April, ’24] 
LATHROP & TRASK: PRUNE ROOT BORER 
291 
The quicklime forms the body of the wash; the copper sulfate was 
added because of its fungicidal nature; while the glue, of course, serves 
as a sticker. The ground wood pulp was obtained from a paper mill, 
and was added to give increased body to the wash and to prevent crack¬ 
ing of the wash upon drying. For these purposes, the pulp served 
very well, but we do not regard its addition as highly important. 
Active Ingredients. In all of the washes applied, the active material 
was either naphthalene or mixtures of naphthalene and paraffine in various 
proportions. In making preparations of naphthalene and parr affine, the 
two materials were melted together over a gas flame. The naphthalene 
was readily soluble in the paraffine in the liquid state, and by rapidly 
cooling the melted material in thin layers on a glass plate, a solid solu¬ 
tion of naphthalene and paraffine resulted. This material was ground 
in an ordinary food chopper to reduce it to a coarse granular form which 
was readily incorporated in the whitewash mixture. 
The following are the combinations which were added to the basic 
formula: 
Formula No. 1—22 Naphthalene: l lb. 
2— 22 Naphthalene: paraffine 2 1:1 1 lb. 
3— 22 Naphthalene: paraffine 2:1 lpj lbs. 
4— 22 Naphthalene: paraffine 3:1 21 oz. 
5— 22 Naphthalene: paraffine 2:1 1 lb. 
6— 22 Naphthalene: paraffine 3:1 1 lb. 
7— 22 Naphthalene: “Parowax” 3 3:1 1 lb. 
Methods of Application of Naphthalene Whitewash. In nearly 
all cases the soil was removed from the bases of the trees to the depth of 
four to six inches before the wash was applied. The base of the trunk was 
then fitted with a paper collar or painted with a protective wash 4 to 
eliminate the injurious effects of the naphthalene fumes below the soil 
level. 
After the paper collar was in place or the “protective wash” had dried 
the naphthalene wash was applied to the crown and trunk of the tree to a 
height of 14 to 16 inches. The soil was replaced about the base of the 
tree. 
2 Paraffine used was a commercial grade obtained from the Standard Oil Com¬ 
pany. Melting point about 48° C. 
3 Trade name for a refined grade of paraffine prepared and sold by the Standard 
Oil Company. 
4 The “protective wash” consisted of the following ingredients: 
Quicklime 4 lbs. 
Copper sulfate 2 oz. 
Glue 4 oz. 
Powdered charcoal 1 lb. 
Water to form a thick paint 
