90 
Journal o f Agricultural Research 
Vol. XXIX, No. 2 
able, and then begin or resume growth 
when conditions become favorable. 
That transit gives ample time for the 
development of lesions already present 
and the starting of new ones is indicated 
by the following data: At 7° C. lesions 
with a radius of 0.5 to 2 mm. developed 
in 7 days when wounds were inoculated. 
Scales inoculated with spore suspen¬ 
sions at 25° developed lesions which 
had an area of 2 to 5 sq. mm. on the 
ninth day and were covered with sporu- 
lating mycelium. Lesions increased in 
radius at 10° at the rate of 1.5 mm. 
every 24 hours; at 15 to 20°, at the 
rate of 4 to 5 mm.; at 27°, at the rate 
of only 2 mm.; and at 30° there was no 
increase. The maintenance of an aver¬ 
age temperature of 7° is very good for 
a refrigerator car. Thus temperature 
conditions in transit are not unfavor¬ 
able for the development and spread of 
the decay. 
RELATION TO TEMPERATURE IN THE 
FIELD AND IN TRANSIT 
The optimum temperature for growth 
of Botrytis lies between 22° and 25° C. 
The range from this to the maximum 
of 32° is only 7°, whereas the range to 
the minimum extends beyond — 2°, or 
more than 27°. Unlike many other 
fungi, this fungus can make a very 
appreciable growth and sporulate be¬ 
tween 5° and 10°. 
The temperatures of the leading 
artichoke-producing section in Cali¬ 
fornia are not unfavorable for the 
growth of the fungus. The nearest 
weather reporting station where weather 
is comparable to that of the Half Moon 
Bay section is San Francisco, Calif. 
Here the temperature rarely exceeds 
the maximum for Botrytis cinerea 
Pers.; the lowest temperature is above 
its minimum and the mean is below 
rather than above its optimum. 5 At 
the annual mean temperature of the 
region (54.9 °F.), the fungus can enlarge 
lesions on inoculated buds at the rate 
of about 4 to 5 mm. per day under 
favorable moisture conditions. 
Abstracts of food products inspection 
certificates show that the amount and 
severity of the decay of artichoke buds 
in transit vary with the temperature. 
Almost always the decay is heaviest in 
the two upper layers of car-lot ship¬ 
ments, and in these it is most severe at 
or near the doors. The following are 
typical reports: “Ten per cent decay 
in fourth and fifth layers; none in lower 
three”; or “Decay in two top layers, 
40 to 60 per cent; in lower two, 2 per 
cent,” or “Practically no decay in 
boxes near bunkers; 30 to 50 per cent 
in boxes at doors’ 7 and “Two top 
layers, all buds decayed; two bottom 
layers, slight decay.” The direct tem¬ 
perature relation is shown by the tem¬ 
perature report for the last above- 
mentioned car, in which the tempera¬ 
ture of the artichokes was 21° C. at the 
top of the load in the door, 11° at 
the bunker, and 4.5° at the bottom 
of the load at the bunkers. 
RELATION TO MOISTURE IN THE FIELD 
AND IN TRANSIT 
The experiments show that while 
moisture ranks second to wounds as a 
limiting factor for infection by Botrytis 
spores, it ranks first as a limiting 
factor for mycelial growth and infec¬ 
tion by mycelium. For sporulation, 
however, changes in humidity are more 
important than continuous humidity. 
Botrytis rot is generally reported as 
serious in sections having abundance of 
weather or in other sections 
during foggy seasons. Since few regions 
offer such consistently favorable condi¬ 
tions as the Pacific coast, this probably 
accounts for the prevalence of Botrytis 
rot in vegetable shipments from Cali¬ 
fornia. The artichoke sections of Cali¬ 
fornia lie within the coastal belt of 
California where fogs are a daily occur¬ 
rence, so characteristic that the coop¬ 
erative growers association markets its 
best brand of artichokes under the 
trade name “Fog-Kist.” During the 
growing season fogs drift in from the sea 
every afternoon and are not dissipated 
until late the next morning, so that 
vegetation is thoroughly wetted at 
least once daily. 6 
The artichoke buds are packed in 
paper-lined boxes which are generally 
loaded into iced cars. In the early part 
of the season buds are packed in iced 
drums. It was found that condensa¬ 
tion of water frequently takes place in 
the buds when the boxes are first 
placed in the iced cars and that often 
the buds are moist when they are 
unloaded in receiving markets. There¬ 
fore moisture conditions in transit are 
also favorable for mycelium develop¬ 
ment, sporulation, infection, and devel¬ 
opment of lesions. 
5 U. S. Dept, of Agriculture, Weather Bureau, summary of the climatological data for the united 
STATES, BY SECTIONS. REPRINT OF SECTION 14, CENTRAL AND SOUTHERN CALIFORNIA. 25 p., ILLUS. 1912. 
6 Palmer, A. H. fog along the California coast. Mo. Weather Rev. 45: 496-499, illus. 1917. 
