DISEASES OF PULSES – Agricultural study materials

Agri Diseases

Common Pulse Diseases

COMMON DISEASESCAUSAL ORGANISM
Dry root rotMacrophomina phaseolina
Leaf spotCercospora canescens
Powdery mildewErysiphe polygoni
RustUromyces phaseoli-typica
AnthracnoseColletotrichum lindemuthianum
Bacterial blightXanthomonas phaseoli
Yellow mosaicYellow mosaic virus
Leaf crinkleLeaf crinkle virus
RED GRAM / PIEGON PEA
WiltFusarium oxysporum f.sp. udum
Stem blightPhytophthora drechsleri f.sp. cajani
Sterility mosaic virusRed gram sterility mosaic virus
CHICK PEA / BENGAL GRAM
WiltFusarium oxysporum f.sp. ciceri
BlightAscochyta rabiei
StuntChick pea stunt virus
BLACK GRAM AND GREEN GRAM 
Leaf curlTomato spotted wilt virus [TSWV ]
SOYABEAN
Downy mildewPeronospora manshrica
Soyabean mosaicSoybean mosaic virus
COWPEA
Cowpea aphid borne mosaic Cowpea aphid borne mosaic virus


1. DRY ROOT ROT – Macrophomina phaseolina

Symptoms

The disease occurs both in young seedlings and grown up plant. Infected seedlings shows reddish brown discolouration at collar region. The lower leaves show yellowing, dropping and premature defoliation. The root rot affected plants suddenly wilt and die. The affected roots are brittle and break when touched. Numerous, minute, black “pycnidia” are seen on the hypocotyls and lower portions of the stems. The lesion coalesce and cause the branches or hole plant to dry up and die.  

Mode of Spread 

    Seed borne and air borne pycnidiospores primarily spread the disease. Secondary spread is through soil borne sclerotia carried by irrigation water and implements 

Survival 

The pathogen survives as sclerotia in soil and dead plant debris

Epidemiology 

Prolonged drought followed by irrigation and high temperature favour the disease

Management

  • Field sanitation
  • Crop rotation with cumbu or sorghum 
  • Seed treatment with captan or thiram or T.viride @ 4 g/kg or carbendazim at 2 g/kg of seed
  • Application of farm yard manure and green leaf manure like Gliricidia maculata @ 10 tons / ha or neem cake @ 250 kg/ha

2. LEAF SPOT – Cercospora canescens

Symptoms

Initially small light brown coloured spots appear on under surface of the leaves, later become dark brown and the infected portion drop off leaving shot hole symptoms.

Mode of Spread and Survival 

The spreads through air borne conidia and survives in the infected plant debris

Epidemiology 

Cool temperature and humid weather favour the disease

Management

  • Field sanitation
  • Spray mancozeb 1 kg/ha or carbendazim 500 g/ha
  • Grow resistant lines like UC 2515/2, 796/1, 2113/1, 2568/1. 

3. POWDERY MILDEW – Erysiphe polygoni

Symptoms

White powdery growth appears on the upper surface of the leaves. Later the leaves turn yellow, wilt and defoliate. Infection after the pod setting may have only slight effect on yield.

Mode of Spread and Survival 

The fungus is an obligate parasite. Primary infection is usually by ascospores from cleistothecia and secondary spread by air borne conidia and rain splashes. Tha pathogen survives in the infected plant debris

Epidemiology 

The disease is severe, generally during late kharif and rabi season. Dry weather, a temperature range of 22-26oC and relative humidity 80-88 % favour the disease.

Management

  • Field sanitation
  • Spray with wettable sulphur 1.5 kg/ha or carbendazim 500 g/ha at fortnightly intervals

4. RUST – Uromyces phaseoli-typica

Symptoms

Dark reddish – brown pustules (uredosori) appear on both surfaces of the leaves and the pustules may be surrounded by yellow halo. Finally the leaves defoliate and drop off.

Mode of Spread and Survival 

The pathogen is an autocious rust which spreads through wind borne uredospores and survives in the infected plant debris.

Epidemiology 

Cloudy humid weather favour the disease development

Management

  • Removal and destruction of infected plant debris
  • Spray with mancozeb 1 kg/ha

5. ANTHRACNOSE –Colletotrichum lindemuthianum

Symptoms 

The fungus attacks young as well as old seedlings. Small, round to oblong, brown spots appear on leaves, stem and pods. Black lesions develop on stem which spreads to leaf petiole and leaves. Numerous acervuli can be seen scattered on the stem. 

Mode of Spread 

Primary spread is through seed and soil-borne conidia and secondary spread is through air borne conidia

Survival

    The pathogen survives in the infected plant debris and seeds [Acervuli-asexual fruiting body]

Epidemiology 

Cool rainy weather and High RH above 90 % favour the disease 

Management

  • Seed treatment
  • Spray with mancozeb @ 1 kg/ha or Carbendazim @ 500 g/ha
  • Grow resistant varieties 

6. BACTERIAL BLIGHT –Xanthomonas phaseoli

Symptoms

Brown, circular to irregular and distinctly raised spots appear on the diseased leaves. The infected young plants show stunting, chlorosis and defoliation

Mode of Spread and Survival 

The primary spread is through seed borne bacteria and it survives in the infected plants and crop residues

Epidemiology 

Cool, rainy weather favours the disease development

Management

  • Use disease free seeds
  • Protective spray with Streptocline at 100 ppm

7. YELLOW MOSAIC –Yellow mosaic virus

Symptoms

On the leaves irregular, yellow and green patches alternating each other appears. Infected plants are stunted, mature later and produce very few flowers and pods. The leaf size is generally not much altered, but sometimes the green areas are slightly raised and the leaves show slight puckering and reduction in size. The leaves become papery white and thin.

Vector 

The disease is transmitted by white fly –Bemisia tabaci 

Epidemiology

Summer temperature (30-350 C) favours multiplication of vectors and the disease spread.

Management

  • Infected plant should be removed up to 40 DAS.
  • Grow barrier crop – sorghum / maize / cumbu.
  • Spray with Monocrotophos @ 500 ml/ha to control vectors.
  • Grow resistant varieties – black gram ___ VBN 1, 2.

8. LEAF CRINKLE – Leaf crinkle virus

Symptoms

Enlargement in size followed by crinkled surfaces of laminae were the characteristics symptoms of the affected trifoliates. The affected plants are stunted, appear bushy, remain green and do not die till harvest. In severe infection, all the leaves are curved downwards.

Vector

The insect vectors white fly — Bemisia tabaci and Aphid – Aphis craccivora and A.gossypii transmit the disease

Epidemiology

High temperature during summer period favours the disease spread.

Management

  • Field sanitation and remove the weed host.
  • Spray with Monocrotophos or Methyl demeton  @ 500 ml/ha to control vectors.

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