Redgram: Diseases and Symptoms

Wilt

• Symptoms can appear 4 to 6 weeks after sowing. The initial visible symptoms are loss of turgidity in leaves, and slight interveinal clearing.
• The foliage shows slight chlorosis and sometimes becomes bright yellow before wilting.
• Leaves are retained on wilted plants. The initial characteristic internal symptom of wilt is the browning of the xylem vessels from the root system to the stems.
• The xylem gradually develops black streaks, and brown or dark purple bands appear on the stem surface of partially wilted plants extending upwards from the base.
• When the bark of such bands is peeled off , browning or blackening of the wood beneath can be seen. in wilt-tolerant genotypes these bands are confined to the basal part of the plant.
• Sometimes, especially in the later stages of crop growth, the branches dry from the top downwards, but symptoms are not seen on the lower portions of the main stem or branches.
• Small branches on the lower part of the plant also dry.
• When the main stem of such plants is split open, intensive blackening of the xylem can be seen.
• In humid weather, a pinkish mycelial growth is commonly observed the basal portions of the wilted plants.
• Partial wilting is usually associated with lateral root infection. Tap root infection results in complete wilting.

• The fungus is soil borne and survive in the soils. Fungus spreads about 3 m through the soil in one season, apparently along roots.
• The fungus was found to survive in infected plant stubble for 2.5 years Vertisols and 3 years in Alfisols.

• Low soil temperature and increasing plant maturity favours wilt.
• Fungal population is highest at 30% soil water-holding capacity and at the soil temperatures between20 and 30° C.

Pigeon pea sterility mosaic disease

• Bushy and stunted appearance of the infected plants due to reduction in the size of the leaves and proliferation of the branches.
• Light and dark green mosaic pattern on the infected leaves of younger plants.
• Partial or complete sterility of the plant resulting in low or no flowering and podding.
• When infections occurs at 45 days after emergence or later only some parts of the plant may show disease symptoms, while the remaining parts appear normal.
• Leaves become small and cluster near branch tips.
• Diseased plants are pale green and bushy in appearance, without of flowers and pods.
• Diseased plants are usually in groups.
• Sometimes a plant may not show symptoms in the first flush, but when ratooned the new growth shows clear symptoms and tend to disappear as the plants mature.

• A single eryophid mite (A. cajani) (vector) is sufficient to transmit the disease.
• Perennial and volunteer pigeon pea and the ratooned growth of harvested plants provide reservoirs of the mite vector and the pathogen.

• Shade and humidity encourage multiplication of the virus.

Stem blight

• This cause seedling to die suddenly.
• Water soaked, irregular lesions on the leaves often cause blighting of the leaf/leaflets and younger plant.
• Infected leaves loss turgidity and become dessicated.
• Brown sunken lesions on the stem and branches causing girdling and makes the infected stem weak and leads to breakage and drying of the plant/branches.
• Infection mostly confined to basal portion of the stem.

• The fungus is soil borne.
• The fungus survives as dormant mycelium in soil and on infected plant debris.

• Soils with poor drainage
• Low lying areas
• Heavy rain.
• Temperature 28-30^o C.

Mung bean mosaic disease

• This disease was probably reported first from Sri Lanka.
• The disease first appears in the form of yellow, diff used spots scattered on the leaf lamina, not limited by veins and veinlets.
• Such spots slowly expand and in later stages of disease development, affected leaflets show broad, yellow patches alternating with green colour.
• Sometimes the entire lamina turns yellow.
• Leaf size is conspicuously reduced in early infections.
• In peninsular India, disease incidence is relatively higher in late-sown pigeon pea.
• The vector is whitefly (Bemisia tabaci)

• A single whitefly vector is sufficient to transmit the disease.
• Perennial and volunteer pigeon pea and the ratooned growth of harvested plants provide reservoirs of the vector and the pathogen.

• Shade and humidity encourage multiplication of the virus.

Dry root rot

• Typical symptoms include root and basal stem rot with a large number of minute, fungal sclerotia visible under the bark.
• Plants dry prematurely, particularly when they face drought stress.
• Disease incidence severe in off -season, irrigated, summer crops in several parts of India, and it is a minor one in the normal-season crop. The pathogen is both soil- and seed borne.

IPM for Redgram

To know the IPM practices for Redgram, click here.

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