SCLEROTINIA 



269 



the death of the clover. The presence of small black 

 sclerotia partially embedded in the substance of the stem 

 and root indicates that the injury is due to the Sclerotinia. 



As a rule, only one ascophore springs from a sclerotium, at 

 first closed then expanding, yellowish-brown 3 mm. to 1 cm. 

 across, stem elongated, slender ; spores 8 in an ascus, hyaline, 

 elliptical, 16-18x8-9 ji. Conidial condition unknown. 



fa 



Fig. 79. Sclerotinia urnula. 1, chain of conidia in young 

 stage; 2, chain of conidia at maturity; the narrow necks 

 or disjunctors deliquesce, and set the conidia at liberty ; 

 3, ascophores springing from mummified fruits ; 4, ascus 

 with spores ; 5, paraphyses. All figs except 3 mag. 



This is a very difficult disease to combat ; if diseased 

 patches are observed while yet quite small in area, the clover 

 should be cut, and after remaining for some time to dry, some 

 dry litter should be spread over the diseased patch, and set 

 on fire. By this means all the sclerotia are destroyed. Clover 

 should not be sown on infected land for some years after an 

 epidemic. A dressing of kainit is good for infected land. 



Cowberry sclerotinia, Sc/erotifiia urnula, Rehm. ( = S. vac- 

 cina, Woron.), produces its conidial form of fruit, under 

 the form of a snow-white, thin mildew on the living stems 

 and leaves of the cowberry ( Vaccinium vitis-idaea). This 

 mildew belongs to the form-genus Oidtum, and was at one 



