134 FUNGOID PESTS OF CULTIVATED PLANTS. 



PEACH FRECKLE. 

 Cladosporium carpophilum (Thiim.). 



This disease is known in the United States as "scab" or "black 

 spot," and was first observed in Austria in 1877, but has not been recog- 

 nised anywhere else in Europe, although known in the United States and 

 Canada and New South Wales, and is said to spread rapidly when once 

 introduced. 



The fungus is a kind of black mould which attacks ripe Peaches, 

 forming minute round spots or freckles, which are greenish, then brownish 

 or olive. Finally the spots run together and form a brown crust, causing 

 the fruit to crack, shrivel, and decay. It has also been observed on the 

 foliage. The spots are orbicular, and the threads short and slightly 

 branched or simple, with pale ovate conidia, which are rarely septate 

 (20x5 /x). 



So nearly allied to the " Apple scab " that similar treatment is 

 recommended. 



Sacc. Syll. iv. No. 1675 ; Mass. PL Dis. 310 ; Me Alpine Fung. Dis. 

 49, pi. vii. 



PEACH- SPOT MOULD. 



Helminthosporium rhabdiferum (Berk.), PI. XI. fig. 24. 



This disease first attacked the Barrington Peach in 1864, but has 

 never spread much since that time or proved of any great importance. 



Shallow pits, about half an inch in diameter, appear on the surface 

 of the fruit the centre of which is occupied by a dark mould bearing a 

 profusion of spores, so as to blacken the fingers when touched. The 

 mycelium penetrates deeply into the fruit, which if not gathered in good 

 time becomes useless. The mycelium consists of more or less waved 

 articulated threads which give off here and there stouter erect threads, 

 with shorter joints, branched slightly above and producing at the tip of 

 each joint a large spore. The spores, or conidia, are at first oblong and 

 pale, showing one or two transverse septa. These rapidly acquire a dark 

 tint, elongate, become more or less linear, and consist of from seven to 

 eleven swollen divisions, of which the terminal one is mostly apiculate. 

 Each division contains a few minute oil granules (50-80 /x long). After 

 the spores have fallen they frequently split in the centre and give out a 

 globular body, which is in all probability reproductive. 



We strongly suspect that this fungus is not a trufe parasite, but made 

 its appearance subsequently, and was not the cause of disease. 



Gard. Chron. 1864, p. 938, fig. ; Cooke Hdbk. No. 1726. 



The "frosty mildew" caused by Cercosporella Persica has been 

 known in America since 1890 on Peach leaves. 



PEACH YELLOWS. 



This is one of the most mysterious of plant diseases, and although it 

 has been known .to cccur in the United States for at least a century it 

 has not found its way into Europe. In recent years " thousands of young 

 and thrifty trees have been destroyed by it, and Peach growing has been 



