Integrated Pest Management

Alternaria blight

Causal Organism

Alternaria brassicae Sacc., A. alternanta

Damage

• The disease attacks on the lower leaves as small circular brown necrotic spots which slowly increase in size.
• Damage may occur throughout crop growth.
• Period of activity is Nov-March.
• Formation of spots takes place in the plant leaves and siliquae.
• The spots produced by this disease are brownish or grayish.
• Many spots coalesce to cover large patches showing brightening and defoliation in severe cases.
• Circular to linear, dark brown lesions also develop on stems and pods, which are elongated at later stage.
• Infected pods produce small, discoloured and shriveled seeds.
• The disease is externally and internally seed born.
• The infected pods dry up and get shriveled.
• The seeds become grey to brown, smaller in size and the oil content is considerably reduced.

Survival & Favourable Conditions

• The pathogen survives through spores (conidia) or mycelium in diseased plant debris or weed
  host.
• Moist ( more than 70% relative humidity) and warm weather (12-25 C temp) and intermittent rains are favours disease development.

Cultural Control

• Use of resistant/tolerant varieties
• Timely sowing between 10-25th October.
• Use healthy certified seeds.
• Take control measures when severity is more than 3%.
• Field sanitation is must.
• Removal of weeds like bathua.
• Application of potash in recommended dose reduces disease index.
• For chemical control, refer chemical control section.

Mechanical Control

• Burning of the crop debris of previous year.

Chemical Control

• Spray the crop with Mancozeb 75 % WP at the rate 2 gm per litre.
• If the infection persists then repeat the spray after 15 days interval.
  OR
• Three or four spray of Iprodione (Rovral) or Mancozeb (Dithane M 45) 75% WP.
  OR
• Zineb at 2 g/litre per ha just at the appearance of the disease.

Bacterial rot

Causal Organism

Xanthomonas campestris pv. cmapestris
(Pammel Dowson)

Damage

• Symptoms visible on 2 months old plant.
• Dark colour streaks on stem from the ground level.
• Gradually these streaks enlarge and girdle the stem.
• Stem become hollow due to internal rotting.
• Lower leaves midrib cracking, browning of veins and withering are observed.
• In severe cases, the vesicular bundles of the stem also turn brown and the plant collapses.

Survival & Favourable Conditions

• The pathogen survives in infected plant residue in soil and seed borne.
• The disease is significant in warm and humid climate.

Cultural Control

• Rotating the mustard crop.
• Follow complete crop and field sanitation.

Chemical Control

• Spray Streptocycline 250 ppm (2.5 g/10 litre water) or Copper oxychloride @0.2% at the initiation of disease. If needed repeat the spray after 15-20 days interval.

Bacterial stalk rot

Causal Organism

Erwinia carotovora

Damage

• Water-soaked lesions on stems at collar region usually accompanied by white frothing.
• This produce dirty white, foul smelling ooze.
• Badly affected plants topple down.

Survival & Favourable Conditions

• The pathogen survives in infected plant residue in the soil.
• The disease is significant in warm and humid climate.

Cultural Control

• Sowing with healthy seeds.
• Keeping the crop weed free.

Broomrape

Causal Organism

Orobanche Spp.
O. aegyptiaca

Damage

• The parasite appears as clumps of whitish, yellowish, brownish or purplish broom along with the stem at ground level.
•  It consists of a stout flashy stem, covered by small thin and brown scaly leaves.
• Flowers appear in the axils of leaves and are white tubular.
• The fruits are capsular and contain numerous tiny seeds.
• The seeds are very small and black in colour.

Survival & Favourable Conditions

• The seed of the parasite survives in the soil or as a seed contaminates.
• Normal weather favours pathogen.

Cultural Control

• Destroy the parasite before seed formation.

Mechanical Control

• Before sowing separate the seeds of broomrape through sieve mechanically.

Chemical Control

• Spray the soil with 25% copper sulphate solution to destroy parasite.

Club root

Causal Organism

Plasmodiophora brassicae

Damage

• Effected plants gets stunted.
• Pale green or yellow leaves developed and later the plants get killed.
• The plant untimely die.

Survival & Favourable Conditions

• The pathogen survives in the soil as resting spores.
• Humid weather and high soil moisture are favourable weather conditions.

Cultural Control

• Apply long term crop rotation.
• Destroy all cruciferous weeds.
• Timely sowing between 10-25th October.
• Improve the drainage system to avoid second irrigation.

Chemical Control

• Apply lime @3 tones/ha to increase the soil pH.
• Mixing compost before sowing.

Downy mildew

Causal Organism

Peronospora parasitica

Damage

• The most susceptible stage for the disease development is the flowering stage.
• Symptoms appear on all aerial parts but usually on leaves and inflorescence.
• Grayish white irregular necrotic patches develop on the lower surface of leaves.
• The most conspicuous and pronounced symptom is the infection of inflorescence causing hypertrophy of the peduncle of
  inflorescence.
• The affected inflorescence does not produce any siliqua or seed.
• The extent of damage is 17-32 % in mixed infection.

Survival & Favourable Conditions

• The pathogen survives as oospores on the affected plant tissues and on weed hosts.
• Cool (10-20 C temp) and wet weather (90%) humidity favours disease development.

Cultural Control

• Destroy the diseased crop debris.
• Follow at least three years crop rotation.
• Varieties of Brassica napus group are resistant to this disease.
• Timely sowing between 10 - 25th October.
• Use healthy certified seeds.
• Field sanitation is a must.
• Destruct the crop residues.
• Crop rotation
• Application of potash in recommended doses reduce disease index.

Chemical Control

• Seed treatment with 6g Metalaxyl (Apron) per kg seed followed by single spray with Metalaxyl (Ridomil MZ) at 2.5 g/litres at 60 days after sowing is effective in managing the disease.
• Spray the crop with Mancozeb 75 % W.P. at the rate of 2 gm per litre of water at the onset of the disease.
• Repeat the spray after 15 days interval.
• Apply potash in recommended dose.
• Seed treatment with Apron-35, followed by first spray of Ridomil (0.25%) at 60 days after sowing and second and third sprays of Rovral (0.2%) at 80-100 days after sowing provide effective control of diseases.

Mosaic

Causal Organism

Turnip virus I Group

Damage

• The symptoms appear as vein clearing, green vein banding, mottling and severe puckering of the leaves.
• The affected plants remain stunted with no or very less flowers.
• Seeds are shriveled.

Survival & Favourable Conditions

• The pathogen survives on other host plant and several weeds.
• This transmitted mechanically and by green peach aphids.
• Moist and cloudy weather with average temp 10 - 18^o C is more favourable for the disease
  development.

Cultural Control

• Roguing and destruction of affected plants.

Chemical Control

• Spray metasystox 25EC or dimethioate30 EC @ 1% at initial appearance of disease and insect vectors.

Phyllody

Causal Organism

Mycoplasmal like organism (MLO)

Damage

• Disease is observed on B. rapa variety toria.
• Transformation of floral structures in leafy parts.
• Ovary without ovules.
• Leafy structures on false septum.
• Up to 90 per cent yield losses recorded by this disease.

Survival & Favourable Conditions

• The pathogen survives on alternate host like sesame and several other plants.
• The disease is transmitted through the insect vector like leaf hopper.
• Warm and dry climate favours disease development

Cultural Control

• Sowing around mid September.
• Rouging of effected plants at early stages.

Chemical Control

• Spray metasystox 25EC or dimethioate30 EC @ 1% at initial appearance of disease and insect vectors.

Powdery Mildew

Causal Organism

Erysiphe cruciferarum

Damage

• This disease occurs at the reproductive stage during Feb-March.
• Symptoms appear as dirty white, circular, floury  patches on either sides of the leaves.
• Under favourable environmental conditions, entire leaves, stems and siliquae are affected.

Survival & Favourable Conditions

• The pathogen survives through cleistothecia present in the crop debris in the field.
• High temperature (15-28 C), low humidity ( less than 60% humidity) and low or no rainfall with
  wind favours disease development.

Cultural Control

• Field sanitation is a must.
• Timely sowing between 10-25th October.
• Destroy crop residues.
• Application of potash in recommended doses reduces disease index.

Mechanical Control

• Destruct the crop residues.

Chemical Control

• Spray the crop with wettable sulphur at 3 g/litre of water at the onset of the disease and repeat it after 15 days if necessary.
• Application of carbendazim at 1.5g/l of water or sulphur 3 g/Litre.

Sclerotinia stem rot

Causal Organism

Sclerotinia stem rot

Damage

• Elongated water soaked lesions appear on stem covered with cottony mycelial growth later on.
• Plant looks like whitish from distance at  internodes or base.
• Premature ripening and shredding of stem, wilting and drying.

Survival & Favourable Conditions

• The pathogen survives as mycelium in dead or live plants and as sclerotinia in infected plant parts or on the soil surface or with seed as contaminant.
• High humidity (90-95%) and average temp (18-25^o C) along with wind current favoures the disease development.

Cultural Control

• Use healthy certified seeds.
• Clean cultivation.
• Deep ploughing during summer.
• Rotating with non host crops like wheat, barley, rice and maize.
• Timely sowing between 10-25th October.

Biological Control

• Soil application of T. viride/T.harzianum @ 2.5 kg/ha, parasitize sclerotia of the pathogen in the soil.

Chemical Control

• Spray Carbendazim @ 0.1% twice during the flowering period at 20 days interval.

White rust

Causal Organism

Albugo candida

Damage

• Occurs at vegetative and reproductive stage in Dec-March.
• Disease appears shortly after the attack of Alternaria leaf blight on the under surface of lower leaves.
• Both local and systemic infections are observed. 
• In case of local infection, white creamy yellow raised pustules appear on the leaves which later coalesce to form patches.
• Swelling and distortion of the stem and floral parts results into hypertrophy and hyperplasia, commonly known as stag head.
• In humid weather, mixed infection of white rust and downy mildew develop on stag head structure.
• Maximum damage occurs when systemic infection of the stem is noticed.

Survival & Favourable Conditions

• The pathogens survives through oospores in affected host tissues, soil.
• Secondary infection is carried out by sporangia and zoospores which produce new infection.
• Moist ( more than 70% relative humidity) and warm weather (12-25 C temp) and intermittent rains favours disease development.

Cultural Control

• Timely sowing between 15th September to 15th October.
• Use healthy certified seeds.
• Use resistant varieties like JM-1, YRT-3, HNS-3, HNS-4, GSH-1, RC-781 and PHR-1.
• Field sanitation is must.
• Crop rotation.
• Sowing seed from stag head free plants to avoid carry over of the oospores.
• Destruction of crop debris particularly stag heads of previous year crop.
• Avoiding over irrigation.

Biological Control

• Seed treatment with Apron SD-35 @ 6g/kg seed or Thiram @2.5 g/kg seed.

Chemical Control

• Spray the crop with Mancozeb 75 % W.P. at the rate of 2 gm per litre of water at the onset of the disease.
• Repeat the spray after 15 days interval.
• Seed treatment with 6g Metalaxyl (Apron) per kg seed followed by single spray with Metalaxyl (Ridomil MZ) at 2.5 g/litres at 60 days after sowing is effective in managing the disease.
• Apply potash in recommended dose.