FIGHTING PESTS.

Stratford Evening Post, Volume XXIX, Issue 107, 27 June 1911, Page 8

FIGHTING PESTS.

THE EFFECT OF HAXFHES. [By llikcno in “X.Z. Herald.”] The judicious manuring of crops varies not only with the locality, but even with oacn held and the state in which that held may bo, hut there are certain broad principles which apply to each variety of crop wherever it may he grown. Firstly, all plants require the essential plant-food constituents, and omission of any one of those moans poor growth and often death to the plant. It is apparent, therefore, that the growth of plants is proportional to the amount of the essential constituents present in the smallest quantities. 'I nis is a broad law, effecting all plant growth, and it follows, if one plant-food constituent is present in too small a quantify to enable the plant to grow normally, that this plant will ho weakened in constitution, and thus be less able to resist the attacks of insect and fungoid pests. Secondly, on the principle that certain constituents have more effect on certain crops than others, we have what is termed “N file’s Law of Dominant -Constituents.” □cminant Soil Constituents, This principle is a thoroughly sound one, and is the keynote of ail scientific manuring. Nitrogen is the dominant constituent of cereals and grasses; hut, as our country is fairly well supplied with nitrates' and deheient in phosphates, we line! that the application of phosphates produces the best results with cereals and grass lands. Jn countries not so well supplied with nitrates, these form the basis of cereal manures. , Again, the dominant constituent of turnips, swedes, maize, and artichokes is phosphoric acid, and that of peas, beans, clovers, lucerne, and potatoes is potash. With a plentiful _supply of its dominant constituent in an available form, a plant is soon brought to its full vigour, and is more disease-resistant. The natural abundance of potash in Now Zealand soils, especially clay soils, makes the application of potash manures unnecessary to such crops as peas, beans and clovers; but in the case of the potato, which is at present the victim of the Irish'blight, the application of potash manures is essential ,if the best, results are to lie obtained in lighting this destructive blight. The above shows that by judicious manuring wo can develop the plant to its fullest, and thus give it increased resistance.

Effoc'i of Manures on Foliage. A very important effect of certain manures is the deposit in the leaves or stem of substances which are injurious or obnoxious to pests. The u&st example of this we nave in the case of the potato or tomato crop, which has been manured with kainit or other potash manure. The leaves seen to have a glaze which is not noticeable in unmanurrd plant's, and the crop is net so liable to Irish blight. Again, with fruit trees, it has been noticed that the trees and leaves have a glazed appearance, and the leaves seem more distasteful to leaf-eating insects, such as pear-slug, when the trees arc manured with potash in the form of kainit. . This manure also has a remarkable elfect in ridding fruit trees of the aphis. Manures and ‘lnsects. The application of distasteful mineral manures has a marked effect on insects, which spend part of their life on or under the surface of the ground. Hero again kainit is very effective, as also is caustic lime. Manuring with farm-yard manure, bonedust, blood, or airy organic manure, helps to harbour insects, and often provides a food supply. Soot is excellent for deterring leaf-eating beetles, onion-fly, and turnip-fly. Dusting over seed, leaves of turnips, and broad-casting over beds of pickling onions is usually followed by cessation of attask of turnip and onion-fly, especially when the dew is on the leaves; at the same time soot stimulates plant-growth and makes good the damage caused by insects. GSocis of Nitrsser.. An excess of nitrogenous manure produces a luxuriant growth., but the tissues of the plant are softer and more easily attacked by leaf-eating insects and fungi. With the present high price of these manures it is seldom that the hold cropper will err in this direction. A substance of great use, when mixed with other manures, is lime. Lime in the Tree state is antagonistic to the growth of fungi, and when included in turnip manures helps largely to prevent linger and too, which is now present in some parts of this country. With a later swede crops in this country the first aim is to force the young swede so that it may produce its third and other leaves before falling a victim to the turnip fly. Here food constituents are required in a quickly available form, and this is host obtained by a lino tilth and the application of a manure, such as superphosphate of lime. The, need for forcing the young plant was clearly exemplified this season in a field in which part of the land was stiff, and had not worked down so fine as another part which had worked to a nice tilth. The swedes on the latter part germinated quickly, and came away leaving the rougher part with its slower growing plants an easy prey for the fly.

Manures as Sprays. Let us now consider to what extent manures can ho used as sprays. Nitrate of soda is used by many gardeners to spray their roses in order to keep the aphis in check. That portion of the spray falling to the ground being absorbed by the plant as a food constituent. Again, market gardeners find that peas, beans, and potatoes benefit by sprinkling with kuinit. Seeing that kainit is so distasteful to all insects, and is so liked by the potato, it appears' that it would be profitable to spray with a mixture of nitrate of soda and kainit, which are both soluble salts. If Li fungicide, say, copper sulphate, could be added to the above in sufficient proportions, the mixture should prove a very efficient spray for potatoes and tomatoes. I hope during the coming season to try some of these mixtures, and I think that at least it would he beneficial to add kainit to the ordinary spraying mixture used for potatoes. At any rate, there is plenty of room for experimenting in this direction. BUYING A PSANO. During our annual balance in Juno month we are prepared to offer terms of payment even more advantageous than the very liberal and exceptional lervns wo extend in the ordinary com so of business. Porhays you do not want terms; but if you do, this is jour special opportunity. All our instruments are absolutely good, bearing, in addition to the names of famous makes, such as the Broadwood, the J’onisch, the Lapp, find the Stein way, the guarantee cf our wide repute and long experience. If wo sell you a Piano during this annual balance’ period, you arc assured of a fine instrument, and the payments will be ton easy to bother yon at all. The Dresden Piano Company, Ltd., Wellington. North Island Manager: Mr. M. J. Droolers; Local Representative: Mr. W. C. Cargili.*