EXPERIMENTS ON THE APPLE WITH SOME NEW FUNGICIDES. 17 



deaux mixture. Possibly this form of .iron sulphid may possess 

 superiority in the case of certain other fungi. 



It is, however, not considered safe to recommend either the iron- 

 sulphid or the copper-sulphid spray for general commercial use until 

 the}^ have been further tested. It is quite possible that different 

 dilutions may be found desirable. Perhaps the self-boiled lime- 

 sulphur may be reenforced in its fungicidal properties by adding 

 just a little bluestone, say 1 pound or even half a pound per 

 barrel. It would thus be a very dilute copper sulphid with an excess 

 of self-boiled lime-sulphur. It is possible that the amount of cop- 

 per sulphate added might be adjusted to suit the susceptibility of the 

 different varieties. The full amount — 2 pounds — could be added 

 for the Yellow Newtown, York Imperial, and probably some other 

 varieties, while the minimum amount of 1 pound or perhaps even 

 half a pound could be added for the Ben Davis. 



The iron sulphid made with the self-boiled lime-sulphur as a basis 

 sticks so much better than self-boiled lime-sulphur and in the test 

 above described was so successful that it seems very promising. It 

 is capable of endless modification. Perhaps a smaller quantity than 

 the 3 pounds used in the experiment could be added to the barrel 

 of 10-10-50 or 8-8-50 self-boiled lime-sulphur with beneficial results. 

 This may serve as a sticker for the self-boiled lime-sulphur mixture 

 and increase its fungicidal powers. It may permit the use of an 

 even more dilute form of the self-boiled lime-sulphur than the 8-8-50 

 formula which is now recommended for commercial preparations. 



There is a possibility of combining the two mixtures of iron sulphid 

 and copper sulphid in various preparations for those fungous diseases 

 or combinations of fungous diseases that occur. For instance, if 

 the cedar rust requires copper for its control it may be preferred to 

 add a little copper to the iron-sulphid mixture. It is evident that 

 considerable experimenting will be needed to settle these questions. 



The harmless character of the iron sulphid is believed to be pretty 

 well shown. It will require tests under severe outbreaks of fungous 

 diseases before its fungicidal powers can be properly determined, 

 however. The iron sulphid or even the copper sulphid will not be 

 recommended for commercial work until further tested. They 

 should be tried, if at all, in experiments in a small way. Mr. Scott 

 has shown that the commercial lime-sulphur solution diluted to 1^ 

 gallons per 50 gallons of water is a more powerful fungicide than the 

 self-boiled lime-sulphur preparation and is perfectly safe at that 

 strength on the apple. This mixture is therefore recommended in 

 spraying the apple and is available for those cases where apple scab 

 or some other serious disease is feared and a stronger fungicide than 

 self-boiled lime sulphur is desired. 



[Cir. 58] 



