STRAWBERRY BEDS

New Zealand Herald, Volume LXXI, Issue 21876, 11 August 1934, Page 8 (Supplement)

STRAWBERRY BEDS

CROP DETERIORATION In gardens where new strawberry beds were planted in the autumn, it will be wise to examine the plants and make firm any that have been loosened by frosts. Roots cannot work unless they have a firm *hold upon the soil. In many districts the continuous frosts of tho last few weeks have loosened the soil sufficiently to make the hoeing process unnecessary just now, but where a hard surface exists it should be broken up by running the Dutch hoe between the rows.

A dusting of old soot or a light dressing of a nitrogenous fertiliser will stimulate the growth which is just beginning. Older beds will benefit by a dressing of chemical fertilisers which can be forked in lightly. A complete manure, which will furnish the three ingredients most necessary for plants, can be made by mixing three parts of superphosphate, two parts of sulphate' (5f potash and one part of either nitrate of soda or sulphate of ammonia. Use the mixture at the rate of 2oz- per square yard. This is advocated on the presumption that a good supply of humus was dug in when the bed was made, for artificials supply the plant food only, and not the humus' which results from the decay of organic manure.

A great deal of interest has been centred in the gradual deterioration in the vigour and cropping power of strawberries of late years. Much re-

search work has been carried out, and what was at the outset, an apparently mysterious disease has been unravelled to a great extent. Much remains to be done, but it is clear that the strawberry is subject to a number of troubles and that the deterioration is due to a number of factorn. Some of the troubles are due to definite pests and diseases, while others are linked up with soil factors. A large proportion of ailing strawberry plants may be grouped under the heading of " small leaf." A plant may be said to be suffering from small leaf when the leaves are below normal size, the leaf stalks are short, and the number of crowns is greater than on a normal plant. The whole plant has a typical flattened appearance, and the leaves may be crinkled or cupped, and yellowish-green in colour with yellow edges. Alternatively, the leaves may bo rusty brown in patches, or there may be areas where the substance of the leaves is brown and dead. Pests which can bring about one or other of these conditions are, red spider, strawberry aphis and strawbff"*y mite. Cutworms, leatherjackets,

slugs and similar soil insects may eat tho roots and so cause the plants to lose vigour. There is evidence, also, that virus and mosaic diseases may also bring about small leaf conditions. Factors other than definite organisms causing small leaf arc waterlogging of the soil due to poor drainage. The opposite of waterlogging is also responsible if conditions are so dry that the soil cracks, the roots break. Severe injury to the root system, even though it is pro])erly formed, may be caused by cultivating too deep and too close to the plant in spring; such damage brings about tho same .conditions. Soil deficiencies may be primary or contributory factors. The avoidance of small leaf and many other causes of trouble lies in prevention rather than cure. It will be appreciated that causes of small leaf arc liable to occur in areas or patches. When such an area is well marked the plants are usually in an advanced stage and many of the plants are dead. Such dying plants have been said to be suffering from " patch disease," but there is no direct evidence that this is a specific disease, but merely the final stage of several troubles. Partial 01 complete blindness of plants (failure tc produce flowers) is due to several causes. A frequent reason is the destruction by mechanical or other means of the main crown during the growing season. Insects may bo responsible, bus careless hoeing is not an infrequent source of injury. Such damaged plants will recover to a large extent the following year and bear fruit in a normal manner.