Transcript Section 2 Fruit Tree Leaf Disease

Chapter 7 Fruit Disease
Section 2 Fruit Disease
苹果轮纹病
苹果炭疽病
苹果青霉病
苹果霉心病
苹果煤霉病
苹果褐腐病
梨黑星病
梨轮纹病
葡萄白腐病
葡萄黑痘病
葡萄黑腐病
柑橘青霉病
柑橘绿霉病
桃褐腐病
桃褐斑病
枣黑腐病（缩果）
枣炭疽病
1. Brown Rot, Monilinia fructicola桃褐腐病
1.1 Occurring and damage
 Brown Rot is one of the most common and
serious diseases affecting peach fruits.
Field losses of nectarines can be extensive
if conditions favorable for disease
development occur during the blossoming
or preharvest and harvest periods. Losses
of peach vary with susceptibility of the
cultivar.
 桃褐腐病又称果腐病、菌核病，是我国南北方
桃树上的重要病害。温暖潮湿地区虫害严重的
果园常流行成灾。可危害桃、杏、李、樱桃等。
1.2 Sympotom （症状）

Fruit rot starts with a small, round brown spot,
which expands to eventually rot the entire fruit.
Infected fruit turns into a mummy on the tree.
Except fruit it can also infect flower blossoms and
shoots. The disease begins at bloom. Infected
flowers wilt and turn brown very quickly. Shoot
infections (usually from flower infections) result in
small (1 to 3 inches), gummy cankers, which
provide the source of infection（侵染） for fruit rot.
Spores from infected flowers and cankers infect
aborting fruit and healthy green fruit during long
wetness periods. Infected, aborted fruit remain
attached in the tree and provide an additional
source of spores for more infections instead of
dropping off in a normal fashion. Infections in
apparently healthy green fruit remain inactive until
the fruit begins to ripen（成熟）.
1.3 Pathogen
该病由子囊菌亚
门核盘菌属
monilina和无性
世代的丛梗孢属
monilia真菌侵染
所致。病菌产生
子囊盘和子囊孢
子，并产生分生
孢子。
1.僵果及子囊盘 2.分生孢子梗
分生孢子链及分生孢子
1.4 Rule of disease occurring
Disease Cycle (侵染循环)
 M. fructicola overwinters in orchards as mycelium on
mummies, fruit stems, blighted blossoms and twigs, and
cankers. Sporodochia develop under cool, wet
conditions during the winter and early spring.
Occasionally, cup-like apothecia of M. fructicola which
produce ascospores can be found on fruit mummies
under the tree.
 影响发病的因素
 开花期低温多雨易引起花腐、叶腐或枝腐，果实成熟期温暖、
潮湿、多雨、多雾易引起果腐。贮藏期间病健接触也能传病。
 果实皮薄多汁发病重。
 虫害的发生程度和病害的危害轻重密切相关，虫害多发病重。
 管理粗放，栽植过密、修剪不当、通风透光差病害发生重
 桃、杏、李混载也有利于发病。
Disease Cycle
1.5 Prevention and Treatment
1.5.1 Cultural practices: Sanitation
is essential if your orchard is to
be considered a low risk for a
brown
rot
epidemic.
The
practices listed below, if followed,
should minimize brown rot spore
populations
and
limit
the
likelihood of an epidemic when
conditions are favorable for rapid
disease development.
1.5.2 Chemical management

Fungicides are usually required if fruit ripening
occurs during a period of warm, wet weather. It is
important to begin spraying just before the fruit
begins to ripen. Look for the first tinge of change
in the yellow background color. Starting a spray
program when rotten fruit is evident will result in
poor disease control. Select a fungicide
containing thiophanate methyl, captan, or
azoxystrobin that is labeled for use on peaches.
These fungicides are only effective if complete
and thorough coverage of the tree(s) can be
obtained. Always apply all pesticides according
to directions on the label.
2 Pear scab（梨黑星病）
2.1 Occurring and damage
 Scab is the most serious disease of apples
and pears in all country. Although it is
costly to control, neglecting or wrongly
applying control measures may reduce fruit
yield and quality. Reduced yield is caused
by the death of blossoms, shedding of
immature fruit, scabbing, cracking and
distortion of fruit, and loss of vigour of
trees after leaf infection and subsequent
partial defoliation. Scab may also develop
extensively in stored fruit from infections
established before harvest.
2.2 Smypotom



Pear scab can invade all greens young tender
organization of pear, like leaf blade and petioleJ(叶
柄), bud, inflorescence(花序), new tree top and
annual branch, the leaf blade and fruit is common.
In the Henan Province mid-north, young leaf is
taken bad beginning in the first ten days of May
most early, occurring generally in the last 10 days of
May to the first 10 days of June.
This symptom main characteristic is: the spot have
black green to the black mildew, initial period sick
tissue to change yellow, later dried up, sick tissue
not to be rotten.
 Blossoms
 Black
patches develop on the
flower stalks. These patches
extend, and soon flower and stalk
may blacken, shrivel and die.
Leaves
On the upper surface of the leaf,
spots first appear as light green
areas that soon turn brown, then
black and velvety. The spots may
be few and scattered, or so
numerous that they coalesce and
cover almost all the leaf surface.
Infected leaves may curve inwards
and become blistered and distorted.
On the lower surface of the leaf, the
disease may appear as a diffuse
dark discolouration, tending to
extend along the veins. Late in the
season many small, rather angular
lesions may be seen on the lower
surface of the younger leaves.
Fruit


Primary infection of Granny Smith apple fruit.
Infection early in the season (right), when fruit
is small, results in distortion and cracking as
fruit grows.
The spots on apple fruit are at first small,
black and circular. They may be so numerous
that as they grow they coalesce to form large
scabbed areas. The central, older parts of the
spots become brown and corky, and growth
of the fruit in these areas is greatly restricted.
Fruit infected early in the season becomes
badly distorted and deep cracks may develop
across the scabbed areas.
larger fruit

Spots formed on larger fruit
late in the season cause
much less distortion; these
spots are often surrounded
by a whitish band of
loosened skin. Early season
infection of pears can result
in the formation of large
corky areas on the fruit.
Infection later in the season
causes the formation of dark
sunken spots.
Fruit before harvest

Infections which occur just before
harvest can be invisible when fruit is
picked, but will be apparent when fruit
is removed from cool store some
months later.
Twigs
 Infected
twigs develop a flaky
appearance, when the bark
becomes blistered and ruptured
in places. Twig infection is rare
with apples, but more common
with pears.
2.3 Pathogen （病原）

pear scab is caused by Venturia pirina(梨黑星
孢 )the fungus. The closely related fungus
Venturia inaequalis causes Apple scab. The
apple fungus cannot infect pears, nor can the
pear fungus infect apples.
图9-1 梨黑星病菌
1．子囊孢子 2.子囊壳 2.分生孢子梗及分生孢子
2.4 Dissemination
 The
fungus is spread by wind
and rain, and is favoured by
warm, wet weather conditions.
2.5 Life cycle
 Throughout the growing season the scab fungus
lives and grows on the tree, producing vast
numbers of spores that spread the disease.
 The fungus can live over the winter in infected
areas on twigs and bud scales, but it mainly
survives the dormant season within the leaves that
fall in autumn. During winter it forms special
structures in the dead leaf tissues, and in these
structures, called perithecia, spores called
ascospores are formed. By late September many
perithecia are mature. When it rains they discharge
their ascospores which are carried by air currents
onto the trees. Most early or primary infection
comes from this source.
Secondary infections

Infections caused by conidia are
sometimes called secondary
infections. They may occur from the
time of the first primary lesions until
the end of the season. The more
spores emitted the greater the chance
of infection. Consequently, in a season
favourable to scab infection, the
disease is easier to control in a clean
orchard than in a heavily infected one.
2.6 Conditions causing disease
1. The following are necessary for infection:
mature ascospores must be present in
the orchard air, or conidia must be
present on lesions.
2. The leaves or fruit must remain wet long
enough for the spores to germinate and
for the resulting fungus growth to enter
the plant tissue; this period of wetness is
called the infection period.
3. Infection occurs most rapidly at
temperatures between 17 and 24. The
trees must remain wet for longer periods
for infection to take place at
temperatures outside this range.
2.7 Disease control
 The
two keys of Prevents and
controls this disease is
eliminating the germ and the
chemical control in time.
2.7.1 Does well the orchard
sanitation Elimination fallen leaf.
2.7.2 Chemical control
 Scab
control depends on spraying
with protective fungicides or
eradicant fungicides, or a
combination of both.
Protective spraying

Protective spraying keeps the susceptible
parts of the tree covered with fungicide.
Spores lodging on these parts are killed
before they can establish an infection.
Frequent sprayings are necessary to keep
the tree covered with fungicide, especially in
October and November. At this time highly
susceptible new growth is developing rapidly;
ascospores are abundant and conidia may
also be present. In wetter districts every
apple and pear orchard should be equipped
so that the entire area can be sprayed
thoroughly in 2 or 3 days.
Curative spraying after
infection periods

Control by protection may be supplemented
by curative treatment using curative
fungicide after infection periods. Some
fungicides have the ability to kill the
invading fungus for a limited period after
infection first started. This is known as the
period, and varies from 0 to 5 days,
depending on the fungicide. Some of the
fungicides with a long kickback action have
a relatively short protective ability.
Postharvest foliage
treatment
Postharvest foliage sprays are a
very useful supplement to scab
control, especially after a season
of high scab incidence. The
principle of control by treatment
after harvest but before leaf-fall is
to prevent the fungus surviving in
the leaves over winter.