IPM Stratergies for Watermelon

  Watermelon: Diseases and Symptoms Downy mildew Powdery mildew Anthracnose Alternaria leaf spot Fusarium wilt Bud necrosis ...

 

Watermelon: Diseases and Symptoms

1. Downy mildew
2. Powdery mildew
3. Anthracnose
4. Alternaria leaf spot
5. Fusarium wilt
6. Bud necrosis disease
7. Cucumber mosaic disease
8. IPM for Watermelon

Downy mildew

Disease symptoms

• Yellow, angular spots restricted by veins resembling mosaic mottling appear on upper surface of leaves.
• The corresponding lower surface of these spots shows a purplish downy growth in moist weather.
• The spots turn necrotic with age. The diseased leaves become yellow and fall down. Diseased plants get stunted and die. Fruits produced may not mature and have a poor taste.

Host range: Musk melon, watermelon, sponge gourd and bitter gourd etc.

Survival and spread

• The pathogen survives in disease plant debris. Primary spread occurs by means of oospores in soil and sporangia from perennial collateral weed hosts in the vicinity. Secondary spread occurs by wind and rain splashes.

Favourable conditions

• Relative humidity > 85%, high soil moisture, frequent rains.

Powdery mildew

Disease symptoms

• Whitish powdery growth on upper foliage, stems and young growing parts. The superficial growth ultimately covers the entire leaf area.
• The diseased areas turn brown and dry leading to premature defoliation and death. Fruits remain underdeveloped and are deformed.

Host range: Pumpkins, watermelon, bottle gourd, coccinia, cucumber, ridge gourd, bitter gourd.

Survival and spread

• The fungus overwinters in dormant buds or plant parts. Primary infection occurs by dormant mycelium or cleistothecia in infected plant debris or conidia from collateral hosts. Secondary infection occurs by means of wind borne conidia.

Favourable conditions

• Morning relative humidity > 50%, cool and dry weather.

Anthracnose

Disease symptoms

• Water soaked lesions are seen on the leaf which later become yellowish irregular spots.
• Foliage spots are irregular and turn dark brown or black. Stem lesions can girdle the stem and cause vines to wilt.
• The most striking diagnostic symptoms are produced on the fruit, where circular, black, sunken cankers appear. The spots may measure 1/4 to 1/2 in (6 to 13 mm) in diameter and up to 1/4 in (6 mm) deep.
• When moisture is present, the black center of the lesion is covered with a gelatinous mass of salmon colored spores.

Host range: Common on watermelon, muskmelon and cucumber.

Survival and spread

• Fungus survives in disease plant debris and overwinters on diseased residue from the previous vine crop in the form of resting spore. Secondary infection occurs by means of wind borne conidia.

Favorable conditions

• 24-30°C and high relative humidity up to 100% for 24 h is optimum for fungal growth and infection with a thin film of water on leaf.

Alternaria leaf spot

Disease symptoms

• The symptoms are first observed at the top of the portion of the plant.
• Round to irregular target board spots on older leaves are seen.

Survival and spread

• Fungus survives in soil, and may persist in plant debris.
• Primary infection occurs by infected soil or inoculum present in plant debris
• Secondary spread is through rain or wind borne conidia.

Favourable conditions

• The disease is favored by continuous wet conditions.

Fusarium wilt

Disease symptoms

• The first symptom appears as chlorosis of the leaves.
• Wilting of leaves from bottom to top occur.
• Brown vascular discolouration inside infected stem or root leads to the death of plants.

Survival and spread

• Pathogen survives in soil in the form of Chlamydospore (resting spore) for many years and primary infection occurs through inoculum present in the soil.

Favourable conditions

• Relatively high soil moisture and soil temperature are favourable for the infection.

Bud necrosis disease

Disease symptoms

• Chlorotic rings, mottling, crinckling on leaves are seen, on stunted plants.
• These spots turn brownish black, and leaves become brown and distorted.
• The surface of the fruits having ring spots which later turn to tan, necrotic or scab like lesions.

Transmission and favourable conditions

• Thrips are the main vector for the transmitting the virus. Dry and hot periods when thrips population increase rapidly favours the spread of the disease.

Cucumber mosaic disease

Disease symptoms

• Symptoms of mosaic appear on the youngest leaves when infection occurs at 6 – 8 leaves stage
• Leaves curl downwards and become mottled, distorted, wrinkled and reduced in size
• Veins appear bunchy because of shortening of internodes
• Fruit set is very less if infection occurs early in crop growth
• Fruits are often misshapen, mottled, warty and reduced in size

Wide host range: Cucumber, pumpkin, gourds, cowpea, tomato, chilli, etc. Cucumovirus with spherical particles having ssRNA, banana, clover, corn, passion fruit, safflower, spinach, sugarbeet, wild cucumber, Commelina communis, C. diffusa, C. nudiflora, Solanum elaegnifolium, Phytolacca sp., periwinkle, Gladiolus sp., Impatiens sp. and Phlox.

Survival and spread

• Primary: Virus particles on collateral and other weeds, ornamentals or crops.
• Secondary: Virus particles transmitted by aphids (Aphis craccivora, Myzus persicae) and spotted and striped cucumber beetles.

IPM for Watermelon

To know the IPM practices for Watermelon, click here.

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage

 

3.09   

 

127 ratings

Watermelon Pests

1. Pests of National Significance
1. Insect and mite pests
2. Diseases
3. Nematode
4. Weeds
1. Broad leaf
5. Grasses
6. Sedges
2. IPM for Watermelon

Pests of National Significance

Insect and mite pests

• Red pumpkin beetle: Raphidopalpa foveicollis Lucas (Coleoptera: Chrysomelidae)
• Fruit fly: Bactrocera cucurbitae Coquillett (Diptera: Tephritidae)
• Thrips: Thrips tabaci Linderman (Thysanoptera: Thripidae)
• Whitefly: Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)
• Aphid: Aphis gossypii Glover (Hemiptera: Aphididae)
• Leaf eating caterpillar: Diaphania indica Saunders (Lepidoptera: Pyralidae)
• Serpentine leaf miner: Liriomyza trifolii Burgess (Diptera: Agromyzidae)
• Red spider mite: Tetranychus urticae Koch (Acarina: Tetranychidae)

Diseases

• Downy mildew: Pseudoperonospora cubensis Berkeley & Curtis
• Powdery mildew: Erysiphe cichoracearum DC, Sphaerotheca fuliginea (Schltdl.) Pollacci)
• Anthracnose: Colletotrichum orbiculare Berk. & Mont. Arx, & C. lagenarium Pass. Ell. & Halst
• Alternaria leaf spot: Alternaria cucumerina Elliot
• Fusarium wilt: Fusarium oxysporum f.sp. niveum (E.F. Sm.) W.C. Snyder & H.N. Hans
• Bud necrosis diseases: Tomato spotted wilt virus (Tospo virus)
• Cucumber mosaic disease: Cucumber mosaic virus

Nematode

• Root - knot nematode: Meloidogyne sp.

Weeds

Broad leaf

• Lamb’s quarter: Chenopodium album L. (Chenopodiaceae)
• Scarlet pimpernel: Anagallis arvensis (Primulaceae)
• Sweet clover: Melilotus indica L. (Fabaceae)
• Swine cress: Coronopus didymus L. Sm. (Brassicaceae)
• Fine leaf fumitory: Fumaria parviflora Lam. (Papaveraceae)
• Corn spurry: Spergula arvensis L. (Caryophyllaceae)
• Pigweed: Amaranthus viridis Hook (Amranthaceae)
• Black nightshade: Solanum nigrum L. (Solanaceae)
• Common purselane: Portulaca oleracea L. (Portulacaceae)
• False amaranth: Digera arvensis Forssk. (Amaranthaceae)
• Carrot grass: Parthenium hysterophorus L. (Asteraceae)

Grasses

• Blue grass: Poa annua L. (Poaceae)
• Rabbit/crow foot grass: Dactyloctenium aegyptium L. Willd. (Poaceae)
• Crab grass: Digitaria sanguinalis L. Willd (Poaceae)

Sedges

• Purple nut sedge: Cyperus rotundus L. (Cyperaceae)

IPM for Watermelon

To know the IPM practices for Watermelon, click here.

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage

 

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125 ratings

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Watermelon: Crop Stage-wise IPM

1. Pre sowing*
2. Sowing*
3. Vegetative stage
4. Reproductive stage

Management	Activity
Pre sowing*
	Common cultural practices: • Timely sowing should be done. • Field sanitation, rogueing • Destroy the alternate host plants and weeds. • Apply manures and fertilizers as per soil test recommendations. • Grow the attractant, repellent, and trap crops around the field bunds. • Growing tomato or marigold as a trap crop for the management of leaf miner. • Sow/plant tall border crops such as maize/sorghum/bajra all around watermelon field as guard crop. • Rotate crop with non-host crops.
Nutrients	• Nutrients should be applied based on the soil test report and recommendations for the particular agro-climatic zone. • Apply FYM @ 16 t/acre and incorporate in the soil 2 to 3 weeks before sowing. • If crop is planted in pit a mixture of soil and 4-5 Kg of FYM or compost, 30- 40 g urea, 40-50 g SSP (single super phosphate) and 80 or 100 g of MOP (muriate of potash) should be added.
Weeds	• Deep ploughing during summer or adopt stale bed technique. • Harrowing and ploughing before sowing.
Soil borne pathogens,nematodes, resting stages of insects	Biological control: • Apply neem cake/pongamia cake @ 100 Kg/acre or press mud @ 2 t /acre in soil at the time of last ploughing for reducing nematodes and soil dwelling pests.
Sowing*
	Common cultural practices: • Use tolerant/resistant varieties. • Select healthy, certified and weed seed free seed. • Avoid overlapping sowings of susceptible crops and sequential plantings side by side to minimise virus spread from one crop to the next.
Nutrients	• Basal application of 10 Kg Nitrogen (N), 15 Kg Phosphorus and 8-10 Kg Potash should be done.
Weeds	• Adopt the recommended agronomic practices like timely sowing, method of sowing and proper spacing etc.
Vegetative stage
	Common cultural practices: • Collect and destroy the crop debris • Provide irrigation at critical stages of the crop • Avoid water stress and water stagnation conditions. • Enhance parasitic activity by avoiding chemical spray, when 1-2 larval parasitoids are observed Common mechanical practices: • Collect and destroy disease infected and insect infested plant parts • Collect and destroy eggs and early stage larvae • Handpick the older larvae during early stages • Handpick the gregarious caterpillars and the cocoons which are found on stem and destroy them in kerosene mixed water. • Use yellow sticky traps for whitefly and aphids and blue sticky trap for thrips @ 4-5 trap/acre. • Use light trap @ 1/acre and operate between 6 pm and 10 pm • Install pheromone traps @ 4-5/acre for monitoring adult moths activity (replace the lures with fresh lures after every 2-3 weeks) • Erect of bird perches @ 20/acre for encouraging predatory birds such as king crow, common mynah etc. • Set up bonfire during evening hours at 7-8 pm Common biological practices: • Conserve natural enemies through ecological engineering • Augmentative release of natural enemies
Nutrients	• Apply 14 Kg of N/acre at 25 days after sowing as top dressing. • Micronutrient deficiency should be corrected by foliar spray of particular nutrient. • To maintain the sex ratio (more number of female flowers), spray borax @ 3-4 g/l at 2-4 leaf stage
Weeds	• Regular hoeing by power hand tillar and/ or hand tools to keep the field weed free up to 30 days crop stage.
Serpentine leaf miner	Biological control: • Foliar spray with neem oil @ 10-20 ml/l or NSKE 5%
Red pumpkin beetle	• See common cultural, mechanical and biological practices. • Spray NSKE 4%
Aphid	Cultural control: • High levels of nitrogen fertilizer favor aphid reproduction, so never use more nitrogen than necessary. Biological control: • Release 1st instar larvae of green lacewing (Chrysoperla zastrowi sillemi) @ 4,000 Nos/acre. • Spraying with tobacco decoction (1 Kg tobacco boiled in 10 l of water for 30 minutes and making up to 30 l + 100 g soap).
Whitefly	• See common cultural, mechanical and biological practices.
Leaf eating caterpillar	Cultural control: • Soil application of neem cake (immediately after germination and again at flowering) followed by spraying of NSKE @ 4% with sticker (0.5 ml/l of water) at 10-15 days interval.
Thrips	Cultural control: • Keep plants well irrigated, and avoid excessive applications of nitrogen fertilizer, which may promote higher populations of thrips. Biological control: • Soil application of neem cake (once immediately after germination and second at flowering) followed by spraying of NSKE @ 4% with sticker (0.5 ml/l of water) at 10-15 days interval.
Red spider mite	• See common cultural practices. Biological control: • Spray neem or pongamia soap at 1% on lower surface thoroughly.
Powdery mildew	Cultural control: • Bower system (maintain gapping) of cropping reduces the disease incidence.
Downy mildew, Anthracnose	Cultural control: • Trellising (provide support system) watermelon. • Control alternate weed hosts (wild cucumber, golden creeper and volunteer cucumbers) in neighbouring fence rows and field edges. • Bower system of cropping reduces the disease incidence. • Seed production should be preferably carried out in summer season because summer crop is often free from diseases.
Alternaria Leaf spot	• See common cultural and mechanical practices
Bud necrosis	Cultural control: • Maintaining a clean buffer zone free of weeds of at least 25 m between a virus source and a susceptible crop can considerably reduce virus levels. • Control the thrips as given above in thrips management.
Fusarium wilt	Cultural control: • Uproot and burn the infected plants.
Cucumber mosaic disease	Cultural control: • Raise 4 rows of barrier crop such as maize/sorghum/bajra. • Avoid planting tomatoes next to cucurbits, spinach, or other vegetables and flowers susceptible to these diseases. • Control of aphid vectors as given in aphid management.
Reproductive stage
Nutrients	• Micronutrient deficiency should be corrected by foliar spray of particular micronutrient.
Weeds	• Left over weeds should be removed from the field before shedding of seeds to avoid further spread of weed seeds.
Fruit fly	Cultural control: • Put fly traps in the field @4-8 traps/acre. Kill the collected fruit flies. • Raking of soil during fruiting time and after the harvest to expose pupae to the predators and sunlight. Biological control: • Spray neem based products
Other pests and diseases	• Same as vegetative stage
Note: The pesticide dosages and spray fluid volumes are based on high volume sprayer. *Apply Trichoderma viride/harzianum and Pseudomonas fluorescens as seeds/seedling/planting materials treatment and soil application (If commercial products are used, check for label claim. However, biopesticides produced by farmers for own consumption in their fields, registration is not required).

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage

 

3.04   

 

134 ratings and

Watermelon: Insect, Mite and Nematode Pests Management

1. Red pumpkin beetle
2. Fruit fly
3. Thrips
4. White fly
5. Aphid
6. Leaf eating caterpillar
7. Serpentine leaf miner
8. Red spider mite
9. Root-knot nematode
10. IPM for Watermelon

Red pumpkin beetle

Biology

• Egg: Eggs are brownish-yellow in colour, elongated, laid singly or in batches in moist soil near rhizosphere. Incubation period is 5-8 days after which tiny larvae hatch out and enter the soil.
• Larva: Grubs grow by feeding on the debris and on roots and stems of plants. There are four larval instars and larvae must enter the soil each time before to moult. Larval period is 18-25 days, which is spent mostly in soil. Fully grown grubs are 10-12 mm in length.
• Pupa: Pupation also takes place in the soil in a waterproof cocoon up to a depth of 25 cm. Adults emerge and make their way out of the soil.
• Adult: Adults are small bright reddish beetles, 4-7 mm long, active beetles, flying from plant to plants and feeding on leaves. Hibernation takes place in adult stage from November to March in northern India, usually in debris or under stones or other hiding places. Longevity of adult is more than a month. Fecundity is 150-300 eggs per female.

Damage symptoms

• Seedlings may be completely destroyed by adult feeding.
• Older plants have foliage riddled with holes or completely defoliated, and the floral parts, including anthers are nibbled.
• Feeding by larvae causes rotting and withering of the roots and stems.
• The surface of young fruit may show feeding marks caused by the adults and the undersurface of fruits where they touch the soil surface may have indications of larval tunnels in the surface.

Natural enemies of red pumpkin beetle

• Parasitoids: Braconid wasp, Celatoria cetosa (tachinid fly)
• Predators: Pennsylvania leatherwing beetle, ground beetle, spider, earwig etc.

Fruit fly

Biology

• Egg: The egg is elliptical, pure white and about 2 mm long. It is almost flat on the ventral surface, and more convex on the dorsal. Eggs are often somewhat longitudinally curved.
• Larva: The maggot is cylindrical cigar shaped. It has anterior mouth hooks, ventral fusiform areas and a flattened caudal end. Last instar larvae range from 7.5 to 11.8 mm in length.
• Pupa: The puparium ranges in color from dull red or brownish yellow to dull white, and is about 5 to 6 mm in length. Pupation takes place in soil.
• Adult: The adult melon fly is 6 to 8 mm in length. Distinctive characteristics include its wing pattern, its long third antennal segment, the reddish yellow dorsum of the thorax with light yellow markings, and the yellowish head with black spots. Total life cycle completes 14-34 days depending on weather conditions.

Damage symptoms

• Newly hatched maggots bore into the fruit pulp by forming serpentine galleries and contaminating them with its frassy excreta and providing entry points for saprophytic fungi and bacteria resulting rotting of fruits.
• Due to feeding, there is pre-mature dropping of fruits and make them unfit for consumption.
• Formations of galls are also rarely seen on stems.

Natural enemies of fruit fly

• Parasitoid: Opius fletcheri
• Predators: Ants, dragon fly, spider, robber fly

Thrips

Biology

• Egg: Eggs are microscopic and white or yellow in colour. Eggs are inserted one by one by the gravid females in the plant tissue. Only one end of the egg will be near the surface of the tissue to allow the immature to emerge. Adults prefer to lay their eggs in leaf, cotyledon, or flower tissues.
• Nymph: Nymphs are tiny, small and pale yellow to brownish colour. Nymphs are similar to adults except wing and are smaller in size.
• Adult: The adult are slender, pale yellow to dark brown in colour and measures up to 1.5-2mm. Adults have fully developed fringe things. There are several overlapping in generations of this pests in a year.

Damage symptoms

• Thrips have a very peculiar feeding behavior as they are typical xylem-feeder.
• They start the feeding by rasping the leaf surface with their mouth parts to release the liquids from the plant cells and suck the plant juice.
• The plant loses more water than normal through the damaged tissues and plant pathogens penetrate the injured plant cells easily.

Natural enemies of thrips

• Parasitoid: Ceranisus menes
• Predators: Predatory mite, predatory thrips, Oligota spp., Orius spp. (pirate bug), mirid bug.

White fly

Biology

It is polyphagous pest and occurs almost throughout the country.

• Egg: Eggs are stalked, sub-elliptical and light yellow to light brown in colour. Gravid female lays eggs singly on under side of the leaves. Incubation period varies 3-7 days during summer season.
• Nymph: Nymphs are louse like, pale yellow coloured and clustered together underside of the leaves.
• Adult: Adults are winged, tiny (1-1.5 mm long), yellowish body covered with white waxy powder. Several overlapping generations are completed in a year.

Damage symptoms

• Affected plant loses its vitality due to sap sucking by both nymph and adult whiteflies resulting yellowing, downward curling and finally drying of leaves.
• Normal photosynthesis is restricted due to growth of black sooty mould on the honeydew excreted by the whitefly.

Natural enemies of whitefly

• Parasitoids: Encarsia formosa, Eretmocerus spp., Chrysocharis pentheus
• Predators: Dicyphus hesperus, lacewing, ladybird beetle, big-eyed bugs (Geocoris sp), mirid bug, spider, reduviid bug, robber fly, dragon fly, Orius spp.

Aphid

Biology

• Egg: Eggs are very tiny, shiny-black, and are found in the crevices of bud, stems, and barks of the plant. Aphids usually do not lay eggs in warm parts of the world.
• Nymph: Nymphs look like the wingless adults but are smaller. They become adults within 7 to 10 days.
• Adult: Adults are small, 1 to 4 mm long, soft-bodied insects with two long antennae that resemble horns. Most aphids have two short cornicles (siphunculi) protruding from 5th or 6th abdominal segment of the body. They complete their life cycle 9-21 days depending upon weather conditions.

Damage symptoms

• Infesting tender shoots and under surface of the leaves.
• Curling and crinkling of leaves
• Stunted growth
• Development of black sooty mould due to the excretion of honeydew

Natural enemies of aphid

• Parasitoids: Aphidius colemani, Aphelinus sp
• Predators: Red ant, robber fly, big-eyed bug (Geocoris sp), earwig, ground beetle, cecidomyiid fly, dragon fly, praying mantis, lacewing, ladybird beetle, spider etc.

Leaf eating caterpillar

Biology

• Egg: A female can lay upto 350 eggs, mostly singly or some time in groups on the lower surface of the leaves. Incubation period is 306 days.
• Larva: Elongate bright green caterpillar with two narrow longitudinal white stripes dorsally.
• Pupa: The pupa color is dull red or brownish yellow to dull white, and is about 5 to 6 mm in length. Pupation takes place in the silken cocoon formed in the leaf fold.
• Adult: The wingspan is about 30 mm. Adults have translucent whitish wings with broad dark brown borders. The body is whitish below, and brown on top of head and thorax as well as the end of the abdomen. There is a tuft of light brown "hairs" on the tip of the abdomen, vestigial in the male but well-developed in the female.

Damage symptoms

• Larva folds the leaves and scrapes the green matter. As a result the leaves get dried up.
• It can also feed on ovaries of flower; sometimes bore into young developing fruits.

Natural enemies of leaf eating caterpillar:

• Parasitoids: Trichogramma spp., Apanteles taragamae, A. machaeralis, Bracon hebetor, Phanerotoma hendecasisella, Chelonus sp., Campoletis chlorideae, Goniozus sensorius, Elasmus brevicornis, Xanthopimpla punctata, Brachymeria lasus, B. margaroniae etc.
• Predators: Reduviid, predatory bird, wasps, ground beetle, spiders, ants, earwig etc.

Serpentine leaf miner

Biology

• Egg: Eggs are minute in size and orange yellow in colour. The egg hatches in 3-5 days.
• Larva: Apodous maggot feeds on chlorophyll mining in between epidermal layers. Full grown maggot measures 3 mm. Larval duration is about 7-9 days.
• Pupa: Pupation is in soil. Some pupae are found in leaves. Pupation takes place inside a thin loose mesh of silken cocoon. Pupal period is about 5-7 days.
• Adult: It is a pale yellowish fly, measuring 1.5 mm in length. The female fly punctures upper surface of leaf to lay eggs singly Total life cycle takes 3 weeks.

Damage symptoms

• Leaves with silvery serpentine mines
• Drying and dropping of pre-matured leaves in severe cases

Favourable conditions

• Warm weather conditions are favourable for multiplication.

Natural enemies of serpentine leaf miner

• Parasitoids: Gronotoma micromorpha (larva and pupa), Diglyphus sp (larva), Halticoptera circulus and Opius sp (pupal) Chrysocharis sp, Neochrysocharis formosa.
• Predators: Lacewings, ladybird beetle, spiders, red ants, dragonfly, robber fly, praying mantis etc.

Red spider mite

Biology

• Egg: Eggs reddish, spherical, provided with a small filament. Incubation period is 2-4 days, before hatching becomes light orange colour.
• Nymph: Upon hatching, it will pass through a larval stage and two nymphal stages before becoming adult. Developmental stages include six legged larva, protonymph and deutonymph.
• Adult: Adult female elliptical in shape, bright crimson anteriorly and dark pruplish brown posteriorly. Mites spin a web of silken threads on the leaf. Each developmental stage is followed by a quiescent stage and life cycle completed in 10-14 days.

Damage symptoms

• Spider mites usually extract the cell contents from the leaves using their long, needle- like mouthparts. This results in reduced chlorophyll content in the leaves, leading to the formation of white or yellow speckles on the leaves.
• In severe infestations, leaves completely desiccate and drop off.
• The mites also produce webbing on the leaf surfaces in severe conditions.
• Under high population densities, the mites move to using strands of silk to form a ball like mass, which will be blown by winds to new leaves or plants, in a process known as "ballooning".

Natural enemies of red spider mite

• Predators: Anthocorid bugs (Orius spp.), mirid bugs, syrphid/hover flies, green lacewings (Mallada basalis and Chrysoperla sp.), predatory mites (Amblyseius alstoniae, A. womersleyi, A. fallacies and Phytoseiulus persimilis), predatory coccinellids (Stethorus punctillum), staphylinid beetle (Oligota spp.), predatory cecidomyiid fly (Anthrocnodax occidentalis), predatory gall midge (Feltiella minuta), predatory thrips etc.

Root-knot nematode

Biology

• Most species of plant parasitic nematodes have a relatively simple life cycle consisting of the egg, four larval stages and the adult male and female. They are microscopic in size.
• Development of the first stage larvae occurs within the egg where the first moult occurs. Second stage larvae hatch from eggs to find and infect plant roots or in some cases foliar tissues.
• Under suitable environmental conditions, the eggs hatch and new larvae emerge to complete the life cycle within 4 to 8 weeks depending on temperature.
• Nematode development is generally most rapid within an optimal soil temperature range of 70 to 80°F.

Damage symptoms

• Infected plants in patches in the field.
• Formation of galls on host root system is the primary symptom.
• Roots branch profusely starting from the gall tissue causing a ‘beard root’ symptom.
• Infected roots become knobby and knotty.
• In severely infected plants the root system is reduced and the rootlets are almost completely absent. The roots are seriously hampered in their function of uptake and transport of water and nutrients.
• Plants wilt during the hot part of day, especially under dry conditions and are often stunted.
• Seedlings infected in nursery do not normally survive transplanting and those surviving have reduced flowering and fruit production.
• Nematode infection predisposes plants to fungal and bacterial root pathogens.

Survival and spread

• Primary: Egg masses survive in infected plant debris and soil or collateral and other hosts like Solonaceous, Malvaceous and Leguminaceous plants act as sources of inoculum
• Secondary: Autonomous second stage juveniles that may also be water dispersed

Favourable conditions

• Loamy light soils

IPM for Watermelon

To know the IPM practices for Watermelon, click here.

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage

 

3   

 

130 ratings

Watermelon: Natural Enemies

1. Natural Enemies of Watermelon Insect Pests
1. Parasitoids
2. Predators
2. Resistant/tolerant varieties
3. IPM for Watermelon

Natural Enemies of Watermelon Insect Pests

Parasitoids

Predators

Resistant/tolerant varieties

Pest/disease	Tolerant/ Resistant Variety
Wilt	Watermelon-F1 sweet sensation, watermelon –F1 big guy
Anthracnose and wilt	Watermelon-F1 midnight, watermelon F1 bengal tiger, watermelon-F1 sweet dragon, watermelon-F1 wonder hybrid.
Alternaria leaf spot	Sugar baby’, ‘Fairfax’, and ‘Calhoun gray
Powdery mildew	Arka Manik
Aphid	PI 299563
Spider mite	'Congo' and 'Giza 1'
	Durgapura Kesar' (RW 187-2), Mithila, Suganthi, Kiran, Simran, Vishal

IPM for Watermelon

To know the IPM practices for Watermelon, click here.

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage

 

3.01   

 

132 ratings

Nutritional Deficiencies of Watermelon

1. Manganese
2. IPM for Watermelon

Manganese

Fine network of green veins as a light green background on young leaves. Leaf remains fairly green. Dark green irregular bands on mature leaves, along the midrib.

Management: Foliar spray of 0.5% MnSO₄.

IPM for Watermelon

To know the IPM practices for Watermelon, click here.

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage

 

3.03   

 

144 ratings

Natural Enemies of Fruit Crops in Arid Region

1. Praying mantid (Mantis religiosa)
2. Zigzag ladybird beetle (Cheilomenes sexmaculata)
3. Strip lady bird beetle (Brumoides suturalis)
4. Green lacewing (Chrysoperla carnea)
5. Ker butterfly parasitoid (Brachymeria albicrus)

Praying mantid (Mantis religiosa)

• Praying mantis or praying mantids are carnivorous (meat-eating) insects. There are about 2,000 different types of mantids.

Prey habitat

• Praying mantids are highly predacious and feed on a variety of insects, including moths, crickets, grasshoppers and flies.
• They lie in wait with the front legs in an upraised position. They intently watch and stalk their prey. They will eat each other.

Description

• The biggest are over 15 cm long and the smallest are about 1 cm long.
• Three distinct body regions: head, thorax (where the legs and wings are attached), abdomen. Part of the thorax is elongated to create a distinctive ‘neck’.

• Front legs modified as raptorial graspers with strong spikes for grabbing and holding prey.
• Large compound eyes on the head which moves freely around (up to 180°) and three simple eyes between the compound eyes.
• Incomplete or simple metamorphosis (hemimetabolous).
• A distinct Styrofoam-like egg case protects Mantid eggs throughout the winter. Up to 200 or more nymphs may emerge from the egg case.
• The nymphs look like adults except for size and the sexual definition.

Zigzag ladybird beetle (Cheilomenes sexmaculata)

• Present almost throughout India and the Oriental region, Iran, Australasia etc.

Prey habitat

• Aphidophagous, also feeds on psyllids, whiteflies, mealybugs, tingids, leaf and planthoppers, mites, and early instar lepidopteran larvae.

Description

• Body is oval to subrounded, dorsum moderately convex and shiny.
• Length 3.3-6.2 mm and width 3.0-5.3 mm.
• Ground colour orange, light red, yellow or pinkish with the following markings in the typical form.
• Head with a black marking in posterior half.
• Pronotum with a T-shaped median marking connected to a broad black band along posterior margin.

• Elytra with six black maculae including two zigzag lines and a posterior black spot.

Strip lady bird beetle (Brumoides suturalis)

• Widespread almost throughout India (Andhra Pradesh, Goa, Jammu & Kashmir, Karnataka, Kerala, Manipur, Punjab, Tamil Nadu, Uttar Pradesh, West Bengal), Nepal, Bhutan,Sri Lanka, etc.

Prey habitat

• This species departs from the normal food habits of the other genera of Chilocorini, which are mainly scale feeders.
• It is more polyphagous and largely predatory on aphids, whiteflies, psyllids, scales, mealybugs and mites.

Description

• Body is oval, dorsum convex. Body length is 4.0 mm and width 2.7 mm.
• Head and pronotum orange yellow.
• Scutellum black.
• Elytra satiny white to creamy yellow, with three black stripes, one on each elytron in a mid-dorsal position not extending to apex and one along sutural line nearly extending to apex.

• Apical portion yellowish to reddish brown.
• Last visible abdominal segment with posterior margin emarginate in male and narrowly rounded in female.
• Larva slaty grey, with prominent spiny protuberances on dorsal side.

Green lacewing (Chrysoperla carnea)

• It is found in many parts of America, Europe and Asia. It was originally considered to be a single species with a holarctic distribution but it has now been shown to be a complex of many cryptic, sibling species.

Prey habitat

• The adults feed on nectar, pollen and aphid honeydew but the larvae are active predators and feed on aphids and other small insects.

Description

• The green lacewing eggs are oval and secured to the plant by long slender stalks.
• The larvae are brown and resemble small alligators, crawling actively around in search of prey.

• They have a pair of pincer-like mandibles on their head with which they grasp their prey, sometimes lifting the victim off the leaf surface to prevent its escape.
• Adult green lacewings are a pale green colour with long, threadlike antennae and glossy, golden, compound eyes.
• They have a delicate appearance and are from twelve to twenty millimetres long with large, membranous, pale green wings which they fold tent-wise above their abdomens.
• They are weak fliers and have a fluttery form of flight.

Ker butterfly parasitoid (Brachymeria albicrus)

• The parasitoid has a worldwide distribution. During the surveys conducted in Rajasthan, Brachymeria albicrus was found parasitizing Anaphaeis aurota infesting ker plant.

Parasitoid habit

• It is a parasitoid of ker butter fly, Anaphaeis aurota

Description

• The parasitoid have elbowed antenna and have a typically enlarged femur (thigh) segment on the hind legs.
• The female typically lays eggs inside the larva of a Lepidopteron using its ovipositor.

• The adult parasitoid emerges typically from the pupa.
• The mean percent parasitism of the butterfly by B. albicrus at CIAH farm and at Desnok, Bikaner was 49.5 and 47.5 respectively and the mean percent emergence of the mature adult parasitoids from the parasitized pupae was 15.5 and 14.0 respectively.

Source: Insect Pest of Arid Fruit Crops

 

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