-
Perennial canker of peach
The
presence
(存在)
of
gum
(树胶)
or
sap
(树液)
exudate
(渗出分泌物)
on the
scaffold
(脚架)
limbs
(四肢)
or trunks
(主干)
of peach trees may be caused by insect
borers
(蛀
虫)
,
by
winter
or
mechanical
injury,
and
by
such
diseases
as
Coryneum,
and
bacterial
and
perennial
(多年生)
cankers.
在桃树的主干或者分支上有胶质汁液渗出,
可能是由于蛀虫、
由于冬天、机械损伤、由于棒
盘孢属细菌引起
的多年生溃疡造成的。
Perennial
canker,
common
in
most
Illinois
orchards
(果园)
,
occurs
throughout
the
Midwest
wherever peaches are grown. This
disease has a variety of names, some of which are
die-back,
peach canker, Valsa
(黑腐皮壳属)
canker,
and
Cytospora
(
壳囊孢属)
canker. Perennial canker
is
caused by two species of fungi,
Valsa
leucostoma
(桃干枯病菌)
and
Valsa cincta
(imperfect
stage
Cytospora
)
(壳囊孢属的无性阶段)
. It is not a new disease, and
mus
research has been
done to develop adequate control
measures for it.
多年生溃疡常发生在桃子生长的美国中西部地区伊
利诺斯州的果园里。
这个病害有有很多名
字,有的叫枯梢、桃溃
疡、桃干枯病、桃干腐病,多年生溃疡是由
2
种真菌造成的,桃
干枯
病菌和壳囊孢属的无性阶段。它不是一个新的病害,研究人员已经制定了适当的控制
措施。
The disease
is often destructive
(破坏性)
in young orchards where it causes the
premature
(过
早的)
death of trees. Older trees that are
affected gradually lose
productivity
(生产力)
and
longevity
(寿命)
.
p>
这种病害在年轻的果园中往往具有破坏性,
因为他会导致树木过早死
亡。
老树一般被影响而
失去生产力、减少寿命。
Cytospora
fungi cause cankers to form on any
aerial
(
空中)
portio
n
(
部分)
of a tree
–
the
trunk,
scaffold limbs (Figure 1), twigs
(Figure 2), and fruit
pedicels
(果茎)
. These fungi
are not primary
(主要的)
invaders
(
入侵者)
of peach trees and are incapable
(
无能力的)
of
attacking healthy
peach bark.
Valsa
fungi require wounds
or
dead
areas
in
the
bark
in
order
to
establish
themselves.
Once
they
are
established,
gum
is
exuded at the point of
infection (Figures 2 and 3).
壳囊孢菌属真菌能使树的任何地方形成溃疡
—
树干、
树枝分叉、
树枝和果茎。
这些真菌并不
是桃树的主要侵入者,
他们没有侵染健康桃树皮的能力。
黑腐皮壳属真菌为了让自己在树上
定殖需要伤口或者死去的区域。一旦他们定
殖,树胶在感染的时候渗出。
This gum, initially a light
amber
(琥珀色)
color,
gradually turns dark brown. Beneath
(在
p>
…
之
下)
the gum, a small
necrotic
(坏死)
lesion
(病变)
is apparent. The lesion gradually
enlarges
(扩大)
, with the
resulting collapse
(崩溃)
of the inner bark tissue. Older cankers
are generally
oval
(椭圆形)
in shape (Figure 4) because the lesion
develops faster vertically
(垂直的)
than
horizon
tally
(
水平的)
. The
outer bark in older cankers is generally broken
and disorganized, while
in new cankers
it remains intact
(完整的)
except at the points of
gummosis
(流胶病)
.
树胶
最初是淡琥珀色颜色,
逐渐转变为深棕色。
在树胶下面一个小的
坏死病变是明显的。
坏
死逐渐扩大,
由
此导致树皮内部组织坏死,
老溃疡病斑形状一般是椭圆形,
因为
坏死垂直发
展的比水平发展的快。
外部树皮的老溃疡斑一般是被
破坏了的和无组织的,
然而在新溃疡上,
除了在流胶的地方,它
仍然是完整的。
The
canker will continue to spread from year to year.
It enlarges by repeated invasion of
adjoining
(毗邻的)
healthy tissue by the fungus during
favorable growing periods. Each spring, growth of
the
host
causes
a
callus
(愈伤组织)
ring
to
form
around
the
canker
as
a
defense
(防御)
mechanism
(机制)
.
The
number
of
these
rings
may
denote
(表示)
the
age
of
the
canker.
Continued growth of
the fungus eventually girdles the affected limb,
causing it to die (Figure 4).
In
addition
to
cankers,
Cytospora
also
causes
a
“die
back”
symptom
on
twigs
in
the
spring.
Affected
twigs
die
back
from
a
light
yellowish
brown,
gum-
encrusted
(被覆盖)
twig
canker
(Figure 2).
溃疡将年复一年的持续扩展。
他在真菌生长的时期通过重复侵染毗邻的健康组织来扩大。
每
年春天,
寄主的生长使这个愈伤组织环作为一个防御机制围绕溃疡病斑形
成。
这些环的数量
可能表示发生溃疡病的年龄。持续生长的真菌
最终围绕受影响的枝条,导致枝条死亡。
除了溃疡病之外,<
/p>
桃干枯病病菌也导致枯梢症状在春天的嫩枝上,
嫩枝条被影响从淡
黄色的
棕色中消失,被嫩枝条上的溃疡所覆盖。
Disease Cycle
Cytospora
spp. survive on
(靠
…
生存)
cankered tissue and dead twigs, and can
be found on the
surface of peach trees
all year long. Fruiting bodies known as pycnidia
form on cankered surfaces.
The pycnidia
are visible
(可见的)
macroscopically
(宏观的)
as tiny black specks
embedded in
the bark. Each pycnidium
contains thousands of microscopic pycnidiospores,
that are exuded as
long gelatinous
tendrils during humid weather. The spores are
disseminated
(传播
)
to injured
bark
tissues by rain, insects,machinery, farm workers,
pruning tools, and birds.
壳
囊孢属靠溃疡组织和枯死的枝条生存,
它全年都能在桃树的表面被发现。
在溃疡病斑表面
的子实体被称为分生孢子器。
分生孢子
器在宏观上肉眼是可见的,
作为黑色小斑点被嵌入在
树皮上。<
/p>
每一个分生孢子器包含有数千的微观的分生孢子;
它在潮湿的天气
渗出凝胶状卷须。
孢子通过雨水、昆虫、机械、农场工人、修剪工具、鸟类传播到受伤的
树皮组织上。
The
spores germinate
(使发芽)
and start new infections when the
temperature and
moisture
(水
分)
conditions are
favorable
(有利的)
. Optimum
(最适宜的)
conditions for the
development
of Cytospora cincta
generally occur in the spring when temperatures
average 64°
to 70°
F
(18°
to
21°
C).
Infection
by
toma
is
favored
by
warmer
temperatures
(optimum,
81°
F
or
28°
C)
that occur in the late summer or early
fall. New pycnidia form 7 to 8 weeks after
infection, thus
completing the cycle. <
/p>
当温度和水分条件合适时孢子萌发,
开始新的侵染。
壳囊孢属无性阶段发展的最适宜条件一
般在春天,当温度平均在在
18~21
℃时。
桃干枯病菌的侵染受到发生在夏
天或早秋气温升高
的影响,新生孢子器在侵染后
7~8
周形成,完成一个循环。
< br>Susceptibility
(易感性)
Perennial canker affects peaches as
well as other stone fruits
–
p
lum,prune
(西梅)
,
apricot
(
杏子)
,
and
cherry.
Peach
varieties
vary
slightly
in
their
susceptibility
to
perennial
canker.
The
winter-
hardy
(耐寒)
varieties, those that
defoliate
(落叶)
rapidly, and those that
heal
(愈合)
rapidly
show the least amount of infection.
多年生
溃疡病不仅影响桃子,而且也影响其他核果,像李子、西梅、杏子、樱桃。桃树品种