DESCRIPTION OF PLATES. 



Plate I. (Frontispiece.) Apple blotch on fruits, twigs, and leaf. 1. — A mature 

 Ben Davis apple affected with blotch, showing the general character of the 

 blotches and the cracking of the fruit caused by the disease. 2. — Two 

 Ben Davis apples about one-third grown, showing the disease as it appears 

 on badly infected fruit about six weeks after infection. 3. — Portion of a 

 water sprout from a Limbertwig tree, showing cankers in different stages 

 of development. 4. — Twig of bearing wood from a Ben Davis tree, show- 

 ing numerous cankers on and near the fruit spurs. 5. — A leaf from, a 

 Missouri tree, showing leaf spots and petiole cankers caused by the apple- 

 blotch fungus. 



Plate II. Fig. 1. — View of a Northwestern Greening orchard in which the 

 trees have been practically killed by apple-blotch cankers on the small 

 shoots and larger limbs. Fig. 2. — Six Ben Davis apples about one-third 

 grown badly affected with blotch. 



Plate III. Microscopic and cultural characters of the apple-blotch fungus. 

 1. — A vertical section of a single pyenidium from a spot on a Ben Davis 

 apple, showing pyenospores in various stages of development X 185. 2, 

 3, 4, and 5. — Mature pyenospores of the apple-blotch fungus from various 

 sources, showing appendages X TOO. (2) From leaf spot on Missouri 

 apple leaf; (3) from canker on Limbertwig water sprout; (4) from blotch 

 on Ben Davis apple; (5) from type specimen of PJujUosticta solitaria 

 E. & E., on leaf of Pyrus corona ria. 6, 7, and 8. — Germinating spores X 

 700. (6) In potato agar; (7) in apple agar, twenty-two hours after 

 sowing; (8) same spore as figure 7, seventy-eight hours after sowing. 

 9. — Mycelium of apple-blotch fungus from corn-meal agar culture X 370. 

 10. — Two colonies of the apple-blotch fungus one month old growing in 

 apple agar. 



Plate IV. Fig. 1. — A Ben Davis apple, showing blotches produced by inocula- 

 tion with spores from twig cankers. Fig. 2. — A Gano apple, showing 

 blotches resulting from natural infection. Fig. 3. — A power spraying out- 

 fit in operation. 



Plate V. Fig. 1. — Entire crop of apples from a Ben Davis tree sprayed three 

 times, beginning at the right period for the control of the disease. The 

 apples in the basket, 3.75 per cent of the crop, are the only ones affected 

 with the disease. Fig. 2. — Entire crop from an unsprayed Ben Davis tree 

 in the same orchard as the apples shown in figure 1. The apples in the pile, 

 94.36 per cent of the crop, are all affected with blotch. 



Plate VI. Fig. 1. — Entire crop of apples from a Limbertwig tree sprayed three 

 times, beginning at the right period. The apples in the basket, 5.1 per 

 cent of the crop, are the only ones affected with blotch. Fig. 2. — Entire 

 crop from a Limbertwig tree in the same orchard as the apples shown in 

 figure 1 sprayed three times, but the first application made too late. All 

 the apples in the right hand pile, 67.7 per cent of the crop, are affected with 

 blotch. 

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