Diseases of fruit plants [microform]

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CIRCULAR No. 20.

(Prinnd by order ol th« L«(tl«l«tur«.)
PROVINCE OF NOVA SCOTIA.

COLLEGE OF AGRICULTURE.

TRURO. H.- »•■ 1»»7.

M. GUMMING,

PRINCIPAL.

H. W. SMITH.

PROF. OF BOTANY

DISEASES OF FRUIT PLANTS.

CONTENTS

Sprays and Kiinpiriilts.

Sulphur DustiiiK-

Apple Diseasos.

Woun(1s of Trees.

Pi)1vix)rus, Brown Rot of Wood.

Uailllus amvlovoriis. Blight, Fire Blight.

Bla. kberry anil Raspbtrry Diseases.

Cherrv and Plum Diseases.

Currant Diseases.

CiODseberrv Diseases.

Pear Diseases.
Stra^^berr^• Diseases.
The Winter Care of Fruit Trees.
Karly Si)ring Care of Fruit Trees Till Apples Hlos-
som.
Later Si)ring Care of Fruit Trees.

DISEASES OF FRUIT PLANTS.

//. W. Smith.

Nearly all the recognized diseases of plants are due to the
growth of parasitic plants; a few diseases are rare and are
due to some physiological cause and some to unknown
causes. This article will deal chiefly with diseases due to
parasitic plants.

When a plant appears unhealthy and an attempt is un-
dertaken to find the cause the fruit grower should first
make sure that it is not due to climate, soil, culture or situa-
tion. He should then look for injuries from animals, par-
ticularly insects and finally for a disease, as the disease is
usually the most difficult to detect. As the symptoms of
disease in fruits are so many and various no attempt
will be made to summarise them here but rather the follow-
ing directions are offered as probably the most efficient
for an inexperienced fruit grower. The experienced fruit
grower will be familiar with the healthy appearance of the
plant and will notice the unusual or unhealthy growth.
It is suggested that where a disease is suspected that the
fruit grower look up the different symptoms of each of the
different diseases till he finds those that corresponds to those
present on his plants. It is to be borne in mind however
that these symptoms are not present except at certain sea-
sons and that their absence is to be so interpreted till the prop-
er time for them to appear. Also it is to be remembered that
diseases may occur that are not here recorded nor in any
text available to our fruit growers. Where the grower is
unable to determine the trouble satisfactorily he should
appeal to the Agricultural College or The Experimental
Farms at Ottawa. Even then a satisfactory answer may
not be forthcoming. It is not always easy or possible to
solve these problems.

For convenience the plant under cultivation is called the
host and the plant causing the disease is the parasite. The
latter is relatively small and often entirely inside of the host
and not visible except where it sends special parts to the
surface for reproduction. Sometimes the parasite may be
external and conspicuous. As a rule plants thus causing
disease are fungi (including Bacteria) and the special repro-
ductive bodies are very minute and of various kinds depend-
ing on how they are produced. In general, these are called
spores.

If none of these parasitic plants occurred in a locality
then there would be no disease which would spread from
plant to plant in that locality. While such an ideal condi-
tion does not exist with us, there are localities free from
certain plant diseases just as localities may be free from
certain contagious diseases among mankind. It is impor-
tant to keep all diseases possible out of each locality. To do
this all unhealthy plants, parts of plants and prunings from
imported stock should be burned. Also it is evident that
healthy plants are less likely to become diseased than un-
healthy and every effort should be made to keep the fruit
plants healthy by selecting suitable soil, situation and ex-
posure, by proper cultivation and treating the plants the
«ame each year, especially by avoiding excessive culture one
year and giving none another year, (or the next year) by
avoiding excessive fertilization as with nitrates or soluble
fertilizers but rather by applying moderate amounts each
year. Finally diseases in the main are to be prevented.
The purpose of spraying is to prevent the spread of diseases.
It will not kill the disease where it has become established.
There is no known cure for plant diseases in the sense used
for animal diseases. In some cases the disease may be re-
moved with part of the plant but the important treatment
is prevention. For this purpose spraying the healthy
plants or parts with some application is often beneficial.
As spraying will be treated in other articles in this series the
reader is referred to them for further information except a
few suggestirnp which might be overlooked. Plenty of lime
in the Bor ux mixture is desirable.

Sprays and Fungicides.

Bordeaux Mixture: This is prepared by dissolving one
pound of quick lime in a little water and adding gradually
more water to this and straining through cloth till the solu-
tion amounts to about nine gallons. In another vessel
dissolve one pound of blue vitriol (copper sulphate) in nearly
a gallon of water. This is more easily done if the water is
hot and the salt is suspended in a cloth near the surface of
the water. Cool this solution and add it to the lime solu-
ution with constant stirring. Use only wooden utensils.
This mixture should be used soon after mixing the two
solutions and should be kept well stirred. There are many
published methods of making this mixture. One method is
about as good as another providing that one of the solutions
or both are as dilute as possible.

Bordeaux mixture was the earliest used and in general
has proven the best spray. It was the spray that demon-
strated the value of spraying to control plant diseases.

Lime-Sulphur: This is the most convenient spray to
use, as it is prepared so that all that is necessary is to follow
the manufacturer's directions but it is only suitable for cer-
tain crops as the fruits and should not replace Bordeaux
mixture for potatoes nor for other crops except where it
has been demonstrated to be as good. Always use lead
arsenate in this spray as it increases its fungicidal value.

Corrosive Sublimate.— This solution is prepared by dis-
solving one ounce of mercuric chloride (Corrosive subli-
mate) in six or seven gallons of water. Use wooden utensils.

Formaldehyde (Formalin).— Thin solution is prepared by
adding one pound of formaldehyde of about forty per cent
strength to thirty gallons of water or one part to three hund-
red parts of water.

Copper Sulphate (Blue Vitriol. — One pound is dissolved
in fifteen gallons of water as directed under Bordeaux
inixture.

Potassium Sulphid. — One ounce is dissolved in two and
a half gallons of water.

Caution. — The above reagents are all poisonous and the
utmost care should be exercised that the solutions and the
utensils used in their preparation are not left where they
may be accessible to live stock nor to persons unacquainted
with them.

Sulphur Dusting.

The attention of the fruit grower is called to the method
of dusting trees with a mixture of very fine sulphur and
dry "fluffy" lead arsenate using eighty five pounds of sul-
phur to fifteen of the poison. This material can be diluted
with terra alba. Where this dry material is properly mixed
and applied it has been found as efficient and much cheaper
than liquid sprays and not only more easily used but more
rapid in application and capable of being applied when
needed. It promises a great step in advance in the control
of fungus diseases in the orchard. In rainy seasons apply
the dust once a week.

With the great increase in the cost of spray materials,
It becomes important to utilize every other method of dis-
ease control. This can not be over emphasized. It does
not mean, however, that no spraying should be done. Quite

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!!l^..u"i^*7' ?"t ,^hat is more important than ever, it
should be done intelligently.

Apple Diseases.

^J-*^*"**^':."!^"* *'■'' f*"*^^ '^y » number of different
dweases and where a canker is discovered the reader is ad-

fXwiii SJes': ''"" d""'P^-n« occurring under the

Blight cankers on twigs, branches and trunk.
European canker, on branches and trunk.
Coral canker, chiefly on twigs and branches.
Blister canker, on twigs, branches and trunk.

Black rot cankers, while occurring on all parts are much
more common on twigs than elsewhere.

Cankers should always be removed and not be allowed
to remain on the tree to spread the disease. It is usually
best to remove the entire limb on which a canker occura

ed *^-th'a tiSfecVanr"'""' '"^ °"* ^"' '''' "°""^ "*^^

Wounds of Trees.

. The healing of wounds in fruit trees deserves further
investigation Much that is written about it see L based
on theory rather than any extended observation. It has
long been known to botanists that an injury to a healthy
apple tree was followed by the formation of a layer of cork

JllfL":" if ?"J* P-^*".*"^' *° ^^^ •"i"'"ed surface. This takes
K! o '" *»^*V*^y ''v'ng wood but so frequently in this climate
SL fnl^*" r l^^r ^^^""^ ^"'? branches of apple trees is killed
It .lf^*'7'>'.*''^^""".^ methods may have to be resorted to.
It seems fairly certain, however, that exclusive of graftinK
wax most if not all substance usually applied to wounds do
more injury than good in promoting healing.

As a rule it would seem best to let the injury alone after
reducing it as much as possible and trimming off any irreg-
ularities and washing it with an antiseptic like corrosive

woon^Xd. " *"■ '°^''' '' ^''^ ^'^^''"^ ^^"^ '^ '^"^^"'

While corrosive sublimate attacks metals and therefore
Jo thl u°-^ "^5"^- ^"^ Y^sh utensils, the injury is very slight
to the kniie used in trimming or pruning if it is wiped dry
or rinsed with clean water when through using, nor does the
dipping of the knife into the solution materially weaken it

The pruner ran easily carry a Riass or porcelain dihh or pail
of granite ware with the solution in It when pruning and a
wooden handle with a swab attached.

Sphaeropsis Malorum, Black ^o/.— This disease causes
(1) decay of fruit especially such as is left on the ground.
(i) Sipots on leaves, which are easily recognized, as they
are definite, usually circular and do not spread to involve
the entire leaf, but the dead center frequently drops out
leaving a hole. (3) Canker on trunks, limbs, and twigs.
I he trunk and limb cankers are not common here but the
twigs are tretjuently affected. Orchards in which the leaves
are affected with the spots mentioned above and twigs
affected with a rough bark are probably injured by this
fungus. The characteristic leaf spots serve for identifica-
tion, but these cankers are hard to distinguish from other
cankers except by careful observation.

Treatment.— Wurn all dead twigs and cankers. Use for
malm or corrosive sublimate wash for utensils and wounds'
I hus far this is not a serious disease in Nova Scotia but it is
common. Thorough spraying with Bordeaux mixture as
practised for scab with the aid of a winter spray of copper
su phate (or lime-sulphur) using one pound of the salt to 20
gallons of water, should help to control this disease.

Polyporus, Brown Rot of Wood.— Varioua Fungi which
have fruit in the form of toad-stools, shelves or brown patch-
es, attach fruit trees. Heart wood of such trees is dead
but the disease can not be identified till the Fungus fruits.

rrca/mtn/.— Usually nothing can be done but prevent
the spread of the disease by destroying all the fruits of the
lungus as soon as they appear.

Bacillus atnylovorus, Blight. Fire Blight.— This disease also
attacks plums and cherries and in certain seasons is very
injurious to pears and apples. It attacks young twigs,
blossoms and young fruit and older parts of the tree The
appear, nee of these attacked parts varies with the season,
ihis cJiease may remain apparently dormant doing little
damage for a number of years then in a single season prove
very destructive. k "»«^

As a rule it is not hard to distinguish the perennial
cankers in this province as they are more characteristic
*han west of here, but the blossom and twig blight due to
this disease is not easily distinguished from that due to other
causes and without accompanying material and data, es-
epcially after drying and the death of the bacillus can not be

distinguished so far as I am aware. Hence the identifying
of this disease in the twigs is dependent upon these other
data.

The Perennial or Older Cankers are situated upon the
trunk or older limbs, those over three years old and usually
much ol ier unless in a very protected situation. These
cankers usually extend lengthwise of the limb of a uniform
width and about one fourth or less of the circumference
but this varies. This strip usually extends till the limb

t'oins another^ and it is bordered by a slightly elevated
>ark. In moist weather this bark is spongy and markedly
unhealthy. As the canker grows older the bark cracks
along these strips and adjacent limbs become involved
in the same way or the entire limb dies. On the large
limbs and the trunk of older trees, the affected area may
not extend along the part and in such a case the canker
becomes rounded. Such cankers where I have had the op-
portunity to see and watch then, do not live many years.
Unless the canker progressively extends each year ii.to fresh
tissues it dies and the tree recovers. While the greater
number of pear trees attacked by thes*. perennial cankers
die the reverse is true of apple trees but the injury often ren-
ders them worthless. These perennial cankers are the
source of future danger to the orchard as it is in them the
disease lives from year to year and they annually take toll
from twigs and blossoms. On or about the time the trees
are in blossom if these cankers are examines in moist weath-
er or late in the evening, in fog or heavy dew, the unhealthy
spongy bark will be found saturated and often the liquid
oozing from it. This sap is loaded with sugary material
and the bacteria which cause the disease. While it is stated
that this sap flows in the day time and is visited by flies and
bees I have found nothing to confirm this in our climate
and after spending many hours searching for these I acd-
dently found some of our transpo.ters of this disease. I had
been collecting moths in the evening from baited trees
and went into the orchard to see if some could not be had
from the apple blossoms. In passing near the cankers
which I had so fruitlessly watched during the day I found
them overflowing with sap and many moths, especially
cutworm r^oths, Noctuidae, feeding upon it. These moths
were also visiting the blossoms and would undoubtedly
carry the bacteria with them.

Blossom and Twig Blight caused by this disease is not so
easily recognized as the older cankers if we are to accept the
commonly held view that most dead twigs are due to this
disease. If a growing branch three years old or younger is

^i^^m-kj^i^^^l^f^i

attacked by this disease in June or July, the bacteria devel-
ops so rapidly that the entire branch is soon killed and the
leaves blacken and remain hanging to it. This is very
characteristic of the disease, especially on pears where it
is common and occasionally on apple, cherry and plum. Pear
leaves are also blackened by leaf blight, but only the leaves
are then affected and not the twigs. Apple leaves may also
be blackened without the twigs being killed, by certain
troubles. When the bacteria of thi3 disease are conveyed to
the blossoms then the Mossom dies and the disease ends
there or the infection enters the twigs and dies. If the
fruit spur is on an older branch then a perennial canker
develops.

Treatment.— This consists in removing all affected
branches and older cankers. The bacteria do not live long
outside of the older cankers but it is best to burn all the parts
removed. The saw or knife or whatever comes in contact
with the disease should be dipped into formalin solution
before using upon the next tree and the wounds washed with
this solution or corrosive sublimate as soon as through
operating. Remove the disease as soon as it is discovered
no matter at what season of the year. Examine for older
cankers in winter and again during blossoming, and damp
weather.

Nectria ditissima, European Canker. — These cankers
occur most commonly on older limbs or trunks or in the
crotches. They annually become larger and each year's
growth is marked by a ring surrounding the canker, which is
quite characteristic. The fruit of the fungus is often con-
spicuous in the early spring as small, round, yellow to
brown bodies on the bark surrounding the canker.

Treatment. — Remove all cankers whenever discovered
and burn. Use corrosive sublimate to wash the wounds.
Spraying the trees with Bordeaux mixture is considered
beneficial.

Nectria cinnabarina, Coral Canker. — This canker occurs
chiefly upon twigs and branches and fruits very abundantly.
These fruits are red to brown when dry but in moist weather
they are a very bright coral red and often in clusters as large
c a pea.

rrca^mew/.— Remove and burn all affected twigs and
branches.

Nummularia discreta. Blister Cawfeer.— Specimens of this
disease have appeared on nursery stock imported recently
and on young trees. The cankers have the dead bark of the

affected area more or less retained and on this the fungus
fruits giving its surface an appearance as if covered with
pimples or blisters.

Treatment. — Remove and burn.

Pseudomonas tumefaciens, Crown Gall. — This disease
occurs particularly on nursery stock and on garden vege-
tables occasionally. On nursery stock the name is so des-
criptive that little further description is required. It should
not be necessary to state that only healthy stock and cion
should be used by the nurseryman and that all diseased
material should be burned but often crown galls appear only
after being planted in the nursery row and the young tree
otherwise seemed healthy enough. The galls are swelling
or growths upon the stem where it was grafted or where
injured in cultivating or sometimes where no apparent
injury has occurred. It is when well developed, a nodular
outgrowth.

Treatment. — Any material having an unhealthy growth
upon it should be burned. If galls are found in the nursery
the plants bearing them should be burned and a careful
watch kept as other diseased plants are sure to appear.
If it occurs commonly such ground should not again be used
for nursery for some time. In no case should the galls
be cut out and the knife used for further pruning until
sterilized by dipping in formalin. In the orchard, affected
trees should be removed but not replaced the same season
by other trees. In every case these galls should be looked
for in spring and again in summer and on large trees removed
early in the season as they break down in autumn. They
are light colored at first and become darker and more
wood-like as the season advances.

Cylindrosporium Pomi, Fruit Spot. — A number of similar
spots occur upon the apple from different causes. Hail
occasionally marks the fruit and an obscure trouble called
"Stippen" may occur but the most common trouble of this
kind is due to a fungus, Cylindrosporium Pomi. When the
fruit is mature a spot like a small round bruise is present
and the affection extends towards the core as a cone of brown
material. Spots can be detected when quite small late in
July. The spores late in the season occur just beneath
the affected skin.

Treatment. — Do not leave affected fruit in the orchard to
decay. Continue the fungicidal spray used for Scab till late
July using it rather weaker and if Bordeaux is used add
more lime to the mixture.

10

Venturia Potni and Veniuri Pyrina, Apple and Pear
Scabs. — The ascospores are mature from about a week or
two weeks before blossoming till some time after the blos-
soms have fallen. All do not mature at once. These asco-
scopes if they fall on the fruit at this time almost always
cause it to fall or "Drop;" if on the leaf a spot or scab is forni-
ed. This takes ten days or two weeks to mature so that it
shows or breaks the epidermis. As soon as a scab appears it
begins to shed spores which are capable of growing on the
fruit or leaves and causing scabs. These scabs live and pro-
duce spores, in this way for a long time. The young or
immature scabs and possibly the older spots after the leaves
have fallen, undergo a change during which the fungus grows
and by the following Spring produces ascospores which may
reach maturity shortly before the trees come in bloom.

The twigs of certain varieties as the Mcintosh and pear
twigs are also attacked by this fungus and may be killed,
seriously injured or only slightly affected. The fungus re-
mains alive over winter in some of these spots but I have
found no ascospores produced there but it is possible that
they may continue to produce conidia and this may be one of
the causes of such varieties being more seriously affected by
this disease. Affected twigs should be removed and burned.

Treatment. — Spray the trees thoroughly with Bordeaux
mixture or Lime-sulphur or Dust Spray as the bud unfold
and at frequent intervals as every ten days or two weeks, for
three or four applications. It is desirable to have one appli->
cation follow blossoming as soon as possible as this is the
season of most rapid growth of foliage and the most abun-
dant production of ascospores. Winter sprays of lime-
sulphur should always be used where twigs are infected. The
complete plowing under of all leaves in the fall or early
spring is desirable.

Pink Rot. — This disease may follow scab but has not pro-
ven injurious in this province. The spray used for other
diseases should control it.

Stereum purpureum, Silver Leaf. — This disease occurs
chiefly on young trees usually within a few years after
transplanting from the nursery. The leaves of a branch
or of the entire tree in midsummer assume a silvery appear-
ance and break or tear apart as they become old. The tree
may otherwise appear thrifty . In the course of a few years,
about the time it should begin bearing, usually it dies and
purple sporophores,* shelf-like fungi, appear on the branch
affected or on the trunk near the ground if the entire tree is
affected. They may appear on limbs also.

11

Treatment. — Remove and burn all affected trees as soon
as detected.

Sderotinia fructigena, Brown rot of Fruits. — This is the
common cause of decay of fruits. It is promoted by warmth
and moisture and retarded by cold. Insects are the effi-
cient means of spores gaining entrance to Che fruit. Practi-
cally all the brown dust or mold on the decaying fruit con-
sists of the spores of this fungus. If such fruit is allowed to
remain on the ground for two years under suitable conditions
it then produces ascospores. Either of these spores if they
find an injured fruit as where bitten by an insect readily
penetrate and cause the fruit to rot. The curculio beetles
are very injuries in this way. This is the common rot of
stone fruits and is common on all early apples and pears.

Treatment. — Spray the trees early in the season with
poisons to kill all insects that eat foliage and fruit and if
plant lice or other sucking insects are present use contact
sprays to destroy them. Pick and burn all wormy fruit
from the trees if possible or utilize pigs to consume the fallen
fruit. Thinning the fruit on the trees where it is set too
thick also helps, ^eep the fruit as cool as possible after it
is picked and during shipping. The fungus often invades
the twig from the fruit and kills it giv'ng it the appearance
of "Blight." Remove all suck branches.

Blackberry and Raspberry Diseases,

These fruits are subject but not equal to the same dis-
eases. In starting a plantation care should be taken to
get or use only healthy plants as it is much easier to keep
the diseases out than to get rid of them. Indeed the latter
is in some cases impossible except by growing other crops on
the land.

Glaeosporium venetum, Anthracnose. — This disease is
characterized by the formation of purple or dark colored
spots on the canes which as they become older usually be-
come lighter in the centers. This produces a "Bird's Eye"
appearance.

Treatment. — Plant only healthy plants. Do not use soil
where the disease has previously existed. When a plant is
affected remove and burn the entire plant as soon as detect-
ed. Spray with Bordeaux mixture during the early part of
the season.

Cane Blight. — This is due to different causes. The canes
wilt or pariially wilt in the growing season. If this is not

12

due to insect injury then it is best to remove the affected
plants and burn them.

Pseudomonas tumefaciens, Crown Gall.— This p, )duce8
swellings on the underground parts of the plants as men-
tioned under Apple Diseases. Nursery land infected with
this disease producing organism should not be used for
either these berries or root crops but devoted to grain "tid
grass for a number of years.

Septoria Rubi, Leaf Spot.— This is easily distinguished
by the numerous small spots on the leaves. Each spot de-
velops a lighter center with a colored border.

Treatment. — If discovered in time pick off and burn all
affected leaves. Spray during the growing season with
Bordeaux mixture and destroy all leaves in the autumn.

Gymnoconia interstialis, Rust.— This disease may be
found on the young canes but becomes conspicuous as the
season advances by the abundance of yellow or orange
colored spores produced. Eventually the host is killed after
a number of years in which little or no fruit is produced.

rrea/mcn/.— There is no cure. Each affected plant
should be dug up and burned as early as the trouble can be
detected. Otherwise all plants will become effected.

Cronartiutn Ribicola, European Currant Rust.— This
disease is not likely present unless it is or has been intro-
duced with importations of White Pine. Wherever white
pine has been imported and grown from imported trees
a careful search should be made of both wild and cultivated
currants for rust. The currant leaves will have spots upon
them covered with a fine down or delicate hair-like growth.
Any suspicious growth or appearance on currant leaves
where imported white pine occurs within half a mile should
be sent either to Ottawa, to the Experimental Farm or to
this college with an account of the attendant circumstances.
While not a serious disease of the currant it is of the pine.

Cherry and Plum Diseases.

Plowrightia morhosa, Black Knot of Cherry and Plum. —
The black knots which disfigure plum and cherry trees are
amiliar to every one and are very conspicuous when the
leaves have fallen but the beginning of one of these is less
frequently seen. The place first swells and feels springy to
the touch and the bark cracks open and exposes the fungus
which is light brown and quite velvety but later gradually
grows into the black knots. It begins to shed spores as

18

soon as the bark cracks open. This may occur at any time
in the growing season but is most frequent in summer and
is then easily overlooked. The ascospores are shed after
the knots become black about June the following year.

Treatment. — Remove and burn all knots as soon as the
leaves have fallen. In June and again in August search for
the newly formed knot. If the trees are badly affected
spray after blossoming with Bordeaux mixture which has
been made with one third to one half more water than
stated in the directions for making. Destroy all wild and
neglected trees bearing knots, any where near the orchard.

Exoascus Pruni, Plum Pockets or Bladder Plums, Witches'
Bloom of Cherry. — This very common disease lives in the
twigs of the plum especially those bearing fruit. After
blossoming the diseased fruit grows much more rapidly
than healthy and soon becomes almost white, swollen and
with little or no pit. The ascospores are shed from the
affected fruit (Or more frequently these ascospores multiply
and produce many small spores, conidia.) and inoculate
other twigs.

Treatment. — As soon after blossoming as the affected
fruit can be detected remove all such fruit and the twigs on
which it is borne and burn them. Any affected fruit that
drops off should be picked up and destroyed. With care
this will remove the trouble in a couple of years, if not too
badly established. Care must be taken to remove all un-
cultivated cherry and plum that might harbor the disease.

Bacillus amylovorus, Blight. — See Apple Disease. This
disease may be confused on plum and cherry with a twig
blight caused by Brown Rot of Fruit.

Sclerotinia fructigena, Brown Rot of Fruit. — This is the
common cause of the decay of these fruits and is promoted
and distributed chiefly by insects. Thinning the fruit is
important and the destruction of all fallen fruit. The des-
truction of insects that feed upon these fruits is of first im-
portance. See this disease under Apple Diseases.

Pseudomonas tumefaciens, Crown Gall. — See Apple Dis-
eases.

Brown Rot of Wood. — See Apple Diseases.

Cylindrosporium Padi, Shot hole disease or Leaf Spot. —
The spore of this fungus soon geiminates after coming in
contact with the leaf of the cherry or plum. It penetrates
the epidermis and in a few days has developed into a fungus
in the interior of the leaf capable of producing spores, the

14

leaf tissue involved is killed and in many cases drops out
leaving a somewhat circular hole which gives it one of its
common names. But under other conditions this piece may
remain attached to the leaf as a circular dead area. The
leaves may be seriously injured.

Treatment. — Often the attack may be so far advanced
when discovered that the trees lose their leaves in Summer.
If the trees are in sod burn over the sod when dry in early
spring so as to destroy the leaves. If in cultivation bury all
leaves by careful plowing. Spray with Bordeaux mixture
which has been made with about one half more water than
the standard mixture. Do not wait for the appearance of
the trouble the following year but repeat the treatment.

Currant Diseases.

Pseudopeziza Ribis, Anthracnose. — Small brown spots
appear on the leaves and eventually on the younger parts
of the cancj and on the leaf stalks when the attack is severe,
and the leaves fall. Compare also "Leaf Spot." This is
a serious disease when introduced. It lives in these spots
and in spring has developed from the same spots which pro-
duced summer spores, ascospores capable of infecting the
fresh growth of that season.

Treatment. — If only a few plants are affected, it would be
well to remove and burn the plants as soon as the disease
is detected. Spray with Bordeaux mixture. Begin as
soon as the buds open and repeat at least five times at
intervals of ten days to two weeks or longer as the season
advances. When possible the fallen leaves should be raked
up and burned in the autumn and any remaining leaves
carefully buried by spading the soil in early spring.

Nectra cinnabarina, Cane Blight. — See coral Canker un-
der Apple. The characteristic fruit occurs.on the canes and
all affected canes s.io"ld be removed and burned.

Septoria Ribis, Leaf Spot. — This disease occurs on both
currants and Gooseberries. The spots are like those on
the Raspberry leaves. They are larger than those of anth-
racnose and have a paler center with a colored border.
They are much more distinctly defined^from the healthy
leaf.

Treatment. — Spray as directed for anthracnose. Pick
affected leaves if only a few and burn them.

Sphaerotheca Mors-uvae, Currant (ind Gooseberry' Mildew.
•^This disease occasionally causes loss in^our.moist.climate,

\Mh^:^jt}*MM.^^i^m^ii^m:'^^.x

15

especially in damp and shaded gardens. It also attacks
currants. It is easily recognized by the leaves, and twigs
and especially the fruit being covered with a white mildew
which often gradually turns brown. Young twigs may be
killed. When once established it is hard to control.

Treatment. — Spray as soon as the buds begin to swell
with potassium sulphid solution or dust with sulphur and
repeat in ten days or less and give a third spray ten days
later. Pick and burn all affected fruit. Prune thoroughly
and destroy the cuttings. Repeat the spray the following
year even if no evidence of the disease appears. Winter
spray of lime-sulphur may be beneficial. Sulphuric acid
one part to 1000 parts of water is recommended as a spray.

Gooseberry Diseases.

Septoria Ribis, Leaf Spot.— See Currant diseases.

Sphaerotheca Mors-uvae Mildew.— See Currant Diseases.

Puccinia Pringheimiana, i?Mj/.— The attacks of this rust
occasionally occur and are very conspicuous. Portions of
leaves and fruit are misshapen and become covered with
cupshaped depressions filled with a yellow powder, the
spores. These do not grow again on the currant or goose-
berry but will produce the fungus on sedges and from these
sedges the gooseberry is attacked the following year.

Treatment.— By drainage and other means destroy
sedges growmg near the gooseberries and pick and burn all
affected fruit and leaves of the gooseberry bushes as soon as
discovered in order to prevent the sedges from becoming
infected. Cutting the sedges late in autumn or early spring
IS beneficial.

Pear Diseases.

Bacillus amylovorus, Blight, Fire Blight.— See Apple
Diseases.

Pseudomonas tumefaciens, Crown Gall. — See Apple Dis-
ease.

Decay of Wood. — See Apple Disease.

Venturia Pyrina, Scab. — See Apple Disease.

Entomosporium maculatum. Leaf Blight. — This disease
attacks pears and quinces. There appear at first small
spots which are fairly round and which may become sq
numerous as to kill the leaf. As they grow older they do

16

not acquire a pale center but the red centers turn brown
and the spots are not very evident on the lower surface of
the leaf. On the fruit the red color of the young spots may
help to distinguish them from "Scab,".

Treatment. — If seen when the infection is slight pick off
and burn the affected leaves and in any case spray with
Bordeaux mixture.

Septoria Pyricola, Leaf Spot. — In this disease the spots on
the leaves grow larger than in leaf Blight and as they become
older the centers become gray and eventually develop
minute black dots in the gray which is in turn surrounded
with a colored border.

Treatment. — Spray with Bordeaux mixture early in the
season.

Gymnosporangium, Rust. — Rust occasionally attacks
apples but pears and quinces are more frequently attacked
in this province. The fungus causing the trouble lives
alternately upon the fruit plant and dwarf juniper or cedar.
The disease is easily recognized on the fruit plants. It may
attack either fruit, twig or leaf. The part becomes swollen,
distorted and produces cupshaped depressions filled with
spores. These spores do not again grow on the fruit tree
but must find the coniferous host. There in the spring they
produce in damp weather gelatinous swellings.

Treatment. — Destroy the bush junipers and cedars
growing near orchards. Where possible pick off and burn all
affected parts on the fruit trees before the spores are shed.

Plum Diseases. — See Cherry.

Quince Diseases.

Bacillus amylovorus, Blight. — See Apple Diseases.

Entomosporium maculatum, Leaf Blight or Fruit Spot. —
iiee Pear Diseases.

Gymnosporangium, Rust. — See Pear Diseases.

Strawberry Diseases.

Mycosphaerella Fragariae, Strawberry Leaf Spot. — These
white spots with purple borders on the leaf of the straw-
berry are easily recognized. The disease attacks most
severely Old Country varieties, and frequently does consid-
erable damage. The spores are shed all summer from the
spots. "Ascospores when produced are said to appear late
in the season."

17

Treatment. — Remove and burn affected leaves, if no
many are affected, early in the season. If very abundant
cut in autumn and burn over the plantation. Exercise
great care to plant only healthy plants and remove all
effected leaves.

Fruit Rot. — This is "a-'sed commonly by three diseases of
quite different botanica. .naracters. Their control however
is practically the same. After the fruit is picked it should
be stored, or shipped in as cool and well ventilated condition
as possible. Crowding, moisture and heat promote decay.
Care should be exercised to reject all berries which are soft
as when decay starts it soon spreads through the box.

The Winter Care of Fruit Trees.

All dead twigs and branches should be removed in win-
ter and burned as the spores of ranker particularly are pro-
duced from the dead wood. It is easy to see the dead
branches and remove them at this season.

All wounds made by pruning can be washed when
made, with a solution of corrosive sublimate or formalde-
hyde, and bound with a cloth that has been coated with
grafting wax. This facilitates healing and excludes the
spores, which might otherwise lodge and grow there.

Where any of the above diseases exist, as their spores
may lodge on branches, twigs, or buds, it is advantageous
to spray the dormant trees with some winter spray. White-
wash, copper sulphate or lime-sulphur is efficient. The im-
portant point is that the spray shall be applied thoroughly
to the twigs and buds as well as the larger branches and
trunk. White-wash should be applied early in winter;
and other sprays towards spring. Old fruit attached to
trees should be picked and destroyed as they furnish a place
for fungi.

Early Spring Care of Fruit Trees, Till Apples Blossom.

All cankers should be examined and every evidence of
dead wood removed and burned. Such cankers as appear
spongy and soft or have a fluid exude when pressed or
from which a fluid escapes should be not only trimmed but
great care should be taken to wash and bind the wound as
directed for wounds in winter, as such cankers may be due to
fireblight and actively shedding their bacteria. These the
corrosive sublimate solution will kill. If there are bud-
moths in the orchard or if tussock, tent or brown-tailed
moths are liable to be present, so that an early spray is re-
quired when the buds are swelling, then use in addition to

18

Bordeaux or lime-sulphur spray the poison spray. If such
poison spray is not required this early spraying may safely
Be omitted in orchards which have been well cared for;
but it is in ivery case important that a thorough spraying
with one of these spray mixtures should be made before the
blossoms unfold. Even though no fungus has been found
in the orchard, this spraying would be advantageous as a
measure to prevent their gaining a foot-hold. This is the
season when most of the ascospores produced on the dis-
eased fruit and twigs begin to develop and grow.

Early in the spring, before blossoming time in cultivated
orchards the ground should be plowed and all leaves and
fallen fruit buried. Orchards in sod where scab is very bad
should have the aftermath in autumn left on the ground
and burned on some dry day in early spring so as to destroy
the fallen leaves and fungi attached. The fruit grower
whose fruit is not seriously injured by scab cannot afford
to sacrifice such good humus. Indeed, in most cases early
plowing would be the wiser course. A jointer should in
every case be attached to the plow where there is difficulty
in completely burying the leaves.

Later Spring Care of Fruit Trees.

After blossoms fall the spray g'ven before blossoming
should be repeated, preferably within a week after the bloom
is off. This spray is second only in importance to the spray
preceding the blossoming. If in previous seasons any of the
above diseases have appeared in the orchards, particularly
scab, this spraying must be made.

The tankers treated previously should be examined.
Search for plum-pockets should be made and all such to-
gether with the twigs to which they are attached, removed
and destroyed. All "black knots" in their early stage of
growth, should be removed and burned.

Where the orchard has been seriously affected previous
seasons with any of the above diseases, it will be desirable
to repeat this spray again, and in some cases a second repeti-
tion at an interval of two weeks.