669 
THE GARDENING WORLD 
October i 2 , 1907; 
be well -to get a good strong shoot from 
the base ready to fill up its place. 
CHRYSANTHEMUMS. 
2272. Leaves Tunnelled by Insects. 
I have some Chrysanthemums which are 
fine healthy plants, but on looking at the 
leaves I find that they are becomrng in¬ 
fested with some insects which are puzzling 
me how they got into the leaves, as you see 
by the two or three I enclose. I should be 
much obliged if you can tell me how to stop 
them before getting worse. I have them in 
a greenhouse with the door open all day. 
(Mr. Cawley, London.) 
Your Chrysanthemums are evidently 
badly attacked with the Chrysanthemum 
leaf miner, a small black fly named Phyto- 
myza nigricornis. This insect lays eggs 
upon the leaves from which little grubs 
hatch out and eat their way into the leaf, 
making tunnels. It is difficult to prevent 
them from doing this, but some growers 
syringe their plants occasionally with 
strong-smelling tobacco water, which is dis¬ 
tasteful to the flies and keeps them from 
laying their eggs there. \\ hen leaves do 
get attacked you should keep a close eye 
upon them and look for the position of the 
grub. It is somewhat difficult in the case 
of thick-leaved Chrysanthemums,_ but if 
you watch the grub in its very early stages 
and squeeze the white tunnel, you will kill 
the grub inside and save further trouble. 
Leaves that are very much riddled should 
be pulled off and burned to destroy the 
grubs inside them. It very often happens 
if you wait too long that the grub passes 
into the pupa stage for a short time, then 
develops into another fly which proceeds to 
lay eggs upon other leaves and thus multi¬ 
plies the trouble. You should always, 
therefore, be inspecting the leaves from the 
commencement and thus save a great num¬ 
ber of the leaves being attacked. If you 
commence with this early in the season they 
do not multiply to any serious extent, 'the 
same fly is much more troublesome when it 
gets into annual Chrysanthemums, especi¬ 
ally those grown under glass, as it very 
soon destroys the whole of the foliage. 
VEGETABLES. 
2273. Root Crops on the Same 
Ground. 
My kitchen garden is divided into four 
squares. One of these has been this year 
devoted to root crops—Potatos, Beet, 1 ar- 
snips, Carrots, etc. For certain reasons I 
want to grow these crops (not including Po¬ 
tatos) in the same plot again next year. I 
propose to trench the ground thoroughly 
and to plant the crops north and south in¬ 
stead of east and west. W ill these changes 
be sufficient or should I use any special 
kind of manure to get a fair crop under 
the circumstances? (Lower Hardres, 
Kent.) 
\Ye have known all of these crops being 
grown on the same ground for many years, 
though not with the best results in the case 
of Potatos- liable to disease and without 
properl}' manuring the ground. While 
trenching the ground you could put in some 
well-decayed farmyard manure in the bot¬ 
tom of the trench, so as to get good roots 
before they come in contact with the manure, 
which is liable to cause them to fork. Some 
gardeners prepare a piece of ground speci¬ 
ally for these root crops, but especially for 
Carrots, and with the addition of fresh 
manure they have no difliculty in getting 
good crops from the same ground every year. 
If you particularly desire large roots of 
either of these you could make holes with 
a large dibber that would go to the depth 
of the trenched ground, making holes about 
3 in. in diameter. These could be filled 
with sifted soil, sand, wood ashes and any 
other artificial manure that you think 
would be useful, though we have known 
the holes to be filled with sand entirely. 
Soil that is sifted in this way is productive 
of very clean roots, and of course to get 
them to large size they should, at least, 
be 12 in. apart in the case of Beet and Car¬ 
rots, and 15 in. apart in the case of Par¬ 
snips. There are two ways, therefore, of 
making sure of a satisfactory crop off the 
same piece of ground in several successive 
years. 
2274. Potatos and Broccoli Diseased. 
I shall esteem it a favour if you will 
examine the enclosed specimens of my gar¬ 
den produce and assist me by telling me the 
name of the disease and what means I must 
adopt to avoid a repetition of the same. My 
garden allotment is 22 yds. by 10 yds. The 
Potato is a specimen of what my whole crop 
is. In some cases there are no Potatos at 
all, but only the growth enclosed. In 
others the Potatos are quite rotten. The 
ground last year was used for Cabbage and 
was well dug and manured when the Potato 
seed was planted. The clubbed roots en¬ 
closed are Broccoli and Savoy, and most of 
my plants have been similarly attacked. The 
ground last year was used for Potatos. 1 he 
plants were put out early in July. Plants 
from the same source in other gardens have 
done well. I should be very thankful if 
.vou will give me some advice as to what 
means I must adopt to destroy the disease. 
(A. W. Cox, Cheshire.) 
Your Broccoli and Savoys are very much 
affected with the Ambury disease, usually 
known as clubbing or clubroot, caused by 
the fungus Plasmcdiophora Brassicae. The 
Potatos seem to have been attacked with 
some similar organism or bacteria. In any 
case, your soil must be very dirty with the 
spores of fungi, which are usually very 
prevalent in small holdings close 'by each 
other, and where no joint action is taken 
to keep the ground clean. Very frequently 
the cultivators, to get rid of Cabbage and 
Cauliflower stems, as well as Potato stems, 
simply bury them in the ground, thus caus¬ 
ing a great spread of the disease. Your 
best plan would be when digging up the 
roots to lift every clubbed portion carefully 
and have the whole put in a heap and 
burned. This would destroy an immense 
number of spores and thus help to save 
trouble in the future. At the same time it 
would be well to trench your ground 25 ft. 
deep, putting the top spit down in the bot¬ 
tom. When the trench is nearly filled up, 
say within a foot of the top, it would be 
well to give a good top dressing of gas lime 
to kill any spores still remaining in the 
ground. These processes are the best that 
have yet been employed for cleaning the 
ground of the vermin and fungi which usu¬ 
ally infest the ground where Potatos and 
Cabbages have been grown. There is no 
exact quantity of gas lime that may be em¬ 
ployed, but it would do no harm if you 
spread it on about an inch deep. This must 
not be done when you are about to plant 
if the gas lime is fresh, which it should 
be to have the most effect. As soon, there¬ 
fore, as- you can get the ground bare you 
should commence the operation of trenching 
and. the use of gas lime so that it will be so 
changed chemically by the lapse of six or 
eight weeks that it will be harmless to anv 
vegetation which you may put into the soil 
after that. The Potato tubers should, of 
course, be burned where they are quite use¬ 
less. Dusting the drills with sulphur is 
very beneficial in the case of Potatos, put¬ 
ting it in the trenches while planting the 
tubers. 
FRUIT. 
2275. Time to Gather Pears. 
J. S. will thank the Editor of The Gar¬ 
dening World to name the Pears herewith 
sent and perhaps he would also at the same 
time say about what time these Pears should 
be ripe enough to remove from the trees, 
having regard to this district (Kingston, 
Co. Down). Does one of the signs of Apples 
being ripe, the pip becoming brown, apply 
to Pears as well? Will Pears become ripe 
in the house if pulled somewhat too soon? 
It appears those Pears became shrivelled 
last year in the house after being taken 
from the trees and did not ripen. '1 hey 
were removed from the trees as they were 
beginning to fall. (Dublin.) 
The Pears you sent were : (i) Williams’ 
Bon Chretien (ripening August and Septem¬ 
ber) ; (2) Fondante d’Automne (August and 
September); (3) Brown Beurre (October); 
(4) Marie Louise d’Uccle (October) ; (5) 
Beurre d’Amanlis (September) ; (6) Duchess 
d’Angouleme (October and November). The 
above are the average times in which those 
Bears become ripe, but they are only a 
guide in a general way, because they vary 
from district to district to some extent, but 
this year are much later than usual. We 
are surprised that Williams’ Bon Chretien 
should still have been ; n season. Pears 
sometimes commence falling before they are 
really ripe or sufficiently mature even upon 
the tree. This may be due to a variety of 
causes, such as -being too dry at the root, 
too many fruits on the tree, or it may be the 
fruits have been penetrated by the grubs of 
the codlin moth. When the pips of Pears 
become brown it is a sign of their being 
about ripe enough to gather just as in the 
case of Apples. Another sign is to lift up 
the fruits in the hand, and if they come 
away without much effort in pulling, it is 
another sign that they would soon drop if 
not gathered. When those two signs have 
been noted it is fairly safe to gather them, 
but Pears are liable to shrivel more so 
than Apples when taken into the fruit room 
before their time or in warm weather. This 
can be counteracted by letting them hang 
as long as they safely will hang or can be 
left on the trees on account of frosty or 
very stormy weather. Those which ripen 
’n August and September should very soon 
be ready, if not already gathered. It is 
well to bear in mind that some of them do 
not become quite so melting as WTlli'ams’ 
Bon iChretien; indeed, Beurre d’Amanlis 
should be eaten some time before it reaches 
that stage. Y'our 'best plan, of course, is to 
put each sort into a fruit room separately, 
with -the name of it written on a piece of 
paper. The gardener, or whoever looks 
after them, should examine them from time 
to time to see whether they are fit for being 
used. If allowed to get too far advanced 
they then become useless in a short time. 
2276. Bush and Pyramid Apple Trees. 
I am grateful for valuable advice and 
suggestions, and as a result of what you 
have said I have changed my plan. I will 
plant bush trees and keep the ground bare. 
I shall be much obliged if you will kindly 
tell me how to plant bush and pyramid 
Apple trees. Is it a good plan to put 
manure in the hole, cover it with soil, tread 
it down well and then plant the tree ? 
(Wold Ranger, Y'orks.) 
We should plant bush and pyramid trees 
of Apples about 6 ft. apart each way. At 
this distance they may be grown for a 
number of years before they get too crowded. 
In the meantime they are sheltering one 
another, which means a good deal when the 
trees are laden with fruit. By the time 
they begin to get crowded you can take 
out every other tree, say, about the middle 
