THE PRINCIPAL FUNGUS DISEASES OF CITRUS TREES, WITH METHODS OF TREATMENT. 
Parasitic Fungus. 
Parts Attacked. 
Symptoms. 
Preventive and Remedial Measures. 
General Remarks. 
— 
First Spraying. 
Second Spraying. 
•Third Spraying. 
False Melanose 
(Cladosporium brunneo- 
atrum.') 
Fruit, leaves, and 
young shoots 
Roundish brown spots, slightly elevated. On 
fruits the spots run together into irregular 
curved lines, giving a streaky appearauce 
Remove and burn diseased 
fruit and shoots. Burn 
all diseased litter 
Bordeaux mixture when 
fruit has set 
Bordeaux mixture a fort¬ 
night or a month later 
In bad cases another spray¬ 
ing a month later 
In orchards which have been seriously affected for many years it may be necessary 
to spray at intervals of a month from setting of fruit till close to maturity, but 
once the disease comes under control probably two sprayings would prove quite 
sufficient. 
Wither Tip ... 
(Phoma omnivor a.') 
Leaves, twigs, 
fruits, and roots 
(a) On Leaves — Brownish or greyish blistered 
patches 
(5) On Twigs—Irregular raised dirty grey 
blotches # * 
(c) On Fruits—Brownish or blackish scabby 
patches 
{d) On Roots (Root rot) — Black irregular 
patches 
Remove and burn all 
affected twigs and 
unmarketable fruit as 
well as diseased litter. 
Bordeaux mixture when 
fruit has set 
Bordeaux mixture two to 
four weeks later 
V 
In bad cases another spray¬ 
ing a month later 
Probably the most injurious of all the fungus parasites. The same treatment is 
recommended as for the “False Melanose.” 
Anthracnose or Black 
Spot 
{Phoma citricarpa .) 
Fruit... 
Forming round sunken spots, at first greyish, 
in centre becoming dark-brown with minute 
black dots 
Burn all badly affected 
fruits 
Bordeaux mixture when 
fruit has set 
- !-- 
Bordeaux mixture two to 
four weeks later 
Bordeaux mixture about a 
month before ripening of 
fruit 
Apparently confined to the skin of the fruit, but a constant source of depreciated 
values. Where prevalent the spraying about a month previous to the ripening of 
the fruit should never be omitted, otherwise, as may be seen, the treatment is the 
same as for " False Melanose/’ 
Sooty Mould 
{Gapnodium citricolum .) 
Leaves, branches, 
and fruits 
Forming black soot-like incrustations readily 
peeling off in flakes 
During pruning season cut 
off and burn all badly 
affected branches and all 
water shoots 
Spray with resin wash or 
kerosene emulsion about 
three weeks before 
blooming 
Repeat previous spraying 
just before the opening 
of the blossom 
If necessary again after 
fruit has set 
The aim of the treatment is to destroy the scale, for no scale no sooty mould is the 
universal experience. The best times to destroy the scale, and with it the sooty 
mould, are early spring and autumn. 
Black Scurf of Fruit 
{Coniothecium scabrum.) 
Fruit... 
First appearing as large black patches, then 
cracking into minute irregular areas with 
a dirty grey scurfy appearance 
Burn badly affected fruits 
Bordeaux mixture when 
fruit has set 
Bordeaux mixture a fort¬ 
night or month later 
Repeat application if 
required 
Practically same treatment as for Anthracnose. 
Scab or Scabbing 
(Various fungi.) 
Leaves and fruit 
Producing greyish or blackish roughened 
patches 
Burn all diseased fruit and 
litter 
Bordeaux mixture when 
fruit has set 
Bordeaux mixture from 
two to four weeks later 
Repeat application if 
required 
Practically same treatment as recommended for Anthracnose. 
Bark Blotch... 
{Ascochyta limonis .) 
Bark of trunk ... 
Minute black dots barely perceptible to the 
naked eye, but often giving a slightly 
blackened appearance to the bark. Bark 
peels off in bad cases 
In early slages cutting 
away diseased areas has 
proved serviceable 
„ Paint the wounds with one or other of the antiseptic mixtures mentioned in the 
text.’ 
✓ 
' 
Collar Rot ... 
{Fusarium limonis .) 
Bark of trunk, 
just above or 
below surface 
of soil 
Discoloration and decay of bark with profuse 
gumming and disagreeable odour. Leaves 
become yellow and sickly 
Cut away and bum diseased 
parts even penetrating to 
the wood ; scrape away 
surface soil and add lime 
Root Rot 
{Phoma omnivor a.) 
Roots 
Black patches on roots. General sickness of 
tree 
••• ••• ••• 
• • • ••• ••• 
••• ... ... 
... 
Attention to drainage and general health of tree. Cut well back in order to induce 
strong and vigorous growth. The addition of 2 lbs. of powdered sulphate of iron 
and an equal quantity of fresh slaked lime to the soil around the trunk might 
prove advantageous. Apply Bordeaux Mixture to the roots as recommended in 
the text. 
t 
BORDEAUX MIXTURE. 
Copper sulphate (bluestoue) ... 6 lbs. 
* Quicklime (to be freshly slaked)... 4 lbs. 
Wat er ... ... ... 100 gallons 
Pulverizo the bluestoue and dissolve it in a wooden 
vessel containing half the quantity of water or 50 
gallons. This can be simply done by tying the blue- 
stone in a coarse sack and suspending it just beneath 
the surface of the water by means of a stick laid 
across the top of the wooden vessel. 
Slake the lime in a small quantity of water so as to 
get it as fine as possible, then add the remaining 
50 gallons of water. 
When cool, pour the milk of lime and copper 
solution slowly together into a barrel holding 100 
gallons. The milk of lime should be thoroughly 
agitated before and while pouring it out; and the 
mixture in the barrel should also be thoroughly 
stirred for several minutes. 
To determine whether the mixture is safe to use on 
tender foliage, insert the blade of a penknife into it 
for at- least a minute, and if copper is deposited on the 
steel more lime must be added until there is no deposit . 
of copper. 
Use the Bordeaux Mixture immediately after it is 
made. 
Air-slaked lime should never be used in preparing 
Bordeaux Mixture. 
By adding soft soap to the mixture equal in quantity 
to the bluestoue used its adhesive property is in¬ 
creased. 
DILUTE COPPER SULPHATE SOLUTION. 
Two to 4 oz. to 50 gallons of water may be used 
when the fruit has nearly matured, instead of Bor¬ 
deaux Mixture. This solution is readily washed off 
by rain, and during rainy weather should be fre¬ 
quently, even daily renewed. 
AMMONIACAL COPPER CARBONATE. 
Copper carbonate ... ... 5 ozs. 
Ammonia (26°) ... ... 3 pints 
Water ... ... ... 45 to 50 gallons 
Mix the copper carbonate in a wooden pail with 
sufficient water to make a thick paste, next add the 
ammonia to dissolve the paste, and when all is dis¬ 
solved dilute with water to make 45 or 50 gallons. 
COMBINED INSECTICIDE AND 
FUNGICIDE. 
Bordeaux Mixture and Paris Green. 
Take 1 lb. of BlundelPs or Lewis Berger and 
Son’s Paris Green, make into a thin paste with 
water, and add it to 200 gallons of Bordeaux Mix¬ 
ture. Mix the two just before using, as if allowed 
to stand they may deteriorate. 
Note. —As ammonia dissolves the arsenic in Paris 
Green, never use the ammoniacal copper carbonate 
with Paris Green. 
QUOTATIONS FOR INGREDIENTS. 
The following are the Melbourne prices quoted for 
the ingredients employed :— 
Copper sulphate, 30s. per cwt. 
Quicklime, 3s. 6d. per bag. 
Paris Green, Is. per lb. 
Copper carbonate, 4s. per lb. 
Ammonia (26° Beaumd), Is. per lb. in 1-lb. bottles. 
N.B.—These quotations are subject to fluctuation, 
but special rates are given for large quantities. 
