Cabbage Pests and Diseases, Control Methods
Introduction to Cabbage pests and diseases: For better yield and quality of cabbage produce, one msu be aware of pests and diseases of cabbage and their preventive methods. Cabbage is a cool-weather crop. The outer leaves are larger than the inner. The stem is very short and stout. Plants flower usually after winter. Using some home remedies to get rid of the bug will be cost-effective and safer than commercial chemical insecticides. Now, let’s get into the details of cabbage pests and diseases.
A guide to Cabbage pests and diseases and their control methods
It is a leafy green or purple plant grown as an annual crop. These are a rich source of vitamin A and vitamin C also it contains minerals such as phosphorus, potassium, calcium, and iron. It can be eaten as raw as well as in cook form. In , cabbage is grown mainly in winter in the plains region.
Commercial Cabbage cultivation
Cabbage cultivation is done on sandy to heavy soils rich in organic matter. On heavy soils, plants grow slowly and the keeping quality is improved. A pH range of 6.0 to 6.5 is considered optimum for growing cabbage.
Cabbage is commonly cultivated in a cool moist climate and it is grown as a winter crop in plains. The seeds are sown in a seedbed and 4 to 6-week old seedlings are transplanting to the field. Raised beds of size 3 x 0.6 m and 10 to 15 cm in height are prepared. In , it is grown in large areas having a cool and moist climate. A temperature of 15 to 21C is considered as optimum for growth and head formation of the crop. The intensity of flowering mainly depends upon the age of the plants and the period for which they are exposed to low temperature ranges.
Cabbages are ready to harvest when the head is fully produced and feels firm and well-packed when squeezed. Cut the head away from the stalk by using a sharp knife. Leaving the stalks in the ground will result in the formation of several smaller heads that can be harvested and eaten. It is ready for harvest at 90 to 120 days after planting. Cabbage harvested promptly when the heads are firm and mature. The below sections will explain you about Cabbage pests and diseases and controlling methods.
Types of Cabbage pests
Cabbage can be mainly attacked by cutworms, cabbage loopers (preceded by small yellow and white moths), imported cabbage worms, cabbage root maggots, slugs, and aphids.
Place a protective collar around young cabbage plants to exclude cutworms. Handpick loopers and worms and destroy them or spray by using insecticidal soap or Bacillus thuringiensis.
Cabbage maggots are the larvae of a fly and plant radishes near cabbages to repel the flies. Put row covers over seedlings or plants through the garden fabric to keep flies from laying eggs in the soil. Mound diatomaceous earth or hot pepper around plant stems if maggots are in the soil.
Aphids on cabbage plants can suck the vital sap from the leaves, leaving the plant weakened, damaged, and susceptible to disease and bug invasions. Growing companion plants nearby will attract ladybugs and other natural predators of aphids. Mint plants deter aphids and help alleviate the problem before it begins. For a homemade spray to fight aphids, mix 1 cup vegetable oil, 1 1/2 cups of water, and 2 teaspoons of dish soap, and then spray on the cabbage plant. This spray suffocates the bugs and repeated every few days to eliminate newly hatched aphid eggs.
Cabbage Diamondback Moth (DBM)
It is one of the most serious pests of cabbage plants grown under comparatively high-temperature conditions. The caterpillars are green or brownish-green. The adult female lays eggs on the leaves singly or in groups. Small slender green caterpillars on emergence feed on the leaf epidermis and later make holes in the plant leaves. Severely affected plant leaves are completely skletonised. And pupation takes place in a loose mesh of silken cocoon spun by the caterpillar.
Control – Spraying the crop with Malathion (0.1%) or Profenofos gives good control of the larvae. Intercropping mustard in the cabbage crop 15 days before sowing and 25 days after planting cabbage was efficient. The pest population is attracted to it, which can be destroyed by spraying the crop with Dichlorvos (1 ml/ liter of water).
Cabbage Butterfly (Pieris brassicae)
The larvae of the pest after hatching from the eggs feed on the foliage and burrow into the heads. In case of severe cases, the heads become unfit for marketing.
Control – The caterpillars must be handpicked and destroyed. Spraying the crop upon the emergence of the pest with Malathion (0.1%) or dusting Carbaryl (0.15%) gives good control of the pest.
Slugs can be difficult to detect because the pests’ natural feeding time is during the night and early morning. Slugs and snails eat large quantities of cabbage plants unless deterred or eliminated. The beer poured into saucers and shallow bowls have been a favorite process of killing slugs and snails. You will want to continue this method to keep slugs at bay. Salt will repel slugs and snails from your cabbage plants. Make a 1-inch wide circle of common table salt around plants. The salt circle must be several inches away from the plant. The few slugs that attempt to cross the salt will soon die because the salt dissolves the pests.
Armyworms and cutworms also can invade cabbage plants. If there are a few worms, simply pick them off the plant, and squish them. For a more thorough elimination, mix 1 tablespoon dish soap with 1 cup vegetable oil, and also 1 cup water. Spray the entire cabbage plant, including the underside of plant leaves. The mixture will repel the worms from the cabbage plant. Self- rising flour is said to kill worms on plants.
Repelling the moths will eliminate future worm problems. Covering cabbage with garden sun cloth so the moths cannot access the cabbage in one method. Cabbage moths are territorial, and if they think there are already cabbage moths in the plants, the new moths will find another location to lay eggs. Crush white eggshells, and scatter around cabbage plants. Growing garlic as a companion plant to your cabbage will repel the moths.
Black rot is also called blackleg, clubroot, and yellows are fungal diseases which can attack cabbage plant. This bacterial disease is very common in areas having a warm and wet climate. Cabbage plants can be infected during any growth stage and the symptoms resemble nutritional deficiencies. Infected seedlings become yellow, drop lower leaves, and could die. Leaves can be affected on only one side of a seedling. Plants infected because of contaminated seed could not develop symptoms for many weeks. The symptom of black rot is caused by a local infection that results when bacteria enter leaves through natural openings of leaf margins.
The infected tissue turns pale green-yellow and turns brown and dies. Affected areas are generally wedge- or V-shaped. These areas enlarge as the disease progresses, and severely affected plant leaves may drop off. The veins in infected plant leaves, stems, and roots sometimes become black.
Control – An integrated approach is required to manage black rot successfully. The use of black rot tolerant varieties is the best process to control the disease. Considerable reduction in disease observed when seeds are treated with Agrimycin-100 (100ppm). Planting must be done on raised beds to facilitate drainage. Cultivation in the fields where crucifers have been continuously grown during the last 2 years must be avoided. Plants must be thoroughly inspected for black rot symptoms and the affected plants must be removed and destroyed.
Downy Mildew (Perenospora parasitica)
The disease is serious in the nursery and it can also appear in field planting. High humidity, fog, drizzling rains, and heavy dew favor the disease development. The symptom observed is small, light green-yellow lesions on the upper leaf surface, later showing on the undersurface. The spots turn yellow as they enlarge. Later the leaf can become papery and die. Cabbage heads increase sunken black spots. While plants are infected at the seedling stage, the symptom does not become apparent until near harvest.
Control – All the weeds serving as an alternate host to the fungus must be destroyed. The crop must be irrigated judiciously to avoid periods of high humidity. Spraying the seedlings in the nursery beds with Copper Oxychloride (0.3%) is efficient in controlling the disease. The first spray must be given as soon as the seedlings appear. Subsequent sprayings are given at weekly intervals until the cabbage plants are transplanted in the field. For controlling the disease in the field, the cabbage crop is sprayed with Copper Oxychloride (0.5%)
Leaf Spot and Blight
Leaf spot is a destructive disease on seed crop. Older leaves are more susceptible and the initial symptoms are in the form of small dark yellow spots on the leaf surface. Later on, the spots enlarge to circular areas with concentric rings and surrounded by yellow halos. In severe cases, the entire plant defoliates. Violets to tan spots develop on infected cabbage a seed pod that intensifies in wet weather.
Control – Use of disease-free seeds, practicing good crop rotation and seed treatment with hot water (50 C for 30 minutes) helps to minimize the disease incidence. Crops grown for seed purpose should be sprayed at full bloom, pod set and pre-harvest stage with Captan (0.2%) for the control of the disease.
Clubroot of Cabbage (Plasmodiophora brassicae)
Cool, wet and acidic soils favor the plant development and spread of the disease. Roots develop clubs (swellings) that can be 12 to 15cm wide. The largest clubs are generally on the larger roots just below the soil surface. Affected seedlings do not show any root swellings until 3 weeks after infection. Infection in the nursery stage results in the death of plant seedlings. When cabbage plants are attacked at a later stage, the disease rarely kills the plant, but the capacity of the affected roots to absorb minerals and water gets reduced. Finally plant leaves become stunted, yellowish and prematurely bolt in hot weather.
Control – Early infection of seedlings can be destructive, it is important to use uninfected seedbeds and clean equipment. Long rotations (6 years or longer) help prevent a pathogen buildup and decrease disease incidence. When susceptible varieties are grown in acidic soils, finely ground limestone is thoroughly mixed into the soil 6 weeks before planting to raise the soil pH above 7.0. Lime inhibits disease development, but will not prevent a disease outbreak if the spore load in the soil is high. The quantity of lime is determined by initially measuring the pH level of the soil.
Effective natural remedies for Cabbage pests and diseases
One way of minimizing the number of pests in the cabbage patch is to plant the cabbage with companion plants. Plant some of these companion plants around and between the cabbage plants to set up a barrier between pests and cabbage.
Beneficial insects attack and eat cabbage pests. And attract them by planting plants they like. Drawn by the scent of their favorite plant, they will stay as they find food the pests you want to get rid of. For example, the Braconid wasp (Diaeretiella rapae) attacks the cabbage worm. Braconid wasps are drawn to nectar plants such as yarrow, daisies, and alyssum.
If you have a few cabbage plants, sometimes the best remedy for cabbage pests is the simplest one is handpicking. Inspect the cabbage every day and when you spot the cabbage loopers or other larvae when they are small, remove them by hand. Check the outer leaves and the crevices of the cabbage head carefully because loopers are well camouflaged.
Garlic water will be working as a repellent for cabbage worms. You can use a commercial product such as Garlic Barrier and also you can make own garlic water. Then mix one percent pure garlic juice with 1 percent fish oil and 98 percent water. Put the mixture in a pump sprayer and saturate the plant leaves and head of the cabbage.
Make a Natural Repellent Spray
There are several natural ingredients, such as garlic and cayenne pepper that could deter cabbage worms. Blend these ingredients with water to create the repellent then use a spray to apply it on the undersides of plant leaves.
Introduce Beneficial Insects
A sustainable approach to getting rid of cabbage worms is by introducing natural predators to the home garden. This can include spiders, praying mantis, and ground beetles. In addition to these insects, you may want to attract other natural predators such as birds and geckos.