December i, 1887.] THE TROPICAL AGRICULTURIST. 
37, 
sence of direct sunshine- and cold winds. If favourable 
weather the progress of the disease is very rapid. 
3. The fundus lives in the tissues of the leaf, chok- 
ing up the air passages and absorbing the nutritive 
fluid formed in the colls. Its stem protrudes through 
the stomata of the leaf into the air. Its branches 
bear spores at their tips. 
4. The reproduction of the fungus is effected by 
means of those spores which float about through the 
air, and also by means of certain special cells formed 
by the fungus and known as resting-sport's. These 
pass the winter in the earth, and are capable of 
retaining the power of germination for two or three 
years. It is by their means that the disease is carried 
on from one season to another. 
5. One method of combating the disease is to make 
the onion plants as strong as possible, so as to with- 
stand the attacks of the parasite. Hence the site 
should bo carefully selected, the soil well prepared, 
good manures used, and the land kept clean and free 
from weeds. 
6. To provent the spreading of the disease all alfeot- 
ed plants must be collected and burned. Whilst 
doiug this care must bo taken that the collector does 
not himself spread the disuaso by carrying the refuse 
loosely. Rotation of crops, or, when this is impossible, 
deep trenching, would lessen the chauce of the disease 
appearing' 
7. Disoased plants may be treated with a mixture 
of powdered sulphur and freshly burnt quicklime 
sprinkled by hand or by bellows ; or they may be 
washed or sprayed with a weak solution of iron sulphate 
(green vitriol). In both oases the fungus is destroyed 
without injury to the onion plant. Further both these 
chemical remedies have the additional advantage of 
boing excellent manures. 
8. Another fungus, MacrQSporitcW pun/siiirum some- 
times attacks the onions after the Perouospora has 
taken a good hold of tho plant and weakened 
it. As this only occurs as a sequel to the Peronospora, 
the extermination of the latter would involve the 
disappearance of the former. The MacPolporium does 
not attack the healthy plant. 
9. Only two kinds of insects, the onion thrips and 
the onion fly were met with, and th') latter on only 
ono occasion. The thrips were not numerous and 
appeared to do little harm. They can easily be removed 
by application of a solution of iron sulphate, such a-s 
is recommended in .Suction IV. iii. 
Should tho onion Uy ever prove a serious pest, it 
may be dealt with by covering the bulb of the oniou 
with a thin layer of earth. This prevents the fly 
approaching tho bulb to lay its eggs. 
♦ 
INSECT POISONS. 
The Bureau of Entomology, Department of Agri- 
culture, Washington, sends out of the following for 
use as insecticides on or about plants, etc.: — 
London Pur/i 1 '. — To 20 pounds flour I ron) one-quarter 
to one-half pound is added and well mix-d. This is 
applied with a sifter or blower. With 40 gallons of 
water ono-quurtor to one-half pound is mixed fir 
spniving. 
Paris Grci a. — With 20 pounds of Hour from three- 
quarters to one pound is mixed and applied by sifting 
or by a blower. The some amount of tli.i insecticide 
to •!<) gallons of water is used as a spray. 
Bindphitr of Carbon. — For uso in tho ground a 
quantity is poured or injected among tho roots that 
are being infected. Against insects damaging stored 
gram of museum material a smoll quantity is used 
in nn air tight vessel. 
Carholi,- icidi — A solution of one part in 100 of 
wator is used against parasites and domestic animals 
nnd their barns and sheds; also on surface of plants 
nnd among tho roots in the ground 
II rhnrf, — The powder is silted on alone or mixed 
one pirt to twenty of flour. With uu» g.iMnn of w.,trr 
DM quarter pound it mixed for spraying. 
AV; e.e .l/iU V.mnltion. — To one part milk mid two 
part I kerosouu, and churn by furoo-putup or other 
agitator. The butter-like emulsion is diluted ad libitum 
with water. An easier method is to simply mix one 
part kerosene with eight of milk. 
Soap Emulsion. — In one gallon hot water one-hal 1 ' 
pound whale-oil soap is dissolved. This, instead o! 
milk, is mixed to an emulsion with kercseue in the 
same manner and proportion as above. 
Pfyretkr&m.'— -(Persian insect powder). — Is blown or 
sifted on dry; also applied in water, one gallon to a 
tablespoonful of the powder, well btirred -iud then 
sprayed. 
Tobacco Decoction. — This is made as strong as pos- 
sible as a wash or spray, to kill insect pests on 
animals and plants. — Southern Planter. 
+ 
THE NOMENCLATURE OF FRUITS. 
A writer iu Hyature has discovered that the names 
of tropical fruits are frequently misappliod, and tells 
us so : — 
Owing to the loose manner in which tropical fruit3 
are termed, apples, plums, pears, peaches, kc, when 
they are neither botanicallj nor intrinsically anything 
of the sort, there has arisen considerable confusion 
respecting them. Again many tropical fruits are suit- 
able only for salads or curries, and should not appear 
at the dessert table at all. Others arc better when 
preserved or cooked, and they are then both whole- 
some and well adapted to the wants of the country. 
There is no ^ood pear (Pyrus communis, L.!, as known 
in England; growu in the tropics, yet we have tha 
name applied to the alligator or Avocado pear (Persea 
gratissima, darts), the anchovy pear (Gria caulitlora, 
L.), the prickly pear (Opuntia ficusindica, Webb) and 
the wooden pear of Australia (Xylomelum pyriforme, 
Knight). Again, the English apple, although grown 
in the hills in the tropics, is practically of little 
value, but the name is as loosely applied as in 
the case of the pear, and hence fruits as widely 
apart as the poles in their botanical classification 
are grouped together under the general term o£ 
apple. To select a few out of many such names, 
wo have the sugar custard applo (Auoua reticulata, 
L.), the Kei applo (Aberia caffra, H. aud S.), tho 
Mammeo applo (Mammea americana, ],.), tho star 
apple (Ohrysophyllum Oainito, L.\ the rose apple 
(Eugenia lambos, L.), and the golden apple i.Spon- 
dias lu'oa, L.). In plums there are the entire plum 
(Harpephyllum catfrum, Leinh.), the coco plum 
(Chrysobylanus icaco, L.), the hog plum (Spondias 
mangefera, Pers.), the Chinese date, plum (Diospyros 
kaki. Linfil ), the blood plum (Hoomatostaphis liirteri, 
H. K.), and the gray plum of Sierra Leone Pariu- 
arium excelsum, Sibiue) ; aud so with tho goose- 
berry, essoutially a cold temperate fruit. English 
colonists have applied the name to such widely 
diverging fruits as thoso of Phpsalis Peruviana, L. 
(Cape gooseberry), Peirescia aculeata, Mill (Hirba- 
does gooseberry), and Oicca disticha, L. (Otahoito 
gooseberry). 
The SO-oalled nuta of the tropics arc in a worse 
state of confusion as regards the c immon names, aud. 
hence it by no means follows that what are imported 
as nuts belong at all to that category of fruits. Tho 
most familiar of tropical nuts is tho coconut (Cocos 
nucifera, L.), a true nut ; but tho Tara or Brazil uut 
(Bertholetia excelsa, 11. B.) is simply tho seed, not 
nut, which is inclosed in a large globular fruit, 
almost as large as a :t(3-lb. c.mnonball ; exactly 
tho same occurs iu the case of the S ipucajo nut 
(LeOythis Zabucnj), Aub. ), as well as in the best of 
these so-called tropical nuts, viz., the souari or batter- 
nut of British Guiaui (Oalyocir nuciferum, L ) l b" 
cashew nut (Anacardiuiu occidentale, L.) is a fruit 
borne upon a swollen pear-like peduncle, and presents 
one of tho most remark ible instances of growth met 
in the tropics. The fruit when roasted i- . .• rn 1 
at dessert, and pisses iu India under the D imo of 
"'promotion uut." Tho Jnmaic.i wiluut (Aleuritea 
■noluccana, Willd.) is tho seed of an Euphorbia 1. II 
also the cob-nut (OmpoalM »riandr», I. 1 — ' 
Agriculturist. 
