Download Section 2 Peony Disease

Chapter 8
Flower Disease
Study keystone of this chapter

The peony(牡丹), the chrysanthemum(菊花), the
Chinese rosa(月季), the orchid(兰花)and the
tulip(郁金香)and so on, the typical flowers’s
disease symptom, pathogen, the rule of
occurring and controlling technology.
Section 2 Peony Disease
1. BOTRYTIS BLIGHT OF PEONY
（牡丹灰霉病）
1 Occurring and damage
 Botrytis blight is one of important
peony's diseases in the world, often
occurs in our country. It is more
serious in Shanghai, Zhengzhou. This
disease may occur in all peony's
growth season, is serious to the young
tender adult plant, causes seedling's
damping off (倒伏) and wilt(枯萎).
2. Sympotoms

The Botrytis fungus grows over new shoots of peony
and covers them with a dense velvety gray mold. Very
young shoots may be blighted early on, turn black.
Botrytis may also grow on developing flower parts
causing bud blast and flower blight. Some buds may die
without opening. Flower infections can move down into
the stem causing a brown and tan target-like
discoloration. Infected petals (花瓣) which drop onto
leaves can result in leaf spots. Late in the season, very
small, shiny black, somewhat sausage-shaped fungal
structures called sclerotia (菌核) may be found just
under the epidermis at the base of infected shoots.
3 Pathogen

Botrytis paeoniae Oud. (牡
丹葡萄孢)，belong to
imperfect fungi (半知
菌).The conidiophore erect,
pale brown, septa.
Conidia gathers to
capitate, egg circular to
the near rectangular
circular; Colorless to pale
brown, single , size 916×6-9μm . Sclerotia’s (菌
核) size1-1. 5mm.
4 Condition of disease
occurring

Botrytis infections are favored by cool
(15oC ), rainy spring and summer weather.
Gray mold can be particularly damaging
when rainy, drizzly weather continues
over several days.

低温、潮湿是发生 病的主要条件。春天温度较低，
阴雨连绵加重幼苗的发病。该病常发生在寄主开花
期后，6月～7月为发病盛期。株丛密度大，氮肥多，
有利于发病。
Disease Cycle




Botrytis blight of peony infects the base of
young shoots as they emerge from the ground.
This disease may also infect buds or flowers
at any stage, depending on when favorable
weather conditions occur.
During wet periods, infection may spread
quickly, blighting most open flowers as well
as emerging buds. Severe infection may
cause much of the foliage to turn brown and
dieback prematurely.
In late summer, sclerotia develop in dead plant
tissue, forming the overwintering stage of the
fungus.
Development of Botrytis gray mold diseases.
(provided by George Agrios, Plant Pathology 4th Edition)
5 Control
1. sanitation
 The best way to manage this disease is by
inspection and sanitation. Remove faded or blighted
flowers, blighted leaves, or entire plants infected at
the base and place them in the paper bag so that
they may be discarded with the trash or burned.
2. Likewise avoid overhead watering, syringing, or
misting plants especially if Botrytis blight has been
troublesome in the past. To promote rapid drying of
plants space them to allow good air circulation.
3. Fungicide sprays may also help by protecting plants
from infections.
 1%石灰等量式波尔多液，70%甲基托布津1000倍液，
65%代森锌500倍液，或50%氯硝胺1000倍液。每隔10
天～15天喷1次，连续喷2次～3次。③加强栽培管理：栽
植密度要适度；雨后及时排水，株丛基部不要培湿土；
重病区要实行轮作；栽植无病种苗，苗木可用65%代森
锌300倍液浸泡10～15分钟。

When Botrytis blight of peony is a
problem avoid the use of dense, wet
mulches and apply the first fungicide
spray in early spring just as the red
shoots begin to push up out of the
ground. With continuous inspection
and careful sanitation gray mold can
be effectively managed. Keep an eye
out for the silvery-gray mold and/or
tiny black sclerotia which are sure
signs of this disease.
2. Phytophthora Blight
2.1 Occurring and damage
 The symptoms of blight caused by
this fungus, Phytophthora cactorum,
may be confused with the symptoms
produced by Botrytis sp. The stems,
leaves, and buds can be affected by
both diseases.
2.2 Sympotoms


1. Comparing grey mildew
disease with
Phytophthora blight, there
is no felty growth or
sporulation on the plant
surface when in a wet
environment.
2. Infected parts become
dark brown or black and
somewhat leathery. The
entire shoot may turn
black and die.
Phytophthora blight
often invades the
crown and causes a
wet rot.
3. Control

Because infections of this disease
generally occur in the roots and
lower portions of the stem, spraying
with fungicides is of little value.
Confirmed cases should be removed
and destroyed, together with adjacent
soil. Planting healthy clumps in new
locations where the soil is well
drained usually prevents further
trouble.
 3.
Cankers may appear along the
stems and cause them to fall over.
 4. Cankers may appear along the
stems and cause them to fall over.
While Botrytis sp seldom invades
the crown, Phytophthora sp often
does, causing a wet rot to develop
and destroy the entire plant.
3. White Mold
3.1 Sympotoms

Mainly causes stem rot on peony as
well as on many different herbaceous
plants found in the garden. The entire
plant or portion of the plant may wilt.
The infected part of the stem turns a
light tan color and may become dry
and stringy. Fluffy white mycelium
often appears under humid conditions,
thus the name, white mold.
3.2 pathogen

Sclerotinia sclerotiorum Sacc.
（小核菌） belong to imperfect
fungi (半知菌).This fungi can
not form conidia (分生孢子).
Various sizes of
irregularly shaped, hard
black sclerotia(菌核) may
be found inside the tan
area of the stem.
Sclerotia are the
verwintering structures
for this fungus and they
can survive for many
years in the soil.
3.3 Control
 Remove
and dispose of any infected
plant parts being careful to not drop
the sclerotia. Sclerotinia is a soilinhabiting fungus that is nearly
impossible to remove. Replant
infested areas with nonsusceptible
plants. Wider spacing to improve air
circulation will minimize infection by
this fungus.