QUINCE DISEASES 391 
Symptoms. 
Diseased fruits (Fig. 114) are very conspicuous in July and 
August. The injured portion is covered wholly or in part by 
masses of orange fringe-like growths, the whole presenting a 
yellow woolly appearance (Fig. 114). Some fruits are attacked 
Fig. 115.— 
Rust on quince- 
Fic. 114. — Quince-rust. twig. 
’ 
at the stem end, others at the calyx-end. Again the whole 
fruit is involved and it may fall. More often, however, it 
hangs to the tree, dies, and becomes black and hard. There 
is usually considerable distortion. 
Twig-infections (Fig. 115) are commonly found at the base 
of new shoots, and knots are produced which resemble black- 
knot of plums. 
Cause. 
The quince-rust fungus, Gymnosporangium clavipes, has a 
peculiar life-history. A part of its cycle is spent on the quince 
