APPLE POWDERY MILDEW AND ITS CONTROL. ee 
frequently results from the use of acid arsenate of lead applied after 
the early foliage has developed. 
SPRAYING FOR APPLE SCAB. 
Considering the climatic conditions of the Pajaro Valley, one 
might expect apple scab to become a serious disease of the fruit, and 
for that reason its relative absence is the more striking. Occasionally 
scab does considerable damage in scattered orchards, but in those in 
which the writers have carried on investigations in its control it has 
never been sufficiently abundant to make the experiments satisfactory. 
It is therefore not of sufficient importance in this district to require 
regular attention in spraying. Apple scab, in the degree in which it — 
is present, is the only fungous disease of the fruit occurring in the 
Pajaro Valley. 
GENERAL FORMULA FOR THE SPRAY MIXTURE. 
Stock iron-sulphid' tmixture sto 20 gallons. 
Arsenicals and nicotine solution to be added__________ as required. 
AV Vsel iS eee OM Tod AGO ea oe eae ee ee oe a 200 gallons. 
When arsenicals and a nicotine solution are to be used in conjunc- 
tion with the iron-sulphid mixture, the combined spray may be 
prepared by first running about 150 or 160 gallons of water into the 
spray tank. The agitator is then started and the 20 gallons of stock 
iron-sulphid mixture is poured in, after which the nicotine solution 
and the arsenicals may be added in the usual way. Sufficient water 
should then be added to make 200 gallons. 
This same strength of iron-sulphid mixture, namely, 20 gallons in 
200 gallons of spray, is to be used in all of the mildew applications. 
It will be seen that the 20 gallons of stock mixture used in each 
200 gallons of spray contains the product from 4 pounds of iron 
sulphate. If commercial iron-sulphid preparations or other com- 
mercial products containing sulphur in very finely divided form are 
employed, they should be used in such quantities as to give the same 
sulphur content as the above amount of iron-sulphid mixture, or, 
better, the optimum dosage for mildew control should first be deter- 
mined by experiments, since the fineness of the product will influence 
_its effectiveness and therefore the amount to be used. 
SPRAYING SCHEDULE. 
The following spraying schedule for the control of apple powdery 
mildew has been worked out for the Pajaro Valley in particular, but 
1 See page 15, “‘ Preparation of the iron-sulphid mixture.” 
