ORCHARD NOTES

Manawatu Standard, Volume LVII, Issue 198, 22 July 1937, Page 5

ORCHARD NOTES

CONTROL OF PESTS AND DISEASES. (By J. W. Whelan, Orchard Instructor. Department of Agriculture, Palmerston North.) For the control of fruit tree* pests and diseases it is of great importance that the identity and lifo history of each pest be known; without such knowledge it is impossible for a grower to arrange and carry out the season’s spraying programme with any degree of confidence. The chief pests are (1) insects and (2) low forms of plant life known as fungi. In addition to these, mosses and lichens which grow on the bark also do damage by lowering the vitality of the tree anil harbouring insect pests, etc. In order to get rid of the moss and lichen a cleansing wash must he used, cither in the winter or early spring. Limesulphur 1 per cent., or Bordeaux 5-4-50, is recommended for this purpose.

The insect pests arc of two kinds, biting and sucking. Biting insects are provided with mouth-pieces or jaws. J trey obtain their food by eating the solid parts of the plants, i.e., leaves and fruit. To control such insects, an internal poison insecticide, such as arsenate of lead, is applied just prior lo the emergence of the insect. Take codlin moth as an example ; these emerge from pupae in the form of a eopperytinged moth at intervals of about eighteen days throughout the spring, summer and autumn. The moth herself does no harm; her object in life is to reproduce her kind. This she docs by laying eggs; each female moth lays from fifty to eighty eggs before her life’s work is- finished. The first of the season coincides with the fall of the petals, and at this time the moth lays one egg in the calyx of the embryo fruit. In a few days’ time the calyx closes, and in doing so protects the egg—incidentally also, the young larva which subsequently emerges therefrom and which is responsible for the damage to the fruit. The first application of avsonate of lead, powder ljlb, paste 31b. to TOO gallons water should lie applied before the calyx closes. As this emergence of the codlin moth from the pupa takes place every two or three weeks throughout the season, it is necessary to repeat the arsenate of lead application every 18 to 21 days, the object being to keen the foliage and fruit of the tree well covered with a film of poison; such applications will also control other eating insect nests which may he present. Sucking insects have no biting iaws. They are. however, provided with a trunk or proboscis, through which they feed by puncturing the plant tissues and sucking the sap therefrom. To control such insects a contact insecticide is necessary, such as red spraying oil. white spraying oil, lime sulphur and nicotine sulphate. Red oil 1-10 applied just prior to hud movement (late dormant period) is recommended for the control of mussel scale. San Jose scale, woolly aphis, and mealy bug. all of which (with the exception of San Jose) emerge from eggs at or about bud movement period. San Jose, unlike other sen ley pests, gives birth to living young. For control of these pests during summer months white spraying oil or lime sulphur is recommended.

It must he remembered, however, that sulphur in any form'must not he applied within at least one week of an oil application. Lime sulphur dilutions should be made up according to the polysulphide content of the particular brand used. The terms, such, a limesulphur 1-100 or 1.120, etc., hitherto I used when referring to a lime-sulphur i solution will in future he substituted by the following’: Linie sulphur T per cent., 0.2 per cent.. 0.1 per cent., or 0.083 per cent., according to stage of growth. Fungous diseases arc controlled by pruning 4 out dead or diseased twigs and branches and spraying with a reliable fungicide. The first bud movement should ho recognised by all growers as a signal to take immediate action by applying the first fungicidal solution for the control of black spot, etc., on pip-fruits, and of brown rot. blndder-ulum. etc., on stone fruits. It is at this period that many of the snores or fungi seeds which have overwintered by means of hibernating cycelium in cankers on laterals and branches and fallen leaves, etc., become active. No fungi spore can live in sulphate of copper; therefore an application of Bordeaux 5-4-50 is recommended as a basal covering, and, if applied at the right time (hud movement) many spores on the point of germinating will be killed outright. Moreover, tliis spray fluid on drying forme a thin film of sulphate of copper on the tree parts, capable of protecting such parts from spore germination for about 10 to 21 days, according to climatic conditions. The object of this treatment is to apply the fungicide before the spores have had time to reach or begin to’grow on the tree parts; therefore it is applied more in the nature of a preventive than a cure.