168 



THE FUNGI WHICH CAUSE PLANT DISEASE 



three to six on the ends of hyaline branches, Fig. 119. These 

 conidia fall apart as they age. 



The hyaline conidia preponderate in early disease, giving the 

 surface of the root a mildewed appearance; the dark conidia pre- 

 ponderate later, covering the 

 root with a black coating. 

 Finally, after the host is dead, 

 the ascocarps appear. 



The delicate hyaline myce- 

 lium wanders through the 

 affected root disorganizing its 

 tissue. The superficial myce- 

 lium is Ughtly tinted. 



Perithecia 80-100 n; asci 

 ovate, 8-spored; spores len- 

 ticular, vacuolate, 1-celled, 

 chocolate-colored, 8-12 x 

 4-5 n; chlamydospores in 

 chains, at maturity separa- 

 ting, . short-cylindric, about 

 5-8 X 12 j«; the entire group 

 25-65 ft long; conidia hyaline 

 about 10-20 X 4-5 n. 



In Europe and Eastern 

 North America on Aralia quinquefolia. Begonia rubra, Begonia 

 sp., Catalpa speciosa, Cyclamen sp., Gossypium herbaceum, 

 Linaria canadensis, Lupinus angustifolius, L. albus, L. luteus, 

 L. thermis. Nasturtium armoracea, Nemophila auriculata, Nico- 

 tiana tabacum, N. rustica, Onobrychis cristagalli, Oxalis stricta, 

 Phaseolus VTilgaris, P. multiflorus, Pisum sativum, Senecio elegans, 

 Trifolium repens, Trigonella ccerulea, Vigna sinensis and Viola 

 odorata. 



Rostrella coffeae Zimm. is described as the cause of canker of 

 coffee in Java.'^^ 



Aspergillus Micheli (p. 167) 



The ascocarps are small, spherical, indehiscent, smooth bodies 

 which at maturity are entirely filled with 8-spored asci; spores 



Fig. 119. — Thielavia basicola, showing two 

 conidial forms and ascus and ascospores. 

 After Van Hook and Zopf . 



