Key Technical Points for the Occurrence and Control of Sesame Diseases
Techniques for the Occurrence and Control of Sesame Diseases
(Agricultural Wealth Network) Sesame, as a high-oil crop, is planted in all regions. Because sesame diseases cause large-scale death or severe yield reduction, and because there is relatively little technical information on sesame, errors easily occur in disease diagnosis and control. The following is a summary of the occurrence of sesame diseases and comprehensive control measures for farmers to use in production.
I. Characteristics of the occurrence of major diseases. The main sesame diseases include sesame stem spot blight, sesame Fusarium wilt, sesame bacterial wilt, sesame Phytophthora blight, and others.
1. Sesame stem spot blight. Sesame stem spot blight is also called sesame stem blight, sesame black root madness, and other names. It mainly damages sesame stems, roots, and seedlings. When disease occurs at the seedling stage, the aboveground part of the diseased seedling wilts and dies, and the roots turn brown and die. After the stem is damaged, the diseased stem initially shows yellowish-brown water-soaked spots, which develop rapidly into ring-like spots, and in the late stage the lesions become dark brown; afterward the stem becomes hollow and breaks easily. After the roots are damaged, the main root and lateral roots gradually turn brown, and a large number of black sclerotia form within the root cortex, causing the roots to die. The pathogen of this disease overwinters as sclerotia on seeds, in soil, and on diseased plant residues. The following year, conidia spread in the field by wind, rain, and air currents, mainly invading and causing damage from the stem base, roots, and leaf petioles. The seedling stage and full flowering stage of sesame are the most susceptible. Diseased plants can produce conidia that spread and infect again. High temperature, high humidity, and abundant rain favor the occurrence and epidemic of the disease, and excessive nitrogen fertilizer, overly dense planting, and continuous cropping increase the damage.
2. Sesame Fusarium wilt. Sesame Fusarium wilt is also called half-side yellowing or yellowing, and is a typical vascular bundle disease. The pathogen mostly invades from the root tip and wounds of seedlings. After invading from the roots, the pathogen enters the vessels and spreads along the vessels to the stems, leaves, capsules, and seeds, causing the whole plant to become diseased and die. The stem base of diseased plants is reddish-brown, the stem vascular bundles are brown, and the leaves turn yellow, wilt, and die. Sometimes, when infection is limited to one side, it appears as disease and death on only one side. When moist, the affected parts have pink mold-like growth. The pathogen of this disease overwinters in the soil, in diseased plant residues, or inside and on the surface of seeds. Disease begins in June and reaches its peak in August. Continuous cropping of sesame, poor soil fertility, and high field humidity favor the occurrence and epidemic of the disease.
3. Sesame bacterial wilt. Sesame bacterial wilt is commonly called sesame plague and is a disease caused by bacteria. The pathogen invades through root wounds or natural openings and spreads upward from below within the plant vessels. Diseased plants initially appear as if lacking water, wilting during the day and recovering at night; after a few days they also wilt at night. The outer part of the root and stem of affected plants shows dark brown streaks, the internal vascular bundles are brown, and bacterial ooze exudes. The veins of affected leaves show dark green streaks, and diseased capsules show dark brown streaks. The pathogen of this disease overwinters in the soil with diseased plant residues and spreads through running water or farming operations. The disease peak mostly occurs in summer from July to August. After storms, when the temperature rises sharply, the occurrence and epidemic of the disease are favored.
4. Sesame Phytophthora blight. Sesame Phytophthora blight is a devastating disease. It mainly damages the stem base, stems, capsules, and leaves of sesame. After the stem base is damaged, it initially appears dark green and water-soaked, then becomes reddish-brown, sunken, and with longitudinal cracking of the cortex. After stems and capsules are damaged, the diseased parts appear dark green and water-soaked, constricted and sunken, and bear cotton-like white mold. After leaves are damaged, yellowish-brown lesions appear, and the lesions have indistinct concentric rings. The pathogen of this disease overwinters as mycelium or oospores in diseased plant residues. The following year, the pathogen infects the stem base, produces sporangia, and spreads by wind, rain, and running water for expanded secondary infection. Disease begins in July at the sesame budding stage and reaches its peak in August. Damage is severe under rainy and humid conditions.
II. Comprehensive control techniques
1. Select disease-resistant varieties and treat seeds. Choose varieties with good quality, high yield, waterlogging tolerance, and strong disease resistance, such as Yuzhi No. 8, Yizhi No. 1, and others. Before sowing, soak seeds in warm water at 55°C for 10 minutes or in warm water at 60°C for 5 minutes, then dry them and sow. Alternatively, mix seeds with quintozene plus thiram (1:1), with the amount used accounting for 0.5-1% of seed weight; or soak seeds in 0.5% copper sulfate solution for half an hour. All of these have relatively good control effects.
2. Agricultural control. Soil-borne diseases and insect pests of sesame are severe, and continuous cropping is most taboo. Implementing a 3-5 year rotation of sesame with cotton, sweet potato, and gramineous crops can relatively well control the occurrence and epidemic of diseases. After sesame harvest, promptly remove diseased residues from the field and burn or deeply bury them centrally to reduce overwintering inoculum sources. Promptly pull out diseased plants and carry them out of the field for destruction to prevent the spread and expansion of the pathogen. Strengthen fertilizer and water management, increase basal fertilizer application, with basal fertilizer mainly consisting of medium- and slow-release organic fertilizer and mixed with phosphorus and potassium fertilizers. At the seedling stage, do not apply or apply little nitrogen fertilizer, cultivate healthy seedlings, and make it difficult for the pathogen to invade. Adopt high-ridge cultivation, promptly clear ditches and drain water, prevent standing water in the field, and reduce field humidity.
3. Chemical control. Control of sesame diseases should mainly rely on agricultural control, and chemical control should be mastered by spraying for protection before disease occurrence or by applying chemicals at the early stage of disease. Control agents include 37% Kuwei Like wettable powder 800-fold solution, 40% carbendazim suspension concentrate 700-fold solution, 50% thiophanate-methyl wettable powder 800-1000-fold solution, 80% copper sulfate wettable powder 800-fold solution, and others.
I. Characteristics of the occurrence of major diseases. The main sesame diseases include sesame stem spot blight, sesame Fusarium wilt, sesame bacterial wilt, sesame Phytophthora blight, and others.
1. Sesame stem spot blight. Sesame stem spot blight is also called sesame stem blight, sesame black root madness, and other names. It mainly damages sesame stems, roots, and seedlings. When disease occurs at the seedling stage, the aboveground part of the diseased seedling wilts and dies, and the roots turn brown and die. After the stem is damaged, the diseased stem initially shows yellowish-brown water-soaked spots, which develop rapidly into ring-like spots, and in the late stage the lesions become dark brown; afterward the stem becomes hollow and breaks easily. After the roots are damaged, the main root and lateral roots gradually turn brown, and a large number of black sclerotia form within the root cortex, causing the roots to die. The pathogen of this disease overwinters as sclerotia on seeds, in soil, and on diseased plant residues. The following year, conidia spread in the field by wind, rain, and air currents, mainly invading and causing damage from the stem base, roots, and leaf petioles. The seedling stage and full flowering stage of sesame are the most susceptible. Diseased plants can produce conidia that spread and infect again. High temperature, high humidity, and abundant rain favor the occurrence and epidemic of the disease, and excessive nitrogen fertilizer, overly dense planting, and continuous cropping increase the damage.
2. Sesame Fusarium wilt. Sesame Fusarium wilt is also called half-side yellowing or yellowing, and is a typical vascular bundle disease. The pathogen mostly invades from the root tip and wounds of seedlings. After invading from the roots, the pathogen enters the vessels and spreads along the vessels to the stems, leaves, capsules, and seeds, causing the whole plant to become diseased and die. The stem base of diseased plants is reddish-brown, the stem vascular bundles are brown, and the leaves turn yellow, wilt, and die. Sometimes, when infection is limited to one side, it appears as disease and death on only one side. When moist, the affected parts have pink mold-like growth. The pathogen of this disease overwinters in the soil, in diseased plant residues, or inside and on the surface of seeds. Disease begins in June and reaches its peak in August. Continuous cropping of sesame, poor soil fertility, and high field humidity favor the occurrence and epidemic of the disease.
3. Sesame bacterial wilt. Sesame bacterial wilt is commonly called sesame plague and is a disease caused by bacteria. The pathogen invades through root wounds or natural openings and spreads upward from below within the plant vessels. Diseased plants initially appear as if lacking water, wilting during the day and recovering at night; after a few days they also wilt at night. The outer part of the root and stem of affected plants shows dark brown streaks, the internal vascular bundles are brown, and bacterial ooze exudes. The veins of affected leaves show dark green streaks, and diseased capsules show dark brown streaks. The pathogen of this disease overwinters in the soil with diseased plant residues and spreads through running water or farming operations. The disease peak mostly occurs in summer from July to August. After storms, when the temperature rises sharply, the occurrence and epidemic of the disease are favored.
4. Sesame Phytophthora blight. Sesame Phytophthora blight is a devastating disease. It mainly damages the stem base, stems, capsules, and leaves of sesame. After the stem base is damaged, it initially appears dark green and water-soaked, then becomes reddish-brown, sunken, and with longitudinal cracking of the cortex. After stems and capsules are damaged, the diseased parts appear dark green and water-soaked, constricted and sunken, and bear cotton-like white mold. After leaves are damaged, yellowish-brown lesions appear, and the lesions have indistinct concentric rings. The pathogen of this disease overwinters as mycelium or oospores in diseased plant residues. The following year, the pathogen infects the stem base, produces sporangia, and spreads by wind, rain, and running water for expanded secondary infection. Disease begins in July at the sesame budding stage and reaches its peak in August. Damage is severe under rainy and humid conditions.
II. Comprehensive control techniques
1. Select disease-resistant varieties and treat seeds. Choose varieties with good quality, high yield, waterlogging tolerance, and strong disease resistance, such as Yuzhi No. 8, Yizhi No. 1, and others. Before sowing, soak seeds in warm water at 55°C for 10 minutes or in warm water at 60°C for 5 minutes, then dry them and sow. Alternatively, mix seeds with quintozene plus thiram (1:1), with the amount used accounting for 0.5-1% of seed weight; or soak seeds in 0.5% copper sulfate solution for half an hour. All of these have relatively good control effects.
2. Agricultural control. Soil-borne diseases and insect pests of sesame are severe, and continuous cropping is most taboo. Implementing a 3-5 year rotation of sesame with cotton, sweet potato, and gramineous crops can relatively well control the occurrence and epidemic of diseases. After sesame harvest, promptly remove diseased residues from the field and burn or deeply bury them centrally to reduce overwintering inoculum sources. Promptly pull out diseased plants and carry them out of the field for destruction to prevent the spread and expansion of the pathogen. Strengthen fertilizer and water management, increase basal fertilizer application, with basal fertilizer mainly consisting of medium- and slow-release organic fertilizer and mixed with phosphorus and potassium fertilizers. At the seedling stage, do not apply or apply little nitrogen fertilizer, cultivate healthy seedlings, and make it difficult for the pathogen to invade. Adopt high-ridge cultivation, promptly clear ditches and drain water, prevent standing water in the field, and reduce field humidity.
3. Chemical control. Control of sesame diseases should mainly rely on agricultural control, and chemical control should be mastered by spraying for protection before disease occurrence or by applying chemicals at the early stage of disease. Control agents include 37% Kuwei Like wettable powder 800-fold solution, 40% carbendazim suspension concentrate 700-fold solution, 50% thiophanate-methyl wettable powder 800-1000-fold solution, 80% copper sulfate wettable powder 800-fold solution, and others.