period Ito test their durability and ' determine costs,” he said.