EXPERIMENT STATION BULLETINS. 169 



fungous tissue is entirely beneath the cuticle, but as the former continiTes 

 to grow the latter is ruptured and it is then that another crop of stalks and 

 spores is formed. In this way the fiingus continues its development 

 throughout the growing season, the crop of spores formed in the autumn 

 living over winter on the old leaves, fruit, and young branches. 



Just as soon as the young leaves start in spring the spores are ready to 

 infect them and what is true of the leaves is also true of the fruit. In case 

 of the former it is very prol)able that infection takes place very early, 

 doubtless before the apples have attained the size of marbles; it is there- 

 fore important in all cases to begin the treatment early. 



Damp, cool weather, especially at the time the fruit is forming, favors 

 the development of the scab fungus and this accounts for the fact often 

 noted by fruitgrowers that the disease is more abundant in seasons when 

 such conditions prevail. At such times it is important to exercise great 

 care in applying the remedies in order that all the parts of the tree subject 

 to attack may be protected. 



We have seen now that scab is due to a parasitic fungus, a microscopic 

 plant whose spores or "seed" are produced abundantly throughout the 

 growing season beginning early in spring from those which lived over 

 winter and giving rise to successive crops until frost. The botanical name 

 of this fungus is Fnsiclndiuni dendn'tlrinn and those desiring to obtain a 

 more detailed account of its history, habits, etc., should consult the annual 

 report of the U. 8. Department of Agriculture for the year 1887, or the 

 first annual report of the Wisconsin experiment station, published in 1884. 



The experiments so successfully carried out by Prof. Taft were designed 

 to test the effects of several fungicides on the development of scab and to 

 discover whether or not these preparations could be safely and profitably 

 used. From what has been said concerning the habits of the fungus it 

 will be understood that its treatment must for the most part be preventive. 

 In other words we must endeavor by the application of certain substances 

 to protect the leaves and fruit from the spores. This being accomplished it 

 naturally follows that we can have no scab. 



REPORT ON THE EXPERIMENTS MADE IN 1889 IN THE TREATMENT 



OF APPLE SCAB IN MICHIGAN. 



BY L. R. TAFT. 



When the trees were in blossom, twelve were selected that appeared of 

 equal vigor, and that promised fair crops of fruit. The college orchard in 

 which the trees are growing is now thirty-two years old, and has been cul- 

 tivated without crops for the last four years. In 1887 it produced a full 

 crop; last year the crop was a small one, but the trees will average about 

 five barrels of marketable fruit this year. 



The Northern Spy was chosen as the variety to be experimented upon, 

 on account of its liability to injury from scab. The trees were on the 

 north end of the orchard near the public road, and were all within the 

 space of a half acre. They were situated as shown on the following plat, 

 the numbers indicating the solutions. 

 22 



