WEEDS WE SHOULD KNOW.

Otago Witness, Issue 3467, 24 August 1920, Page 8

WEEDS WE SHOULD KNOW.

A weed is like a fly. Give it a good start, and before you realise it you have hundreds, thousands, millions —instead of just one. We kill the flies to protect ourselves against diseases, which they so readily spread; we kill weeds to save our crops from being smothered, or should do so. In the States there is a popular slogans "Swat the fly." Farmers might adopt it, in addition to "Swat the weed." Weeds have their uses, no doubt, but in growing crops weeds usurp the place of

the crop it is desired to grow, and farmers have to devote, much time and trouble to their suppression. What is a weed? it may be asked. It may be defined as a plant growing in the wrong place, so that a potato' plant may, in a general way, be considered a weed if growing in a cereal field, as is a wheat plant in the kitchen garden. In order to combat these "foreign" plants successfully it is necessary to wage warfare agafthst them continually. Carlessness in handling new country, in seeding same, etc., has resulted in thousands of acres being overrun with these ugly pests. Since perpetual war is necessary against weeds, it is desirous that the mode of procedure adopted should be determined partly by the length of life of the weeds themselves, and partly by the nature of the crop. We have annual, biennial, and perennial weeds to contend against. Any weed is an annual which lives but one season, and many of our farm weeds belong to this group. They start from a seed in the spring, grow up, blossom, and produce seeds and die. This is all done in less than a year, and so they are spoken of as annuals. Under the most expert tillage operations, some of these annual pests will escape and remain buried, snug and safe, and, if we may use the term, "ungerminated." Nature, in her varied way, has provided many of the weed seeds with hard shells, more or less impermeable to moisture, which enables them to resist decay for fairly long periods. When ploughed up later on and acted upon by atmospheric air they are ready to germinate and cause trouble. In a general way, however, it is safe to say that since annual weeds spread largely by their seeds it is comparatively an easy matter to keep them in check by preventing them from seeding. Any method which will prevent them from forming seeds will answer. Such checking, however, must be made before any seeds have been formed at all, because a fair sized plant _ will doubtless have sufficient nourishment in its leaves and stem to carry seed formation to fruition. Again, such checking by cutting or pulling must be done with care—well beneath the surface of the soil. Otherwise it is quite possible that low shoots or branches may flower and form seeds quite capable of causing infinite trouble later on. Cultivation is the main way of keeping in check annual- weeds. It must be done at the right time, and it is just here where one farmer eclipses his neighbour in knowing just how and when to use his various farm implements, and so has the satisfaction of viewing his cea*eal crops "coming away" unharassed by clinging weed.pests. Biennial weeds are more troublesome to eradicate. They take two years to mature seed." Starting from seed, they grow on during the first season into bis: healthy plants, die down in the fall of the year, and start off the following year from the root. They frequently come away early in the spring of the year, their fleshy roots being well stored with food, which is drawn upon by the plant. Such plants as carrots and parsnips are good examples of this, although not weeds. As biennials usually spread from seeds, very similar methods may be adopted.for combating them as •\\(ith annuals. The foregoing are bad enough, but they are as nothing compared with the perennials. A perennial weed lives on for an indefinite period of time, and may produce seeds every year. Many of the worst of them spread in other ways than from seeds, and this is why they are so difficult to eradicate. They are indeed noxious weeds. To deal with them it is necessary to know their life habits. Some of the worst plants in this order are those which spread by a system of underground stems as well as by their seeds. Every jointed piece of these underground stems is capable of growing into new plants, and the least carelessness in cultivating a bad patch may be the cause of starting a new area in some other part of the paddock. We know of no royal method of eradicating Californian thistle, for instance, but will venture to say this—any plant will die in time if it is not allowed to form leaves, so any method which Avill achieve this will be effective.