WINTER SPRAYING.

New Zealand Herald, Volume LXVII, Issue 20622, 22 July 1930, Page 15

WINTER SPRAYING.

COMBATING PARASITES.

As 50on a* the trees havo been pruned they should be given a thorough application of spray to help to combat various pests and diseases. These enemies aro not visible in most cases at this time of the year und one is apt to forgot, for the timo being, that there are such things as insect and fungus pests. Actually, this is when one should remember them most, as it. is now that one can do most toward ridding tlie trees of tho pests. Tho effectiveness of a winter application is overlooked too often, with the inevitable result that the trees nro affected just, as badly tho following season. It tho spores of tho fungus diseases aro destroyed in largo numbers and n coating of spray left for the remainder to come in contact with as soon as they begin to germinate, tho trees can bo kept practically five oi the pests for tho ensuing year, if further applications aro mado to combat the spores that aro trdught from other parts by tho action of tho v.irid. in the case of the insect pests the eggs of theso are lying in tho cracks and crevices cn tho trees in iargo numbors and they may he destroyed by a spray that wilj keep tho air out and smother them. Advantage o! Winter Spraying.

One distinct advantage of winter spraying is that it is possible to use a eti .nicer solution owing to tho trees being dormant,, | The solutions that aro used for the winj ter applications would scorch tho foliago I in tho summer, but they are quito harmless, as far as tlii trees are concerned, in tho winter. With a strongor spray pos. sihlo one has moro chanco of destroying tho pests during tho dormant period. The applications that should bo made at- this time begin with the insect pests. The method of attack is to dostroy the eggs, and foi this purposo one uses what is termed an " egg-wash." Aphides and scale insects are tho chief pests that are destroyed in tho egg stage by tho winter spraying. The eggs of tho latter aro sheltered nt this timo beneath tho dead j scales of the previous generation and tho caustic soda is tho only spray that can find its way into the interior and destroy the eggs Although its caustic naturo allows it to penetrate tho scales in this manner, it does not harm the bark of tho tree. The oniy effect that it has on the bark is to cause it to tighten np (" bark-binding"), but this can be prevented by a subsequent application of red oil. Effect ol Caustic Soda. The effect of tho caustic soda is not limited to the destruction of the insects' eggs, howevei. All mosses, lichens and other growths on the trunks of tho trees are killed by the soda solution and it results in <\ general " clean-up" of the whole tree. Old stono fruit trees are particularly liable to harbour the abovementioned growths To make Iho caustic soda solution, lib. of soda is dissolved in a gallon of water, while 4oz. of soft soap aro dissolved in about a pint of boiling water. The soda solution is diluted to 5 gallons b}' tho addition of further water and tho soft, soap is added and stirred in. In order that it will pe. «iwu« evei crevice in the bark tho solution should be applied through a high-pressure nozzle. About a fortnight afterward tho red oil solution (1 in 20) should bo administered. Dealing with fungus pests one may use either Bordeaux or lime sulphur to kill tho spoics. Both of theso are effective sprays Tho winter strength of the solutions should 1<? usi'd, as these are more ! effective and will not harm tho trees. In I tlie case of the Bordeaux the formula is 8-8-40. and with the lime sulphur the strength is 1 in GO. It is commonly thought that the wini tor spraying immediately destroys tho spores, but this may not be altogether i correct. It is prohablo that somo of the dangerous spores aro rendered useless, but some of them aro not killed until they begin to germinate, and it is then that tho minute delicate shoots como in cou- | tact, with tho spray and wither. This explains why it is necessary to apply tho I spray before tho disease attacks the plant.. ' Once the tree is coated with the spray any spores that fall on it- will be destroyed as soon as they germinate.