PROGRESS IN THE CONTROL OF ELM DISEASES IN NURSERIES 
JUieiGere UELGel 
An investigation of the effectiveness of fungicidal materials in controlling the 
elm diseases commonly known as "wilts"* has been underway since 1931. Reports of the 
results obtained have been made periodically, and this report brings up to date the 
information the investigation has yielded, particularly for experiments not completely 
reported on previously. A special point has been made, in two sets of experiments, of 
observing the effect of treatment on tree growth and on the sale value of the treated 
trees. 
All of the tests have been conducted in commercial nurseries, in cooperation with 
the nurseries, and have been performed on trees receiving the cultivation usual in 
commercial production. The trees have been sprayed or dusted with fungicidal prepara- 
tions containing either sulfur or copper. All of the dusts were sulfur dusts, and some 
of the sprays were sulfur sprays. All of the copper treatments were sprays. 
The following specific materials were used: kKoloform, Kolodust, dry wettable 
flotation sulfur, flotation sulfur dust, "Mike" sulfur, lime sulfur, a commercial Bor- 
deaux, instant Bordeaux and Z-O. The characteristics of these materials are stated 
later. 
Two of the experiments reported here have been in progress for several years and 
furnish data on the effectiveness of a commercial Bordeaux and two wettable sulfurs as 
Summer sprays. Two other experiments, under way for four years, furnish data on the 
effectiveness of two copper sprays, instant Bordeaux and Z-O, used both as dormant and 
as summer sprays. The fifth experiment, also in progress for four years, furnishes data 
on the effectiveness of two wettable sulfurs as summer sprays with lime sulfur as a 
dormant spray. A sixth experiment only two years old gives preliminary indications of 
the value of "Mike" sulfur as a summer spray. The last experiment, under way for four 
years, gives data on the effectiveness of two summer sulfur dust treatments. 
In these seven experiments over 6,500 trees have been used. The smallest number 
of trees used in any experiment was 400 and the largest number was 1,659. 
MATERIALS 
The sprays and dusts named above have the characteristics given below and each was 
used in the strength stated. 
KOLOFORM is a wettable sulfur dust distributed by the Niagara Sprayer and Chemical 
Co., Inc. It contains not less than 54 per cent of sulfur, as the active ingredient: 
and not more than 46 per cent of inert ingredients. A portion of the sulfur is col- 
loidal sulfur produced by the adsorption of molten sulfur by bentonite clay. It was 
used as a spray, at the rate of 15 pounds to 100 gallons of water. 
KOLODUST is a sulfur dust also distributed by the Niagara Sprayer and Chemical 
Co., Inc. It is similar to Koloform but is adapted for direct use as a dust rather than 
as a spray ingredient. It contains not less than 87 per cent of sulfur, as its active 
ingredient, and not more than 13 per cent of inert ingredients. 
# The terms "wilt" and "elm wilt" have been in general use by nurserymen for years to 
designate any disease of elms that results in the wilting of any small or large part 
of a tree. It is used in this sense in this paper, rather than in the technically 
limited sense of the plant pathologist. The fungi most frequently associated with 
"wilting" of elms in the experimental plots belong to the fungus genera Coniothyriun, 
Cytosporina, Phoma and Vermicularia (see page 5). 
This paper is a contribution from the Section of Applied Botany and Plant Pathology. 
