306 STATE HORTICULTURAL SOCIETY. 



Paris green as an insecticide is not materially affected by the Bordeaux 

 mixture when the two are applied together. 



The results obtained when London purple or Paris green was added to 

 the Bordeaux mixture indicate the comparative value of such combina- 

 tions. In the King the number of wormy apples was reduced to 1 per 

 cent, by the Paris green and 3 per cent, by the London purple. The 

 Baldwins show a reduction to 9 per cent, by the Paris green and to only 

 15 per cent, by the London purple. In each case the result is in favor of 

 Paris green. 



The foliage of the trees was uninjured, except in the case of the Paris 

 green applied alone. Some trees, and parts of trees, to which this had 

 been applied, looked thinner than the rest of the orchard during the lat- 

 ter part of the season. The leaves were undoubtedly somewhat injured 

 by the Paris green but not sufficiently to weaken the trees to any extent. 

 The cause of the injury is undoubtedly due to the amount of arsenic 

 which entered into solution. This was found by analysis to be about one 

 half of one per cent. (.08) of the total amount. The addition of a 

 little lime would have destroyed all caustic action, for no injury could be 

 seen where the Bordeaux combinations were used. A sample of London 

 purple has been analyzed by the station chemist. It was found that about 

 60 per cent, of the arsenic was soluble and it is this dissolved arsenic which 

 injures foliage. On account of its caustic properties the London purple 

 was used only in connection with the Bordeaux mixture. 



PART II. THE PREVALENCE OF APPLE SCAB. 



Early in October a circular was sent from this station asking for infor- 

 mation regarding the degree in which the varieties of apple were attacked 

 by the scab fungus. The varieties were to be divided into three classes: 

 first, those whose market value is practically ruined every year, as the 

 Fameuse, or Snow apples; second, those whose market value is not seri- 

 ously affected, as the Baldwins; and third, those which are entirely free 

 from scab. The division was to be based upon the amount of scab found 

 upon the fruit. Many growers responded. Although the data are not so 

 complete as might be desired, still the resistant powers of many varieties 

 are shown in the tables given below. The matter is a difficult one to study 

 and it is hoped that apple-growers, in whose interest this work is being 

 done, will watch the disease next summer and report any results that may 

 be of interest in time for publication in a succeeding bulletin. The newer 

 varieties should receive particular attention, for among them there are 

 undoubtedly some that withstand the attacks of the scab much more than 

 others; it will be interesting to know whether they will remain so. Some 

 parts of the trees also appear to be more injured than others; in some 

 varieties the fruit suffers more than the leaves, and in others the reverse 

 is true. Location also influences the amount of scab present in an 

 orchard. It is the common opinion that the disease is worse in low, wet 

 places; but all growers do not agree with this statement. The character 

 of the soil is another important factor to be coubidered. Is the disease 

 as serious upon well drained laud as upon that which is not drained? Are 

 there any neglected trees or orchards in the neighborhood which might 

 explain the presence of the scab fungus in an orchard or certain parts of 

 an orchard? To what extent do the amount and the time of rainfall 



