nursery plantings and indicate strongly that pruning out diseased parts of infected 
trees is a necessary supplement to the dusts if adequate prevention is to be secured. 
It has been noticed that healthy nursery elms grow more rapidly if they are treated 
with a fungicide several times each season. Since both copper sprays and sulphur 
sprays and dusts stimulate growth, and in this respect repay their cost, quite apart 
from the disease control they effect, the use of a fungicide is always desirable. 
Instructions 
Sulphur dusts should be applied with a power duster, in order to develop 
a dust fog sufficient to cover all portions of trees being treated. Trees up to 10 
feet in height can be treated with a small, hand power duster. However, this is 
much slower and less satisfactory than a more powerful outfit. It is desirable to 
dust in earlymorning or just after a light rain, while moisture is still on the 
foliage and when the air is nearly still. For best results, application of dusts 
‘should be made at regular intervals and frequently enough to maintain a complete 
protective covering on the foliage and wood. The new leaf growth that develops cone 
tinually throughout the growing season should receive as much protection as possible. 
In most cases, dusting at two-week intervals during late April, May, and June, when 
rains are most frequent, and at three-week intervals during July and August will 
reduce the number of new wilt cases which may occur during any one season and will 
at the same time give adequate control of leaf spot diseases. 
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