32 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. 
TABLE 6.—Approzximate areas of kelp fields in which harvesting was carried 
on in the various months of 1916, 1917, 1918; with the average quantities of 
kelp cut per square nautical mile. 
{Tons of wet kelp.] 
1916 | 1917 1918 
t 
| j t j 
Month. | Square | Tons per! Square | Tons per; Square | Tons per ; 
nautical square. nautical | square | nautical | square ; 
| Miles. | mile. | miles. | mile. | miles. mile, 
Bae ge CT Cara A Te Taf ee Ree Ce oe aie 
Jhrehty. Leos o tie babe 1.26; 1,130; 9.09 4,124 | 11. 82 3,649 | 
CETTE ee ES SRS Ray Sain 8 1.26 2,603 |" 9.28 3,603 | 12 2,221 
Miroir: tek as ke Dalle Le Es 1.26 | 2,603 | 8.53 3,514 | 11.83 2,543 
Dwi. it te ace ens bs cag hdcct Minutes 1.26 | 2,603 | 12.90 1,810 9.96 | 4,319 
cis Rae Na Maia lal het ARG, by ele a 1.26 2,603 | 12.10 3,447 15.36; 2852 
ATL GE ie 2 ae ea ee es ee eae i Seem 1. 26 2,603 | 16.17 2,575 | 29.34 | 1,194 
TE [3 OBA iia OPS aE SP PPR RRA ei 1. 26 2,602 | 21.38 1,165 28.25 | 1,489 
AMIBTIStres {ketene Ee, Sen eae 7.3€ | 5,125 | 395.06 730 36.55 | 1,382 
DRDSOIND OBees 2s ose ous oh to cave tec ssbctmessoe 3. 26 | 5, 823 | 24.94 1,313 47.04 | 753 
111251) Sah tia a a pela a aR! AB | 3.03 | 3,617} 25.02 1,420} 37.29 | 906 
PND DO eas ote aoe ek een kek sii 7.36 | 2,409 32.93 1, O78 i) scte mre | be ache dats Pr 
PREG oe Cr ee ue eae | 5.06 5,608 18.42 1,693). saceee | en eae 
: | | 
MOOR hed Se occ cidaee $5 -byaie soem | 2.9 3,277 18.9 2, 206 | 1 23.94 | 12,230 
1 Computed on the basis of 10 months’ records. 
BLACK ROT. 
Black rot was observable in some places as early as April. It 
gradually increased where the kelp was not cut, until by August it 
was in complete possession in most of such beds. In uncut beds, 
the summer growth was scant and light in weight. Beds which had 
been cut closely and systematically as late as May or June, were 
free from disease, and had the normal number of young fronds. 
These fronds, however, did not mature properly. Their stipes re- 
mained slender and their leaves pale, small, very thin, and of the 
texture of paper. The plump, thin-walled cysts characteristic of 
kelp growing in quiet water appeared in places. The weakening 
effect of unfavorable growing conditions was noticeable in the tips. 
They dwindled down, failed, usually, to develop the last leaf-blades, 
and, in some cases, ceased to grow while they were still throwing off 
laterals. The chemical composition was also affected. Kelp manu- 
facturers in general complained that the material was watery and 
yielded only half the normal amount of potash, and the Hercules 
Powder Co., stated that it did not properly ferment. 
The United States reserve bed at Summerland may be taken as an 
example of extreme deterioration, since it was barely visible from 
shore. It had never been cut over clean, and, as a result, had become, 
in early summer, a veritable breeding bed for black rot. Many old 
spring fronds could be seen floating lhghtly, their leaves entirely 
gone and nothing but stipes and some cysts left. These were of | i 
good length, ranging from 30 to 40 feet. Rising beside the dis- 
mantled stipes were the midsummer fronds, some of which had 
reached the surface and floated out for a few feet, but many were 
from 1 to 4 feet under water. Their lower leaves were of normal 
size, but the tips were noticeably shortened. That these fronds had 
stopped growing was indicated by the fact that the color of the 
tips was the same as that of the older leaves, whereas rapidly grow- 
ing tips are light olive green. Probably the warmer surface water 
