the growth of trees, They are generally more prevalent and abundant under 
nursery conditions, because of the short intervals between trees, the shade 
present, and the more moist atmosphere, 
The effectiveness of the fungicides used in our tests on the 
general prevention of leaf spottings is shown in the preceding diagram, 
which is based on data very carefully taken in 1932, a season of 
exceptionally severe leaf spotting. 
3e--General effect on growth of trees, In order to determine 
whether, aside from the control of disease, the use of treatments might 
have an effect on the growth of trees, the diameter of all trees, both 
under treatment and in check rows, was taken near the end of the 1934 
growing season. A reasonable sale price was established for the several 
diameters anda money value figured for all plots and treatments, The 
effect of the treatments can be expressed tentatively in terms of dollars, 
merely to show what may be realized from the use of treatments in the hands 
of a nurseryman able to dispose of his stock at a fair price. The estimated 
money value for each treatment is listed in table 2. 
Recommendations 
The results thus far obtained in our tests indicate that sulfur 
dusts can be recommended as practical for summer use, for the purpose of 
preventing new infections by the so-called elm "wilt" diseases. Sprays, 
especially the wettable sulfurs, do not, however, appear to be as practical 
for the same purpose, although good control may sometimes be obtained with 
them, Where the problem is the prevention of leaf spotting, any of the 
materials tested will give good results, but the use of dusts may offer 
some economies in eqvipment and time. 
Tnstructions 
1.--Application of dusts: Sulfur dusts may be applied with a 
small hand power duster until tho trees reach a height of 8-10 fect. 
Thereafter, a larger apparatus is necessarye Dust should be applied when 
the foliage is slightly moist, as in the early morning when dew is present 
or just after a light rain, Dusting whon no moisture is present gives poor 
adherence of the dust and may, moreover, result in burning of the leaves. 
2e--Bordeaux mixture must be sprayed onto the trees, Any sprayor 
that develops sufficient power to force tho mixture in a fine mist to the 
tops of the trees and give good coverage of both leaves and bark will be 
satisfactory. Both "3-3-50" and "4-4-50" mixtures have been used without 
injury to the leaves. 
mot) 
