Pacific Planters’

Digest

)Anger For

Mango Trees

rHERE is an old saying that a heavy mango crop indicates a lurricane ahead. Fiji’s mango trees lave been burnished with blossoms, >ut these days few heed the old aying.

The current dryness in the air is esponsible for the record blooming md good fruit set. Wet weather at his stage favours mango Anthracnose >r Wither Tip, the disease which auses blight and death of blossoms, ruity panicles and twigs. With Vither Tip, leaf and fruit spots and ruit rot appear; the fruit spots leing dark brown, circular or ir egular, and of variable size.

Many plant varieties are quite re istant to Wither Tip (but none is ompletely), and care should be aken what variety is planted. All arieties grow better in dry areas.

To prevent Wither Tip, spraying hould be done just prior to and uring flowering and early fruit stage, ising fungicides such as Captan, 4aneb or Zineb, approximately one iz of chemical to three gallons of A misting machine would be ecessary to carry out the spraying fficiently on mature trees.

Igatoka Spot Disease

JIGATOKA Spot disease is now 5 present in every important anana-growing region in the world, nd as far back as 1911 it became rst serious in the Sigatoka Valley f Fiji—hence the name by which : is known the world over.

Sigatoka is found only on the ;aves of the plant, and young leaves re usually the most susceptible to hack. The banana bunches produced n heavily-infected plants will usually e undersized, and have a tendency ) ripen prematurely, thereby causing re fruit to be below marketable rade.

The first indication of infection is le presence of very small, light ellow spots which are visible only ! the leaf is held up to the light, /ithin a few days, these specks nlarge to form dark brown spots r hich vary in size up to half an ich in length. The centres of these

spots eventually dry and become light grey.

The spots are often surrounded by a light yellow zone, and they unite to cover a large part of the leaf surface, giving it a burned appearance. The leaf stalks of severely infected plants often break, so that the infected plant may have only a few erect leaves.

Control of the disease is mandatory in some Pacific areas, and in Tonga, Samoa and Fiji control has been achieved with a mixture of Dithane and light orchard oil, applied at the rate of two gallons of Dithane and half a gallon special orchard oil per acre in five to eight gallons of water.

A special banana misting oil, hitherto used for control, fell out of favour because of its inability to clear itself of the suspicion that it affected yields.

Spraying with Dithane should continue as often as every 10-14 days during rainy seasons and when nightly dews occur. During dry weather spraying cycles can be lengthened considerably. The con tinued cycles are necessary for im provement as mixture suppresses spot development without preventing infection.

Several experts believe that the much publicised Black Death disease, which is right through the banana areas of the Pacific, is but another form of Sigatoka Spot.

Navua Sedge Will Take Over

GIVE it an inch, and Navua Sedge (Cyperus aromaticus ) will take a mile—and take it most thoroughly; choking out pastures and crops, and resisting all but the most rigid forms of control.

Not palatable to stock, and difficult to eradicate because of its rhizone underground runners and tubers, Navua Sedge has the dubious distinction of being viewed by agri culturalists as “the worst weed in Fiji”.

Many of the Islands are reluctant hosts to the unwanted sedge, in cluding New Hebrides and Samoa.

That it will impose its presence on other areas is more than probable, for it is reported to be spreading rapidly.

This is understandable, for its light, inconspicuous seed attaches itself easily to clothing and farm sacks. Car, ship and plane travellers are suspect carriers.

A perennial, usually 1 ft to 2 ft high, but sometimes up to 6 ft, the sedge is known under many names in the Islands. It is easily recognised by its three-ranked leaves, mostly clustered at the base of the stem, two to eight inches long and about i in wide, and also by the spikes borne in a cone or button-like cluster at the apex of the stem, subtended by three long and three short leaf like bracts.

The pest may be attacked either with chemicals or by traditional culti vation and repeated planting of crops plus chemical control.

For those preferring the latter means, infected areas should be thoroughly ploughed, disced and harrowed, and given a follow-up deep harrowing as soon as the weed seedlings appear.

This procedure should be followed three to four times and then the area planted immediately with a vigorous grass.

During cultivations and planting, chemical control of the verges is necessary, and later spot chemical control in the area itself will be found necessary.

For full chemical control a mixture of 4 C.P.A. (8 lbs acid equivalent) and 2 lbs 100 per cent, sodium chlorate mixed with 80 gallons of water will be necessary to treat one acre of land suffering 100 per cent, infestation.

The use of the full 80 gallons to the acre is strongly advised; any stinting is false economy. Mixture should be applied to crowns and growing parts of plants.

Spray pressure should be adjusted to 250 lb-300 lb per square inch.

No satisfactory results have been achieved with mist blowers.