Black Arm Disease or Bacterial Blight Disease or Angular Leaf Spot disease:
Black Arm disease Causal Organism= Xanthomonas compestris pv. malvacearum
Black arm disease Symptoms=
Black arm disease of cotton, the bacteria attack all stages from seed to harvest usually five common phases of symptoms are notices. They are following:
A. Seedling Blight=
· Small, water soaked, circular or irregular lesions develop on the cotyledons.
· Then the infection spreads on stem through petiole and cause withering and death of seedling.
B. Angular Leaf Spot=
· Small dark green water-soaked areas developed on lower surface of leaves.
· Enlarge gradually and become angular when restricted by veins and veinlets and spots are visible or both surface of leaves.
C. Vein Bligh or Vein Necrosis or black vein=
· The infection of veins cause blacking of the veins and veinlets, gives a typical blighting appearance on the lower surface of leaf, bacterial oozes are formed as crusts or scales.
D.Black Arm=
· On the stem and fruiting benches, dark brown to black lesion is foamed.
· Which may girdle the stem and branches to cause premature dropping off of the leaves.
E. Squar Rot/ Boll Rot=
· On the bolls, water-soaked lesions appears and twin into dark black and sunken irregular spots
· The pathogen also infected the seed and cause reduction in size and viability of the seed.
Favourable condition=
· Optimum temperature = 28 degree.
· High atmospheric temperature= 36-45 degree
· Relative humidity= 80%
· Potassium deficiency in soil.
· Poor tillage, late irrigation.
· Rain followed by blight sunshine during the months of October and November are highly favorable
Disease Cycle of Black Arm Disease=
Perennation= Dried plant debris in soil.
Primary infection=seed- borne bacterium.
Secondary infection=
· through wind, wind blow, rain splash, irrigation water, insects.
Management=
Cultural method
· Remove and burn the infected plant debris and bolls in the soil.
· Proper field sanitation application applies in field.
· Proper tillage application applies in field.
· Proper weed management application applies in field.
· Remove all infarcted part of the plant.
· Use disease registrant varieties:
· Proper spacing maintain between row to row and plant to plant
· Proper drained facility available in filed area.
· Proper light or ventilation maintain in the field.
· Maintain the soil moisture.
Chemical method
· Spray with streptomycin sulphate + tetracycline mixture 100g along with copper oxychloride @1.25kg/ha.
· Treat the delinted seeds with Carboxin or Oxycarboxin at 2 g/kg or Carboxin 37.5% + Thiram 37.5% WS @2.5 g/ kg
Other crops
related diseases links:
RICE CROP DISEASES | agriculturestudymaterial
WHEAT CROP DISEASE | agriculturestudymaterial
SUGARCANE CROP DISEASE | agriculturestudymaterial
GRAM CROP DISEASE | agriculturestudymaterial
COTTON CROP DISEASE | agriculturestudymaterial
Other
important links:
