BASIC SLAG.

Stratford Evening Post, Volume XXXIV, Issue 32, 1 October 1912, Page 4

BASIC SLAG.

The great value of basic slag as a soil ■fertiliser is well known in Taranaki, but that it should be successfully employed as an insecticide will be news to many farmers. In the Journal of the Department of Agriculture the subject is dealt with, and it is pointed out that root crops' manured with slag are not affected with certain diseases which are often present when other manures are used. According to investigations made in France, basic slag is proving of distinct value in the destructiqn of the plant-louse. In Europe this insect has been very destructive, especially to sugar T beet. All mixtures or liquors used for spraying plants as a protection against there insects have been applied in vain. The “false brown rust” or “curl” of the peach is caused by the plant-lice, and it cannot be successfully fought because neither liquors nor powders can be.made to reach the little ,animals.When the beet-plant is attacked the leaf curls up and protects the insect against any treatment the farmer may apply. It has been found that by the application of large quantities of nitrates after rains the beet is stimulated to push out new leaves, which take the place of those destroyed by the plant-lice. But this method MS its dangers, since an excess of nitrogen in the soil may be just as harmful to the plants as the action of the insects. J. P. Wagner, a sugar-beet expert, recently told the National Society of Agriculture of France of a successful attempt to fight these insects by means of basic slag. He spread about 14001 b of the basic slag to the acre on fields that were infested with the plant-louse. Not only did this treatment prevent the insects from attacking the leaves, but they were driven away from leaves they had already attacked. On another field the slag was applied in large quantities. Every plant was already attacked by the insects when the dross was applied. Within eight days all the insects had disappeared, and the plants recovered their healthy appearance and. colour. The method by which the basic slag operated in these cases is not known. Wagner thinks that the compound forms a thin layer on the leaf, spreading out over the whole surface, and that it is either distasteful or injurious to the insect. It is well known that many lime compounds are injurious to animals with soft, naked skins, such as snails, caterpillars, naked larvae; but it has not been shown that a similar effect is actually produced in the treatment against plant-lice with basic slag.