THE FARMER.

Otaki Mail, 20 January 1919, Page 4

THE FARMER.

HINTS ON WEED CONTROL. Mr H. W. Davey, F. 0.5., Melbourne; contributes to the “Journal of Agriculture’’ (Vic.) a useful article on the above subject. , Weeds arc often referred to as plants out of plac«. They certainly are plants that intrude-themselves where they are least wanted, and their persistence and power to hold their own in competition with other plants is well known to most people.

In spito of all that has beon -written and spoken as to the great losses suffered by agriculturists through weeds, little is dono to eradicate them. Weed seeds arc often introduced as impurities among other seeds, and, through carelessness, these are sown with the good seed, and so a weed is introduced to land previously free from that particular plant. Weeds are also spread in many other ways, the chief agencies probably being travelling stock, birds, irrigation water, trucks in which stock have been carried, stable manure, chaff, and hay, and threshing machines, the latter being the most likely to carry weed seeds from one farm to another.

To enable one to successfully cope with a weed a knowlcdgo of its life period and habits is necessary, inasmuch, for instance, as while an animal plant may-be eradicated by not allowing it to seed, a perennial plant cannot bo got rid of in this way. Cultivation is a great factor in the control -of .most weeds, and especially so in the case of annuals. ,

In fallowing land, we have a means of killing weeds and their soeds, as can be seon by the millions of tiny plants that aro destroyed' every time the cultivator breaks afresh the crust of the soil. Those seedlings die on exposure to the sun or wind, and each fresh cultivation of the soil brings more seed's within the influence of warmth: and air, thus inducing germination, and further cultivation is then necossary to destroy these late growths. On the other hand, if cultivation bo not carefully carried out it may sjiread such plants as Canadian. Thistle, and St. John’s Wort, for small pieces of the roots of such weeds aro each capable of forming new plants, and the harrows, in ' dragging those about, may easily start a fresh patch.

Seeds deeply buried often remain dormant for very long periods, so that deep ploughing sometimes buries many seeds too deeply in tho ground for germination to tako place immediately, but they will gorminate when subsequent plougliings bring then; to or near the surface.

Cultivation for the suppression of perc-nnial weeds must, be frequent onough to stop tho formation of leaves, thus preventing tho elaboration of crude sap sent up by the roots, and then the plant will bo gradually suffocated and will die. Ploughing should be of varying depths, so that all the roots may bo brought to the surface to enable wind or sun to dry them out.

One of the chief means of controlling weeds, especially perennials, is to stop the development of seeds. This may be achieved in many ways, such as bymowing the plants, hand-pulling, or by digging them out. Heavy stocking with sheep or goats when the plants are young is often effective. The planting of strong-growing crops to smother weeds has also proved useful. Where it is found impracticable to employ these methods, chemicals can be used effectively to destroy all growth above the ground. Small patches of very persistent weeds can be killed by covering them with heavy mulching! of straw, sheets of bark, sheets of heavy paper, or, in fact, any material that will exclude all light from them, it being.impossible for any plant containing chlorophyll in its leaves to exist in total darkness.

The best time to attaek weeds by mowing them is just before they come into full bloom. This is especially so with annuals and biennials, as at this time their roots are more or less exhausted, their reserves having been fully drawn upon to enable them to reach the flowering period.