FUNGICIDES, PREPARATION AND APPLICATION 439 
Finely powdered gypsum or other inert carriers may be added, 
but their use is of doubtful value. 
Tron-sulfate. 
This salt has of itself little value as a fungicide, but added 
to lime-sulfur solution forms an iron-sulfide. It reduces the 
burning qualities and increases the adhesiveness of lime-sulfur. 
It appears that iron-sulfide is quite as effective as lime-sulfur. 
It is made by adding 24 to 3 pounds of granulated iron-sulfate 
to each 50 gallons of diluted lime-sulfur solution. 
APPLICATION OF FUNGICIDES 
Fungicides, to be effective, must be properly applied. There 
are two important factors never to be neglected. They may 
be designated as timeliness and thoroughness. 
Having determined on the proper kind of fungicide and the 
correct strength to be used in the case in hand, the question 
of the time of application comes up for consideration. Time- 
liness in making the application is the key to success in the 
control of diseases with fungicides. The stage of the develop- 
ment of the host must be the primary consideration ; the tree, 
not the calendar, must be the guide. For example, the time 
to spray apple-trees to protect from scab is determined by the 
stage of development of the blossoms or fruit; first applica- 
tion, just before the blossoms open when the central blossom 
shows color and after the individual blossom-buds in the cluster 
have separated (Fig. 124). Second application, just after 
the petals fall (when two-thirds off) (Fig. 125), andsoon. One 
must watch the trees closely and act promptly when they are 
just right for application. Seasons differ, varieties differ, 
and these facts must be taken into consideration. Next to 
the stage of the development of the host, as determining the 
time ‘to spray, comes the weather. Spray just before rains, 
not after them. Remember that the fungus usually reaches 
