- 26 
superficial. Small projections occur on the filaments, but no proof has |} 
been found that these penetrate the tissue of the leaf. Apparently}} 
they are merely organs of attachment. Large disks (hyphopodia) are} 
also frequently developed, which evidently serve as organs for attach- | 
ing the mold to the leaf. Reproductive bodies of several forms are} 
developed in great abundance, and these are easily carried from tree}} 
to tree or from grove to grove through the agency of the wind, insects, } 
birds, or animals. | 
This disease injures the plant by interrupting the process of assimi- 
lation. This is brought about by the cutting off of light and by hin- 
dering the passage of necessary gases in and out of the plant. The 
accompanying insects further injure the plant by sucking the nutritious} 
juices from the cells of the leaf. The growth of the tree is usually§ 
greatly retarded, and in serious cases is frequently entirely checked until 
some relief is found. The blooming and fruiting are commonly light, | 
and in very bad cases are wholly suppressed. In slight droughts the} 
leaves wither quickly and curl up, resembling those on blighted trees. )| 
The young fruit becomes covered with the sooty mold and is retarded 
in its development, frequently never reaching complete maturity. It 
is usually smaller and less juicy than that normally developed, and’ 
remains very insipid. It does not change to the normal bright orange 
color of mature fruit till very late, and if the membrane of the sooty 7 
mold covering it is quite thick the rind remains somewhat green, appar- 
ently for an indefinite period, rendering the fruit unsalable. The black 
coating formed by the sooty mold renders the fruit unsightly and unsal- 
able until it is thoroughly washed, which necessitates a considerable 7 
expenditure of timeand labor. Even when carefully washed, a process 
which injures the keeping quality of the fruit, much of it being still] 
small and green is unfit for market. 
Treatment.—Where sooty mold followed the attacks of the orange 
mealy wing, spraying with resin wash or fumigation with hydrocyanic 
acid gas was found to be very effective. When resin wash! is used 
the best time for treatment is in winter, between December and the = 
first of March. During this period the mealy wing can not fly away 
1The following is the formula for resin wash: Resin, 20 pounds; caustic soda (98 . 
per cent), 41 pounds; fish oil (crude), 3 pints; water to make 15 gallons. Place the © 
resin, caustic soda, and fish oil in a large kettle. Pour over them 13 gallons of 7 
water and boil till the resin is thoroughly dissolved, which requires from three to 
ten minutes after the materials begin to boil. While hot add enough water to make ~ 
just 15 gallons. This may be most readily accomplished by taking a tight keg or 
other tall receptacle and measuring into it 15 gallons.of water. Then plainly and — 
permanently mark the height to which the 15 gallons reach. After boiling the 
hot solution may be poured directly into this measuring keg and sufficient water 
added to bring it up to the 15-gallon mark. This serves as a stock preparation. 
When this stock preparation cools, a fine, yellowish precipitate forms and settles — 
to the bottom of the vessel. The preparation must therefore be thoroughly stirred 
each time before measuring out to dilute, so as to uniformly mix this precipitate 
with the clear, dark, amber-brown liquid, which forms by far the larger part of the 
