4o8 DISEASES OF CULTIVATED PLANTS 



The perithecia are globose-depressed, the opening or 

 mouth alone bursting through the epidermis. Conidia very 

 minute, cylindrical, 3-4 X 1*5-2 /*. 



The only means of checking an epidemic is to promptly 

 remove and burn diseased plants. 



Prillieux, Malad. des Plantes Agric., 2, p. 295 (1897). 



Carrot disease (Phoma sanguinolenta, Rostrup) forms 

 greyish-brown, canker-like wounds that eat deeply into the 

 root of the carrot. The mycelium persists in the root, and 

 during the following season passes up into the flowering 

 stem, which here and there shows depressed areas covered 

 with the fruit of the fungus. 



Perithecia gregarious on depressed areas of the flowering 

 stem or on canker-like wounds on the root ; conidia 4-6 x 

 1*5-3 //,, escaping through the mouth of the perithecium in the 

 form of a red, viscid tendril. 



Diseased roots should not be planted for seed, as the 

 flower stem becomes diseased, and no seed is produced. 

 Neither should diseased carrots be mixed with sound ones 

 when storing, as the disease spreads by contact. 



Rostrup, Zeitschr. Pflanzenkr., 1894, p. 195. 



Squirt berry (Phoma tuberculata> M'Alp.) is the cause of 

 a grape disease in Australia. The fruit is the part attacked, 

 and when diseased grapes are gently pressed between the 

 fingers, the contents are readily squirted out, hence the popular 

 name of the disease. Diseased grapes first show a circular 

 ashy-grey or slaty-blue patch dotted with numerous minute 

 pustules. Eventually the berries become partially dry, but 

 remain pliant. 



Stroma of fungus more or less columnar, bearing the peri- 

 thecia on its surface. Conidia oblong or ovate, minute. 



M'Alpine, Add. to Fungi of Vine in Australia, p. 23. 



Phoma hennebergii (Kiihn) often proves destructive to the 

 wheat crop, attacking the glumes and causing the ear to 

 shrivel. The fungus also sometimes attacks the leaves. 



Perithecia scattered on brown spots, erumpent, rounded, 

 black, about 100 p in diam., conidia cylindrical, sometimes 

 slightly curved, 14-18 x 2-2*5 / z - 



