54 STORRS AGRICULTURAL EXPERIMENT STATION. 
beetles were very numerous on potatoes, tomatoes, and many 
other plants. Paris green had no apparent effect on these in- 
sects, but all plants sprayed with Bordeaux mixture were 
troubled much less by them than were those unsprayed. 
Early blight does its share of damage to potato plants. This 
fungus does not cause rotting of tubers, but cuts down the 
yield by destroying the leaf tissues of the plant. 
WHEN TO SPRAY. 
When to spray, then, depends upon what we spray for. 
Some good results have been obtained from two applications 
of Bordeaux mixture. ‘These were made in August and Sep- 
tember, just as the late blight began to make its appearance. 
If striped potato beetles are numerous, spraying with poison 
must be done early in the season. ‘The attacks of the first 
brood of flea beetles are likely to occur at the same time, and, 
as in the case of the striped beetle, their work continues 
throughout the season. 
Early blight comes in July and may do considerable dawene 
to the foliage before there is danger of late blight. Arsenites 
applied with Bordeaux mixture are more effectual and less 
dangerous than when applied alone. ‘The work of applying 
Bordeaux and arsenites is not much greater than when poison 
is used alone; therefore we recommend that Bordeaux mixture 
be used early in the season, particularly if it is necessary to 
use arsenites for potato beetle. 
Whether early spraying is done or not, applications for late 
blight should be begun about the first of August, and should 
be followed at intervals of two to three weeks until vines are 
ripe or killed with frost. 
THOROUGHNESS OF WORK NECESSARY FOR SUCCESS. 
We believe that thoroughness of work is more important 
than the number of applications. It must be borne in mind 
that Bordeaux spraying is a preventive rather than a cure. 
Nine-tenths of the surface of a leaf may be covered with Bor- 
deaux, but if the spores of the fungus fall and develop on the 
one-tenth of exposed surface, the whole leaf may be killed by’ 
the blight. 
