Apple Scab and its Treatment. 267 



slight specks or scabs, and, third, fruit that was badly scabby. It is not neces- 

 sary to bore you by going into details and I will only say that the two trees 

 that were sprayed bore 1002 apples, of which there were, free of scab 1334. 

 slightly scabby 351, and badly scabby 217 ; the two trees that were not sprayed 

 bore 2117 apples, of which there were only ini free from scab, 32ii slightly 

 scabby, and 1646 badly scabby. To summarize the results, the two trees that 

 were not sprayed bore 215 apples more than the others, but the trees that were 

 sprayed bore nearly nine times as much fruit free from scab as the trees that 

 were not sprayed. To put it upon a percentage basis, on the trees that were not 

 sprayed, 7 per cent of the fruit was free from scab, and on tliose that were 

 sprayed. 70 per cent were free from scab — not a high percentage, by the way. 

 but quite satisfactory considering the severity of the test. 



There was one other result that I observed from this spi'ayiug that interested 

 me much more than the effect upon the scab, and is in line with a suggestion 

 made by Mr. Walden. that is its effect upon the size of the fruit. Tlits was so 

 noticeable that I determined the increase in size by two methods : first, by 

 taking measurements, and second, by weighing the fruit. To measure the fruit, 

 in order to leave out all personal bias, I obtained a pair of callipers, set the 

 points 21^ inches apart, and every apple that passed through without touching 

 the callipers was placed among the culls and the others were placed by them- 

 selves. On the two trees sprayed, of the 1902 apples, 1147 measured over 2i/.j 

 inches, and 755 measured less than that. On the trees that were not sprayed, 

 although there were some two hundred more apples than on the sprayed trees, 

 only 054 were over 2i/(, inches in diameter and 1463 were less than that. 



A consideration of the figures reveals the fact that the fruit on all these 

 trees was small, wliich was to be expected from the fact that the orchard lias 

 never been properly cared for, and this year received only the most .cursory 

 cultivation. Of some 2,000 or perhaps 2,500 boxes of fruit borne upon the 400 

 trees, there were not over 600 boxes that would grade from 4 to 41/0 tier, or 

 possibly 5 tier. The small size was not due to the spraying, the figures showing 

 that this spraying increased tlie size of the fruit to a very marked extent. There 

 was upon the two trees sprayed practically twice as much fruit of a marketable 

 size as on tlie trees that were not sprayed, as well as nearly nine times as much 

 free from scab. 



This was only a demonstration exercise. Nevertheless we may learn some- 

 thing from it. I wish also at this time to make some suggestions upon apple 

 scab based more upon theory than upon experiment : I have not the data to 

 support them. Apple scab as we see it upon the fruit and leaves is an imperfect 

 form of fungus. Most fungi have two forms, a summer or imperfect form, and 

 the winter or perfect form. Until recently botanists have been unable to connect 

 the summer form of apple scab with its winter form. It was inferred that the 

 summer form wintered upon fallen leaves and upon the twigs about the buds, 

 etc., and. consequently, we liave had the advice constantly given to spray before 

 the buds start. Recently, however, it lias been demonstrated that apple scab 

 has a permanent winter form which occurs upon the fallen leaves. We have no 

 proof, whatever, that it winters anywliere else than upon the fallen leaves. 

 Hence all infestation of leaves and fruit in spring must come from the winter 

 spores upon the fallen leaves. It has also been demonstrated that apple seal) 

 has two periods of development, a spring growth and a fall growth. Hitherto 

 we have sprayed only in spring for apple scab and have neglected the fall ap- 

 plication which may yet prove to be of the utmost value. For if it is true 

 that the fungus winters only upon fallen leaves, it is evident that fall applica- 

 tions which would prevent the development of the disease upon the leaves in 

 fall would thereby prevent the development of winter spores which are the only 

 source of infestation of fruit and leaf in spring. And if some means could be 

 taken to dispose of the fallen leaves before spring, by raking them up and 

 burning them, or by plowing them under, it might prove of the utmost value 

 and save much of the expensive operation of spraying for apple scab. 



