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Fungal diseases of vegetables-Cabbage
- 1. Fungal diseases of vegetables- Cabbage Vaishali S.Patil Professor, Department of Botany Shri Shivaji College of Arts, Commerce & Science Akola
- 2. 1.Wirestem caused by Rhizoctonia solani Symptoms- Constriction occurs at the base of the stem on the seedling which progresses upwards giving the plant a wire- like appearance. Affected plants remain stunted or may break off at ground level. Plants affected soon after transplanting usually die. Seedlings that have suffered mechanical injury from transplanting operations, wind damage or insect attack are vulnerable to infection(Root rot)("damping-off").The plant becomes weak. It shows stunted growth and smaller heads. Control: Use certified disease-free transplants.
- 3. 2.Fusarium yellows caused by Fusarium oxysporum Symptoms- Leaf yellowing, defoliation of older plants, stunting and death of seedlings. Stems are often twisted to one side. It also cause a curve in the midrib, resulting in a plant that is stunted to one side. Control: use yellows-resistant varieties
- 4. 3.Blackleg caused by Leptosphaeria maculans/ Phoma lingam Symptoms-Stem damage can lead to cankering and severing of the plant at the base. The lesions are light brown with a purplish outline which often contain pinhead-sized, black dots. The lesions tend to be linear and irregularly distributed. Control: Use certified disease-free seed and transplants, treat seed with hot water, choose varieties tolerant, Select well- drained sites with good air circulation, Good sanitation practices, not handling plants when they are wet.
- 5. 4. Leaf spot/target spot caused by Alternaria brassicae & A. brassicicola Symptoms- The circular leaf spots vary from mid to dark brown to black. The spots often have a target-like appearance as a yellow halo surrounds the sunken centre, as well as affecting the leaf. It can cause blackening of curds. dark leaf spots in affected plants. They are both seedborne and airborne. Control: Remove and destroy all crop debris, seed treatment and rotation, fungicides.
- 6. 5.Clubroot caused by Plasmodiophora brassicae Symptoms- Clubroot causes galls to form on roots of infected plantsi.e. swellings. The galls interfere with the plant’s uptake of water and nutrients. Under warm conditions, plants often wilt which is usually the first sign of clubroot infection. The death of seedlings takes place. Wilting plants should be removed from the ground to check for galls on the roots. Leaves become stunted, yellowish and prematurely bolt. Control: use only uninfected seedbeds and clean equipment. Long rotations, use of susceptible varieties.
- 7. 6.Damping off caused by Fusarium or Pythium sp. Symptoms- Obvious signs are missing plants or wilting of newly-emerged seedlings. There may be a wet rot of the stem and seedling stems may become constricted. These fungi are soil-borne and survive in soil without a host being present. Control: Planting on raised beds and providing good drainage. Start seeds in commercial potting soil, not in garden soil use of biocontrol fungicide.
- 8. 7.Downy mildew caused by Peronospora parasitica Symptoms- Leaf symptoms appear as yellowish, irregular areas on the upper surface corresponding to a white fluffy growth on the undersides of leaves. Older lesions become dry, brown and papery in texture and may cause the entire leaf to drop and curds may be infected with black spots within or on the surface. Control: Use varieties with resistance or tolerance, crop rotation, remove plant debris, use wide plant spacing, avoid wetting the leaves, fungicides.
- 9. 8.Powdery mildew caused by Erysiphe cruciferarum Symptoms- white lesions on the top of the leaves,produces a white powdery mould on the top surface of leaves. Control: Fungicides, resistant varieties, avoid drought stress, don’t use too much nitrogen fertilizer.
- 10. 9.White blister caused by Albugo candida Symptoms- White blisters form on the undersides of leaves, with a corresponding yellow patch on the upper surface. It can cause distortion of the plant stem as well as formation of galls on leaves. Control: Use of resistant varieties, fungicides, crop rotation.
- 11. 10.Ring spot caused by Mycosphaerella brassicicola Symptoms- lesions are grey and contain black, pinheads dots in concentric rings. Severe ring spot on leaves can reduce growth, delaying harvest and damaging crops that are harvested in leaf. Control: treat seeds with hot water prior to planting, fungicide, removing infected plants and destroying all crop debris.
- 12. 11.White mould/ Sclerotinia rot caused by Sclerotinia sclerotiorum, Sclerotinia minor. Symptoms-water-soaked areas which later become covered by a fluffy white mould. At the late stage of infection, black sclerotes about the size of rice grains may be seen in the white mould or inside the stem of the plant. Control: restrict air circulation, Mechanical injuries should be avoided, crop rotation.
- 13. 12.Bottom rot caused by Rhizoctonia solani Symptoms-Tan or brown lesions on the outer leaves. Then the fungus invades the center of the head, which can rot completely within 10 days. Control: Planting in raised beds will help to protect crop, keeping crop healthy and providing the proper amount of fertilizer.
- 14. 13.Phytophthora root rot caused by Phytophthora megasperma Symptoms-Discoloration of the margins of the leaves, changing to red and purple as the roots die. As symptoms progress to the stem, the leaves die back. Plants that are infected generally wilt and frequently die. Control: soil drainage, rotate, soil treatments, fungicides.