Jan. 27,1923 
Production of Conidia in Philippine Sclerosporas 267 
frequently intermittent and alternated with gusts of wind which blew the 
water from the leaves and dried the developing conidiophores sufficiently 
to kill them. None the less conidium production could and did take place 
during these tropical storms despite their unfavorable violence. In all 
but the most destructive typhoons at least a few plants in each plot were 
sufficiently sheltered from mechanical injury so that their leaf sheaths, 
the under sides of midribs at the base of the leaves, or other protected 
parts, permitted the production of considerable numbers of conidia. 
In some cases conidium formation actually took place on the inner sur¬ 
face of leaf sheaths (PI. 4, E), husks, or bracts which were so situated 
that they shed direct beating rain. Moreover, the storms frequently 
began with a cold rain which fell steadily for from one to about three 
days, and the wind, when it arrived, came first in intermittent gusts 
before increasing to its full strength. Under these conditions conidia 
were produced in abundance on large numbers of plants and for several 
hours were given ample opportunity to be distributed by the wind before 
its violence was sufficient to injure the developing conidiophores. 
As a concrete example of conidium production under unfavorable 
storm conditions observations made in the typhoon of December 25 and 
26, 1918, are of interest. This storm was an unseasonable one, occurring 
at the beginning of the dry season, and preceded as well as followed by 
calm, dry weather. It was also a violent one. During December 25 and 
26 the rainfall was 59 mm. and the wind, by anemometer, blew 262.8 
miles, while during the rest of the month the rainfall averaged 1.17 mm. 
and the wind 62.2 miles, a day. Cloudy, sultry, threatening weather 
immediately preceded the storm which began in • the afternoon of 
December 25 with occasional gusts of wind and squalls of rain. The 
temperature, which during the hottest part of the day, had reached 82° 
F., decreased rapidly, dropping after sunset to 70°. The plants under 
observation were well covered with moisture despite the increasing 
violence of the storm. By 11 o’clock that night the rain fell heavily and 
almost continually, while the wind was violent but intermittent. From 
1 to 2.30 a.m., December 26, the storm raged at its height with rain and 
wind of such terrific force that examination of the plants was imprac¬ 
ticable. After this, however, a gradual decrease was apparent, and b; 
4 a.m. the rain and wind had lessened, although violent squalls occurred 
from time to time. The maize plots were then examined. Many plants* 
both healthy and diseased, had been blown flat and beaten into the wet 
earth. However, several heavily infected plants which had been under 
observation showed conidiophore production in abundance on the better 
protected parts of their leaves and sheaths. Microscopic examination 
showed many conidiophores which had already discharged their conidia, 
hence production had probably been going on for about two hours and 
even during the worst of the storm. Formation of conidia continued 
until about 6 a.m. when it was checked as the plants began to dry. 
During this time the wind continued to blow in gusts favorable for spore 
dispersal. By afternoon the storm had disappeared. 
It was, of course, impracticable to determine the precise amount or 
extent of dispersal of conidia during storms by any such direct means as 
Petri dishes. Observations in the field, however, showed repeatedly that 
in regions where the disease had been spreading slowly on the slight 
nightly air currents, a sudden scattering of the disease appeared, after 
the normal incubation period following the storm, for several miles along 
the track of the typhoon. 
