The common name of plant pest, cabbage disease often reflect the type of symptom they cause. If you identify the symptoms you may be also to successfully take steps to limit the cabbage disease. Here are the most common cabbage disease and there management.
Cabbage disease there control
1 Club rot
The earliest above ground symptoms are unthirfty development of the plants and flagging of the leaves in hot suuy weather showing the plants as if suffering from lack of weather. The affected plants show large, irregukar galls on the roots and those on the lateral roots take the shape of spindle. The attack both in the seed beds and in the main fields. The disease is more serious in soil with ph below 7. The infected roots enlarge rapidly to from clubs. The fungus persists in the soil and on the crop debris. Persistence in the soil is for many years.
i) Select seed beds in the disease free area.
ii) Seed beds can be fumigated with firstname.lastname@example.org litres/10M2area or methyl bromide.@0.5 to 1kg/10 M27 days prior to actual date of swing.
iii) Apply hydrated lime to improve the soil acidity.
iv) Addition of PCNB solution (0.05%) @250ml/hole has been recommended.
2. Damping off and Rhizoctonia disease
Typical symptom is the appearance of soft water-soaked spots on the skin of the seedlings at the base of the young stem or at the soil line.The young seedling topple over due to collapsing of the infected tissues. When the attack is in later stage of seedling growth, plants are brownish to black just above and below the soil line, the stems are usually smaller than normal but tough and woody. This type of disease is called wire stem. In older cabbage plants, the fungus causes a kind of hard rot known as bottom rot. The infection is more under high humidity and high temperature. The fungus persists in the soil and on the dead plant debris.
i) Treat seeds with Captan or Thiram @ 3g/kg of seed before sowing.
ii) Drench the soil around the seedling with 0.5kg of Captan/250 litres of water twice, i.e. on 7th and 15th day after sowing.
3. Downy mildew
The characteristic symptoms of the cabbage disease are the appearance of purplish brown spots on the undersurface of the leaves. The upper surface of the leaf on the lesion is tan or yellow. The downy fungal growth usually appears on the undersurface of the leaves. During the bolting stage, the seed stalks show blackish patches and in severe cases the whole curd is spolied. The fungus perennates in the infected plant debris as ospores and also contaminant.
i) Treat seeds with Agrosan GN or Emisan @ 3g/kg of seed.
ii) Spray cauliflower with Indofil M-45 @ 1.25kg in 250 litres of water/ha at 7days interval with the appearance of disease. Sometimes spray interval may be less according to the severity of the disease.
iii) Collect and burn all the plant debris after the harvesting is over.
iv)Avoid inclusion of any crucifer plants in the rotation.
4. Powdery mildew
The fungus causes silvery while patches on the upper surface of the leaves which in severe attack, may coalesce to cover the entire leaf and cause defoliation.
Spray Karathane 25WP @ 2g/litre of water at the first sing of disease appearance and thereafter repeat at 15 days interval if needed.
5. Black leg of cabbage
The first symptom cabbage disease is an oval or linear, depressed light brown canker near the base of the stem. The canker enlarges until the whole stem is girdled. Vertically split stems of affected plants show severe black discolouration of the sap system. The whole root system decays from the bottom upwards. The spots develop on the leaves and large number of black dots appear on the spots. The affected plants may die in case of severe infection. The fungus persists within the seed coat of the seeds and also on the infection plant debris.
i) Collect and destroy all the plant debris after harvest.
ii) Treat seeds with Agrosan GN or Emisan @ 2.5g/kg of seed or with Bavistin @ 2g/kg of seed.
iii) Grow tolerant cultivars like Pusa Drum head.
6. Black sport or dark leaf spot
The leaf spots due to A. brassicicola are small, coloured which spread rapidly to form circular lesion upto 1cm in diameter or even more. The sports enlarge in concentric rings. The fungus may appear as bluish in the centre during humid weather. The sports are linear onb the stems, petioles and pods. The sports on the roots of turnip are nearly circular, often zonate and show various shades of brown or black colour. Cabbage after harvest acquires a black mouldy appearance. These sports are yellow, raised spherical to elliptical and upto 1cm in diameter. Black spores may be seen in the sports. The fungi are reported to be seed borne.
i) Treat seeds with Captan or Thiram @ 3g/kg of seed.
ii) Diseased crop debris be should be collected and destroyed.
iii) Spray the crop with Indofil M-45 @1.25kg.ha at 7days intervals.
7. Ring spot of cabbage
The leaves are normally cabbage disease but the fungus can attack all the living parts. Initially small purple sports appear between the veins or leaves. These sports increases in size to produce concentric rings of affected tissue. The central protion of the sports turns grey from brown. Fugal fruiting bodies appear in concentric rings in these sports. The spot is bordered by a green band which remains green after the whole leaf has turned yellow. Badly affected leaves fall down. Presence of these large sports in the heads of cabbage reduces the market value of the produce. The fungus perpetuates in the seed and in the disease infested plant debris in the field.
i) Use clean seed beds free from pathogen.
ii) Spray the crop with the fungicides recommended for Alternaria leaf spots.
iii) Collect and destroy the crop refuse after harvest.
iv) The final spray must be applied at least 7 days before harvest.
8. Cabbage yellows
The foliage of the affected plants becomes lifeless and yellowish-green in colour. The yellowing may be unifrom but sometimes it is intense on one side.The lateral curling of the leaves and stem occurs. The yellowed tissue turns is stunted. The symptoms of cabbage yellows may be confused with the black rot caused by Xanthomonas campestris but in case of black rot the veins become black rather than brown and the smaller veins od diseased leaves are much more discoloured. Young seedling may occasionally show sing of damping off. The fungus is soil borne and perpetuates on the disease plant debris in the form of resting chamydospores.
i) Grow resistant varieties of cabbage.
ii) Prevent trnsfer of diseased seedlings, soil or plant part containing pathogen from diseased to healthy areas.
iii) All sanitary measure should be observed.
9. Damping off cabbage seedling
The infected seedlings are pale green and a brownish water soaked lesion is seen at the basal portion of the stem. The lesion girdles the stem and later on extends upwards and downwards. The affected tissues rot and the seedling topple down. Besides p. aphanidermatun, other pythium spp. and phytophthora spp. are also associated with damping off disease. The fungi are mostly soil borne.
i) Burning of 10cm think trash on the seed bed provides sterilizion of the soil.
ii) Treat seeds with Agrosan GN or Ceresan @ 2.5g/kg of seed.
iii) Drench the seedlings with Captan @ 2g/litre of water in the nursery beds.
Isolated white, shite pustues appear on the leaves. The pustules are raised, white, shiny areas, 1 to 2 mm in diameter. The fully developed pustules become powdery in appearnace. Marked swelling and distortion of the attacked parts often results particularly in the inflorescence. The axis of the inflorescence and flower stalks could be enormously thickened while the floral organs become wholly or in part swollen, fleshy, green or violet in colour. The petals become like sepals and the stamens turn leaf like. The axis of the inflorescence become twisted giving a zig-zig appearance. The fungus perpetuates in the from of oospores in the disease plant debris in the soil and also on the perennial hosts.
Management in cabbage disease
i) Collect seeds from the disease free fields.
ii) Grow resisant varieties.
iii) Spray Dithane M-45 or Difolatan @ 2g/litres of water with the first appearance of the disease in the case of seed crop production.
The disease can appear at any stage of crop growth. The first symptoms is the occurrence of chlorotic lesions near the leaf margins which progress towards the centre in the from of V-shaped yellowish sports. The veins and veinlets turn brown and finally black, which is the characterstic symptom of the disease. Such vascular discolouration extends to the main stem and proceeds upward and downward. The leaves turn yellow and drop off and the plants may die. The heads may rot in case of late infection. Cabbage and cauliflower heads are invaded and discoloured. The bacterium survives on the debris in the soil and through seeds also.
Management in cabbage disease
i) Take seed from the bacterium-free areas from the plants free of disease.
ii) Treat the seed before sowing with hot water at 500c for 30 minutes and dry. Then treat with Captan or Thiram at 3g/kg of seed.
iii) Spray the plants with 2.5kg streptocyline or 12.5 g of copper oxychloride in 12.5 litres of water at transplanting, curd formation and pod formation stage.
iv) Application of stable bleaching powder at the rate of 10-12.5 kg/ha as soil drench gives effective control of black rot and soft rot.
v) Follow two years crop rotation.
vi) Use sanitary measures. Destroy the disease debris in the field after harvesting.
12. Browning or brown rot or red rot
Browning occurs in cauliflower in which small, concentric water soaked areas develop in the stem and in centre and also on the branches of the curd. The head appears brown and the smaller leaves on the curd become deformed. The stems may become hollow with water soaked tissue surrounding the walls of cavity. In more advanced stages, pinkish or rusty brown areas develop on the surface of the curd. The affected curds develop a bitter taste.
i) Apply Borax or Sodium borate@ 20kg/ha
ii) Spray 0.25 to 0.5 per cent solution of Borex @ 1-2 kg/ha in case of acute deficiency.
iii) Application of 120 kg N, 40kg P and 15 kg of Borax/ha gives maximum yield.
When cauliflower plants are young, they sometimes develop small heads. This may be due to overage seedlings, poor nitrogen supply, wrong cultivars, crowding plants or late planting, etc.
Adequate nutrition along with irrigation should be supplied.