Fig. 54. Onion Diseases. 



a. Downy mildew, b, mature conidiophore and conidia of Peronospora schleideni, 



c. fertilization of the female oogonium by the male antheridium, d. oospore (a. to 



d. after Whstzel), e. onion smut, /. spore ball of the smut fungus, g. spore germina- 

 tion, formation of sporidia at x, h. Vermicularia anthracnose, i. section through 

 acervulis of Vermicularia circinans, j. seta? and spore formation in V. circinans (e. 

 to g., i. and i. after Thaxter),_. pink root of onion, healthy and diseased bulbs, /. 

 pink root of onion showing nipple formation, m. a formaldehyde drip attachment 

 to a planet junior seed sower, n. a copper tank drip with flexible black tin tube and 

 valve (m. and n. after Stone). 



