Early Leaf Spot Symptoms
Sub-circular dark brown spots are produced on the upper leaflet surface. The spots are of lighter shade of brown on the lower side of the leaflets. Yellow halo is seen around the brown spots.
Early Leaf Spot
Oval to elongate spots are also seen on stems, petioles, and pegs.
Severe disease attack leads to shedding of leaflets (Fig.) resulting in premature ageing of the crop.
Late Leaf Spot
Late leaf spots are nearly circular and darker than early leaf spots (Top Fig.)
Early Leaf Spot SYMPTOMS Late leaf spots can be distinguished from those of early leaf spots (Bottom Fig.). Late leaf spots are darker with no or light yellow halo.
The late leaf spots on the lower leaflet surface are rough in appearance. Circular rings of fungus fruiting structures can be seen on the lower leaflet surface with the the aid of a hand lens (Fig.).
Severe disease attack leads to shedding of leaflets (Fig.) resulting in premature ageing of the crop. Oval to elongate spots similar to early leaf spot are also formed on stems and pegs. Late leaf spot attack is usually seen along with rust disease.
Late Leaf Spot The comparisons of early and late leaf spot of groundnut
Character Early leaf spot Late leaf spot Stage Of Occurrence Early Infection Usually late infection Surface on which Upper surface Lower Surface most spores are produced and their
random in concentric rings Shape Of Spot Circular to irregular Usually circular Leaf
The comparisons of early and late leaf spot of groundnut
Character Early leaf spot Late leaf spot color of leaf spot on upper leaf surface Light brown To black tending towards brown With some yellow halo Brown to black tending towards black Color of spot on Lower leaf surface Brown
Management of Early leaf Spot
As the disease is soil-borne, proper crop rotation is important. Good weed control is helpful as dense weed growth encourages disease development. Growing moderately resistant cultivars like ICGV 89104, ICGV 91114 (EM), ICGV 920920, ICGV 92093 (MM). Fungicidal control of leaf spots is effective. Foliar spray with Kavach or Bavistin @ 2 g/liter of water and 500 liters/ha. Copper, sulfur, and copper/sulfur dusts give good control of leaf spots and also some control of rust. But, these may be expensive. Bordeaux mixture spray gives good control of rust and leaf spots. But, difficult to prepare than modern fungicides. Maneb and Mancozeb sprays are effective in controlling leaf spots and give some control of rust.Benomyl spray results in excellent control of leaf spots. But, likely to stimulate production of tolerant strains of fungus.
Management of Late leaf Spot
Collect and destroy the infected crop debris. Follow cereal-cereal- groundnut crop rotation. Bavistin at 1 g/liter water or Kavach at 2 g/liter water, and 500 liters/ha. Grow moderately resistant cultivars like ICGV 89104, ICGV 91114 (EM), ICGV 920920, ICGV 92093 (MM).
Submitted by bharati on Thu, 09/07/2009 - 16:34