Though cabbage farming in Kenya is a profitable venture, it has challenges. Cabbage crops are susceptible to various cabbage diseases that can significantly impact yield and quality.
To help cabbage farmers overcome these obstacles, this article provides a concise overview of the most common diseases affecting cabbages in Kenya. By understanding the symptoms, causes, and preventive measures, farmers can effectively manage these diseases and protect their crops.
From black rot and clubroot to downy mildew and cabbage aphids, this guide equips farmers with valuable insights to safeguard their cabbage farms and ensure long-term success. You can know more about cabbage farming in Kenya by reading some of our previous guide.
10 Cabbage Disease and Mitigation Strategies
Below we discuss ten common cabbage diseases that affect farmers. We will discuss how to identify them and strategies for mitigating the disease. These diseases are:
- Black Rot (Xanthomonas campestris pv. campestris): This bacterial disease causes V-shaped, yellow lesions on the edges of cabbage leaves, leading to wilting and plant death.
- Clubroot (Plasmodiophora brassicae): A soil-borne disease that causes swelling and deformation of cabbage roots, resulting in stunted growth and reduced yields.
- Fusarium Yellows (Fusarium oxysporum f. sp. conglutinans): This fungal disease causes yellowing and wilting of cabbage plants, leading to root rot and reduced vigour.
- Downy Mildew (Peronospora parasitica): It is a fungal disease that causes yellowish lesions on the upper side of cabbage leaves and a greyish-purple fuzzy growth on the lower side.
- Alternaria Leaf Spot (Alternaria spp.): This fungal disease causes circular, dark brown spots with a yellow halo on cabbage leaves, leading to defoliation and reduced yield.
- Cabbage Mosaic Virus: A viral disease that causes stunted growth, mottled or mosaic-like discolouration on leaves, and reduced quality of cabbage heads.
- White Rust (Albugo candida): This fungal disease appears as white, blister-like pustules on the undersides of cabbage leaves, leading to defoliation and reduced yield.
- Diamondback Moth (Plutella xylostella): While not a disease, this pest is a major concern for cabbage farmers. The larvae of diamondback moths feed on cabbage leaves, causing extensive damage and reducing plant vigour
- Cabbage Aphids (Brevicoryne brassicae): These small, soft-bodied insects feed on cabbage sap, leading to distorted growth, yellowing leaves, and the transmission of viral diseases.
- Powdery Mildew (Erysiphe polygoni): This fungal disease appears as a powdery white coating on cabbage leaves, inhibiting photosynthesis and reducing plant vigor.
1. Black Rot Cabbage Disease
Black Rot is a bacterial disease that affects cabbage crops, caused by the pathogen Xanthomonas campestris pv. campestris. It is one of the most destructive diseases for cabbage farmers, leading to significant crop losses if not managed effectively.
Symptoms of Black Rot Disease
- V-shaped, yellow lesions: The disease starts with V-shaped, yellowish lesions at the leaf margin, which gradually spread towards the centre of the leaf.
- Wilting and yellowing leaves: Infected leaves exhibit wilting, yellowing and eventually become necrotic.
- Leaf drop: As the disease progresses, infected leaves may drop prematurely.
- Vascular discolouration: When you cut the stem of an infected plant crosswise, you may notice dark brown or black discolouration in the vascular tissue.
Causes and Spread
Black Rot spreads through contaminated seeds, infected crop debris, or contaminated tools and equipment. The bacteria can survive in the soil for several years, infecting subsequent cabbage crops. It can also be transmitted through water splashes, insects, and human activities.
Management and Prevention
- Use disease-free seeds: Start with high-quality, certified seeds free from black rot.
- Crop rotation: Avoid planting cabbage or brassica crops in the same field for at least three years to reduce the impact of the disease.
- Sanitation practices: Properly dispose of infected crop debris and remove any volunteer plants to prevent the disease from spreading.
- Field hygiene: Keep the field clean from weeds that can harbour bacteria and practice good hygiene by sterilizing tools and equipment.
- Avoid overhead irrigation: Use drip irrigation or other methods that prevent water splashing, as the bacteria can spread through water droplets.
- Copper-based sprays: Applying copper-based fungicides or bactericides can help reduce the spread of black rot, particularly during the early stages of the disease.
2. Clubroot Cabbage Disease
Clubroot is a soil-borne disease that affects cabbage plants and other cruciferous crops. The pathogen Plasmodiophora brassicae causes it and can lead to severe damage and reduced yields if not properly managed.
Symptoms
- Stunted growth: Infected cabbage plants exhibit stunted growth, with reduced size and vigour compared to healthy plants.
- Abnormal root development: The roots of infected plants develop swellings or galls, which can vary in size from small to large. These galls are often irregularly shaped and may be whitish, yellowish, or brown in colour.
- Yellowing and wilting: Infected plants may show yellowing and wilting of the leaves, particularly during hot weather or periods of drought.
- Nutrient deficiency symptoms: Since the infected roots cannot effectively absorb water and nutrients, plants may exhibit nutrient deficiencies, such as pale or yellowing leaves.
Causes and Spread
Clubroot is caused by a soil-borne pathogen that can survive in the soil for several years, even in the absence of a host crop. The disease spreads through soil movement, infected crop debris, contaminated equipment, or through the movement of soil particles by wind, water, or animals.
Management and Prevention
- Crop rotation: Avoid planting cabbage or other cruciferous crops in the same field for at least three to four years. Rotate with non-cruciferous crops to break the disease cycle.
- Soil sanitation: Remove and destroy any infected plant debris and roots from the field to prevent the disease from persisting. Also use the best fertilizer for cabbages to increase yeilds
- Soil pH adjustment: Maintain the soil pH between 6.5 and 7.2, as clubroot tends to be more severe in acidic soils.
- Resistant varieties: Plant cabbage varieties that are resistant or tolerant to clubroot. Consult seed suppliers or local agricultural experts for suitable types.
- Soil sterilization: If clubroot is severe, consider soil sterilization methods such as solarization or fumigation to reduce the pathogen load in the soil.
- Improve drainage: Clubroot thrives in soggy conditions, so ensure proper field drainage to minimize disease development.
3. Fusarium Yellow Cabbage Disease
Fusarium yellows is a fungal disease that affects cabbage and other cruciferous crops. It is caused by the pathogen Fusarium oxysporum f. sp. conglutinans and can cause significant damage to cabbage plants if not properly managed.
Symptoms of Fusarium Yellows Disease
- Yellowing and wilting: Infected cabbage plants exhibit progressive yellowing of the lower leaves, eventually leading to the plant wilting and dying.
- Vascular discolouration: Upon closer inspection, you may notice brown discolouration in the vascular tissue of infected plants, primarily in the lower stem and root system.
- Stunted growth: Infected plants often show reduced growth and fail to reach full size and vigor.
- Root rot: The disease can cause root rot, leading to decay and a characteristic foul smell.
Causes and Spread
Fusarium yellow is primarily soil-borne and can persist in the soil for several years. The pathogen can enter plants through wounds or natural openings and colonize the vascular tissue, impairing water and nutrient uptake. The disease can spread through infected plant debris, contaminated soil, or the movement of soil particles by wind, water, or human activity.
Management and Prevention of Fusarium Yellows Disease
- Crop rotation: Avoid planting cabbage or cruciferous crops in the same field for at least three years. Rotate with non-cruciferous crops to break the disease cycle.
- Resistant varieties: Plant cabbage varieties that resist or tolerate Fusarium yellows. Consult seed suppliers or local agricultural experts for suitable types.
- Soil sanitation: Remove and destroy infected plant debris to reduce the source of inoculum.
- Improve soil health: Maintain good soil fertility and drainage to promote healthier plants that are better able to withstand disease.
- Seed treatment: Consider treating cabbage seeds with appropriate fungicides to reduce the risk of seed-borne infection.
- Biological control: Some biocontrol agents can help suppress the growth of Fusarium oxysporum. Consult with agricultural experts for suitable biological control options.
4. Downy Mildew Cabbage Disease
Downy mildew is a fungal disease that affects cabbage and other cruciferous crops. It is caused by the parasitic pathogen Peronospora and can cause significant damage to cabbage plants if not properly managed.
Symptoms of Downy Mildew in Cabbages
- Yellowish lesions on leaves: Infected cabbage plants develop yellowish lesions on the upper surface of the leaves.
- Fuzzy growth on the underside of leaves: Upon closer inspection, a greyish-purple fuzzy growth, known as the downy mildew sporulation, can be observed on the lower surface of the infected leaves.
- Leaf curling and distortion: Infected leaves may exhibit curling, warping, and reduced overall plant vigour.
- Reduced photosynthesis: Downy mildew can hinder the plant’s ability to perform photosynthesis, leading to stunted growth and reduced yields.
Causes and Spread
Downy mildew is favoured by cool and moist conditions, typically occurring in humid environments. The pathogen can overwinter on crop debris and infected seeds. The disease spreads through airborne spores, water splashes, and movement of infected plant material.
Management and Prevention of Downy Mildew
- Crop rotation: Avoid planting cabbage or cruciferous crops in the same field for at least three years. Rotate with non-cruciferous crops to break the disease cycle.
- Resistant varieties: Plant cabbage varieties that are resistant or tolerant to downy mildew. Consult seed suppliers or local agricultural experts for suitable types.
- Proper spacing and ventilation: Adequate spacing between plants and proper ventilation can help reduce humidity levels and inhibit disease development.
- Fungicide applications: Fungicides labelled explicitly for downy mildew control can be applied in severe cases. Consult with agricultural experts for suitable fungicide recommendations and proper application timing.
- Field sanitation: Remove and destroy infected plant debris to minimize the source of inoculum.
- Avoid overhead irrigation: Water the plants at the base to avoid creating a conducive environment for the disease.
Alternaria Leaf Spot Cabbage Disease
Alternaria leaf spot is a fungal disease commonly affecting cabbage and other cruciferous crops. The pathogen Alternaria spp causes it and can lead to significant damage if left unmanaged.
Symptoms
- Circular, dark brown spots: Infected cabbage leaves develop circular, dark brown spots with a characteristic concentric ring pattern.
- Lesion enlargement: The spots may increase in size and coalesce, leading to extensive browning and necrosis of the leaf tissue.
- Yellowing and wilting: Severely infected leaves may exhibit yellowing and wilting, particularly as the disease progresses.
- Defoliation: In severe cases, the infected leaves may wither and drop prematurely, resulting in defoliation of the cabbage plants.
Causes and Spread
Alternaria leaf spot thrives in warm and humid conditions. The disease spreads through airborne spores, rain splashes, contaminated tools or equipment, and infected crop debris. Overhead irrigation and high plant density can contribute to its spread.
Management and Prevention
- Crop rotation: Avoid planting cabbage or cruciferous crops in the same field for at least three years. Rotate with non-cruciferous crops to break the disease cycle.
- Resistant varieties: Choose cabbage varieties that are resistant or tolerant to Alternaria leaf spot. Consult seed suppliers or local agricultural experts for suitable types.
- Sanitation practices: Remove and destroy infected plant debris to reduce the source of inoculum.
- Adequate spacing: Provide enough spacing between cabbage plants to promote air circulation and reduce humidity, which can help prevent disease development.
- Fungicide applications: In severe cases, fungicides labelled for Alternaria leaf spot control can be applied. Consult with agricultural experts for suitable fungicide recommendations and proper application timing.
6. Cabbage Mosaic Virus
The cabbage mosaic virus is a viral disease that affects cabbage plants and other cruciferous crops. Different strains of the Potyvirus group cause the virus and can cause significant damage to cabbage crops if not correctly managed.
Symptoms
- Mottled or mosaic-like discolouration: Infected cabbage plants exhibit irregular light and dark green patches, creating a mottled or mosaic-like pattern on the leaves.
- Leaf distortion: The leaves may become puckered, curled, or deformed, with a leathery texture.
- Reduced growth and stunting: Infected plants often show reduced vigour, growth retardation, and smaller overall size than healthy plants.
- Reduced yield and quality: The disease can lead to reduced head formation, smaller and distorted heads, and poor-quality cabbage.
Causes and Spread
Cabbage mosaic virus is primarily spread through infected plant material, such as seeds, transplants, or sap-sucking insect vectors like aphids. The virus can also persist in weed and alternate hosts, contributing to its spread.
Management and Prevention
- Use disease-free seeds and transplants: Start with certified and healthy transplants from reliable sources.
- Rogue-infected plants: Remove and destroy plants showing virus symptoms to prevent further spread.
- Control aphids and other vectors: Implement measures to control aphids and other insect vectors that can transmit the virus. This can include the use of insecticides or employing physical barriers.
- Weed control: Control weeds in and around cabbage fields, as some can serve as reservoirs for the virus.
- Crop rotation: Rotate cabbage crops with non-cruciferous crops to reduce the build-up of the virus in the soil.
7. White Rust Disease
White rust is a fungal disease affecting various plants, including cabbage and other cruciferous crops. The pathogen Albugo candida causes it and can cause significant damage if not properly managed.
Symptoms:
- White pustules: The primary symptom of white rust is the development of white, powdery spots on the undersides of infected leaves. These bumps may be raised and have a blister-like appearance.
- Leaf discolouration: Infected leaves may show yellowing or browning on the upper surface as the disease progresses.
- Leaf distortion: The affected leaves may become curled, twisted, or deformed.
- Premature leaf drop: Severe infections can lead to prematurely and defoliation.
Causes and Spread
White rust thrives in excellent, humid conditions. The disease spreads through airborne spores, water splashes, contaminated tools, equipment, or clothing, and infected plant debris. Overhead irrigation and high humidity levels contribute to its spread.
Management and Prevention:
- Crop rotation: Avoid planting cruciferous crops in the same field for several years to break the disease cycle.
- Resistant varieties: Choose cabbage varieties that are resistant to white rust, if available. Consult with local agricultural experts or seed suppliers for suitable options.
- Sanitation practices: Remove and destroy infected plant debris to minimize the source of spores.
- Adequate spacing: Provide sufficient spacing between plants to improve air circulation and reduce humidity levels.
In conclusion, effectively managing cabbage diseases is crucial for farmers in Kenya to protect their crops and maintain productivity. By implementing preventive measures, timely detection, and appropriate control strategies, farmers can mitigate the risks posed by diseases such as black rot, clubroot, Fusarium yellows, downy mildew, and Alternaria leaf spot,
Staying informed, consulting experts, and practising good agricultural techniques are vital to ensuring successful cabbage farming in Kenya.
