BROWN ROT OF STONE-FRUITS 
This disease is especially destructive on plums, peaches and sweet 
cherries. Apples, pears and quinces in America are sometimes affected. 
In the case of certain varieties of apples, affected fruits become jet 
black instead of brown. (See illustration specimen.) The brown color 
of the affected tissues of plums and peaches has given to the disease 
the name of brown rot. 
SYMPTOMS 
The disease is usually confined to the fruit, although it may appear 
also on other parts of the host,—blossoms, leaves, twigs and limbs. 
On the blossoms. The blossom-blight form of the disease is the 
first symptom to appear if the spring weather is at all favorable. Examine 
the specimens provided and OBSERVE :-— 
1. Effect of the disease on the blossoms; similar to the effect 
of the fire-blight on apple blossoms. 
2. The grayish brown spore-tufts of the fungus on the petioles 
and young fruits. : 
DRAW to show blossom-blight symptoms. 
On the fruit. Diseased fruits of plum, peach, cherry or apple have 
been provided. (Do not remove preserved specimens from bottles.) 
OBSERVE :— 
3. The brown discoloration of the diseased area. The margin 
of the spot, distinct or indefinite? 
4. That at first the diseased tissues do not collapse, the diseased 
portions retaining their original plump character. Compare this with a 
fruit in an advanced stage of decay. To what is the difference due? 
DRAW to show fruits in early and advanced stages of the rot. 
With the finger Test :— 
: 5. The relative firmness of the diseased and healthy portions 
of the fruit; strength and character of the epidermis. 
Cut into the fruit and NotE:— 
6. The effect of the disease on the tissues as to discoloration, 
firmness, taste and odor. 
The fruit is often attacked and killed before it matures and for this 
reason clings to the tree, instead of falling as is the case with ripe or pre- 
maturely ripened fruit. Such diseased fruits dry and wrinkle forming the 
so-called mummies of brown rot. In the dry material provided oBSERVE :— 
7. The dry and shriveled condition of the fruit. 
8. Often a cluster of the mummies clinging together, bound to 
each other by threads of mycelium where they touch. 
_ 9. The tufts of the fungus crowded or scattered over the surface; 
color? 
SKETCH a mummied plum. 
_ On the twigs. In some seasons the twig-blight form of this disease 
1s severe, especially on plums and peaches. Examine the specimens 
provided and oBsERVE:— 
: 10. The dead and shriveled brown leaves of the upper part of the 
twig, in appearance not unlike the effect of fire blight on apple or pear 
twigs. 
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