Alternaria leaf spot
1.Alternaria Leaf Spot :
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Alternaria ricini

Symptoms:

All aerial parts of plant i.e. stem, leaves, inflorescences and capsules are liable to infection.
 Symptoms appear first on cotyledons in the form of spots.
 Lesions on leaves are brown, zonate variable in size surrounded by yellow halos.
 Premature defoliation due to abscission results during severe infection.
 On capsule: Purple or dark brown discoloration with sunken areas gradually cover the whole capsule.

Management:

Seed treatment with thiram or mancozeb @ 4 g / kg seeds.
 Spraying of mancozeb of chlorothalonil (kavach) @ 0.3 %.


2.Root Rot :
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Macrophomina phaseolina

Symptoms:

 Small brown depressed lesions are formed on and around node.
 Necrotic lesions increase in size often girdles the stem causing leaf drop.
 Entire branch and top may dry up.
 Drying and death start from apex.

Management:

Crop rotation

 Application of organic manure helps in reduction of inoculum.
 Antagonistic fungi- Trichoderma spp. @ 1 kg / 25 kg of FYM or seed treatment @ 8 g / kg seeds.


Fusarium Wilt
3.Fusarium Wilt :
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Fusarium oxysporium f.sp. ricini

Symptoms:

The disease appears as yellow sickly appearance of plants and marginal necrosis of leaves, later advances to interveinal area.

 Leaves shrivels, lower one drop away leaving few top leaves and finally develop wilting of the affected plant.
 In stem due to formation of tyloses (Fusaric acid) cause necrosis of pith.
 Partial wilting is observed commonly.

Management:

Seed treatment with carbendazim (bavistin) 3 g / kg seeds or Trichoderma harzianum @ 2-4 g/kg of seeds.Application of organic manures i.e. FYM, neem cake, castor cake @ 5 t /ha.
Antagonistic fungi- Trichoderma spp. @ 1 kg / 25 kg of FYM or seed treatment @ 8 g / kg seeds.
Resistant varieties GCH-4, GCH-6, GCH-7.