May 15, 191S Seedling Diseases of Sugar Beets 1 63 



The vegetative stage of the fungus is strikingly like that of P. dehary- 

 anum, so that they can not be distinguished readily except by the fruit- 

 ing bodies, which develop readily in water cultures in plates in from 24 

 to 48 hours. The zoospores develop first, to be followed somewhat 

 later by the Pythium-like oospores. The asexual fruiting bodies are 

 first noted as the swollen ends of hyphae, which vary greatly in length and 

 are characteristically somewhat branched. They average from 150 to 

 900j« in length or even more. When mature, these bodies discharge 

 their contents in a spherical mass which cleaves in the course of 20 or 

 30 minutes, giving rise to numerous zoospores. 



OTHER FUNGI FOUND ON SUGAR BEETS 



In the course of the isolation work various other fungi were secured. 

 Some of these were known saprophytes, while others, like IMacrosporium, 

 Mucor, and Bqtrytis, have sometimes been reported in parasitic rela- 

 tions, but gave negative results in our trials. Fusarium and Verticillium 

 cultures were secured frequently, but inoculation experiments with these 

 genera were deferred pending the completion of taxonomic work by 

 other investigators. 



There remains to be discussed a peculiar type of decay of growing 

 beets and a root sickness of seedlings associated with Rhizopus nigricans 

 Ehr. Cultures of this fungus were frequently isolated in the course of 

 experimental work from seedlings. Specimens of mature beets affected 

 by a pecuhar light-brown decay were received in the laboratory from 

 California during the campaign of 1910. The interior portion of these 

 beets yielded a very large proportion of cultures of Rhizopus. The 

 decay was very characteristic and unlike anything before seen. In the 

 early stages the material was almost normal in appearance, except for 

 the discoloration. It later assumed a somewhat flabby texture and 

 developed pockets in the interior which were filled with a nearly colorless 

 fluid rich in acetic acid, as was determined by the odor and by chemical 

 tests. 



In 1 91 2 a somewhat similar trouble was reported from Colorado, and 

 a visit was made to the field (PI. XXV, fig. i ) . The beets at that time w^re 

 dead over considerable areas. Those most recently attacked showed the 

 same light-brown color previously referred to (PI. XXV, fig. 2), while those 

 in the more advanced stages of decay presented various symptoms be- 

 tween the early condition and almost complete dissolution of all except 

 the vascular tissue. Some, however, were apparently pickled in acetic 

 acid, formed probably from the fermentation of the carbohydrate con- 

 tent. A very large number of attempts to isolate an organism of known 

 pathogenic properties was made. The trials yielded Rhizopus nigricans 

 in pure cultures to the extent of almost 100 per cent. Inoculation work 

 in the laboratory upon donnant beets in moist chambers resulted in the 



