There are several formulae for making caustic winter washes to be applied to trees in a dormant condition. These caustic washes cleanse the bark of fruit trees and bushes from such parasitic plant growths as mosses, lichens, and algae, thus allowing them to breathe more freely. If applied quite hot with a strong-haired brush, the eggs of many insect pests are also destroyed, such as Scale, American Blight, etc. These washes must be used in winter up to February and March, but not after the flower and leaf buds begin to open.

The following formulae for winter washes are given: -

I. Caustic soda (98 per cent) ......... 2 to 2 1/2 lb.

Water ..................10 gal.

This is made simply by dissolving the caustic soda in the water and applying hot if possible. Care, however, must be taken of the hands and face.

II. Iron sulphate ... ... ... ... ... 1/2 lb.

Quicklime ... ... ... ... ... 1/4 „

Caustic soda ... ... ... ... ... 2 „

Water .................. 10 gal.

Paraffin (solar distillate) ... ... ... 5 pt.

In this formula dissolve the iron sulphate in 9 gal. of water; slake the lime in a little water and make into milk of lime by adding more water.

Then add milk of lime to the dissolved iron sulphate, passing through a hair sieve or piece of sacking to strain off gritty particles. The paraffin should then be added to the sulphate and lime, and last of all the caustic soda. The mixture should be well agitated during application, and if applied hot so much the better.