PREVENTION AND CURE. 65 
were planted on the Arlington Experimental Farm of this Depart- 
ment and grown for one season in a moist, stiff, heavy, clayey soil. 
The results were as follows: 
Of a total of 470 trees grown from grafts with continuous fine thread 
wrapping, 38.1 per cent was diseased with crown-gall and 16.8 per 
cent with hairy-root. Of a total of 419 trees grown from grafts with 
ordinary fine-thread wrapping, 48.7 per cent was diseased with 
crown-gall and 25.2 per cent with hairy-root. This is a difference 
of 19 per cent in favor of the new thread wrapping, aside from an 
increase in the stand of 10.2 per cent, indicating that it will probably 
prove to be as good as cloth, if not better. The new thread wrapping 
when applied with a machine made for the purpose can be used with 
far greater rapidity than any wrapping hitherto in use, and as it 
holds the union more firmly together it is destined, for thie reason 
alone, to supersede the ordinary wrapping. 
None of the forms of wrapping mentioned will prevent the forma- 
tion of galls and of woolly-knot on the scion of a root graft above the 
union, since these occur above the wrapping, especially in such varie- 
ties as the Wealthy (PI. II, fig. 3). In the case of Wealthy trees, 
such occurrence of disease on the scion often equals, or even exceeds, 
that at the union, as was noted in the foregoing experiment. To 
reduce this loss, budding or top-grafting must be resorted to, since 
wrapping reduces only the disease occurring on the union. In the 
nursery top-grafting is not practicable, owing to the amount of time 
that it consumes. The additional labor adds to the expense, so as 
to make the process unprofitable for the grower; not so with the 
orchardist who grows a few trees and who wishes to take the time. 
The Walbridge is a good, vigorous-growing tree, quite free from 
crown-gall, and is recommended as a good sacle for top-grafting 
with the Wealthy in an orchard. The Walbridge and the W ealthy 
are hardy with reference to cold, and such a combination of scion 
and rootstalk should do well in hie northern apple-growing States 
in the Mississippi Valley, such as Nebraska, Iowa, and other States 
in the same latitude. 
THE USE OF WEAK ANTISEPTICS FOR THE PREVENTION OF DISEASE IN 
ROOT GRAFTS OF DOUBTFUL VALUE. 
At various times a number of nurserymen have tried dipping 
scions and seedling roots in weak solutions of copper sulphate, 
either before or after making them into root grafts. Those who 
have experimented have reported little or no results in the prevention 
of disease. 
In order to test the use of copper svi. an experiment was 
conducted with two equal sets of root grafts, planted, prepared, and 
50414°—Bul. 186—10——9 
