Diseases of Cumbu

Major diseases of Cumbu are:-

1. Cumbu Downy Mildew: Sclerospora graminicola

Symptom:

• Symptoms often vary as a result of systemic infection.
• Leaf symptoms begin as chlorosis at the base and successively higher leaves show progressively greater chlorosis.
• Infected chlorotic leaf areas can support abundant white asexual sporulation on the lower leaf surface.
• Severely infected plants are generally stunted and do not produce panicles.
• Green ear symptoms result from transformation of floral parts into leafy structures.

Management:

• Grow downy mildew resistant varieties CO7, WCC 75, CO(Cu)9, TNAU-Cumbu Hybrid-CO9
• Transplanting reduces disease incidence. At the time of planting infected seedlings should be removed.
• In the direct sown crop, infested plants should be removed up to 45 days of sowing as and when the symptoms are noticed.
• Spray any one of the fungicides Metalaxyl + Mancozeb @500 g or Mancozeb 1000g/ha.

 

2. Ergot: Claviceps fusiformis

Symptom:

• Cream to pink mucilaginous droplets of “honeydew” ooze out of infected florets on pearl millet panicles.
• Within 10 to 15 days, the droplets dry and harden, and dark brown to black sclerotia develop in place of seeds on the panicle.
• Sclerotia are larger than seed and irregularly shaped, and generally get mixed with the grain during threshing
• Conditions favoring the disease are relative humidity greater than 80%, and 20 to 30 0C temperatures during flowering.

Management:

• Spray any one of the fungicides like Carbendazim 500g or Mancozeb 1000g /ha when 5 – 10% flowers have opened and again at 50% flowering stage.

 

3. Cumbu Rust: Puccinia substriata

Symptom:

• Small reddish-brown to reddish orange, round to elliptical uredinia develop mainly on foliage.
• As severity of infection increases, leaf tissue will wilt and become necrotic from the leaf apex to base.
• In infection sites developing late in the season, uredinia are replaced by telia which are black, elliptical, and subepidermal.

Management:

• Sowing during December – May result in less incidence.
• Adopt control measures when there is rust incidence in the early stages as spread of infection to top leaves results in poor grain filling.
• Spray any one of the following fungicides when the initial symptoms of the diseases are noticed. Wettable sulphur 2500g / ha Mancozeb 1000g/ha
• Repeat application 10 days after if necessary.

 

4. Cumbu Head Mold: Various fungi

Symptom:

• Pink, white, brown or grey fungal growth on grain. Apparently asymptomatic seed may be contaminated.
• Many pathogens cause grain molds.
• Grain molds on pearl millet tend to be more severe with humid conditions during grain fill and if grain harvest is delayed
• Several fungi cause grain molds, and these differ by the region of cultivation, crop management, environmental conditions prior to harvest, and storage conditions.

Management:

5. Bipolaris Leaf Spot: Bipolaris setariae

Symptom:

• Foliar symptoms vary, as brown flecks, fine linear streaks, small oval spots, large irregular oval, oblong, or almost rectangular spots measuring 1-10 x 0.5-3 mm.
• Large fusiform lesions are sometimes produced.
• Lesions may expand and coalesce.
• Lesions may be solid dark brown but usually become tan or greyish brown with a more or less distinct dark brown border.

 

6. Cercospora Leaf Spot:Cercospora penniseti

Symptom:

•  Foliar lesions are typically oval, 1-8 x 0.8-2.5 mm, with dark brown margins and pale tan to grey or white centers, dotted with rows of black conidiophore tufts. Lesions can form on stems.

 

 

 

 

 

 

Source-

• TamilNadu Agritech Portal