3 6 



FUNGOUS DISEASES OF PLANTS 



nutrient media, 

 germ tubes being 

 pushed out from 

 either end or from 

 the middle (Fig. 

 179). This fungus 

 has been readily 

 cultivated upon 

 bean stems and 

 pear twigs, and I 

 have reported the 

 growth as follows : 



Here the fungus 

 grew slowly at first, 

 producing after sev- 

 eral weeks the pyc- 



FIG. 178. SHPTORIA PYRICOLA : SECTION OF PYCNIDIUM nidia of the Se P toria - 



After several trans- 

 fers this fungus grows quite luxuriantly on bean pods or stems, as seen in fig- 

 ure . . . , producing the pycnidia in a short time, and the pycnidia are then not 

 so definite in form but formed of a 

 very loose stromatic mass. The sub- 

 merged hyphae are dark in color, while 

 the aerial growth is dense and white, 

 except the stromatic mass inclosing 

 the pycnidium. I have had cultures 

 for eighteen months; and although 

 they have been subjected to various 

 climatic conditions, nothing of further 

 interest has as yet come from them. 

 In nature the fungus is being closely 

 watched for other stages, but I can 

 say nothing definite upon this point 

 at present, although other fungi have 

 been found on the old leaves. FIG. 179. SEPTORIA PYRICOLA: GER- 



MINATING SPORES 

 Control. This fungus has 



been readily controlled hi the orchard by the use of standard Bor- 

 deaux mixture applied as for pear scab. Where vigorous nursery 

 stock would be produced, it is necessary to spray every season ; 

 but a single application, after the first flush of growth, is often 

 sufficient. 



