322 BOTANICAL GAZETTE [NOVEMBER 
branched, branches almost even in length, about 35 4; conidia 
olivaceous to brown, echinulation none in culture four months old, 
tapering very slightly to apical cell, tapering frequently absent, 
apical cell frequently hyaline, conidia catenulate, as many as eight 
in one chain, catenulation both on host and on culture media, longi- 
tudinal septation very rare, considerable constriction of the walls 
at septation, size of the conidia taken from artificially inoculated 
cabbage leaf 29.7—61.2 uw by 8.7—-12.3 uw, average size 43.7 by 10.5 u. 
Conidia developed on standard lima bean agar measured on the 
seventh day as follows: 1-septate, 13.4-16 uw by 6.5—7.5 u; 2-septate, 
17.5-18.7 u by 8.7 u; 3-septate, 20-26.5 u by 8-12 4; 4-septate, 
34-36 mw by 12.5-14 mw; 5-septate, 30-38 w by 9.5-14 uw; 9-septate, 
64.7-70 wu by 10-14 py (fig. 2). 
Inoculation experiments with pure cultures were made on grow- 
ing cabbage and cauliflower plants in the field and in pots under 
control in glass cages, at the field station of the Office of Cotton, 
Truck, and Forage Crop Disease Investigations, located at Alham- 
bra, California. The varieties of cabbage used in these experiments 
were Winningstadt, Late Drumhead, Early Jersey Wakefield, and 
Fat Dutch, and the varieties of cauliflower were two selections 
commonly grown in the San Francisco district. In Alhambra the 
relative humidity of the atmosphere is considerably lower than in 
the San Francisco district, where the disease is prevalent. On 
account of this variation, open field inoculation did not progress 
above a small speck. When the inoculated leaf was covered with 
a wax paper sack in which there had been suspended a water-soaked 
mass of gauze, lesions of normal size were produced readily. Suc- 
cessful infections were produced by spraying conidia, suspended in 
water, on uninjured leaves, and by wounding and inserting conidia. 
Infections were obtained more rapidly in glass cages where high 
relative humidity could be maintained. Within seven days lesions 
ranging in diameter from 1 cm. to 1.5 cm. were produced. Similar 
inoculation experiments were made with Allernaria brassicae 
obtained from old cauliflower and cabbage leaves, and with Alter- 
naria sp. from spots on tomato fruit. The former produced spots 
with definite zonations, while the latter failed to grow on cabbage 
and cauliflower. 
