1. 7-2 Solanceous Fruits Diseases

2. 7.2.1 Tomoto Leaf Mould Leaf mould is a disease of tomatoes only.
The disease is a common and destructive disease on tomatoes worldwide grown under humid conditions.
Leaf mold is primarily a problem on greenhouse tomatoes, but occasionally develops on field and garden-grown tomatoes if conditions are favorable.
he disease is most destructive in the greenhouse during the fall, early winter, and spring when the relative humidity is most likely to be high, and air temperatures are such that heating is not continuous.

3. Tomoto Leaf Mould
When humidity is high, the fungus develops rapidly on the foliage, usually starting on the lower leaves and progressing upward.
If the disease is not controlled, large portions of the foliage can be killed, resulting in significant yield reductions.
Early infections are most threatening.

4. Symptoms
Major symptoms occur on the foliage but they may also occur on petioles（叶柄）, stems, and fruit peduncles（果梗） (but not on the fruit itself).
All stages of growth are attacked.

5. Symptoms
The first leaf symptom is the appearance of small, white, pale green, or yellowish spots with indefinite margins on the upper leaf surface.
On the corresponding areas of the lower leaf surface the fungus begins to sporulate.
The fungus appears as an olive green to grayish purple velvety growth composed mostly of spores (conidia) of the leaf mold fungus.

6. Symptoms
Infected leaf tissue becomes yellowish brown, and the leaf curls, withers, and drops prematurely.
The withering and defoliation progress up the plant until the entire plant may appear dry and dead.
Disease development is slow and severe symptoms are usually present only late in the season; however, major yield losses are possible if infection occurs early.
Seed-borne infection has not been reported.

8. Fulvia fulva，synonym Cladosporium fulvum
Pathogen
Fulvia fulva，synonym Cladosporium fulvum
Spores germinate in water films or when humidity levels are above 85 percent, at temperatures between 4 and 34℃. The optimum temperature for germination is between 24 and 26 ℃.

10. Disease Cycle
The fungus survives between seasons as conidia (spores), as sclerotia on plant debris, in seed, and as a soil saprophyte.
Conidia are resistant to drying, and may survive in the greenhouse at least 1 year in the absence of a susceptible host, and new conidia can be produced from surviving sclerotia.
The conidia act as primary inoculum to infect plants when conditions become favorable.

11. Disease Cycle
Leaves are infected through stomata when humidity levels are 85 percent or higher.
Infection occurs most rapidly when humidity levels at the leaf surface fluctuate between 85 percent (day) and 100 percent (night).
Symptoms usually begin to appear approximately 10 days after inoculation, with spore formation beginning a few days later.
Spore production is most abundant at relative humidity between 78 and 92 percent, but can occur at humidity as low as 58 percent.

12. Conditions for Disease Development
Many cycles of disease development are possible during the growing season.
Disease development is influenced by temperature, relative humidity, and long periods of leaf wetness.
The presence of moisture on the foliage from dew, rainfall and fog provides good conditions for disease development.
Increasing periods of leaf wetness are associated with increasing disease severity; consequently, the disease may become more serious during the rainy season when warm temperatures prevail. I
ts spores will not germinate if the relative humidity is less than 85%.

13. CONTROL
1. Whenever possible, keep the relative humidity in the greenhouse below 85 percent. This will inhibit the development and spread of the leaf mold fungus.
Provide good ventilation and as much light as possible.
b. Attempt to avoid wetting the leaves when watering. Water early in the day to allow leaves to dry by mid-afternoon.

14. CONTROL
c.Maintain a temperature of at least 16 to 18℃ throughout the season.
d.Provide adequate plant and row spacing to avoid excessive shading.

15. CONTROL
2. Leaf mold resistant varieties are available, but because the fungus mutates readily (there are at least 12 races of the pathogen) resistant varieties are of limited use. Because new virulent races can develop in only a few years, a tomato variety which is resistant one year may be very susceptible the next. If available, grow varieties with more than one leaf mold resistance gene.

16. CONTROL
3. A fungicide spray program may help control the disease, but should be considered secondary to environmental control measures.
A weekly spray program may be necessary. For current recommendations refer to the above mentioned circular. Be sure to thoroughly cover all aboveground parts of every plant, especially the lower surface of the foliage, with each spray.

17. CONTROL
4. Reduce primary inoculum levels through sanitation, steam treatment of greenhouses, and seed treatment.
a. After harvest, carefully remove and destroy (burn) all plant debris.
b. Where possible, steam entire greenhouse sections between crops, preferably on a bright, hot day when little steam will be needed. Close all ventilators, and maintain the temperature at 57℃ for at least six hours.
c. Where necessary, use hot water treated seed. Treat seed for 25 minutes at exactly 50℃.

18. 小结 发生概况：分布？ 危害？产量损失 病害识别：发病时期？症状特点？ 病原：分类地位；生物学特性 病害发生发展规律：越冬、传播、入侵方式
发病及其影响因素：气象因素（温暖、高湿）；栽培管理；寄主抗病性
综合防治：选用抗病品种；种子消毒；加强栽培管理；合理生态管理；消灭菌源；化学防治

19. Early blight of tomato

20. Significance
Early blight of tomato, caused by the fungus Alternaria solani, is perhaps the most common foliar disease of tomatoes in the Northeast and is also common on potatoes. This disease causes direct losses by the infection of fruits and indirect losses by reducing plant vigor. Fruit from defoliated plants are also subject to sunscald.

21. Symptoms
Early blight produces a wide range of symptoms at all stages of plant growth. It can cause damping-off, collar rot, stem cankers, leaf blight, and fruit rot. The classic symptoms occur on the leaves where circular lesions up to 1/2" in diameter are produced. Within these lesions dark, concentric circles can be seen. The leaf blight phase usually begins on the lower, older leaves and progresses up the plant. Infected leaves eventually wither, die, and fall from the plant.

24. Pathogen
Alternaria solani (Ellis et Martin) Jones et Grout.

25. Disease Cycle Environmental Conditions
Alternaria spores germinate within 2 hours over a wide range of temperatures but at 80 to 85oF may only take 1/2 hour. Another 3 to 12 hours are required for the fungus to penetrate the plant depending on temperature. After penetration, lesions may form within 2-3 days or the infection can remain dormant awaiting proper conditions (60oF and extended periods of wetness).

26. Disease Cycle
Alternaria sporulates best at about 80oF when abundant moisture (as provided by rain, mist, fog, dew, irrigation) is present. Infections are most prevalent on poorly nourished or otherwise stressed plants.

27. Disease Cycle Survival and Dispersal
The fungus spends the winter in infected plant debris in or on the soil where it can survive at least one and perhaps several years. It can also be seed borne. New spores are produced the following season. The spores are transported by water, wind, insects, other animals including man, and machinery. Once the initial infections have occurred, they become the most important source of new spore production and are responsible for rapid disease spread

28. CONTROL Use only clean seed saved from disease-free plants.
Remove and destroy crop residue at the end of the season. Where this is not practical, plow residue into the soil to promote breakdown by soil microorganisms and to physically remove the spore source from the soil surface.

29. CONTROL
Practice crop rotation to non-susceptible crops (3 years). Be sure to control volunteers and susceptible weeds.
Promote good air circulation by proper spacing of plants.
Orient rows in the direction of prevailing winds, avoid shaded areas, and avoid wind barriers.
Irrigate early in the day to promote rapid drying of foliage.

30. CONTROL
Healthy plants with adequate nutrition are less susceptible to the disease.
Minimize plant injury and the spread of spores by controlling insect feeding.
Hand picking diseased foliage may slow the rate of disease spread but should not be relied on for control. Do not work in a wet garden.
Use resistant or tolerant varieties.
The preventative fungicide used on a seven to ten day schedule gives effective control.

31. 小结 发生概况：分布？ 危害？产量损失 病害识别：为害？发病时期？症状特点？ 病原：分类地位；生物学特性
病害发生发展规律：越冬、传播、入侵方式
发病及其影响因素：气象因素（高温、高湿）；寄主的生育期和长势；寄主抗病性
综合防治：选用抗病品种；选用无病种子；加强栽培管理；化学防治

32. Botrytis blight
Botrytis blight, or gray mold, as it is commonly known, has an exceptionally wide host range with well over 200 reported hosts.
The fungus can occur as both a parasite and a saprophyte on the same wide range of hosts.
This fungus disease is intriguing in that it can cause a variety of plant diseases including damping-off and blights of flowers, fruits, stems, and foliage of many vegetables and ornamentals.

33. Botrytis blight
It is a major cause of postharvest rot of perishable plant produce, including tomatoes at harvest and in storage. The disease can occur both in the greenhouse and in the field.
Besides tomato, gray mold is of concern to other vegetables including snap and lima beans(菜豆), cabbage, lettuce and endive, muskmelon（香瓜）, pea, pepper, and potato.

34. Symptoms
“Ghost spots” appear on fruits after periods of prolonged high humidity.
These superficial spots have a pale halo with a brown to black pinpoint spot in the center.
On unripe fruit, the halo is pale green or silvery, and generally the tissue inside the halo is paler green.
On ripe fruit, the halo is pale yellow. If warm and sunny weather occurs, then ghost spot symptoms usually do not develop further, although the marketability of the fruit may be affected. Fruit rot does not develop under these specific conditions.

35. Symptoms
Botrytis may develop on dying flowers and subsequently infect the fruit calyx. The lesions on fruit appear as light brown to gray spots, up to 3 cm in diameter, and irregular in shape. Later, a dark gray, velvety growth develops on the fruit surface, followed by a watery, soft rot.

36. Symptoms
Foliar symptoms are more common under humid greenhouse conditions.
Affected leaves show light tan or gray spots, and the infected areas become covered by a brown fungal growth.
The leaves wither and collapse. The fungus proceeds into the stem producing tan, elliptical cankers with concentric rings. Invasion of lesions by secondary fungi occurs. Stem cankers cause wilting of vines.

39. Pathogen
Gray mold is caused by the fungus Botrytis cinerea. One-celled spores are borne on branched conidiophores, and the arrangement of the spores gives the fungus its name, from the Greek botrys, meaning a bunch of grapes. Use of a hand lens may reveal the characteristic grape-cluster arrangement of spores. As the conidiophores dry out, they gently move and liberate the spores: usually air movements are sufficient to get the spores airborne.

41. Pathogen
The fungus often establishes itself on injured tissues and can persist as a saprophyte for long periods. Upon occasion, black sclerotia of variable size form on or just below, the host surface. The sclerotia have a black rind and a light interior composed of a dense mass of hyphae, or threads, of the fungus. Sclerotia measure up to 3 mm (occasionally 5 mm) in length and are usually smaller and thinner than those of the white mold fungus Sclerotinia sclerotiorum.

42. Pathogen
The sclerotia germinate to produce conidiophores or, rarely, give rise to small cup-shaped structures (apothecia), which are the sexual stage of the fungus. Sclerotia are resistant to environmental extremes and act as overwintering resting bodies.

43. Disease Cycle
The fungus overwinters as sclerotia or as mycelium in plant debris and may be seedborne as spores or mycelium in a few crops.
Other crops may also serve as sources of the pathogen and are likely to cross-infect.
The fungus is easily dispersed large distances by wind. Small pieces of infected plant tissue or fungal spores from infected plant debris are also disseminated shorter distances by splashing and windblown rain. High relative humidities are necessary for prolific spore production.

44. Disease Cycle
In the field, spores landing on tomato plants germinate and produce an infection when free water from rain, dew, fog, or irrigation occurs on the plant surface. Optimum temperatures for infection are between 18 and 24℃, and infection can occur within 5 hours. High temperatures, above 28℃, suppress growth and spore production.

45. Disease Cycle
Dying flowers are a favorable site for infection, but infections can also result from direct contact with moist infested soil or plant debris.
In the greenhouse, stem lesions develop either by direct colonization of wounds or through infected leaves. The presence of external nutrients, such as pollen grains in the infection droplet, can markedly increase infection.

46. Disease Cycle
The type of wound is said to influence stem lesion development; breaking off leaves is reported to give a lower incidence of stem lesions than cutting off leaves with a knife, leaving a stub.

49. Conditions for Disease Development
The fungus has a very wide host range that includes many vegetable crops.
Gray mold development, particularly fungus
sporulation and infection, is favored by cool, wet and humid weather.
The fungus requires a water film of several hours for spore germination, and a longer period of surface wetness for symptom development.

50. Conditions for Disease Development
Optimum relative humidity for spore production is about 90%, and most spores are produced during the night when the temperature is lower and the relative humidity is higher than during the day.
Temperatures of 17–23℃ are ideal for disease development. The length of the surface wetness period needs to be longer at the lower temperatures for disease development.

51. Conditions for Disease Development
The fungus generally infects plants through wounds; for example, the rough handling of young transplants. Penetration of intact tissue is rare.
Fruit can be infected through the stem scar, growth cracks, or other breaks in the skin.
Plants approaching maturity are more susceptible. The fungus can also penetrate dead flower tissue or dying foliage.

52. Conditions for Disease Development
Excessive application of nitrogen makes plants such as young transplants more susceptible to gray mold. Dense plant canopies will limit air movement within the crop, thus creating conditions for extended surface wetness at night and subsequent increased gray mold severity.

53. CONTROL
1. There is no known resistance to B. cinerea in tomato cultivars.
2. In the field, incorporate Botrytis-affected debris into the soil and allow it to decompose before establishing a new tomato crop, or burn diseased plant debris.
3. Plant in fields where good drainage is available and maintain weed control to minimize periods when plants are wet due to reduced air circulation.
4. In the greenhouse, maintain a relative humidity of
less than 80%, especially during the night.

54. CONTROL
5. Fungicide sprays help to control the disease. New specific fungicides for Botrytis are available but they should be rotated with general multi-site protectant fungicides to prevent the development of resistance in the fungus to the new chemical controls.

55. 小结 发生概况：分布？ 危害？产量损失 病害识别：为害？发病时期？症状特点？ 病原：生物学特性；寄主范围
病害发生发展规律：越冬、传播、入侵方式
发病及其影响因素：气象因素（低温、高湿）；栽培管理
综合防治：清除病残体；苗床处理；生态防治；加强栽培管理；化学防治

56. 7.2.4 Tomato Viral Diseases
Several virus diseases of tomato occur in Kansas, although they generally are not as prevalent as the wilt and foliar diseases. Three of the more common virus diseases are tobacco mosaic, cucumber mosaic, and tomato spotted wilt.

57. Tomato Viral Diseases
The tobacco mosaic virus can attack a wide range of plants, including tomato, pepper, eggplant, tobacco, spinach, petunia, and marigold.
On tomato, virus infection causes light and dark green mottled areas on the leaves. Stunting of young plants is common, and often is accompanied by a distortion and fern(蕨类植物)-like appearance of the leaves.

58. Tomato Viral Diseases
Older leaves curl downward and may be slightly distorted. Certain strains of the virus can cause a mottling, streaking, and necrosis of the fruits. Infected plants are not killed, but they produce poor quality fruit and low yields.

60. Tomato Viral Diseases
The cucumber mosaic virus has one of the broadest host ranges of any of the viruses. The disease affects a number of important vegetables and ornamentals including tomato, pepper, cucumber, melons, squash, spinach, celery, beets, and petunia. Tomatoes infected with the cucumber mosaic virus develop a slight yellowing and mottling of the older leaves.

61. Tomato Viral Diseases
Expanding leaves typically become twisted, curl downward, and develop a 'shoestring' appearance as a result of a restriction of the leaf surface to a narrow band around the midrib of the leaf. Diseased plants are stunted and produce small quantities of fruit.

63. Tomato Viral Diseases
The tomato spotted wilt virus also has a wide host range and can affect a number of ornamental plants as well as tomato. Early symptoms of spotted wilt on tomato are difficult to diagnose. Young, infected plants may show an inward cupping of leaves, and the foliage may appear off-color or have a slight bronze cast. In some cases, leaves with exhibit dark purple flecks or small necrotic concentric rings.

66. Development of Disease
The tobacco mosaic virus is very stable and can persist in dry contaminated soil, in infected tomato debris, on or in the seed coat. The virus is transmitted readily from plant to plant by mechanical means.

67. Development of Disease
This may simply involve picking up the virus while working with infected plant material, then inoculating healthy plants by rubbing or brushing against them with contaminated tools, clothing, or hands. Aphids are not vectors of the tomato mosaic virus, although certain chewing insects may transmit the pathogen.

68. Development of Disease
The cucumber mosaic virus overwinters in perennial weeds and may be transmitted to healthy plants by aphid vectors (although tomatoes are not the preferred host of aphids) or by mechanical means.
The cucumber mosaic virus cannot withstand drying, or persist in the soil. It also is more difficult than tobacco mosaic to transmit mechanically. Thus, cucumber mosaic tends to progress more slowly than tobacco mosaic in a field or garden.

69. Development of Disease
The spotted wilt virus is transmitted from plant to plant by several species of small insects called thrips. Thrips are less than one-quarter inch in length, light green to brown, and are extremely difficult to find on the plants. Several weedy hosts and ornamental plants may serve as alternate hosts for the virus.

70. CONTROL
Virus diseases cannot be controlled once the plant is infected. Therefore, every effort should be made to prevent introduction of virus diseases into the garden.
Many varieties of tomato are available with resistance to tobacco mosaic virus.
Sanitation is the primary means of controlling the other two virus diseases. Infected plants should be removed immediately to prevent spread of the pathogens.

71. CONTROL
Perennial weeds, which may serve as alternate hosts, should be controlled in and adjacent to the garden.
Avoid planting tomatoes next to cucurbits, spinach, or other vegetables and flowers susceptible to these diseases.
Control of insects, especially aphids and thrips, will help reduce the likelihood of cucumber mosaic and spotted wilt.

72. 小结 发生概况：分布？ 危害？产量损失 病害识别：发病时期？症状特点？ 病原：毒源种类 病害发生发展规律：不同毒源的传播途径、侵染来源
发病及其影响因素：种苗带毒情况；寄主抗病性；气象因素；栽培管理
综合防治：选用抗病品种；减少毒源数量；加强栽培管理；早期避蚜治蚜；化学防治；弱毒株系利用

73. 7.2.5 Phytophthora Blight of Pepper
Introduction
Phytophthora blight, a highly destructive disease of peppers, has increased in importance in recent years in Ohio and eastern states.
Other names applied to this disease of peppers are damping off and Phytophthora root rot, crown rot, and stem and fruit rot. All of these names can apply since all parts of the pepper plant are affected.

74. Phytophthora Blight of Pepper
P. capsici was first described by Leonin in 1922 on chili pepper in New Mexico.
The disease was subsequently reported in many pepper growing areas in the world.
Phytophthora blight causes yield losses up to 100% in pepper fields in Illinois.

75. Phytophthora Blight of Pepper
P. capsici has a broad host range, among which cucurbits, eggplants, and tomatoes are severely affected in Illinois.
It can become a serious problem during periods of heavy rainfall; the pathogen can spread rapidly through the crop, resulting in severe losses within a short time.

77. Symptom Phytophthora blight affects both seedlings and nature plants.
Infected seedlings show typical damping-off symptoms. Infection of older plants begins at or below the soil line.
Water-soaked, dark brown lesions on the lower stems (collar rot phase) usually extend upward for an inch or more above the soil line and may expand to girdle the stems, preventing upward movement of water and nutrients.
This often results in a sudden wilting of foliage.

79. Symptom
Root infections may also occur which kill roots and cause wilting of the plant without the appearance of stem cankers.
The foliar phase of this disease commonly occurs at forks in the branches, resulting in dark, girdling cankers and wilting of leaves and fruits.
Infected leaves develop circular or irregular, dark green, water-soaked lesions which dry and appear light tan.

80. Symptom
Fruit lesions may also appear as enlarging, watersoaked areas, which then shrivel and darken.
A mass of white fungal growth may develop inside the fruit, and seeds usually turn dark brown or black.
A fine, grayish-white to tan mold may also become evident over the lesion on the fruit surface.
Under humid conditions, fungal growth develops extensively over the entire fruit.

81. Pathogen Phytophthora capsici is a soilborne pathogen.
The pathogen produces several types of spores which enable it to spread throughout the field, and to persist in the field between crops.
P. capsici survives between crops as oospores or mycelium in infected tissue.
An oospore is a thick-walled sexual spore.
Oospores are resistant to desiccation, cold temperatures, and other extreme environmental conditions, and can survive in the soil in the absence of the host plant for many years.

82. Pathogen
Once pepper plants are transplanted into a field, and the environmental conditions are favorable, oospores germinate and produce sporangia and zoospores (asexual spores).
Rainfall, soil saturation, and temperatures between 24-29°C) are necessary for developmentof Phytophthora blight.

83. Disease Cycle
Zoospores, released in water, swim, and upon contact with host tissue, initiate infection.
Following infection, a girdling lesion is formed at the base of the plant near the soil line.
Sporangia are produced on the lesion surface and spread by splashing rain.
Production and spread of sporangia are repeated throughout the season.
Plants eventually die and oospores formed within the lesions are released into the soil as the plant decomposes.
Oospores will persist in the soil until another susceptible crop is planted.

84. CONTROL
A combination of methods is needed to effectively control this disease.
Strategies recommended for management of Phytophthora blight of pepper include preventing the pathogen from being moved to the field, reduction of soil moisture, reduction of Phytophthora spores in the soil, utilization of resistant varieties, and applying fungicides.

85. 小结 发生概况：分布？ 危害？产量损失 病害识别：发病时期？症状特点？ 病原：分类地位；形态特点；生物学特性
病害发生发展规律：越冬、传播、入侵方式
发病及其影响因素：气象因素（温湿度）；品种抗病性；栽培管理
综合防治：选用抗病品种；农业防治；化学防治（种子处理、及时处理中心病株）

86. Anthracnose of Pepper
Several species of plant pathogenic fungi in the genus Colletotrichum cause anthracnose in peppers and many other vegetables and fruits. Until the late 1990s, anthracnose of peppers and tomatoes was only associated with ripe or ripening fruit.
Since that time, a more aggressive form of the disease has become established in Ohio and other states. This form attacks peppers at any stage of fruit development and may threaten the profitability of pepper crops in areas where it becomes established. This disease can also affect tomatoes, strawberries, and possibly other fruit and vegetable crops.

87. Symptom
Circular or angular sunken lesions develop on immature fruit of any size. Often multiple lesions form on individual fruit.
When disease is severe, lesions may coalesce. Often pink to orange masses of fungal spores form in concentric rings on the surface of the lesions . In older lesions, black structures called acervuli may be observed. With a hand lens, these look like small black dots; under a microscope they look like tufts of tiny black hairs.

88. Symptom
The pathogen forms spores quickly and profusely and can spread rapidly throughout a pepper crop, resulting in up to 100% yield loss. Lesions may also appear on stems and leaves as irregularly shaped brown spots with dark brown edges .

90. Pathogen
Colletotriehum nigrum

91. Spores of Colletotrichum released
from a fungal fruiting body (acervulus)
with numerous black, spines (setae) on pepper.

92. Disease Cycle
The pathogen survives on plant debris from infected crops and on other susceptible plant species.
The fungus is not soil-borne for long periods in the absence of infested plant debris.
The fungus may also be introduced into a crop on infested seed.
During warm and wet periods, spores are splashed by rain or irrigation water from diseased to healthy fruit.
Diseased fruit act as a source of inoculum, allowing the disease to spread from plant to plant within the field.

93. Disease Cycle

94. CONTROL
Practice crop rotation with crops other than tomato, eggplant, and cucurbits for at least 3 years.
Avoid poorly drained fields for growing these crops.
Plant the crop on a ridge, or better yet on raised, dome-shaped beds to provide better soil drainage. Unmulched, lowprofile beds will deteriorate during the season and may not provide sufficient drainage in July and August when disease spread can occur.

95. CONTROL
Maintaining the uniform soil moisture necessary to prevent blossom end rot of peppers is difficult with raised beds unless trickle irrigation is used. Overhead irrigation, like rainfall, will encourage disease spread and should be discontinued if the disease is present.

96. CONTROL
Fungicide use will vary depending upon the crop grown and in some cases the particular disease phase to be controlled. Refer to the current Cornell Recommendations for Commercial Vegetable Production for a list of available fungicides and their proper use. Soil fumigation, although useful in greenhouse situations, is not practical for field use because the fungus quickly reinvades treated soil.

97. 小结 发生概况：分布？ 危害？产量损失 病害识别：发病时期？症状特点？ 病原：分类地位；形态特点；生物学特性
病害发生发展规律：越冬、传播、入侵方式
发病及其影响因素：气象因素（温湿度）；品种抗病性；栽培管理
综合防治：选用抗病品种；种子处理；加强栽培管理；清洁果园；化学防治

98. 7.2.7 Verticillium Wilt of eggplant

99. 1.significance
Verticillium wilt, caused by two species of soil-borne fungi-Verticillium dahliae and Verticillium albo-atrum, infects more than 200 species of plants, including many vegetables.
V. albo-atrum prefers cooler soils while V. dahliae can become a problem in greenhouse vegetable production. Sometimes, both species will occur in the same field.

100. Symptoms
Symptoms are subtle and may be confused with insufficient moisture or other vascular wilts.
A yellowing of lower leaves followed by wilting is the first sign of disease.
Lesions have a characteristic V-shaped pattern which is widest at the leaf margin.
Brown, necrotic tissue within lesions is surrounded by a large, irregular area of yellowing due to a systemic leaf toxin produced by the fungi.

101. Symptoms
Because Verticillium affects the water-conducting vessels, symptoms can appear on one side of the plant or on one side of a leaf.
Leaf necrosis is followed by wilting, stunting, and plant death.  When the stems of infected plants are cut lengthwise, the vascular tissue exhibits a brown discoloration. 

103. Pathogen
Verticillium dahliae
Verticillium albo-atrum

104. Disease cycle
Verticillium species survive on infested crop residues as microsclerotia or resistant mycelium and in symptomless weed hosts.
Infection generally occurs through wounds in the roots caused by cultivation, secondary root formation, or plant parasitic nematode feeding.
Both species are capable of long term survival in the soil. The disease is favored by cool weather and neutral to alkaline soils.

105. Control
There is no effective chemical treatment for Verticillium Wilt, short of soil sterilization by steam, broad spectrum fumigants, or soil solarization.
Practice long crop rotations with non-susceptible hosts. Benefits of this technique are limited by the extremely wide host range of the pathogens. Cereals or grasses should be included in the rotation.
Remove and destroy infested crop debris well away from production fields.
Control weeds in both the main crop and rotational crop, as many weeds are also hosts for Verticillium. 

106. 小结 发生概况：分布？ 危害？产量损失 病害识别：发病时期？症状特点？ 病原：分类地位；形态特点；生物学特性
病害发生发展规律：越冬、传播、入侵方式
发病及其影响因素：气象因素（温湿度）；品种抗病性；栽培管理
综合防治：选用抗病品种；无病留种和种子处理；加强栽培管理；化学防治