Liu Jianhua Chen Shaoguang

About 50 species have been reported in the world, up to 199 1, and there are nearly 30 species in China. Canker disease, stem blight, root-knot nematode disease and brown spot disease are serious hazards. Seedling disease and rotten fruit (gray mold, etc.). Sometimes it will cause great losses in storage and transportation.

ulcer

It is a devastating disease, which occurs in the United States, Japan, China and Hunan. Damage to the trunk, branches and leaves of kiwifruit, causing branch blight or whole plant death. Dark brown water-stained ulcer spots are formed at the bud points of stems and branches, lenticels, branches or trimmed wounds, the affected cortex is depressed or broken, and the mixture of reddish brown fungus pus and tree juice oozes after the colostrum is white; Small brown spots are formed on new leaves, surrounded by yellow halo, and dead spots are occasionally formed on calyx and pedicel. Pathogen Pseudomonas syringae. Kiwi e is a kind of bacteria, which is also harmful to plums and peaches. The pathogen mainly overwinters on diseased plants and residues, invades through natural orifices and wounds, spreads through wind and rain, insects and agricultural operations, and reinfects frequently. The average temperature in spring reached about 65438 00℃, and the disease began to spread. In case of rainstorm, rain and high humidity, it is easy to be popular. In Hunan, there are two peaks every year: spring is from bleeding to flowering, autumn is before and after fruit ripening, and spring is the worst. Low temperature, freezing injury, fog exposure, excessive pruning and weak trees will aggravate the disease. Disease control: warm winter planting should be chosen; Strict seedling quarantine; Select high-yield and disease-resistant varieties or raise seedlings in disease-free areas; Keep out the cold in winter, remove the sick and disabled, and avoid pruning or excessive pruning during bleeding; Spraying DTM bactericide, agricultural streptomycin or kasugamycin in spring and autumn, defoliation or pruning, and injecting streptomycin solution into the main borehole for treatment.

withered

It was found for the first time in Shandong, China, and it mainly harms branches and vines over two years old. The new branches and vines are not diseased, and the lesions mostly occur at the incision, incision and bifurcation of branches and vines. The lesion site is reddish brown and dark brown, irregular, with rotten tissue and a little depression in the later stage, with black particles (pathogen conidia) on it. When wet, the particles gush out white spore horns, and the diseased spots spread around branches and vines, leading to the death of the upper part. The pathogen is Clostridium staphylococci, belonging to Coccidae. It also infringes on grapes and hawthorn, and the tree is weak, frozen and mechanically injured, and the disease is aggravated when the tree is old. Bacteria overwinter in diseased tissues, invade through natural orifices or wounds, spread through wind, rain and insects, reinfection and potential infection. The peak of the disease is concentrated in the germination and flowering period. Disease control: strengthen cultivation management and improve tree vigor; In cold winter, remove diseased branches and vines; Carbendazim, bacteria, etc. should be applied after harvest, before germination or before topping.

root knot nematode disease

Common, the diseased plant has a large number of root nodules, the overground part grows weakly, the leaves are Huang Yi, and the results are few and small. The pathogen is meloidogyne incognita, belonging to the order meloidogyne incognita. Pathogenic nematodes have a wide host range, overwinter in soil or host roots, infect new roots with larvae, and spread slowly, which can be spread over a long distance through diseased seedlings. Disease control: adopt disease-free seedlings and treat the diseased seedlings or soil with warm water or nematicides such as carbofuran and triadimefon.

brown spot

It happened in the south. It mainly harms leaves, but also infects branches and fruits. In the early stage, dark green water spots were found on the edge of leaves, and then they expanded into large dark green or irregular spots with brown center and many small black spots on the edge. Damaged leaves are curled, cracked, dry and easy to fall off. The pathogen is Actinidia pseudocercospora var. Actinidia. Garcinia, belonging to Myxomycetes. High temperature and humidity, too much nitrogen fertilizer. When the leaves are tender, the disease is serious. Pathogens overwinter in diseased tissues or diseased remnants, conidia invade from stomata after germination, spread by wind, rain and insects, and then infect more. Hunan Province generally starts from May to June, and the peak period is from July to August. Disease control: clearing the garden in winter and burning diseased branches and leaves; Apply more phosphorus and potassium fertilizer; Spraying carbendazim, chlorothalonil and other pesticides in winter and bamboo shoot picking period.

gray mold

The main diseases of rotten fruit of kiwifruit during storage occurred in the main producing countries of kiwifruit. The diseased fruit begins to rot from the pedicle, the diseased part is dark and elastic, the pulp is watery, transparent, often pink-brown, and the surface is covered with gray-white mold. The pathogen is Sclerotinia sclerotiorum, which belongs to leptospira of Ascomycetes. The asexual state is botrytis cinerea, belonging to Myxomycetes. The host range is wide. Overwintering in diseased tissues, diseased bodies or soil, infecting petals first in the following spring, and producing a large number of conidia in full bloom, which are spread by wind and rain and falling flowers, and then infect more. The spores attach to fruits, invade through contact with wounds in the process of harvesting, grading and packaging, and become ill after storage for a period of time. Disease prevention and control: Pay attention to the prevention and control with carbendazim, benlaite, Dijundan, diamide and chlorpheniramine in the early flowering period and 3-7 days before fruit harvesting, and soak the fruit with the above bactericide and calcium chloride within 24 hours after fruit harvesting.

Dahlia leaves turn yellow and wither) Verticillium dahliae vascular bundle (plant Penicillium italicum, Actinidia pseudostemona, brown stem rot, black rot and white rot, Sclerotinia sclerotiorum, Sclerotinia sclerotiorum, fruit of Sclerotinia sclerotiorum, Pseudomonas aeruginosa, bacterial flower rot, root cancer, Agrobacterium crown gall, roselle white stripe disease, Athlete's bacterial leaf blight, Phytophthora. Root rot, Armillaria mellea root rot, cucumber scab, root rot, cucumber scab, stem rot, cucumber scab, kiwifruit rust, tomato leaf powdery mildew, tomato leaf powdery mildew, anthracnose, leaves, branches, flowers and fruits. The name of the disease is the damaged part.

Other common diseases of kiwifruit

See table for other common diseases.

Density effect

Density effect

Zhao meiqi

Influence of host plant density on disease spread and epidemic. This influence includes: ① In a certain range, the greater the planting density, the farther the disease spread and the higher the epidemic speed. This is a positive effect conducive to the spread of the disease. It has a more obvious effect on soil-borne diseases and rain-borne diseases not far away. (2) The plants are too dense, which reduces the air velocity in the canopy and hinders the spread of spores. This is a negative effect that is not conducive to communication. There is still a lack of quantitative research on the size of this impact. So the so-called density effect usually refers to the former. In addition, density also affects farmland microclimate, such as temperature, humidity, canopy density, etc., and indirectly affects host disease resistance and disease epidemic.

As early as 1960s, researchers have discussed the qualitative aspects of density effect, and compared the density effect in plant disease epidemic and human epidemic. The quantitative analysis of density effect began in 1980s. If D represents the primary or generational transmission distance and Den represents the plant spacing (or leaf spacing) of the infected host, it is obvious that only when D≥Den is within the range of disease transmission can the infected host be infected and the value-added of pathogenic bacteria be realized. Den = d is the threshold of disease transmission. This is an important threshold for the prevalence of soil-borne diseases. Facts have proved that the witches' broom disease of paulownia forest planted in patches is more serious than that of individual trees planted by farmers.

In the case of frequent reinfection, the positive effect of density is the bacterial proliferation rate of each infection. When D≥Den, the greater the density (that is, the smaller the Den), the more susceptible plants the host will have within the transmission distance of one generation or another. The number of the second generation diseases is directly proportional to the density. The second generation propagation distance calculated according to the same disease gradient increases with the increase of density. By analogy, after many generations of transmission, the condition and transmission distance are different.

The higher the density of plants that reach or exceed the threshold of disease transmission, the faster the epidemic. Therefore, disease epidemic can be regarded as a density effect, and disease epidemic is the result of high density. This will help to better implement intercropping or control planting density in cultivation and control, take measures to sow disease-resistant varieties and susceptible varieties or plant multi-line varieties, reduce effective density (for disease transmission), and play a role in alleviating diseases.

Cotton diseases

Cotton diseases

Gu Benkang

There are more than 120 known species. About 40 species have been found in China, among which 15 species are seriously harmful, mainly including seedling diseases, boll diseases, Fusarium wilt and verticillium wilt, stem and leaf diseases in adult stage and physiological diseases. Cotton-growing countries lose about 65,438+00% of cotton production every year due to diseases.

brief history

The United States first began to study cotton diseases, and Pahmeier reported the root rot in Texas in 1888. Cotton Fusarium wilt was discovered by Atkinson in 189 1 year, and cotton Fusarium wilt, anthracnose, angular leaf spot and nematodiasis were studied in 1892. 1895 ~ 1900, River and Orton successfully selected cotton varieties resistant to Fusarium wilt in the hardest hit areas. 19 14 Verticillium dahliae was found in Virginia. In China, cotton seedling diseases were described as early as in the Complete Book of Agricultural Administration compiled by Xu Guangqi (1562 ~ 1633) in the Ming Dynasty, but the investigation and research on cotton diseases began with the Study on Cotton Angular Spot published in the Agricultural Business Daily of19. In the next 20 years, more than 20 papers were published on the occurrence and harm of cotton diseases and the research and control methods of cotton diseases in various countries in the world. 193 1, Deng published the prevention and control of cotton seedling blight, and 1935 published the study on the occurrence and control of major cotton diseases. During the period of 1934- 1936, Shen et al. published China's monographs on cotton diseases in China and cotton diseases in China. From the late 1930s to the mid-1940s, Zhou, Zhou, Zhou and Zhou successively carried out research on cotton diseases. In 1950s and 1960s, attention was paid to the research of seedling diseases and verticillium wilt, and effective control measures were put forward, such as the application of Wuxi mixture, 40 1 402 antibacterial agent, etc. In 1970s, the National Cooperative Group for Comprehensive Control of Cotton Blight and Verticillium Wilt was established, which made breakthroughs in disease investigation, physiological differentiation of pathogenic bacteria, breeding of disease-resistant varieties and research on comprehensive control measures. In the 1980s, great attention was paid to the research on cotton verticillium wilt, and achievements were made in physiological differentiation of cotton verticillium wilt, identification of cotton variety resources resistance, breeding of new varieties resistant to verticillium wilt, and prevention and control of cotton diseases by farming and cultivation measures.

kind

There are more than 10 kinds of cotton seedling diseases, the most important of which are anthracnose [cotton coccidioides, cotton damping off], damping off [Donk scab, sheath blight] and angular leaf spot [Xanthomonas campestris]. Smith dye] and so on. , causing rotten seeds, rotten buds, root rot, leaf spot and other symptoms. There are more than 20 kinds of cotton boll diseases, mainly including Phytophthora ramie, anthracnose, angular leaf spot and Fusarium moniliforme. Pink disease [Trichosporon pink (bull. ) link] and Diplodia gossypina Cooke. In addition, there are many weakly parasitic or saprophytic fungi on the clock. Cotton wilt. (ATK。 Snyder et Hansen] and verticillium dahliae Kleb. It is a soil-borne Fusarium wilt, which is listed as a plant quarantine disease in China and is seriously harmful in some cotton areas in China. Stem and leaf diseases of cotton in adult stage are common, such as stem rot (Sclerotium rolfsii Sacc). ) and red rot. Stem blight that damages the stem; Leaf spot, brown spot. Et Martin), Alternaria macrospora Zimm. ) and white spots (Colporium areola Atk. ) It's harmful to leaves. There are many reasons for physiological diseases of cotton, such as root rot and seedling death caused by waterlogging or drought in cotton field, and large-area red leaves (or yellow leaves) caused by imbalance of fertilizer and water in the later stage of cotton growth. Stem blight is the most common symptom. In addition, the lack of potassium, magnesium, boron and other elements in the soil causes various nutrient deficiency diseases.

It has caused harm to some cotton-producing countries in the world. The unreported diseases in China include root rot [duggar) hennebent], cotton rust in southwest China [Puccinia cacabata Arthur et hoeway], spiny nematode (Belonclaimus longicaudatus Rau), cotton leaf curl virus, cotton stenosis virus and other virus diseases. The most important one is root rot, which has been listed as the quarantine object of imported plants in China. The host range of pathogenic bacteria is extremely wide, including more than 2000 kinds of plants such as fields, fruit trees, vegetables, flowers and weeds.

Be distributed

China is divided into five major cotton areas according to natural regions, and the diseases in each cotton area are different. ① South China cotton region. Including most of Yunnan, Xichang, Sichuan, Guizhou and southern Fujian, Guangdong, Guangxi, Taiwan Province and so on. Boll disease is the main disease, and cotton verticillium wilt also occurs. ② Cotton region in the Yangtze River basin. Daiyun Mountain, Jiulianshan Mountain and Wuling Mountain, the watershed in central Guizhou to the north of Daliangshan Mountain, the cotton area in the Yellow River basin to the south, the seashore in the east and the western edge of Sichuan Basin in the west. There are many epidemics in seedling stage, including anthracnose, damping-off and red rot. Fusarium wilt is serious, and verticillium wilt occurs in some areas, among which bell rot is the most common, and anthracnose is also quite serious in the middle and lower reaches. ③ Cotton region in the Yellow River basin. Irrigation canals in Qinling Mountains, Funiu Mountain, Huaihe River and northern Jiangsu are in the north, and the super-early cotton area in the north is in the south. From Longhai in the west to the seaside in the east. Rhizoctonia solani is the main disease in seedling stage, and red rot and anthracnose also occur, and Fusarium wilt and verticillium wilt occur together. Among the boll diseases, boll rot is the most common, followed by red rot and anthracnose. (4) Extra-early-maturing cotton areas in the north. West of Gansu-Shaanxi Mountains and east of northwest inland cotton areas, including most of Liaoning, Jinzhong, northern Shaanxi and Longdong, seedling diseases are serious, mainly verticillium wilt, Fusarium wilt and boll disease also occur. ⑤ Northwest inland cotton area. To the west of Liupanshan Mountain, including Hexi Corridor in Xinjiang and Gansu, and irrigation areas along the Yellow River in Gansu and Ningxia, the occurrence of verticillium wilt is relatively light, while Fusarium wilt, carbon rot and black root disease are serious in some areas, and the seedling diseases are not prominent, and boll rot rarely occurs.

Occurrence law

Anthracnose, angular leaf spot, red rot, etc. , mainly infected by infected seeds, while damping off, damping off and epidemic disease are mainly soil-borne diseases. Pathogens of Fusarium wilt and Verticillium wilt can survive in soil for a long time, so soil-borne diseases are the main diseases in epidemic areas, and seed-borne diseases are an important way of long-distance transmission. Most pathogens of stem and leaf diseases in adult stage overwinter in the disease body and become the primary source of infection in the coming year. Many pathogens in cotton boll diseases can be damaged at seedling stage and adult stage, and their transmission routes are the same. Some weakly parasitic fungi, such as auricularia auricula, auricularia auricula, Aspergillus, soft rot fungi, etc., are widely distributed in nature and can be destroyed by wind and rain, water and insects.

The occurrence of cotton diseases needs a suitable ecological environment, among which meteorological conditions and soil environment are particularly important. Low temperature and rainy weather in early spring is beneficial to the occurrence and harm of seedling diseases. From August to September, the average daily temperature is 25 ~ 30℃ and the relative humidity is above 85%, which often leads to serious bell rot. Verticillium wilt is more serious in cotton fields with rainy climate and rich organic matter. The harm of root-knot nematodes will weaken the resistance of cotton plants to Fusarium wilt, which is beneficial to the occurrence of Fusarium wilt. Unfavorable environmental conditions can also induce non-communicable diseases, such as element deficiency caused by various trace elements, and "red leaf stem blight" and "yellow leaf stem blight" which occur in a large area due to water and fertilizer shortage in the later stage of cotton.

disease control

According to different disease types, take corresponding comprehensive prevention and control measures.

Cotton seedling diseases are mainly controlled by cotton seed treatment, timely sowing and strengthening cultivation management, supplemented by field spraying protection when necessary.

The prevention and control of cotton verticillium wilt should focus on strict plant quarantine and protection of epidemic-free areas. Disease-resistant or disease-resistant varieties should be selected in disease-free areas, and comprehensive prevention and control measures such as cultivation management, chemical treatment of seeds and soil, and paddy-upland rotation should be implemented. In 1950s, there were 52- 128 in China, 40-1in Shaanxi in 1960s, 86- 1 in 1970s and medium 12 in 1980s. These varieties can resist more than two diseases.

The prevention and control of stem and leaf diseases in adult stage is mainly to strengthen cultivation management and spray pesticides when necessary.

The prevention and control of cotton boll disease is an unsolved problem at present. The occurrence of boll rot is related to cotton varieties, field climate, cultivation management and pests and diseases. At present, reasonable fertilization, timely pruning and leaf picking, removal of a small number of fruit branches at the base, spray protection and other measures are mainly taken to reduce the loss of rotten bells.

There are many reasons for physiological diseases. On the basis of judging the reasons, we must take corresponding measures to adjust the soil ecological conditions to a normal level, so as to effectively control them.

philology

Shen, editor-in-chief: basic research and control of cotton diseases, Science Press, Beijing, 1992.