GARDENERS AND TAR SPRAYS.
This year has been conspicuous for a notable advance, on the Continent as well as in England, of a rural art not mentioned by the Ministry's Intelligence—the art; or science, of spraying. Some account was given last week of the Swiss treatment of larch trees attacked by the tortrix caterpillar. Since then my attention has been drawn to some German experiments in preserving forests and vineyards by spraying from aeroplanes. Plagues of the hawk-moth, the oak-roller and other caterpillars were completely stayed by the joint aid of aeroplanes and arsenical sprays. The Ameri- cans, as described in an excellent number of The Estate Maga- zine, have for some years established such spraying as an integral part of forestry conservation. In British horticulture I have seen this year most striking examples of the value of the new tar distillate sprays—especially in one Worcestershire district, against gooseberry caterpillars and various apple aphis, especially capsid. This, of course, was not on the forestry scale, and the washes and powders were sprayed by hand. It is estimated that the aeroplane can effectively spray five acres within a minute !
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