Digest

Pacific

Planters '

Treatment For Sucking Pests

EXPERIMENTAL trials are in pro gress in the Solomons, New Heb rides and Fiji with Solvirex granules for use against sucking pests in sugar cane, groundnuts, rice, potatoes, melons, tomatoes, etc.

Results should be interesting, as the granules represent a new ap proach to pest control problems.

Overseas, the granules have been shown effective when applied in a variety of ways, and at all stages of the growth of the plant.

The granules contain a systemic organophosphorous ester that is readily absorbed in the plant’s sap stream.

One indication that the chemical is suited for tropical conditions is that it is not adversely affected by rainfall. Another encouraging factor is that the distribution of the insecti cide in the tissues is in step with the development of the plant, providing long-lasting control of insect pests.

Solvirex is a free-flowing granule without dust. It can be placed by hand or mechanically in the furrow or planting hole at the same time as the seed, thus giving pre-emergence treatment.

The granules can also be applied after germination on top of the emerging plants (top dressing), or in an advanced stage of growth to the soil at the base of the plants (side dressing).

In temperate climates Solvirex has shown itself effective against aphids, white flies, leaf hoppers, mealybugs, woolly aphis, mites, and the nymphal and adult stages of thrips.

How To Control Navua Sedge

"DANE of farmers in almost every part of Fiji is the weed, Navua sedge, which is also known under a variety of names in other areas of the Pacific.

Navua sedge belongs to a tropical species recorded from India and it was accidentally introduced to Fiji.

The exact date of introduction is not known but plants were seen in 1933.

The weed is recognisable by leaves which are linear-lanceolate and mostly clustered at the base of the

plant. It is a grass-like, perennial plant usually between one and two ft high, but occasionally seen be tween four and six ft high. The flowers’ leaf-like bracts are six in number, three of which are long, and three short.

Navua sedge is extremely difficult to eradicate and it loses no time in smothering pasture grasses. The leaves and stems of the weed are dry and fibrous and unpalatable to cattle. In agricultural and plantation lands the sedge competes with the crop plants for the available mineral nutrients, water and sunlight, reduc ing crop yields.

It is a plant with apparently no redeeming features at all, for it is also a potential breeding place for rats, insect pests and plant diseases.

Farmers should be on constant guard against its introduction on their land, and use only clean crop seeds and planting material, including grass or cuttings.

Cattle, horses, goats or pigs from infected districts should not be moved to clean land without first being held in clean, concrete yards for 10 or more days, fed with fodder which is free of Navua sedge and their bodies washed and brushed once a day to remove all sedge seeds.

Gravel or soil from infested areas should be refused. Navua sedge plants should be killed before they set seed, and roadsides, fence lines, creek and river beds should be free of the weed.

Regular weeding is of the utmost importance. Although some grasses compete with the sedge better than others, no grass will, under grazing, control Navua sedge without assis tance from the management pro gramme.

Uprooting and burying is an effec tive method of control. Although the sedge is shallow rooted, sections of the root left in the soil are capable of sending up new shoots.

Each plant should be cut round with a spade, making sure that all of the root system will be lifted from the soil when the spade is worked under the plant to turn it over.

The seed of the weed is small and light, and easily shaken from the stalks, and because of this, unrooted plants should be buried as near as possible to where they were growing, to prevent the seed from being spread.

This method is more suitable for the control of isolated plants and new infestations than for large areas.

If mechanical control is to be used the traditional practices of ploughing, discing and harrowing are more suitable for the initial control of large infestations on arable lands.

In both agricultural and pastoral

sites, the ploughing must be directed at destroying the growing sedge and bringing the roots to the surface.

The furrow must be turned over so that the sedge is buried and the immature seed prevented from maturing. Upturned roots should then be heavily disced to cause the greatest possible amount of damage to them; then the land should be heavily harrowed and conditions created to encourage the germination of the seed and root stocks, to be harrowed again and killed.

The operation may have to be re peated several times at short inter vals of two to three weeks, but it should be kept up once started, re gardless of the weather.

Several chemicals will effectively control Navua sedge if correctly applied. The most successful is the ester formulation of 4 cholorphenoxy acetic acid plus sodium chlorate. These two herbicides are mixed together at the rate of 4 lb a.e. of 4 C.P.A. plus 2 lb sodium chlorate 100 per cent, diluted in 80 gallons of water. As the sedge matures and sets seed, this mix ture has to be increased using up to 8 lb a.e. of 4-C.P.A. plus 2 lb sodium chlorate diluted in 80 gallons of water per acre.

This chemical treatment will cause some burning of the grass, which will recover. It is important that the herbicides are applied in 80 gal lons of water per acre and that the spray is forced down into the crown of the sedge plants and on the ad jacent soil. The best results have been obtained with high volume spraying at high pressures.

But chemical control can only be successful if supported by a regular weeding programme timed to kill the growing weeds and prevent re infestation.

After the initial knock down, the bare earth under the sedge will be exposed to the sun, and three to six weeks after the original plants have rotted the site will be a mass of ger minating seedlings, which must be sprayed to maintain control and en courage the grass to take over.

Seed Rot In Rice

APS appearing in rows of dry land rice are more than likely caused by seed rot and seedling blight.

The disease can be recognised by seed rotting in the ground, or else the seedlings die soon after emer gence. Survivors are stunted, yellowed, and have poor roots.

The disease is associated with the use of dirty, fungus-infected seed from a previous crop. Bad soil pre paration is a contributing factor.

Rice suffering from seed rot will show under conditions of wet weather during harvest when the grain may “sweat” and the fungi will then in vade the grain.

This grain is discoloured brown, black, red, green, yellow or pink, depending upon the type of organism involved.

Pre-emergence blight is worse in very cool soil, and in warm soil, post emergence is more noticeable.

Seed that is badly discoloured should not be used. Harvesting should take place if it is possible under dry weather conditions, and rice should be thoroughly dried by spreading it out in the sun before bagging. If a

drying machine is available it should be used.

Avoid sowing dates that are too early as early-planted rice suffers more from seedling blight than does late-planted rice.

For really effective control, seed should be treated with a mercurial dust at 2 oz/100 lb of seed. • Mr. L. Pronk has been ap pointed shipping director for Burns Philp (NG) Ltd., and will be based at Port Moresby. He will supervise all the company’s shipping activities in Papua-New Guinea. He was formerly secretary of the Australia- Malaya Shipping Conference.