Ash gourd (Benincasa hispida) is a popular vegetable cultivated throughout Kerala. The fruits are cultivated mainly for culinary purpose. The fruits are covered by white, chalky wax, which deters microorganisms and helps impart an extraordinary longevity to the gourd.
Climate & Soil
The optimal temperature for the growth of ash gourd is in the range of 24–27'C. The plants are adapted to a wide range of rainfall conditions. It tolerates a wide range of soil but prefers a well drained sandy loam soil that is rich in organic matter. The optimum soil pH is 6.0–6.7, but plants tolerate alkaline soils up to pH 8.0.
Co 1: High yielding variety released from the Tamil Nadu Agricultural University. Large sized, round fruits with average fruit weight of 8.0 kg.
KAU local: High yielding variety released from the Kerala Agricultural University. Fruits are oblong, and medium sized.
Indu: High yielding variety with good flesh thickness released from the Kerala Agricultural University. Yield potential is 24.5 t/ha. Mean fruit weight is 4.82 kg.
Apart from the regular variety, an extra small fruited type, known as Vaidyakumbalam, is also grown for medicinal purpose. This medicinal ash gourd is morphologically different from the common vegetable type in fruit size, rind thickness and shelf life.
Propagation & Planting
The recommended seed rate for ash gourd is 0.75-1.0 kg/ha.
January-March and September-December are the ideal seasons for growing ash gourd. For the rainfed crop, sowing can be started after the receipt of first few showers during May-June. Prepare the soil to a fine tilth by ploughing and harrowing. Pits of 60 cm diameter and 30-45 cm depth are taken at a spacing of 4.5 m x 2 m. Well rotten FYM and fertilizers are mixed with topsoil in the pit.
Sow four or five seeds per pit at 1-2 cm depth. Avoid deeper sowing as it delays germination. Irrigate with a rose can daily. A pre-sowing irrigation 3-4 days before sowing is beneficial. The seeds germinate in about 4-5 days. Unhealthy plants are removed after two weeks and only three plants are retained per pit. Soaking seeds overnight in cold water is found to improve germination. To reduce the attack of soil born fungus, soaking seeds in 0.2 % solution of bavistin for two hours is also recommended.
In high range zone, seedlings can be raised in greenhouses to ensure good germination and are later transplanted to the main-field. Sow two or three seeds in small plastic pots/containers filled with potting mixture. Thin to a single seedling when they have four to six true leaves. Water the seedlings thoroughly every morning. Seedlings are ready for transplanting 15-20 days after sowing or when they are 10-15 cm tall. Transplant seedlings into the field at spacings similar to those used for the direct seeding method.
Ash gourd is grown trailing on the ground by spreading dried twigs and coconut fronds on the ground.
Balanced fertilization is essential for high yield and good keeping quality of the fruits. Apply FYM @ 20-25 t/ha as basal dose along with half dose of N (35 kg) and full dose of P2O5 (25 kg) and K2O (25 kg/ha). The remaining dose of N (35 kg) can be applied in two equal split doses at the time of vining and at the time of full blooming. A fertilizer dose of 70:25:25 kg N:P2O5: K2O / ha in several splits is recommended in Onattukara region. The fertilizer dose per pit would be 28:10:10 g N:P2O5:K2O.
During the initial stages of growth, irrigate the crop at 3-4 days interval, and alternate days during flowering/fruiting. Furrow irrigation is the ideal method of irrigating. But in water limited environment, trickle or drip irrigation can be resorted to. During rainy season, drainage is essential for plant survival and growth.
Ash gourd is a cross pollinated crop. Insects, especially bees, pollinate flowers. Pollination can be a problem during the wet season since bees are less active during overcast conditions. Introduction of bee-hives ensures good pollination and avoids the need for hand pollination.
Spraying vines with flowering hormones increases the number of female flowers and can double the number of fruits. For example, one application of gibberellic acid at 25-100 ppm increases female flowers by 50 % and can work for up to 80 days. Application of ethrel (an ethylene releasing compound) has also been found to increase femaleness.
Conduct weeding and raking of the soil at the time of fertilizer application. Earthing up is done during rainy season. Hand or hoe weeding can be performed as needed. Mulching is commonly used for ash gourd crop grown on raised beds. Use organic or plastic mulch depending on availability. Mulch can be laid down before or after transplanting and after sowing.
Fruit flies: Bactocera cucurbitae
Fruit fly maggots feed on the internal tissues of the fruit causing premature fruit drop and also yellowing and rotting of the affected fruits. This fly is difficult to control because its maggots feed inside the fruits, protected from direct contact with insecticides.
Control: Apply carbaryl 10 % DP in pits before sowing of seeds to destroy the pupae. Breaking of soil to expose pupae, and burning the soil in pit by dried leaves are also effective. Bury any infested fruits to prevent the build up of fruit fly population. Cover the fruits in polythene/paper covers help to prevent flies from laying eggs inside the fruits. It can also be effectively controlled by the use of banana fruit traps prepared.
Epilachna beetle: Epilachna spp.
The yellowish coloured grubs and adults of the beetle feed voraciously on leaves and tender plant parts, and the leaves are completely skeletonized leaving only a network of veins. When in large number, the pest causes serious defoliation and reduces yield.
Control: Remove and destroy egg masses, grubs and adults occurring on leaves. Spray carbaryl 0.2 %.
Pumpkin beetle: Aulacophora fevicolis, A. cincta and A. intermedia
Adult beetles eat the leaves, makes hole on foliage and causes damage on roots and leaves. Grubs cause damage by feeding on root. It also feeds on flowers and bores into developing fruits that touch the soil.
Control: Incorporate carbaryl 10% DP in pits before sowing the seeds to destroy grubs and pupae.
Aphids: Aphis gossypi
Aphids in large number congregate on tender parts of plant and suck sap resulting in curling and crinkling of leaves. Ants carry aphids from one plant to another.
Control: Apply 1.5% fish oil soap. First dissolve soap in hot water and then make up the volume. Alternatively apply dimethoate 0.05%.
Downy mildew: Pseudoperonospora cubensis
Cottony white mycelial growth is seen on the leaf surface. Chlorotic specks can be seen on the upper surface of the leaves. It is severe during rainy season.
Upper leaf surface Lower surface
Control: Complete removal and destruction of the affected leaves. Spraying 10 % solution of neem or kiriyath preparation. If the disease incidence is severe spraying mancozeb 0.2% will be useful.
Powdery mildew: Erysiphe cichoracearum
The disease appears as small, round, whitish spots on leaves and stems, which later enlarge and coalesce rapidly. White powdery mass appears on the upper leaf surface. Heavily infected leaves become yellow, and later become dry and brown. Extensive premature defoliation of the older leaves occurs resulting in yield reduction.
Control: Control the disease by spraying Dinocap 0.05%.
Mosaic (Cucumber Mosaic Virus)
Mosaic disease is characterized by vein clearing and chlorosis of leaves. The yellow network of veins is very conspicuous and veins and veinlets are thickened. Plants infected in the early stages remain stunted and yield gets severely reduced. White fly (Bemisia tabaci) is the natural vector of this virus.
Control: Control the vectors by spraying dimethoate 0.05%. Uprooting and destruction of affected plants and collateral hosts should be done.
Ash gourds are mature when the stems connecting the fruit to the vine begin to shrivel. Cut fruits from the vines carefully, using pruning shears or a sharp knife leaving 3-4 inches of stem attached. Snapping the stems from the vines results in many broken or missing "handles."
The fruits can be harvested at different stages depending on the purpose for which it will be used. Normally, green fruits are ready for harvest within 45-60 days; matured ones coated with powdery substance are harvested between 80 and 90 days after sowing. The fruit yield can vary depending on variety and crop management. Average marketable yields are 20-25 t/ha. The harvested fruits can be stored for several weeks in ambient conditions. It will keep for 2-3 months in temperatures from 10 to 12°C and 50-75 % relative humidity. Avoid cutting and bruising the ash gourds when handling them