This pest is widely distributed and is polyphagous. It is responsible for major yield loss in tomato. Eggs are yellowish-white, ribbed and dome-shaped. Full grown caterpillars are apple green with whitish and dark grey broken longitudinal stripes. On hatching, young larvae scrap and feed on tender foliage while advanced stage larvae bore circular holes and thrust part of their body inside the fruit and eat the contents. The larvae move from one fruit to another, and a single caterpillar may eat and destroy 2 to 8 fruits.
Adults are white tiny scale-like covered with a white waxy bloom. Nymphs and adults suck the sap on the ventral surface of leaves. The affected parts become yellowish, leaves wrinkle and curl downwards and are shed ultimately. Besides the feeding damage, these insects also exude honeydew which favours the development of sooty mould. This hampers photosynthetic activity of the plant resulting in stunted growth.
Cool, dry and humid conditions are favourable for multiplication of aphids while heavy rains wash away the aphid colonies. Winged aphids on tomato usually migrate from one field to another, especially from potato crop. Aphids suck the sap from lower leaves and tender shoots and reduce the vigour of the plant. Secret honeydew which attracts ants and develops sooty mould. The yields are also reduced directly by sucking sap and more through the spread of virus diseases acting as vectors indirectly.
Damping off occurs in the pre-emergence and post-emergence stage, usually noticed in patches. In pre-emergence, seeds become soft, turn brown, and decompose, and in postemergence, roots, hypocotyls and the crown of the seedling turn pale brown, soft, water-soaked, and thinner. Infected seedlings topple and collapse.
On leaves, small, dark, circular lesions develop which turn distinctly zonate. Spots rapidly enlarge, coalesce and turn into complete blight. On the main stem and side branches, small, dark, slightly sunken lesions form which enlarge and form dark brown, elongated spots. On green or semi ripe fruits, dark, velvety, sunken spots having distinct concentric rings develop at the stem end.
It appears on the leaves, stems, and fruits. On the leaves, symptoms appear as pale green and water-soaked spots. Under favourable conditions, lesions enlarge rapidly, turn dark brown to purplish-black. High humidity and leaf wetness, favours the growth of a cottony, white mould on the lower side at the edges of lesions. On the stem, brown to black lesions develop which enlarge rapidly under moist conditions. On fruits, the fungus produces grey-green water-soaked spots, which enlarge, coalesce, and darken, resulting in large, firm, brown, leathery-appearing lesions.
Small water-soaked spots appear with a pronounced yellowish-green halo. Later spots turn brown with cankered appearance. On ripe fruits, dark brown to blackish brown water-soaked spots appear which later develop cracks in these spots.
Infection first appears on lower immature green fruits touching the soil with lesions having dark brown centre surrounded by water soaked zonations. As the spot enlarges, lesions assume a pattern of concentric rings of narrow, dark brown and wide light brown bands.
Symptoms include mosaic, interveinal yellowing, vein clearing, crinkling and puckering of leaves accompanied by inward rolling of leaf margins. The older leaves become leathery and brittle. The disease also induces severe stunting, bushy growth, and partial or complete sterility depending on the stage of the crop. Infected plants bear few or no fruit.
They are microscopic, soil borne, vermiform pests that feed vigorously on roots and cause galling of roots which hamper the uptake of nutrients and water. Affected plants are weak, stunted with yellow leaves and reduced fruit production. Poor development of root system makes the plant highly susceptible to drought.
Validated Integrated Pest Management Interventions for Tomato Crop
- Prepare raised nursery beds about 10 cm above ground level for good drainage to avoid damping off etc.
- Follow soil solarization for 2-3 weeks using 0.45 mm thick polythene sheet tightening sides of the sheet to enable avoid escape of heat. Sufficient moisture should be present in the soil for solarization.
- Mix 50 g of an effective strain of fungal antagonist Trichoderma from a reliable source in 3 kg FYM and leave for 7 -14 days for enrichment followed by mixing of Trichoderma enriched FYM in the soil nursery in 3 m2 bed.
- Use of nylon net (40-50 gauge) to avoid vectors like a whitefly.
- Seed treatment with effective strain of Trichoderma @ 10 g / kg or captan 75 % WP @ 0.25 % a.i. and need based soil drenching with captan 75 WP @ 0.25 %.
- Raise marigold nursery 20 days before tomato nursery.
- Before transplanting, dip the roots of seedlings for 15 minutes in imidacloprid 17.8 SL @ 7.0 ml/litre to protect against sucking pests including white fly.
- Transplant 45-day marigold seedlings in a pattern of one row of marigold for every 16 rows of tomato for flowering synchronization. A first and last row of the field should be marigold, and it should be sprayed with HaNPV @ 250 LE / ha.
- Adopt wide spacing of 60 x 45 cm (for varieties) and 90 x 60 cm (for hybrids) to reduce the chance of spread of diseases.
- Apply neem cake @ 250 kg/ha at 20 days after transplanting (DAP) to reduce fruit borer, leaf miner, and nematode incidence.
- 2-3 sprays of 5% NSKE are also effective against leaf-miner, aphids, and mites.
- Need based spray of imidacloprid 17.8 SL @ 150-175 ml or thiamethoxam 25 WG @ 200 g or spiromesifen 22.9 SC @ 625 ml or dimethoate 30 EC @ 990 ml / ha in 500 lit water for white fly control.
- Spraying of fenazaquin 10 EC @ 1250 ml or spiromesifen 22.9 SC @ 625 ml/ha in 500 lit water against mites.
- Install pheromone traps @ 2 / acre for monitoring fruit borer activity. Replace the lures with fresh lures at every 20-25 day’s interval.
- Monitor top three leaves for fruit borer eggs
- The release of egg parasite, Trichogramma chilonis @ 1.0 lakh/ha 4-5 times at weekly interval.
- Spray HaNPV (250 LE) on marigold flowers and buds to kill the fruit borer in them.
- Spray good quality HaNPV (250 LE/ha) (2 x 109 POB) @ 28 DAP and repeat two more times at weekly interval. Mix 2% jaggery and spray in the evening to prevent fast degradation due to UV light.
- Collection and destruction of leaf curl affected plants in the initial stages and tomato fruits infested at regular intervals.
- If high incidence of fruit borer is noticed, spray chlorantraniliprole 18.5 SC @ 150 ml or novaluron 10 EC @ 750 ml or indoxacarb 14.5 SC @ 400 ml / ha in 500 lit water.
- Give prophylactic or protective spray with captan 50 WP @ 2.5 kg or captan 75 WP @ 1667 g or zineb 1.5-2 kg / ha in 1000 lit water or mancozeb 35 SC @ 2.5 lit / ha in 500 lit water or mancozeb 75 WP @ 1.5-2 kg / ha in 750 lit water against early and late blight and need based application of azoxystrobin 23% SC, or azoxystrobin 18.2% w / w + difenoconazole 11.4% w / w SC or famoxadone 16.6 % + cymoxanil 22.1 % SC @ 500 ml / ha in 500 lit water or metalaxyl 3.3 % + chlorotholanil 33.1 % SC @ 1000 ml / ha in 500 lit water depending on weather, severity and stage of the crop. Cyazafamid 34.5 % SC @ 200 ml or cymoxanil 8 % + mancozeb 64 % WP @ 1.5 kg or metiram 55 % + pyraclostrobin 5 % WG @ 1.5 kg or tebucunazole 50 % + trifloxystrobin 25 % WG @ 350 g / ha in 500 lit water can also be used as need based spray against late blight and early blight, respectively.
- Spray seedlings with streptocycline 40 to 100 ppm solution and in the main field to manage bacterial spot.
- Stake plants to reduce buck eye rot and need the based application of mancozeb 75 WP @ 1.5-2.0 kg, or propineb @ 1.5 kg/ha in 500 lit water.
Conservation of natural enemies
The commonly seen natural enemies of pests in tomato cropping system should be protected from unwanted and excessive sprays of chemical pesticides.
- ICAR- National Research Centre for Integrated Pest Management.