Oil seed and Cash crops Diseases | Diseases of Field & Horticultural Crops & Their Management-II

 Diseases of Field & Horticultural Crops & Their Management-II 3(2+1)

Unit-II

Syllabus
Oil seed Cash crops:

Sunflower: Sclerotinia stem rot and Alternaria blight; 

Mustard: Alternaria blight, white rust, and downy mildew; 

Sugarcane: red rot, smut, wilt, grassy shoot, and ratoon stunting; 

Cotton:  vascular wilt, and black arm

Sunflower

1. Sclerotinia stem rot: Sclerotinia stem rot is a fungal disease that affects sunflower crops, causing wilt, lodging, and white mould on stems, leaves, and flower heads. Management of Sclerotinia stem rot in sunflower crops involves a combination of cultural, chemical, and biological approaches.
   • Cultural practices: Cultural practices such as crop rotation, proper plant spacing, and removing infected plant material can help reduce the incidence and severity of Sclerotinia stem rot in sunflower crops. Planting disease-resistant varieties and using certified disease-free seeds can also aid in the prevention of disease spread.
   • Chemical control: Fungicides can be used to manage Sclerotinia stem rot in sunflower crops. Fungicides should be used as a preventative measure or at the first sign of disease.
   • Biological control: Some beneficial microorganisms, such as certain strains of bacteria and fungi, can help suppress Sclerotinia stem rot. These biocontrol agents can be applied to crops as a preventative measure.
2. Alternaria blight: Alternaria blight is a fungal disease that affects sunflower crops, causing circular, dark spots on leaves and stems, and can lead to yield loss. Management of Alternaria blight in sunflower crops involves a combination of cultural, chemical, and biological approaches.
   • Cultural practices: Cultural practices such as crop rotation, proper plant spacing, and removing infected plant material can help reduce the incidence and severity of Alternaria blight in sunflower crops. Planting disease-resistant varieties and using certified disease-free seeds can also aid in the prevention of disease spread.
   • Chemical control: Fungicides can be used to manage Alternaria blight in sunflower crops. 
   • Biological control: Some beneficial microorganisms, such as certain strains of bacteria and fungi, can help suppress Alternaria blight. These biocontrol agents can be applied to crops as a preventative measure.

It's important to note that different sunflower varieties may require different management strategies for Sclerotinia stem rot and Alternaria blight and that an integrated approach combining multiple strategies is often the most effective. Regular monitoring and early detection are also important for the successful management of these diseases in sunflower crops.

Mustard

Alternaria blight

Alternaria blight is a fungal disease that affects mustard crops, causing brown or black spots on leaves and stems, and can lead to yield loss. Management of Alternaria blight in mustard crops involves a combination of cultural, chemical, and biological approaches.

1. Cultural practices: Cultural practices such as crop rotation, proper plant spacing, and removing infected plant material can help reduce the incidence and severity of Alternaria blight in mustard crops. Planting disease-resistant varieties and using certified disease-free seeds can also aid in the prevention of disease spread.
2. Chemical control: Fungicides can be used to manage Alternaria blight in mustard crops. A combination of different fungicides with different modes of action is recommended to prevent the development of resistance.
3. Biological control: Some beneficial microorganisms, such as certain strains of bacteria and fungi, can help suppress Alternaria blight. These biocontrol agents can be applied to crops as a preventative measure.
4. Integrated pest management: An integrated approach combining multiple strategies is often most effective in managing Alternaria blight in mustard crops. This may include a combination of cultural practices, chemical control, and biological control, as well as regular monitoring and early detection.

It's important to note that different mustard varieties may require different management strategies for Alternaria blight and that the timely application of fungicides is critical for the successful management of the disease. Regular monitoring and early detection are also important for the successful management of Alternaria blight in mustard crops.

White Rust

White rust is a fungal disease caused by the pathogen Albugo candida, which affects mustard plants, causing leaf spots, stem lesions, and blisters on pods. In severe cases, the disease can cause significant yield loss. Here are some management strategies for white rust in mustard crops:

1. Cultural practices: Cultural practices such as crop rotation, removal of crop debris, and maintaining appropriate plant spacing can help reduce the incidence and severity of white rust in mustard crops. Planting resistant varieties and using certified disease-free seeds can also help prevent the disease from spreading.
2. Chemical control: Fungicides can be used to manage white rust in mustard crops. A combination of different fungicides with different modes of action is recommended to prevent the development of resistance.
3. Biological control: Some beneficial microorganisms, such as certain strains of bacteria and fungi, can help suppress white rust. These biocontrol agents can be applied to crops as a preventative measure.
4. Integrated pest management: An integrated approach combining multiple strategies is often most effective in managing white rust in mustard crops. This may include a combination of cultural practices, chemical control, and biological control, as well as regular monitoring and early detection.

It's important to note that different mustard varieties may require different management strategies for white rust and that the timely application of fungicides is critical for the successful management of the disease. Regular monitoring and early detection are also important for the successful management of white rust in mustard crops.

Downy mildew

Downy mildew is a fungal disease caused by the pathogen Peronospora parasitica, which affects mustard plants, causing yellowing and wilting of leaves, stunted growth, and reduced yield. Here are some management strategies for downy mildew in mustard crops:

1. Cultural practices: Cultural practices such as crop rotation, proper plant spacing, and removing infected plant material can help reduce the incidence and severity of downy mildew in mustard crops. Planting resistant varieties and using certified disease-free seeds can also help prevent the disease from spreading.
2. Chemical control: Fungicides can be used to manage downy mildew in mustard crops. Fungicides should be used as a preventative measure or at the first sign of disease. A combination of different fungicides with different modes of action is recommended to prevent the development of resistance.
3. Biological control: Some beneficial microorganisms, such as certain strains of bacteria and fungi, can help suppress downy mildew. These biocontrol agents can be applied to crops as a preventative measure.
4. Integrated pest management: An integrated approach combining multiple strategies is often most effective in managing downy mildew in mustard crops. This may include a combination of cultural practices, chemical control, and biological control, as well as regular monitoring and early detection.

It's important to note that different mustard varieties may require different management strategies for downy mildew and that the timely application of fungicides is critical for the successful management of the disease. Regular monitoring and early detection are also important for the successful management of downy mildew in mustard crops.

Sugarcane

1. Red rot: Red rot is a fungal disease caused by the pathogen Colletotrichum falcatum, which affects sugarcane plants, causing reddish-brown discolouration and soft rotting of the internodes. The pathogen can survive in the soil and on infected plant debris and can spread through wind, water, and infected plant material. Here are some management strategies for red rot in sugarcane crops:

   • Use certified disease-free seed cane for planting: It is important to use high-quality, certified disease-free seed cane for planting to minimize the risk of introducing the pathogen into the crop.
   • Plant resistant/tolerant varieties: Some sugarcane varieties are more resistant or tolerant to red rot than others. Planting these varieties can help reduce the risk of disease.
   • Practice proper sanitation measures: Remove and destroy diseased plant debris to prevent the buildup of the pathogen in the soil. Proper sanitation can help reduce the risk of disease.
   • Avoid planting sugarcane in soils with a history of red rot infestation: The pathogen can survive in the soil for long periods of time, so it is important to avoid planting sugarcane in soils with a history of red rot infestation.
   • Apply fungicides at the recommended time and rate as a preventative measure: Fungicides can be applied preventatively to protect plants from infection. Timing and rate of application will depend on the specific fungicide used and the severity of the disease.

2. Smut: Smut is a fungal disease caused by the pathogen Sporisorium scitamineum, which affects sugarcane plants, causing the formation of black, powdery spores on the inflorescences. The pathogen can survive in the soil and on infected plant debris and can spread through wind, water, and infected plant material. Here are some management strategies for smut in sugarcane crops:

   • Use certified disease-free seed cane for planting: It is important to use high-quality, certified disease-free seed cane for planting to minimize the risk of introducing the pathogen into the crop.
   • Plant resistant/tolerant varieties: Some sugarcane varieties are more resistant or tolerant to smut than others. Planting these varieties can help reduce the risk of disease.
   • Practice proper sanitation measures: Remove and destroy infected plant debris to prevent the buildup of the pathogen in the soil. Proper sanitation can help reduce the risk of disease.
   • Avoid planting sugarcane in soils with a history of smut infestation: The pathogen can survive in the soil for long periods of time, so it is important to avoid planting sugarcane in soils with a history of smut infestation.
   • Apply fungicides at the recommended time and rate as a preventative measure: Fungicides can be applied preventatively to protect plants from infection. Timing and rate of application will depend on the specific fungicide used and the severity of the disease.

It is important to note that different sugarcane varieties may require different management strategies for red rot and smut and that regular monitoring and early detection are important for the successful management of these diseases.

1. Wilt: Wilt is caused by the soil-borne fungus Fusarium sacchari. The symptoms include yellowing of leaves, stunted growth, and premature death of plants. The management of wilt includes the following steps:
   • Use healthy, disease-free seed cane for planting.
   • Avoid planting sugarcane in fields where wilt has occurred in the past.
   • Practice crop rotation with non-host crops like legumes, cereals, or vegetables.
   • Use clean cultivation practices to minimize soil-borne inoculum.
   • Apply fungicides like Carbendazim, Propiconazole, or Thiophanate-methyl to the seed cane before planting.
2. Grassy shoot: Grassy shoot is caused by a bacterial pathogen known as Spiroplasma kunkelii, which is transmitted by the leafhopper insect. The symptoms include stunted growth, malformed leaves, and excessive tillering. The management of grassy shoot includes the following steps:
   • Use healthy, disease-free seed cane for planting.
   • Avoid planting sugarcane in fields where grassy shoot has occurred in the past.
   • Practice crop sanitation by removing and destroying infected plants.
   • Use insecticides to control leafhopper populations.

In addition to the above-mentioned management techniques, it is also important to maintain proper cultural practices such as proper drainage, balanced fertilization, and weed control. Regular monitoring of the sugarcane crop for the presence of these diseases is also important to detect and manage them effectively.

Overall, the key to managing these diseases in sugarcane is to use healthy, disease-free seed cane, practice crop rotation and sanitation, and use appropriate fungicides or insecticides to control the pathogens responsible for the diseases.

1. Ratoon stunting is a disease of sugarcane caused by the bacteria Leifsonia xyli subsp. xyli. The disease affects the ratoon crop of sugarcane, which is the crop that grows from the stubble of the previous crop. The disease can lead to stunted growth, reduced yields, and ultimately, the death of the plant. Here are some management techniques for ratoon stunting in sugarcane:
   1. Use healthy, disease-free seed cane for planting. Infected seed cane is a major source of the disease, so it is important to use only healthy seed cane.
   2. Practice crop rotation with non-host crops like legumes, cereals, or vegetables. This helps to reduce the build-up of bacteria in the soil.
   3. Practice good sanitation by removing and destroying infected stubble and debris from the field after harvest. This helps to reduce the source of bacteria in the field.
   4. Control the insects that transmit the bacteria. The disease is transmitted by the sugarcane leafhopper, so it is important to control leafhopper populations in the field.
   5. Apply appropriate fertilizers and irrigation practices to promote healthy plant growth. Strong, healthy plants are better able to resist the disease.
   6. Use antibiotics such as oxytetracycline, penicillin, and streptomycin to control the bacteria in infected plants. These antibiotics can be applied through foliar sprays or soil drenches.

It is important to note that ratoon stunting can be difficult to manage once it is established in a field. Therefore, prevention is key to managing the disease. Regular monitoring of the sugarcane crop for the presence of ratoon stunting is important to detect and manage the disease early.

Cotton

Cotton is susceptible to a number of diseases, including vascular wilt and black arm. Here are some details about these two diseases and management techniques:

1. Vascular Wilt: Vascular wilt is caused by the soil-borne fungus Fusarium oxysporum f. sp. vasinfectum. The fungus infects the roots and blocks the xylem vessels, which results in the wilting and eventual death of the plant. The disease can be managed through the following techniques:
   • Use resistant varieties of cotton, which are available in the market.
   • Practice crop rotation with non-host crops like cereals or legumes. This helps to reduce the build-up of fungus in the soil.
   • Practice good sanitation by removing and destroying infected plants, debris, and soil from the field after harvest. This helps to reduce the source of the fungus in the field.
   • Apply appropriate fertilizers and irrigation practices to promote healthy plant growth. Strong, healthy plants are better able to resist the disease.
   • Use fungicides such as azoxystrobin, carbendazim, and thiophanate-methyl to control the fungus in infected plants.
2. Black Arm: Black Arm is caused by the bacterium Xanthomonas campestris pv. malvacearum. The bacterium infects the plant through wounds, such as those caused by insects, and causes the wilting and death of the plant. The disease can be managed through the following techniques:
   • Use resistant varieties of cotton, which are available in the market.
   • Practice good sanitation by removing and destroying infected plants, debris, and soil from the field after harvest. This helps to reduce the source of the bacterium in the field.
   • Control the insects that transmit the bacterium. The disease is transmitted by insects such as thrips and aphids, so it is important to control their populations in the field.
   • Use bactericides such as copper oxychloride and streptomycin to control the bacterium in infected plants.
   • Apply appropriate fertilizers and irrigation practices to promote healthy plant growth. Strong, healthy plants are better able to resist the disease.

It is important to note that prevention is key to managing both vascular wilt and black arm in cotton. Regular monitoring of the cotton crop for the presence of these diseases is important to detect and manage them early.