FERN ERADICATION

Wairarapa Times-Age, 26 April 1938, Page 3

FERN ERADICATION

MAJOR HILL-COUNTRY PROBLEM RESULTS OF EXPERIMENTS. The eradication of hard fern (Paesia scaberula), also called ring fern, creeping ferm or carpet fern, is one of the major problems confronting the hill-country grazier of the highrainfall belt of the North Island of New Zealand, states Mr K. M. Montgomery, in the March number of the New Zealand Journal of Agriculture.

The grazier effects a partial control by the periodical burning of clumps and re"seeding the area. The effectiveness of the method depends mainly on whether or not a really hot fire is obtained, thereby destroying the rhizomes by which the ’plant spreads. Unfortunately, it is only in hot, drj’ seasons that a sufficiently roasting fire can be secured to kill the rhizomes. In most cases, after an apparently good fire, the fern again makes its appearance in the form of a ring around the area previously burnt out. To ensure the complete destruction of the rhizomes, spraying with arsenic pentoxide has been .found to be very effective.

Experiments conducted by Levy and Madden show that a 1-320 solution is the most reliable to use. In preparing the solution, care should be taken not to immerse the hands therein. Spraying is best done with a knapsack spray-pump fitted with fine double nozzles. The fern should be well wetted all over, care being taken to spray the edges of each patch well. An arsenic pentoxide is poisonous, all stock should be kept off the area for at least a week or until rain falls. Where burning and autumn seeding is to be done following the spray, some three or-four weeks should be allowed for the chemical to kill the plants before the area is burnt. After burning, the patches should be seeded with a secondary burn mixture as outlined in the Journal for January, 1938. The application of a fertiliser is also recommended, because it has been found in actual practice that there is usually insufficient as to give the young pasture plants, particularly ryegrass, a good start. One of the principal difficulties in this method of eradicating hard fern is the packing of water on to the area; but by making some arrangements beforehand —constructing a rough temporary dam below a seep—the distance the water has to be carried can often be considerably reduced. Arsenic-pentoxide spraying is expensive on account of labour costs; but it is the best method known at present to deal with hard fern. Although in the past the main work has been carried out with the use of arsenic-pentoxide, still much remains to be done. Since the main experimental work was carried out a new implement to deal with secondary growth—namely, the flame-thrower — has been perfected; but whether the flame-thrower will give a fierce enough heat to destroy the rhizomes has still to be determined.