Very serious pest is causing losses up to 80%. Maximum damage occurs during July-August. Gravid female inserts the white, cigar shaped eggs into the flowers and tender fruits. The newly hatched maggots bore into the fruit pulp by forming serpentine galleries and feed inside, contaminating them with its frass and providing entry points for saprophytic fungi and bacteria, which cause rotting of the fruits. Due to feeding, there is pre-mature dropping of fruits.
The larvae are pale to dark green with a white stripe running along both sides of the body. Caterpillars scrap the chlorophyll portion of the leaves by webbing them together. It also bores into flowers, and after the fruit starts to develop, the larvae can chew shallow holes in the surface.
3.Red Pumpkin Beetle
It is a serious pest of bottle gourd. Adult beetles are mainly responsible for the damage of the plant above ground, attacking the leaves, flowers and fruits. Making holes and causing death or retardation of growth. In case of heavy infestation, re-sowing is required to be done. Larvae live in the soil and feed on the roots and stem of the plant.
Both the nymphs and adults suck the plant sap mainly from the underside of the leaves and secrete honeydew on which black sooty-moulds develop which in turn reduces photosynthesis by the plants. Apart from causing direct damage by their feeding, they also act as a vector of viral diseases.
Serpentine mines are made by larvae in leaves. Drying and dropping of leaves due to severe infestation. Adults are pale yellow. Pupates within mines.
It is one of the serious diseases which initiates as water soaked angular lesions under conditions of high humidity and moderate temperature, soon turning chlorotic and finally on the corresponding lower surface purplish during growth is seen.
2.Cercospora leaf spot
The disease occurs on almost all cucurbits but is more common on cucumber, bitter gourd and bottle gourd and is usually found on foliage. Small block circular spots with a grey centre with
yellow hold appear on leaves. These sports enlarge and later encircle the leaves. Severely infected leaves fall off. The fruit size is reduced. More prevalent during the rainy season.
The symptoms are expressed at flowering & fruiting stage in bottle gourd and water melon. Replacement of tap root by some lateral roots. Yellowing, dropping of leaves and wilting and during of the whole plant are the major symptoms. Caused by seed has borne and soil borne fungus. Vascular bundles in the collar region become discoloured / brown.
The characteristic white, powdery fungal growth is readily recognizable on leaves, stems and vines. It is observed on almost all cucurbits and causes considerable loss. Affected leaves wither and dry. Powdery mildew affects fruit quality and reduces yield by reducing
number and size of the fruit.
Yellowish water soaked spots appear which enlarge and turn dry brownish black with centre giving shot hole appearance. On fruits spots are circular sunken with dark borders containing numerous pin head size fruiting bodies.
This disease is a serious constraint in cucurbits which cause leaf curl, yellow mosaic and stunting. In cucumber mosaic, typical mosaic symptoms develop on young leaves which mottle with alternating light green and dark green patches.
Validated Integrated Pest Management Interventions for Cucurbitaceous Crops
- Seed treatment with effective strain of Trichoderma @ 10 g / kg of seed
- Two to three applications of neem 300 ppm @ 10 ml/litre against hadda beetle on bitter gourd or red pumpkin beetle on bottle gourd in early stages of crop growth.
- Two sprays of Bacillus thuriengiensis @ 2g / litre for protection against cucumber moth on, bitter gourd.
Installation of cue lure traps for fruit flies for wider area management @ 10 / acre. Wooden plywood blocks are dipped in a solution of Ethanol: Cuelure: Insecticide (DDVP)@ 8:2:1 for 48 hours.
- Raking of soil for exposing fruit fly pupae to sunlight and predatory fauna.
- Install yellow coloured sticky traps @ 10 / acre for fruit fly management.
- Collection and destruction of fruit fly infected fruits periodically.
- Preferably grow cucumber on bamboo support or tresilising or in green houses can reduce downy mildew with reduced lead wetness and free air flow.
- Need-based spray of DDVP 76 EC @ 627 ml or trichlorfon 50 EC @ 1.0 kg/ha in 500-1000 lit water in the early stage for red pumpkin beetle control.
- Need based spray of dicofol 18.5 SC @ 1350-2700 ml/ha in 500-1000 lit water is effective
against red spider mites on the bitter gourd and bottle gourd. Addition of sticker (0.1%) is
essential for retention of spray fluid on leaves. Spray of cyantraniliprole 10.8 OD @ 900 ml /
ha in 500 lit water is highly effective for white fly, leaf miner, thrips, red pumpkin beetle and
white fly in cucurbits.
- Need based application of neem cake @ 250 kg / ha for nematode management
- Need based spray with carbendazim 50 WP @ 300 g / ha in 600 lit water to manage powdery mildew and anthracnose. Thiophenate methyl 70 WP @ 1430 g / ha in 750-1000 lit water can be used to manage anthracnose in bottlegourd
- Need- based spray with azoxystrobin 23% SC @ 500 ml or cymoxanil 8% + mancozeb 64% @ 1.5 kg / ha in 500 lit water against downy mildew in cucumber. Zineb 75 WP @ 1.5 – 2 kg / ha in 750-1000 lit water can be used to manage downy mildew and anthracnose and need based spray of ametoctradin + dimethgomorph 20.27 % w / w SC @ 420-525 ml / ha in 800-1000 lit water to manage downy mildew in cucurbits. Fenamidone 10 % + mancozeb 50 WG @ 1.5 kg / ha in 375-500 lit water or famoxadone 16.6 % + cymoxanil 22.1 % SC @ 500 ml / ha in 500 lit water can also be used in gherkins.
- An application of 10 kg borax per hectare to the deficient soil before planting will prevent boron deficiency. Foliar sprays of borax (100 g / 100 L) may also be used.
Conservation of Natural Enemies
The above shown natural enemies of pests in cucurbitaceous cropping system should be protected from unwanted & excessive sprays of chemical pesticides.
- National Research Centre for Integrated Pest Management