THE GARDEN

Star (Christchurch), Issue 18208, 15 July 1927, Page 11

THE GARDEN

NOTES FOR THE AMATEUR

By

D. COMBRIDGE.

'he unusual turn in the weather last

:ek should not tempt readers to irt early sowing operations. It is

not usual for us to have warm nor’west days in July and it can be expected to be a precursor of some very dirty weather which will simply ruin any seed sown too early. It has been a grand opportunity to push on any digging or trenching work, also it has given us a chance to plant out our trees, shrubs and fruit trees that arrived during the wet spell a fortnight ago. A dry spell following so much wet is also beneficial in making it possible to patch up our paths and muddy corners that have been so noticeable during the wet.

Readers who have attended to the pruning of their pip fruits and plums should now give attention to the spraying that is done during the winter time. Generally speaking it is to control or combat, for instance winterspraying does not directly control Codim moth, neither does it directly combat green aphis, but it is often expected to do so. The old method of carefully whitewashing the trees is not a wise one, for this reason, that it makes a blanket over the branches and crevices and protects the pests from the severity of the winter. The lime certainly kills where it touches, but its effect is not nearly as good as a specially prepared spraying compound, the ingrer-i : 1 ■ of which have been put together to definitely kill the pest it is used to control. Pests and Diseases. Among our fruit trees these fall into two broad sections (1) Insects, 12) Fungus. Insects are again divided into three sections broadly speaking (1) Biting insects, (2) sucking insects, (3) scale insects. Fungus diseases cover those attacks that plants are subject to which are not attributable to any insect. Under fungus diseases are often included those troubles with fruit as water core and bitter pit in apples which are classed as physiological disorders and are not directly traced to a fungus. In combatting the enemies of fruit trees it has been found necessary to study the. life history of the pest in order to be able to attack it at the weakest part of its life cycle. Insects generally pass through three stages of life: (1) Egg, (2) caterpillar, (3) fly, or perfect imago. The intermediate stage of chrysalis comes between caterpillar and imago and in some insects it takes the place during the winter of the egg stage, and in those cases it is a very important stage. Some pests when they reach the imago stage produce living young, others lay eggs and so multiply. Some produce living young until the last brood j in the autumn when a brood arrives which only lays one egg, which is carefully deposited in a suitable crevice Ito carry on the work next season. I Among the scale insects there are some j that deposit eggs under their shells at ; the expense of thir own life, which eggs are protected by their dried skin, j whilst others propagate from living young which quickly fasten themselves | to the tender branches and gradually 1 cover the branches.

In the fungus section we are dealing with a plant organism, certainly a very low form, but which is dependant for its very existence upon a host. The commonest example of fungus is of course blue mould on stale damp bread, but we are aware that if conditions arc not correct blue mould will never commence. Unfortunately for our orchards they are often subjected to atmospheric conditions that are most helpful to the spread of fungus diseases and once they have started it is impossible to remove the mark of their ravages as for instance black spot in apple and pear, brown rot of peach and nectarine. We control them bv providing a film of chemical atmosphere round the branch or fruit in which it is impossible for the fungus to carry on. Fungus like every other living organism must have an environment in which to commence its existence. Spoil the environment and its life is checked.

The pests and diseases that most trouble our home orchards are the following: Woolly Aphis, Red Spider, Red Mite, Mussel Scale, Jan Jose Scale, Codlin Moth, Green and Black Aphis, Black Spot, Powdery Mildew, Leaf Curl and Brown Rot. Truly an alarming list; but for the orchardist who has to have his fruit up to export standard the list is fourfold. The first five in the list are all in a condition during winter when they are vulnerable to a correct spraying compound, whilst some of the chrysalis of the codlin moth may be killed at this time as also some of the eggs of the aphis. The last four items are fungus diseases and are not dealt with during July, but need to be sprayed during late August and early September. Woolly Aphis,-—These are well known by the patches of white woolly looking hairs that cover the colonies of this aphis in the summer time, the effect of their presence having been on the tree is s§en in winter by the knobs and crevices on the underside of the j bark and the damage done to some of the most important buds. In the winter the presence of the aphis themselves is not easily noticed, but small

colonies are always secreted in the cracks and crevices made during the preceding summer; these few specimens always seem to survive our winter and are ready to carry on the species next spring. There is an egg stage, but the eggs are usually laid on the elm tree and the life history is carried on from there back to the apply. Tire control is Red Oil sprayed on thoroughly at the rate of one part of red oil to 10 parts soft water. Trees badly swollen on the branches from summer attacks should have the oil painted on with a stiff brush at the rate of one part of oil to two parts soft water, force it well into the crevices. In two seasons with this painting method the abnormal swellings will quite disappear. Red Spider and Red Mite—W hilst these two are distinct pests they can be treated similarly. The correct spray for them is lime sulphur in the springtime when the eggs are hatching and the young are multiplying, but during winter the minute mites pass through the egg stage. It will be noticed upon examination that round the buds on the underside of the branches are clusters of eggs almost like red dust; these await the coming of spring to hatch into the tiny mites that swarm over the underside of the new leaves and suck the sap from them until they turn a sickly yellowy-brown. Red oil applied at this time of the year at the strength of one part red oil to ten parts soft water, will account for many of the eggs not hatching next spring, but by far the best remedy rs lime sulphur applied. Later instructions regarding it will be given in season.

Mussel Scale and San Jose Scale.— These two scales can be treated for convenience together. The former is more frequently found on the apple and pear, whilst the latter —a most serious pest—attacks all fruit trees. The life history of each is different in this that the former lays its eggs beneath its own shell gradually snivelling up to a mere dried skin, whilst the latter produce living young, but continue to live and multiply, being capable of prodticing four broods in a season. As these pests are protected by a scale covering it must be recognised that the scale must be thoroughly wetted by the spray compound.

The best time to attack the former pest is when the young are emerging in spring and making their new home, in this case lime sulphur is the best remedy. The same thing applies in the latter pest as lime sulphur can be used right through the season, but in winter the trees can stand a strong application of red oil, and if this is carefully applied and made to penetrate every square inch of the tree, much good is done; use at the rate of one part red oil to ten parts of water. In the case of peaches and apricots it is wiser not to use oil, but to wait until spring when the buds are swelling and use lime sulphur. This will also combat leaf curl, which by the way, brings us to the consideration of our fungus diseases. Black Spot—This fungus winters in a dormant stage on decayed leaves, fruit and the twigs and young branches of the tree. Only waiting favourable weather conditions to fructify and infect the new leaves and fruit. The wintei control is applied in late August and is Bordeaux powder, one pound to eight gallons of water or Bordeaux mixture, winter strength 6-4-50, which means six pounds bluestone, four pounds quicklime, 50 gallons water. For a small mixing this works out at Sozs bluestone, 6 ozs quicklime, 4 gallons water. Black Spot is most prevalent on pears and apples, and is eas ily recognised by the sunken black, cracked spots sometimes as large as a shilling or larger on the fruit in aut umn. Wet springs the disease is always more virulent.

Powdery Mildew—This affects apples more specially and is always prevalent on heavy land lacking in humus. Burn ing the primings is one of the best winter controls. The spring spraying control will be given later. Leaf Curl —This fungus is very bad in our peaches and nectarines. The flowering peaches of our shrubberies arc also spoilt by it. Bordeaux mixture applied in August at bud swelling 13ozs bluestone, lOozs quicklime, 4 gallons water is the surest remedy, followed by the lime sulphur spray after have fallen.

Brown Rot.—This i's Becoming a most serious disease amongst our apricots, nectarines and peaches, the fruits showing its attack after they are gathered and marketed. The fungus is carried through the winter as so many of them are on mummified fruit on the ground and hanging on the trees also in cankers formed by the attacks of the fungus on the limbs and branches. These should be cut out and carefully burned as also the mummified fruit The fallen fruit should be ploughed in as deep as possible or in the case of a few trees gathered up and burnt. Spray the trees at bud swelling with Bordeaux as recommended for leaf curl and during the growing season with lime sulphur. Space will not permit of describing the mixing of spray compounds, but instruction will be given next week.