440 MANUAL OF FRUIT DISEASES 
the leaf or the fruit and produces infection during the rain, not 
before nor after. Get the fungicide on ahead of the rain and 
thus ahead of the 
fungus. Watch 
the weather maps 
and the develop- 
ing blossoms. It 
will be more prof- 
itable in some 
cases to spray a 
little before the 
host is in just the 
right condition in 
order to get in 
ahead of a rain- 
period.. Long, 
rainy, cloudy 
periods are the 
dangerous ones. 
Heavy — showers 
followed by rapid clearing seldom afford conditions favorable 
to serious infection by orchard fungi. 
The period for effective applications of fungicides, in practi- 
cally all cases, is a brief one; at most a few days, more often 
only a day or two. This means that equipment, labor and 
materials necessary to cover the trees in a short time must 
be provided. The continuous running of one sprayer in a large 
orchard throughout the season is largely a loss of time and 
money. Fungicides to be effective must be applied at just 
the right time. 
Thoroughness is second only to timeliness as a factor in 
determining the success of spraying or dusting operations. 
Since fungicides are applied to protect, every part of the sus- 
ceptible surface must be covered. In spraying this cannot be 
Fic. 125. — Apple-blossoms in proper stage for the 
first application of a fungicide. 
