Radish is a cool season vegetable, cultivated for its edible napiform taproots. It is a crop with very short duration and many varieties attain maturity within 30 days after planting. Hence the crop is highly suitable for growing in the high ranges of Kerala during winter season.
Cabbage grows well on a wide range of soils from light sand to heavier clays, but well drained sandy loam to clay loam soils are ideal for its best growth. The optimum soil pH should be in the range 6.0–6.5. Good drainage is important, and soils that become waterlogged after heavy rain or irrigation are unsuitable.
Japanese White, Arka Nishanth, Pusa Chetki, Pusa Reshmi, Pusa Desi and Bombay Red Long
Radish can be grown in high ranges from June to January. Seed rate is 7 to 8 kg per hectare. The land should be thoroughly ploughed to facilitate proper root development. Incorporate well decomposed FYM @15-20 t/ha at the time of land preparation. Application of fresh undecomposed FYM should be avoided as it leads to forking of the fleshy roots. Radish is usually grown on ridges to facilitate good root production. Ridges of about 20 cm height are taken 45 cm apart and seeds are sown 10 cm apart on the rows. The seed is mixed with fine sand and sown in rows by hand, and covered with soil to make it firm around it.
Uproot excess seedlings (thinning) three weeks after sowing leaving a plant to plant spacing of 10 cm to facilitate better tuber growth.
Apply 20 t/ha FYM as basal. N: P2O5: K2O 75:37.5:37.5 kg/ha is the fertilizer requirement. Full dose of P2O5 and K2O and half dose of N are applied as basal. Remaining half dose of nitrogen is applied as topdressing when the plant starts growing vigorously.
Adequate soil moisture should be available for uniform seed germination and growth of plant. The first irrigation is given immediately after sowing. Depending upon the planting season and the available soil moisture, radish may be irrigated at 10-12 days interval during winter and 5-6 days interval during summer.
Intercultural operations like weeding and hoeing are necessary to check weed growth and provide soil aeration for better growth and yield. During rainy season, two weedings are required to keep the growth of weeds under check.
In radish, the growing roots tend to push out of the soil surface. Therefore, earthing up and weeding during the early stages of growth are necessary for proper development of quality roots.
Aphids (Myzus persicae )
The nymphs and adults suck the cell sap and devitalize plants. Affected parts become discolored and malformed.
Control: Spraying malathion (0.1%) at 10-15 days interval control pest population.
Mustard sawfly (Athalia proxima)
A serious pest of radish, which feeds on the leaves by making small holes. The pest attack is observed in the vegetative and flowering stage of the crop.
Control: Hand picking of larvae and spraying malathion 50 EC @ 1ml/litre twice at an interval of 10 days is recommended.
Alternaria blight (Alternaria raphani)
Small, yellowish, lesions appear on leaves, stems and seed pods. The affected pod becomes black and shriveled, and infected seed fails to germinate.
Control: Regular spraying with dithane M 45 (0.2%) or ridomil (0.1%) controls the disease effectively.
White rust (Albugo candida)
Flowering shoots get deformed and bear only malformed flowers. White powdery substance in patches is observed on the under surface of the leaves.
Control: Clean cultivation and use of resistant varieties help to prevent the disease. Regular spraying with dithane Z 78 (0.2%) effectively controls the disease.
Root rot of radish (Erwinia rhapontici)
Symptoms appear as rotting of pith tissues resulting in cavity formation and wilting of plants. It is a bacterial disease, which spreads through implements and irrigation water.
Control: Dipping of the seeds in a solution of agrimycin-100 (100 ppm) at the time of sowing is effective in checking the disease.
Radish mosaic virus (RMV)
Small, circular to irregular, chlorotic lesion appear on the leaves and the stem. Leaf distortion, stunting or abnormal formation are not observed. The disease is transmitted through aphids.
The diseased plant assumes a dull grey to light violet colouration. The symptoms of the disease appear at the time of flowering when all the floral parts become green violet and leafy. The sepals and petals become green thick knob headed leaves. The disease is transmitted by jassids.
The radish crop becomes ready for harvesting in about 50-65 days depending on the variety. At the time of harvest, the roots should not be pithy or solid. Crop is harvested manually by uprooting individual plant. A light irrigation may be given a day before harvesting to facilitate lifting of roots. The average yield varies between 20-25t/ha.