EXPERIMENTS ON THE APPLE WITH SOME NEW FUNGICIDES. 11 



ably due to water or to the lead arsenate. No other russet injury to 

 fruit was noted, but a few fungous spots were found on the leaves. 



Plat 7, copper-sulphid mixture No. 1. — This mixture russeted the 

 fruit of the Ben Davis the least of any copper spray. The mark 

 given was 10 per cent, or one-sixth of the damage caused by stand- 

 ard Bordeaux mixture. On the other hand, the leaf injury was only 

 1 per cent, so slight as to be scarcely noticeable, and on the Yellow 

 Newtown and the York Imperial practically perfect marks were 

 given to this mixture. On both leaves and fruit this mixture could 

 be used commercially under the conditions of the past season on 

 these varieties, and were it not for the slight russeting on the Ben 

 Davis it would have ranked with the best and had practically perfect 

 marks throughout. Possibly, by diluting, this injury could be reduced 

 still further. 



Plat 8, copper-sulphid mixture No. 2. — This spray was made with 

 the strong lime-sulphur solution instead of the self-boiled lime- 

 sulphur and was inferior to the copper -sulphid mixture No. 1. 

 The damage to the fruit of the Ben Davis, however, was marked 15 

 per cent, only slightly greater, but the foliage injury was quite serious, 

 reaching 40 per cent on the Yellow Newtown. Substituting the 

 commercial lime-sulphur solution in making the copper sulphid in- 

 creased the russeting from 10 to 15 per cent on the fruit of the Ben 

 Davis and resulted in some considerable injury to the foliage, 15 per 

 cent on the York Imperial and 10 per cent on the Ben Davis. 



Plat 9, iron-sulphid mixture. — This new fungicide received practi- 

 cally perfect marks both as to fungicidal action and as to injury. In 

 the matter of record, or percentage of spray injury and percentage of 

 fungous spots, it scored the highest mark. It has, however, a slight 

 physiological effect on the apple, which is described later, that may 

 sometimes be disadvantageous. There was absolutely no injury in 

 the way of russeting the fruit even on the Ben Davis. 



There is a slight russeting around the stems of apples in humid 

 climates that is caused by. water in the form of rain or dew in the 

 cavity. The only apples free from this slight stem russeting are 

 those grown in desert or dry countries. The stem russeting on the 

 iron-sulphid plat, however, was reduced to the smallest quantity, being 

 so slight that it was considered exactly the same as that on unsprayed 

 fruits. There was absolutely no injury, and the iron sulphid pre- 

 vented the fungous diseases so completely that by close observation 

 only a few spots could be found on the leaves. A mark of one-half of 

 1 per cent for fungous injury was therefore given to each variety. 

 On the fruit no spots were found and a perfect mark was given. 



The fruit on the iron-sulphid plat was slightly greener in appearance 

 than the unsprayed fruit, particularly toward the stem end. This 



[Cir. 58] 



