Lentil Diseases and their Management

0 0 الأحد، 30 مايو 2021

Lentil Diseases Fusarium Wilt Lentil rust Ascochyta blight Anthracnose Root rot and seedling diseases Powdery mildew Scl...

Lentil Diseases

Fusarium Wilt

Disease symptoms:

Symptoms can occur at both the seedling and plant developmental stages and appear as patches in the field The root system appears healthy, but with a reduced proliferation and nodulation rate.
In most cases, there is no discolouration of the vascular system. Other symptoms at the seedling stage include seed rot.
It usually occurs near or at the reproductive stages (flowering to pod-filling) of crop growth. Symptoms include the drooping and wilting of the uppermost leaflets . Plants become completely yellow and die. Plants are affected during the mid- to late-pod filling stages, seeds are often shrivelled

Survival and spread:

Chlamydospores of the pathogen can survive in the soil for many years in the absence of a host plant. The pathogen can also survive within infected plant material in the field. This indicates that the pathogen is well adapted to survive adverse conditions

Favourable conditions:

Moist soil, warm and humid conditions favour the development of wilt.

Lentil rust

Disease symptoms:

First sign of infection is small white pustules on theleaves.
Minute yellowish slightly raised pustules, that as they enlarge change to orange-brown in colour, often surrounded by a light coloured halo.

Survival and spread:

Rust spores are small, light and may survive for several days. They can be spread to large distances by wind.

Favourable conditions:

Rusts can build up rapidly and are mostly seen as the weather warms above 20ºC. Leaves, stems and pods can be infected.

Ascochyta blight

Disease symptoms

Grey to tan spots or lesions on leaflets, stems, flowers and pods, with dark margins and often with tiny black fruiting bodies (pycnidia) in the centers
Lesions first appear on lower leaflets close to soil surface and spread up the plant canopy. Lesions on stems can girdle the plant resulting in wilting. Leaves may turn brown and die off.

Survival and spread:

It can be spread to large distances by wind and infected plant debris.

Favourable conditions:

Ascochyta blight is present at commencement of flowering in susceptible varieties.
Cloudy and humid weather for a week period favours the disease development and its spread.

Anthracnose

Disease symptom:

Tan lesions with darker borders on leaves which often appear prior to flowering or shortly after bloom.
Diseased leaves may drop from the plant prematurely.
Tan to light brown lesions appear on lower stems and begin to spread upwards, appearing higher on the plant; lesions may contain numerous black dots; as plant matures, the lesions expand and may cover large areas of the stem
Lesions may also be present on pods and are light to tan brown with a dark margin; diseased pods often produced discolored seeds; disease can cause severe losses in yield.

Survival and spread:

The pathogens survive on seed and plant debris
Disease spreads in the field through air-borne conidia

Favourable condition: Disease emergence is favored by wet conditions; fungus is spread by splashing water

Root rot and seedling diseases

Disease symptoms:

Failure of seedling to emerge.
Light brown, seedlings with light brown to red, .water-soaked roots and stems.
Infected plants dry up and die.
Stunted plant growth, rotting taproot with few lateral roots

Survival and spread:

Pathogens survive in soil as well as seed as resting mycelia or sclerotia for longperiod.
These organisms often survive as saprophytes, living on dead plant material, or as dormant mycelia or spores.
Root exudates from germinating seedlings or growing roots stimulate the dormant fungi to become active.

Favourable conditions: Diseases are prevalent under cool wet conditions that keep the soil temperatures below 13°C.

Powdery mildew

Disease symptom:

Powdery mildew appears as gray-white areas which coalesce to cover entire plant
If plant is heavily infected it may die.

Survival and spread:

The pathogen has a wide host range and survives in conidial form on various hosts in off-season.
Secondary spread is through air-borne conidia produced in the season.

Favourable conditions: Cool and dry weather favours disease development

Sclerotinia rot/collar rot

Disease symptom:

Lesions girdle stem causing upper plant parts to become chlorotic and wilted.
Plants become necrotic after they die; disease often causes a patchwork of symptomatic plants throughout a field with plants initially becoming chlorotic and finally dying.
Fungus causes characteristic white lesions on stems which may be covered in a fluffy white growth during periods of wet weather.

Survival and spread: The fungus survives as sclerotia or mycelium in infected plant residue and soil

Favourable conditions: Disease emergence is favored by cool, wet conditions

Pea mosaic virus

Pea enation mosaic virus, Pea seed borne mosaic virus and Bean yellow mosaic virus

Disease symptoms:

Infected plants develop mosaic and chlorotic vein flecking and veinal enations (blister like outgrowths), which are very characteristic for PEMV.
Plants are stunted, and proliferation of basal branches is common. Pods are distorted, split open, and may show prominent enations.
Distinct mottling of the foliage is the most conspicuous symptom.
The tissue yellows between the veins, leaving patches normal green tissues scattered irregularly over the surfaces of both leaves and stipules.

Survival and spread:

Mainly it is spread through aphids as well as seeds.
Occupying of perennial legumes bordering the planting area also increase the primary virus reservoir.

Favourable conditions:

Normal temperature and moisture are satisfactory for disease development. Warm, dry, weather which encourages aphid population build-up, may aid virus spread in the field.
Seed transmission may be suppressed by high temperatures

IPM for Lentil

To know the IPM practices for Lentil, click here.

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

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Lentil Insect Pests

Cow pea aphid

Biology

Egg: Eggs are laid on the growing region from which nymphs emerge.
Nymphs: Eggs hatch into nymphs. The nymphs are slate grey.
Adult: Adults are small (up to 2.5 mm long) and are shiny black. Females reproduce parthenogentically in the tropics and subtropics.

Life cycle:

Damage symptoms:

Cowpea aphids are phloem feeders and inject toxins into the plant while feeding; they most likely reduce vigour and yields. Aphid-feeding also produces honeydew, which grows sooty mould that reduces photosynthesis and makes harvesting difficult.

Natural enemies of cowpea aphid:

Ladybird beetles, Syrphid flies, Rove beetle, Damsel bug, Green lacewing and parasitoids such as Aphidius spp. (aphid parasitoid).

Leaf weevil

Biology:

Eggs: Females lay eggs in the soil near to growing plants.
Larva: Larvae develop under the soil and are “C” shaped and milky-white with a dark-brown head capsule ranging in length from 3.5-5.5 mm. Larvae develop through five instar stages. After hatching, larvae seek and enter the roots of a lentil plant. Larvae enter and consume the contents of the nodules of the legume host plant.
Pupa: Pupation takes place in the soil.
Adults:Adults are slender, greyish-brown measuring approximately 5 mm in length). The weevil has a short snout and feed upon the leaf margins and growing points of legumes

Lygus bugs

Biology:

Eggs: Eggs are slightly curved and approximately 1 mm long with an eye-shaped cap. After mating and once the eggs mature, females seek suitable host plants, on which lay their eggs. Eggs are laid individually into the stems and leaves of host plants.
Nymphs: There are five nymphal instars. Young nymphs are light green and wingless. Older nymphs develop black dots on the top of the thorax and abdomen. Wing buds are evident in the fourth and fifth instars.
Adults: Adult lygus bugs are about 3 mm wide and 6 mm long. They vary from pale green to reddish brown to black and from fairly uniform color to mottled. Lygus bugs share characteristics with all ‚true bugs, the distinctive, triangular or ‚ 'V'- shaped marking in the upper centre of their backs and membranous wingtips. Adults are active and fly readily when approached.

Cut worm

Biology:

Egg: The egg is white in color initially, but turns brown with age. It measures 0.43 to 0.50 mm high and 0.51 to 0.58 mm wide and is nearly spherical in shape, with a slightly flattened base. Females may deposit eggs, duration of the egg stage is 3 to 6 days.
Larva: The caterpillar is rather uniformly colored on the dorsal and lateral surfaces, ranging from light gray or gray-brown to nearly black. The head is brownish with numerous dark spots. They sever plants at the soil surface and cause extensive damage; the caterpillars are cannibalistic.
Pupa: Pupation occurs in the soil at a depth of 3 to 12 cm. The pupa is 17 to 22 mm long and 5 to 6 mm wide and dark brown. Duration of the pupal stage is normally 12 to 20 days.
Adults: The adult is fairly large in size, with a wingspan of 40 to 55 mm. The forewing especially the proximal two-thirds, is uniformly dark brown. The distal area is marked with a lighter irregular band, and a small but distinct black dash extends distally from the beanshaped wing spot. The hind wings are whitish to gray, and the veins marked with darker scales. The adult preoviposition period is about 7 to 10 days.

Life cycle:

Damage symptoms: Larvae cut off the plant at or just below ground level.

Thrips

Biology:

Egg: White to yellow; kidney-bean shaped; microscopic in size. Develop within leaf tissue with one end near the leaf surface. Hatch in 5-10 days.
Nymph: Nymphs are active feeding stages.
Adults: About 0.06 inch (1.5 mm) long; elongate, yellow and brown body with two pairs of fringed (hairy) wings. Mouthparts are beak-like and antennae are 7-segmented.

Natural enemy of Thrips: Minute pirate bugs, Orius spp.

Pod borer: Helicoverpa armigera

Biology:

It is a polyphagous pest, infesting gram, lablab, safflower, chillies, groundnut, tobacco, cotton etc.
Egg: Spherical, yellowish eggs are laid singly on tender parts and buds of plants. The egg period lasts for 2-4 days.
Larva: Caterpillars are of varying in colour, initially brown and later turn greenish with darker broken lines along the side of the body. Body covered with radiating hairs. When full grown, they measure 3.7 to 5 cm in length. The larval period lasts for 18-25 days. The full grown caterpillar pupates in the soil.
Pupa: Pupation takes place inside the soil in an earthen cell. Pupal stage lasts 7-15 days.
Adult: Moth is stout, medium sized with brownish/greyish forewings with a dark cross band near outer margin and dark spots near costal margins, with a wing expanse of 3.7cm.

Life cycle:

Natural enemies of pod borer:

Common mynah, spider, assassin bugs, Trichogramma spp., Bacillus thuringiensis var kurstaki, entomopathogenic nematodes (EPNs), Yellow wasps, etc

IPM for Lentil

To know the IPM practices for Lentil, click here.

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

2.93

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Lentil Pests

Pests of National Significance

Pests of National Significance

Insect pests

Cow pea aphid: Aphis craccivora Koch (Hemiptera: Aphididae)
Pea aphid: Acyrthosiphon pisum Haris (Hemiptera: Aphididae)
Leaf weevil: Sitona spp. (Coleoptera: Curculionidae)
Lygus bugs: Lygus spp. (Hemiptera: Miridae)
Cut worm: Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)
Thrips: Thrips tabaci Lindeman (Thysanoptea: Thripidae)
Pod borers: Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae)
Spiny pod borer: Etiella zinckenella (Treit.) (Lepidoptera: Pyralidae)
Pulse beetles: Bruchus spp., Callosobruchus spp. (Coleoptera: Bruchidae)

Diseases

Root rot and seedling disease: Pythium ultimum Trow, Rhizoctonia solani Kühn
Fusarium wilt : Fusarium oxysporum (Schlecht)Snyder & Hansen (Hypocreales: Nectriaceae)
Lentis rust: Uromyces fabae (Pers.) Schröt.
Ascochyta blight: Ascochyta lentis Jellis & Punith
Anthracnose: Colletotrichum truncatum (Schwein.) Andrus & Moore
Powdery mildew: Erysiphe pisi DC.,
Sclerotinia rot/collar rot: Sclerotinia rolfsii Sacc.
Pea enation mosaic virus
Bean yellow mosaic virus
Pea seed borne mosaic virus (PSBMV).

Weeds

Broadleaf weeds

Field bind weed: Convolvulus arvensis L. (Convolvulaceae)
Lambs quarter: Chenopodium album L. (Chenopodiaceae)
Sweet clover: Melilotus indica (L.) All. (Fabaceae)
Scarlet pimpernel: Anagalis arvensis (Primulaceae)
Onion weed: Asphodelus tenuifolius Cav. (Liliaceae)
Carrot grass: Parthenium hysterophorus L. (Asteraceae)
Benghal dayflower: Commelina benghalensis L. (Commelinaceae)

Grasses

Wild oat: Avena ludoviciana (L.) Nees. (Poaceae)
Canary grass: Phalaris minor Retz. (Poaceae) Sedges
Purple nutsedge: Cyperus rotundus L. (Cyperaceae)
Yellow nutsedge: Cyperus esculentus L. (Cyperaceae) Parasitic weed
Dodder: Cuscuta spp.(Convolvulaceae)
Broomrape: Orobanche spp. (Orobanchaceae)

Nematode

Cyst nematode: Heterodera ciceri (Tylenchida: Heteroderidae)

IPM for Lentil

To know the IPM practices for Lentil, click here.

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

2.9

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Lentil Crop Stage Wise IPM

Management	Activity
Pre-sowing
	Common cultural practices: Summer deep ploughing Follow crop rotation with non host crops Field sanitation, rogueing Destroy the alternate host plants
Nutrients	Apply well decomposed FYM @ 4-5 tons / acre incorporated with Trichoderma 2-3 weeks before sowing
Weeds	Destroy weeds manually or by deep summer ploughing
Sowing
	Common cultural practices: Do summer ploughing Timely sowing should be done Solarize the field in summer to help reduce the inoculums. Use resistant varieties Select seed from disease free fields
Nutrients	Seed treatment should be done with Rhizobium culture @ 200 g/ acre. Fertilizers should be applied on soil test basis. Generally, it is recommended to apply 8 to 10 kg N, 16 kg P2O5 , 8 kg K2O, 8 kg sulphur and 6 kg ZnSO4 per acre at the time of sowing as basal application..
Weeds	Always use certified and weed free seeds. Timely sowing should be done. Line sowing should be done to facilitate inter-culture operations. Plant population should be maintained to its optimum right from its beginning to minimize the crop weed competition. Adopt suitable crop rotation to minimize dodder and orobanche weeds.
Pests, Soil-borne pathogens	Deep ploughing of fields during summer to manage juvenile population of nematodes and insect pests. Soil solarization: Cover the beds with polythene sheet of 75 gauge thickness for six weeks before sowing to reduce the soil borne pests.
Vegetative
	Common cultural practices: Avoid excess application of nitrogen Adopt the ecological engineering strategy. Conserve natural enemies Remove and destroy weeds periodically Removal and destruction of infected/infested plants
Nutrients	Correct micronutrient deficiency if any in standing crop
Weeds	Keep field boundary & bunds free from weeds. The crop field should be weed free initially for 4-5 weeks by following timely hoeing and weeding. Inter-culture operation/hoeing should be done twice at 20 and 35 days after sowing-using hand hoe to remove all weeds in between the row
Cow pea aphid	Mechanical control: Use yellow sticky trap Biological control: Conserve the predators such as Syrphid flies, Rove beetle, Green lacewing, Ladybird beetle and parasitoids such as Aphidius spp. Aphelinus sp.
Cut worm	Biological control: Conserve and augment the predators and parasitoids
Thrips	Cultural control: Ploughing, harrowing and solarisation can kill pupae in the soil from previously infested crops. Mechanical control: Adult thrips can be monitored by mass trapping with blue sticky traps or water pan traps in field. Biological control: Conserve and augment the various biological control agents, including minute pirate bugs, Orius spp., Big eyed predatory bug, Geocoris sp. and entomopathogenic nematodes,
Pod borers	Biological control: Conserve and augment biocontrol agents.
Fusarium wilt and root rot diseases	Cultural control: Use resistant varieties (PL 406, PL 639 and PL 234) Follow crop rotation Weeds control Delayed sowing can reduce disease incidence Use of clean and certified seed. Deep ploughing over summer and removal of infected trash can reduce inoculum levels of Fusarium wilt Mechanical control: Solarisation of soil by covering the soil with transparent polythene sheet (75 gauge) for 6-8 weeks during the summer for effective management.
Lentil rust	Cultural control: Use resistant varieties (PL 234, PL 406, LL 931, LL 699 and Narendra Masur-1)
Ascochyta blight	Cultural control: Use of resistant cultivars (LL 699) Use of disease free seed, Follow crop rotation
Powdery mildew	Cultural control: Use of resistant varieties
Mosaic virus	Cultural control: Use of disease free seeds Mechanical control: Use yellow sticky traps for vector monitoring
Reproductive
Nutrients	Incorporate crop residues in soil immediately after harvest
Aphids	Same as vegetative stage
Lygus bug	Cultural control: Removal of weeds along field borders to prevent buildup of lygus bugs. Biological control: Conserve and augment biocontrol agents
Cut worm and Thrips	Same as vegetative stage