exception, those extending on the negative side are sprays. 
The role played by pruning as a supplement to other treatments appears to 
be very important, Although not always dependable and as an average very moderately 
effective by itself (see table 5), pruning has a fairly consistent beneficial effect, 
It tends to increase the effectiveness of treatments which are themselves effective, 
as is the case with Kolodust and flotation sulphur dust, and it tends to lend value 
to treatments in themselves ineffective, as in the case of commercial Bordeaux and 
instant Bordeaux sprays. On the other hand, when used to supplement sulphur sprays 
it has increased greatly the ineffectiveness of these apparently ineffective spraySe 
Commercial Bordeaux mixture and pruning, as a unit of treatment, is not 
sufficiently effective to justify its use merely for disease prevention, and the 
same may be said of pruning when used alone. Instant Bordeaux mixture, when con= 
bined with pruning, holds considerable promise but needs more adequate testing. Both 
Kolodust and flotation sulphur dust are effective to a small degree when used alone, 
and in both cases this inherent effectiveness is increased in greater than expected 
proportions by supplementing the fungicides with pruning. 
Although certain differences in results will be found between this and 
the prior report, the main conclusion remains the same. Summer applications of sul- 
phur dusts are the only treatments that have served consistently to prevent new 
infections of “elm wilt," and the effectiveness of even these treatments is very 
greatly enhanced by concurrent pruning. 
Recommendations 
a me ee ne rn 
As previously reported and as stated herein, our results point definitely 
to summer usc of sulphur dusts for the prevention of the "clm wilt" discase in 
