Encouraging Results for Tropical Agriculturalists

Chemical War On Fiji's Weeds

CONSIDERABLE experimenting in the

chemical eradication of weeds . has been undertaken by the Department of Agriculture in Fiji in the past few months.

A description of tests made with two weedicides has been received from the Fiji Public Relations Office and is reprinted here for the information of planters etc. in other tropical territories.

The Department of Agriculture, Fiji, has recently, carried out a series of trials with Methoxone and a complementary weedicide called Dinoc (dinitro-ortho cresol).

Both are selective weed killers. The action of Dinoc is to accelerate meta bolism so that the plant uses up nutrients more quickly than it is able to replace them and is unable to survive.

Its effectiveness is increased by the addition of sulphate of ammonia as an activator and when used together with Methoxone a great increase in toxicity is obtained as the action of the two materials on plant tissues is complemen tary.

The local trials, which are still under way, have been made in various parts of Viti Levu with a view to studying the effect of the two weedicides on the follow ing important noxious weeds of the Colony.

Noogoora burr, hibiscus burr, solanum, paddy’s lucerne, guava, water hyacinth, tobacco weed and nut grass.

Most of these plants are woody peren nials and two concentrations have been used, one at the rate of two pounds an acre, the other at four pounds an acre, applied in water solution at the rate of 100 gallons an acre.

Effective results with Methoxone have

been obtained for Noogoora burr and water hyacinth and also for the pasture weeds, goatweed and tarweed, which are completely destroyed.

DINOC has been most effective when used against tobacco weed and mint weed and is more toxic than Meth oxone to Paddy’s lucerne, solanum and hibiscus burr.

Some of the larger shrubby weeds are severely defoliated at the concentrations used but some regrowth occurs. This calls for further investigation as regards the best time of growth and the cover age necessary to obtain complete des truction.

The combined spray is most effective and good results with young growths of solanum, Paddy’s lucerne and hibiscus burr have been obtained.

Observatons have yet to be completed.

Grasses are not harmed by the concen trations used and legumes such as tropi cal trefoils and sensitive plants are not affected.

Supplies of the weedicides are strictly limited and none are yet available for general use. Other compounds which have yet to be tried are Denocate, Den oxylon and Phenoxyl, small quantities of which have recently come to hand, Mr. and Mrs. I. E. Lucchinelli, well known residents of Fiji, were in Sydney on leave in November and December. Mr.

Lucchinelli is Superintendent of Police in Suva. He entered the Customs De partment as a clerk over 30 years ago, and has risen steadilv in the Fiji Govern mental service. He now holds many public and semi-public positions in Fiji.