Pacific Planters’

Digest

The Algae Problem

IN many areas where irrigated rice is grown algae are a serious problem. Algae in various forms are found almost everywhere in the tropics. They account for the slip pery slime on concrete paths and the mould-like stain which appears on houses.

Algae are minute plants which often develop into mats on lakes or ponds, reduce water flow in canals and in circulation pipes, or clog drains.

To control the blue-green type of algae in lakes or ponds, a spray of three ounces of Phygon-XL mixed with water per acre-foot will be found effective. For the green algae six ounces should be used.

Do not treat drinking water or shallow ponds which contain desir able fish. Where the growth of algae is heavy one-third of the pond should be treated at a time, to allow fish to move to an area with better oxygen supply.

To keep clear the pipes of industrial water recirculating systems, the chemical should be applied at some point where there is large-volume movement so as to get rapid dis persion through the system. The chemical should be used at the rate of four pounds per million gallons of water twice weekly, or eight pounds weekly.

Algae in irrigated rice is a serious problem. In rice good control has been achieved with the use of phygon, Copper sulphate has shown control in some areas, and yet in others the same material has not achieved the same result. More research will re veal the determining factor or factors which results in copper sulphate hav ing varied control in the tropics.

Mould-like algae on houses and footpaths can be removed with phygon used at the rate of three ozs of the chemical to one gallon water.

If one oz of the chemical is added to one gallon of the paint when paint ing marine craft an effective algae pre ventative is applied.

Coconut Fertilisers

IN most parts of the world where coconuts are grown planters are faced with the problem of lowered soil fertility.

The washing out of the soil by con

stant heavy rains accounts for some loss but most of it is taken away in the copra the plant produces. The copra would normally return to the earth to be the plant food for the palm from which it was taken.

Not only in the Pacific but in other parts of the world, because of this loss of fertility planters are now faced with the problem of lowered copra yields; in many cases also the over-aged palms now need replacing, but the soils have become too poor to properly nourish the replanted trees.

There are three main kinds of fertilizers which will help and these are usually mixed together so as to provide the right amount of plant food in the coconut growing soil. They are: Nitrogen, or N, which is concerned most with the growth and size of the palm; this is obtained from urea.

Phosphorus, or P, which is most needed in connection with flower and fruit development, and is obtained from superphosphate.

Potassium also called Potash, or K, which is concerned in the general nutrition and health of the palms and which is often particularly needed by coconuts; this is obtained from potassium sulphate.

Here is the best general fertilizer mixture for coconuts: Two parts by weight of urea.

Five parts by weight of superphos phate.

Three parts by weight of sulphate of potash.

This mixture should be applied at the following rates: Palms up to one year —\ lb per palm per annum. Palms one-two years old, 1 lb per palm per annum.

Palms two-three years old, 2 lbs per palm. Palms three-four years old, 3 lbs per palm. Palm four-five years old, 4 lbs per palm. Palm five years old and over 5 lbs per palm.

Fertilisers are best applied twice a year rather than all at once.

The small grower can utilise local products to replace some of the im ported fertilisers, e.g., burnt coconut

husks and other wood ashes are good sources of plant food.

Husks can be placed around the base of each tree to act as a mulch while they are rotting, or they can be heaped and, when rotten, spread around the palms. Weeds and rubbish cut from the area should also be spread around the palms as a mulch.

For areas close to the shore sea weed is a valuable source of plant food if it is spread as a mulch and allowed to rot. Coral sand has long been used by experienced planters when preparing planting holes and this sand is of great use on areas of sticky, red clay soils. Coral sand is a form of limestone which sweetens acid or sour soils and also opens up or makes heavy red soils lighter and easier to drain.

Cocoa Troubles

rpHE cold climate beverage, cocoa, A has long been proven a crop well suited for cultivation in tropical areas.

One of the most serious disorders in cocoa plants in the Pacific is black pod disease, also known as brown pod. It has been estimated this disease accounts for 50 per cent, of the losses in cocoa in West Samoa.

A minimum—and probably a very conservative —estimate suggests 10 per cent, of the world production of cocoa is lost through black pod.

The pod disease is caused by a fungus which is most common in humid, tropical weather. It infects other crops and is responsible for economically imported diseases of rubber, citrus, coconut and Palmyra palms.

On cocoa black pod causes pods to rot and the first sign of infection is a minute translucent spot which soon turns chocolate brown. These spots expand rapidly, so that the whole sur face of a mature pod is discoloured within about 14 days.

The fungus sporulates on the sur face of the pod and has the appear ance of a white or yellowish down.

At present there are no varieties of cocoa completely resistant to black pod, although Lafi 7 from Samoa has shown a high degree of resistance in some countries.

Regular and frequent harvesting and removal of infected pods reduces the severity of the disease and copper fungicides such as cupros oxide, copper oxychloride or bordeaux mixture have been most effective in controlling the disease.

Any one of these fungicides acts as a protectant but will not cure an in fection once it has started, hence the need for a frequent checking for in fected pods, and their removal.

The amount and distribution of the fungicide on pods is continually be ing reduced by the action of wind and rain and by pod growth. For these reasons spraying should be repeated fairly frequently to maintain a toxic deposit over the entire pod surface.