THE PEARS OF NEW YORK 115 



lime and sulphur at the summer strength, if applied annually, are usually 

 sufficient to control the fungus. The first of these applications should be 

 made when the blossoms show color, a few days before they open. The 

 second should be put on when most of the petals have fallen. In seasons 

 favorable to the scab, a third application two weeks after the second may 

 be the means of saving the crop. The spread of the disease is greatly 

 favored by damp warm weather. 



Pear-growers are plagued by two leaf-spots, one of which is also known 

 as leaf-blight. The leaf-spot here to be discussed (Mycosphcerella sentina 

 (Fr.) Schroet.) is sometimes called the ashy leaf-spot. The disease is not 

 often seriously troublesome in New York, but is capable of doing great 

 damage in both the nursery and orchard. The spots which give name to 

 the disease are conspicuous enough, but even when present in great numbers 

 are often not seen by the pear-grower until there is a premature dropping 

 of the leaves in August or earlier. The trees often put out new growths, 

 with the result that the wood does not ripen and the tree is left in no con- 

 dition to stand the cold of winter in this northern climate. 



As with nearly all diseases of plants, some varieties suffer more than 

 others. Sheldon, Seckel, and Flemish Beauty are more injured than 

 Kieffer, Lawrence, and Mount Vernon. Nursery stock is more often 

 injured the second than the first year set. Only the leaves suffer. The 

 fungus first shows its work in minute purplish spots on the upper surface 

 of the leaf. The mature spots measure about one-sixth of an inch in diam- 

 eter, are angular in shape, with well-defined margins, and have an outer 

 zone of brownish-purple, with a grayish center. Late in the season, dots, 

 the spore-cases of the fungus, appear in the gray central area. The fungus 

 passes the winter in diseased leaves which fall to the ground in late summer. 

 From these leaves spores are discharged into the air to be carried to the 

 leaves after growth begins in the spring. The disease is usually controlled 

 by the sprays necessary every year to keep pear-scab in submission. In 

 the nursery, two-year-old trees are sprayed just after the new leaves open 

 and twice thereafter at two-week intervals. One-year-olds seldom need 

 to be sprayed. 



Leaf-blight (Fabrcza maadata (Lev.) Atk.) is a common and destruc- 

 tive fungus in pear-nurseries in New York and is sometimes troublesome 

 in orchards. The quince suffers even more than the pear from this fungus. 

 In the nursery, leaves and twigs are attacked, and in the orchard the pears 

 themselves sometimes suffer. The disease appears in the spring as minute, 



