FUNGICIDES, PREPARATION AND APPLICATION 439 



Finely powdered gypsum or other inert carriers may be added, 

 but their use is of doubtful value. 



Iron-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 2|- 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), and so on. 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 



