HOME GARDENS

Bay of Plenty Beacon, Volume 14, Issue 53, 19 October 1949, Page 6

HOME GARDENS

(By J. S. Yeates, Massey AgricuL tural College)

WEEDKILLERS FOR THE

GARDEN

There has been so much interest of late years as a result of the discovery of “hormone” weedkillers, that most gardeners tend to expect too much of these materials. It is proposed this week to indicate the most suitable weedkillers which are available for the various purposes. The “hormone” weedkillers must come first, simply because everyone is so keenly interested in them. For the gardener, hormone weedkillers are useful in general for two purposes only—for use on lawns—as already described a month or so ago, and for the destruction of convolulous. They are usually very effecttive on eonvolulous if used correctly, though it must be admitted that there are occasional failures which are very hard to explain.

It has been found as a result of experience that the best chance of killing convolulus is to let it grow completely undisturbed right through spring, and then to spray it in January or February. Try to get the spray on to as many of the leaves and stems as possible, and then leave the plants alone for the material to do its slow work. . Weedkillers For Paths And Roads

There are some places where the aim is to kill all plant growth, iinc'uding grasses which are in general not readily killed by the hormone weedkillers. In all sorts of odd corners such as around sheds where the surface is gravelled, a chemical weedkiller is often the best answer. Where Ihe area is small, so that the expense is a small matter, sodium chlorate or its trade form “Atlacide” is one of the handiest things to use. Atlacide is easier to buy because shipping companies object to the fire risk of sodium chlorate.

There is no risk of poisoning from Atlacide and the easiest way to use it is simply to dust it on to the ground, using at least four ounces per square yard. Put it on a season when a few inches of raih can be experienced in the next few weeks, and let it wash into the soil. Arsenical Weedkillers The arsenic compounds are some of the most effective weedkillers, but they have the great disadvantage that they are very poisonous to human beings and to domestic animals. You can buy arsenic in any of the three forms: Arsenic pentoxide, a greyish-white material which has to be kept in a tightly closed tin to prevent its taking up water and becoming a sticky mass; “white arsenic” Carsenic tri-oxide) is almost insoluble in water; finally you can buy tins of proprietary liquid arsenical weedkiller which contains sodium arsenite.

The cheapest form in terms of poisoning done per shilling is arsenic tri-oxide or “white arsenic.” To apply it, it should first of all be converted into sodium arsenate as follows: Mix four pounds of arsenic trioxide and one pound of dry caustic soda thoroughly in a bucket; then add about one pint of water, stirring and breaking up lumps. The mixture dissolved add another pint of water. This concentrated mixture contains about 50 per cent (by weight) of arsenic trioxide. For use on most weeds it is diluated with 50 times its own volume of water. This is a good cheap general used weedkiller for weeds on paths. Where the weed growth is extra strong or includes grass which is harder to kill, it would be a good policy to use it at three or four times the above strength, i.e. dilute the concentrated material only about 12 times before spraying it on.

When using arsenic on paths it is a good idea to give a heavy dose, because it is capable of remaining in the top few inches of soil for three or four years, with the result that no weeds will grow if their roots are in those few inches of top soil. If used in this way to keep the soil bare, about four ounces of the arsenic trioxide (made up to eight ounces of concentrate) per square yard is a good average amount to use.

Extreme care should be taken in handling arsenical weedkiller. It is better to wear rubber gloves when spraying with them, because even with great care, small amounts of the liquid get under the finger nails and cause most acute discomfort for some days. The proprietary forms of sodium arcenite may be used if you cannot be bothered mixing your own. Arsenic pentoxide, dissolved, about 12 ounces to a 3-gallon knapsack pump, and used on a lawn at a total rate of 30 pounds of the pentoxide per acre, is the old method of killing lawn weeds. For most purposes today the hormone weedkillers are to be nreferred on the home lawn. Used at the rate of about two pounds per three gallons and sprayed so as to thoroughly wet the weeds, arsenic pentoxide is a good all-round weedkiller, though more expensive than the tri-oxide.