214 ECTANICAL GAZETTE [OCTOBER 
Summary 
1. A cracking of green and ripe fruit of Bonny Best, Baltimore, 
and Stone tomatoes in Burlington and other counties of New Jersey, 
due to one or more physiological causes, was observed to be severe 
in 1921. 
2. Oidium or Oosbora lactis was isolated from infected tomatoes. 
Inoculations of ripe fruit with this fungus were positive. 
3. Oidium or Oospora lactis is a widely distributed fungus. It is 
known to appear in milk products, cheeses, decaying vegetables, 
and fruits. On tomato fruit the fungus mycelium is dense, grayish 
white, and prominent, while in other cases spores are very promi- 
nently produced. 
4. The treatments with wet Bordeaux sprays and dusts gave 
slight control of the disease. 
Appreciation is expressed for the helpful suggestions offered by 
Dr. Met. T. Cook, and for the identification of the organism by 
Miss ANNA E. JENKuNS, Office Pathological Collections, Washing- 
ton, D.C. 
AGRICULTURAL EXPERIMENT STATION 
New Brunswick, N.J. 
EXPLANATION OF PLATE VII 
1G. 1.—Cracked ripe and green Bonny Best tomatoes, showing various 
forms of cracking. 
G. 2.—Ripe tomatoes inoculated with Oidium lactis (after 48 hours’ 
growth in partially dry chamber, 18°-20° C.): a, in fresh slices; b, punctures; 
¢, no inoculation but punctured. 
Fic. 3 «Diseased ripe tomatoes spread open in moist chamber for 24 
hours at 20° C.; white fungus prominent on open material. 
FIc. 4. =Siiced ripe and green tomatoes inoculated with Oidium lactis 
(from 4 to 6 days’ growth 18°-20° C. in partially dry chambers): a, on sliced 
ripe fruit; 6, on green to half ripe fruit; ¢, no inoculation on sliced ripe tomato. 
Fic. 5.—Oidium or Oospora lactis: a and d, mycelial branches and spores; 
b, spores of various sizes in chains; c, spores; e, spores in budding-like forma- 
tion. 
