Chapter 7 Fruit Tree Disease

Study keystone of this chapter

Know the kinds and damage of main fruit in north area.

Section 1 Fruit tree leaf disease Section 2 Fruit tree fruit disease

Section 3 Fruit tree stem and root disease

苹果斑点落叶病 Alternaria mali

Section 1 Fruit tree leaf disease

苹果褐斑病 Marssonina coronaria

苹果锈病 Apple rust

苹果白粉病 Apple power mildew

梨火疫病 Pear fire epidemic disease

梨火疫病

葡萄霜霉病 Plasmopara viticola

桃缩叶病 Taphrina deformans

桃穿孔病

细菌穿孔病Xanthomonas pruni

霉斑穿孔病褐斑穿孔病

枣锈病 Phakopsora ziziphi-vulgaris

4. The whole tree disease

苹果花叶病Apple mosaic disease

苹果小叶病Apple lobule disease

苹果锈果病Apple rust disease

枣疯病

Jujube Witche’s Broom

葡萄病毒病Grape virus disease

生理性病害 --- 缺铁Lack iron

1. Grape Downy mildew（葡萄霜霉病）

Downy mildew is a major disease of grapes throughout the word. The fungus causes direct yield losses by rotting inflorescences( 花序 ), clusters and shoots. Indirect losses can result from premature defoliation( 落叶 ) of vines due to foliar infections. This premature defoliation is a serious problem because it predisposes the vine to winter injury. It may take a vineyard several years to fully recover after severe winter injury.

1.1 Symptoms Attacks all green parts of the vine. Initially, lesions

are yellowish and oily, and become angular, yellow to reddish brown spots. Infected shoots thicken and curl, then turn brown and die. Young berries become gray when infected. Rachis infection can spread into older berries causing a brown rot. All infected parts, except older fruit, are covered with white fungal growth during moist weather.

主要危害叶片，也危害新梢、叶柄、卷须、幼果、果梗及花序等幼嫩部分，叶正面形成多角形的黄褐色病斑，叶背产生白色的霜霉状物。

1.2 pathogen

该病由鞭毛菌亚门单轴霜霉属真菌葡萄单轴霉 Plasmopara viticola 侵染所致。病菌产生孢子囊及卵孢子。

1.3 disease recycle病菌主要以卵孢子 (oospore) 在病组织中或随病叶等在土壤中越冬 (overwinter) 。气候温暖地区，也能以菌丝在芽鳞或未脱落的叶片内越冬。卵孢子在潮湿的土壤表层存活最好，可长达 2 年。The fungus overwinters primarily in infected leaves on the ground. It may survive as mycelium in buds during mild winters.Next spring, when the condition is suitable, oospore disseminates by wind and rain to the adult plant, sprouts and invades host, causes initially infection and reinfection.

1.4 the condition of disease 1.4. 1 Plant disease occurrence and popularly correla

te with the climatic conditions, humidity is the main factor, the temperature, the illumination also has the certain relations. Every increase soil, the air and the host surface humidity factor and the daytime do not have the direct light as well as the gloomy environment, like rains, the bad fog, the cloudy day and so on are advantageous to the germ invasion. The multi- rain, the humidity, cool is easy to cause plant disease to be popular.

病害的发生和流行与气候条件密切相关，其中湿度是主导影响因子，温度、光照也有一定关系。凡增加土壤、空气和寄主表面湿度的因子和白天无直射光以及阴暗的环境，如降雨、大雾、阴天等均有利于病菌侵入。多雨、高湿、冷凉最易引起病害流行。

1.4.2. Cultivation management: late executes the nitrogenous fertilizer or more, the shelf excessively lowly, a surface dense, draining water impeded, overgrown with weeds, deadwood, the fallen leaf has pile randomly, ventilate bad, microclimate moist, all can cause plant disease seriously to occur and be popular.

品种间的抗病性有明显差异，一般来说，美洲种葡萄、夏葡萄、园叶葡萄、沙地葡萄、心叶葡萄较抗病，欧亚种葡萄高度感病。一般抗病性较强的品种有康拜尔早生、尼加拉、岚 -5 、镇 3 、留 -8 、留 -9 、商 -23 、白 -35-1等。感病的品种有红地球、巨峰、新玫瑰香、甲州、甲斐路、粉红玫瑰、里查玛特等 。

1.5 Disease control

1.5.1清除果园菌源 秋季结合修剪，剪除架上病梢、病枝和病果，清除架下枯枝落叶，集中烧毁或深埋，减少越冬菌源。发病始期发现病花序、叶片及果粒及时摘除深埋。

The fungus overwinters primarily in infected leaves on the ground. It may survive as mycelium in buds during mild winters.

对于常年严重发病的葡萄园应考虑定植或更新抗病性较强的品种。

Grape varieties vary greatly in their susceptibility to downy mildew. In general, vinifera (Vitis vinifera) varieties are much more susceptible than American types, and the French hybrids are somewhat intermediate in susceptibility.

Cabernet Franc, Cabernet Souvignon, Catawba, Chancellor, Chardonnay, Delaware, Fredonia, Gewurytraminer, Ives, Merlot, Niagra, Pinot Blanc, Pinot Noir, Riesling, Rougeon and Sauvignon Blanc are reported to be highly susecptible to downy mildew.

1.5.2 Strengthens the cultivation management

Severe annual pruning is a very important practice for controlling disease .

It is necessary to prune out and burn all excess growth.

To improve air circulation, control weeds and tall grasses in the vineyard and surrounding areas.

适当增施磷钾肥，提高植株抗病能力。

1.5.3 Spray medicine to protect plant in ti

ming

Pre bloom sprays are necessary for con

trol.

Promptly spray protecting agent before

disease, copper preparation is the good

medicament controling the frost mildew.

可在发病前结合防治其他病害喷布 1:0.7:20

0~240倍的波尔多液 (Bordeaux mixture ) 。

2. Jujube witches’s broom

Jujube witches broom is the destructive disea

se in jujube trees. The disease distributed arou

nd the whole country, especially in hebei, hena

n, and shandong province. If the disease occurs,

the young jujube tree will die in 1-2 years, and

the adult trees in 3-4 years, leading to large are

a jujube trees to be destroyed.

2.1 symptom

In general, the jujube witches broom happen fro

m one or more twigs,and then spread to other twi

gs or the whole plant. a dense cluster of twigs gro

wing from a central source . Infected branches, th

e flower organ become to leaves or small twigs. T

he diseased twigs are slim, and the knot become s

hort, the leaves are small and chlorosis.

2.2 Causal Organism

The pathogen of jujube witches broom mianly i

s phytoplasma. Phytoplasma is irregularly spheric

al, the diameter is 90-260nm, and often live in con

globation and bunchiness

Transmission of phytoplasmas to plants occurs

when leafhoppers feed from plant phloem. The ba

cteria are introduced into plant phloem with insec

t saliva. In plants, phytoplasmas remain restricted

to the phloem tissue where they systemically sprea

d throughout the plant.

Phytoplasmas cause severe symptoms , such as, stuntin

g, phyllody （变叶病） , witches broom, yellowing, and y

ield losses in over 300 economically important plant speci

es worldwide. These organisms are not transmitted via pl

ant seeds, but may be transmitted to next-generation leaf

hoppers. The molecular and genetic mechanisms underly

ing the diverse interactions between plant pathogenic ph

ytoplasmas and their plant or insect hosts remain unkno

wn.

2.3 Disease cycle

The roots of infected jujubes can carry the pathogen all

the year round. So the phytoplasma can overwinter in t

he roots of jujube； in the next year, the phytoplasma

in roots can be transported to overground part of jujub

e with the nutrients causing witches broom. Invaded ph

ytoplasma must move to roots along the phloem and re

produce in roots and then move to the branches causin

g disease. Graft and insect vecter all can transmit phyt

oplasma, but vector transmission is the main way to tra

nsmit phytoplasma.

2.4 Control

2.4.1 Using resistant varieties

Resistant varieties is the key measure to control jujub

e witches broom. Using resistant wild jujube or resist

ant jujube as stock to cultivate resistant jujube varieti

es, or using the pathogen-free scion to reproduce dise

ase-free stock.

2.4.2 Cultivation management

intensifying the fertilizer and water management, imp

roving the soil condition by increasing the organic fer

tilizer , promoting the growth of jujube tree to enhanc

e the resistance to phytoplasma

2.4.3 Control the vector insects

Spraying the insecticide in time to kill the vector i

nsect-leafhopper, in general, the optimal date of s

praying the insecticide are the last ten-day of Ap

ril, May, and June. 10% cypermethrin （氯氰菊酯） is in common use.

2.4.4 Surgery measure

Ring-cutting the trunk can block the movement o

f phytoplasma, by this way , the disease can be co

ntrolled or alleviated

2.4.5 Medication control

injecting acheomycin into the diseased tree or i

mmersing the roots or scion in the acheomycin

solution can alleviate the jujube witches broom.

2.4.6. Control the pathogen source

Decrease the primary infection source by elimin

ating the diseased seedlings and prohibiting the

diseased seedlings to transport.