Fusarium Wilt
Wilt:
--------

C. O.: Fusarium oxysporum f. sp. vasinfectum (Fov)

Symptoms:

• Areas of reduced or patchy plant stand can be seen in affected fields, usually spreading in the direction of irrigation flows.
• Plant death, wilting, yellowing and defoliated plants are typical of disease symptoms.
• The vascular tissue of affected plants exhibits a brown/chocolate discolouration through the entire main stem.
• Some plants affected with the disease show some re growth.

Management:

• Deep ploughing.
• Grow resistant varieties.
• Intercrop with moong bean/ragi/ soybean/ groundnut/ maize/ cowpea/ onion.
• Fields with long history of disease should be avoided for growing the crop.
• Use of nitrogen fertilizers, particularly ammonium nitrate should be discouraged while use of potassium fertilizers should be encouraged
• Treat the seed with 4 g Trichoderma viride formulation/ thiram 3g per kg seed.
• Apply 2 kg of Trichoderma viride commercial formulation with 50 kg farm yard manure along with the rows.


Angular leaf spot
Angular Leaf Spot or Bacterial Blight:
-----------------------------------------
C. O.: Xanthomonas malvacearum

Symptoms:

• The disease attacks all parts of the plant above ground level, at all stages, causing seedling rot, angular spots on leaves and stems (sometimes called black arm disease) and boll rot
• In initial stages, water soaked lesions (spots) appears on lower surface of the leaves.
• Later on, these spots increase in size, turn brown to black, becoming necrotic, angular and are visible on the upper surface.
• These spots vary in size and then coalesce, forming irregular patches and giving rise to gummy bacterial exudates.
• Heavily infected leaves turn yellow and drop down.
• The disease produces elongated black lesions on the stem, branches and petioles.
• Stems show cracking and gummosis (gummy substance) and are easily broken, even by wind.
• Bolls are marked by the appearance of water soaked lesions, which are dark brown to black, invariably sunken, results in reduced boll size
• poor production of lint and loss in viability in seed

Management:

• Plant high-quality, disease free, acid delinted seed
• Plant blight-resistant varieties if available.
• Scout fields and identify infected plants and varieties.
• Shred stalks and incorporate cotton debris.
• Do not cultivate or move equipment through fields when foliage is wet


Root rot
Root Rot:
----------

C. O.: Macrophomina phaseoli, Rhizoctonia spp., Fusarium spp.
Symptoms:

• The disease affects the roots exclusively, causing pre-wilt shedding of leaves, yellowing of foliage, disintegration of root tips, discoloration and shredding of roots
• exudation of drops of smelly liquid from the rotted plant parts.
• Mostly, wilting of shoots occur in only few diseased plants, which ultimately results in the death of entire plant.
• disease generally appears, when plants are about 4-6 weeks old and continue up to boll formation.
• Diseased plants can be easily pulled out of the soil, appears in patches.
• Roots and root-lets show rotting, yellowing, disintegration and shredding.

Management:

• Intercrop with moth bean.
• Grow resistant variety.
• Deep ploughing.
• Avoid mono-cropping and cultivation of cucurbitaceous and solanaceous crops, in adjoining fields.
• Fields having long history of disease should be avoided for sowing.
• Field should be deeply ploughed and left for solarization.
• Early sowing and harvesting is recommended to avoid extreme temperatures. Sowing in April or June instead of May reduces disease incidence.
• Crop should be rotated. Intercropping using Vigna acontifolia reduces the incidence quite significantly.
• Treat the seed with benomyl or carbendazim @2.5 g/ kg seed.
• Apply 2 kg of Trichoderma viride commercial formulation with 50 kg farm yard manure along with the rows.
Seed dressing with bio-pesticide preparation of Trichoderma viride or Gliocladium virens or with brassicol + captan and carbendazim slurry effectively reduces the disease incidence.


Alternaria leaf spot
Alternaria leaf spot:
-----------------------

C.O.: Alternaria macrospora

Symptoms:

• Small brown, round spots surrounded by a purple margin appear on leaves.
• On older leaves the necrotic center of the spots may be marked by a pattern of concentric zonation.
• Several spots coalesce to form large necrotic areas particularly near leaf margin.
• Under humid weather conditions the spots appear as sooty black leading to premature defoliation.
• The leaf stalk and bolls become infected with spherical or elliptical purple spots

Management:

• Grow certified acid delinted seeds of resistant varieties
• Follow recommended agronomic practices for land preparation, stubble management, seed rate, fertilizers and irrigation management.
• Do not extend the normal crop period and avoid rationing
• Avoid dense cropping that helps in reducing the disease incidence by allowing free air current
• Remove and destroy crop residues after last picking.

Spray mancozeb 2.5 g or copper oxychloride 3g/ litre 4-5 times at 15 days interval.


Grey mildew
Grey mildew / Areolate mildew:
--------------------------------

C.O.: Ramularia areola

Symptoms:

• The disease first appear on the lower canopy of older leaves when bolls set.
• Irregular, angular translucent spots (areola) are formed by the veins of leaves.
• Leaves become yellow, turn to brown and defoliate prematurely

Management:

• Grow certified acid delinted seeds of resistant varieties
• Crop should be rotated with cereals, and preference should be given to tolerant varieties.
Foliar application of sulphur dust/wettable sulphur @ 10 kg/ha or 2-3 g/l at 10 days interval from the day of first appearance, or sulphex 80 WP (0.25%) or benomyl, carbendazim @ of 200-300 g a.i. /ha


New wilt
NEW WILT:
-----------

Symptoms:

• The wilt generally appears at flowering and boll development stages and plants show drooping
of leaves which start from the crown downwards.
• There is partial epinasty, drooping of lamina, reddening of leaf surface, petiole, stem and branches without chlorosis or necrosis and without loss of turgor.
• Leaves shed and some plants show partial recovery whereas others may die.

Management:

• Growing late maturing genotypes.
• Promotion of arboreum species which are known to be relatively tolerant to moisture stress.
• In drought conditions, irrigation can reduce the disease incidence.
• Judicious water management throughout the cropping season and particularly during the dry spells and soon after the cessation of the rainfall.
• Complete field and crop sanitation.
• Scrapping around cotton plants for aeration and revival in case of wet conditions