Monday, 21 January 2013

Disease Management in Guar Crop

Antharacnose

This disease is caused by Colletotncum capsici. The disease is more severe in high rainfall subtropical to temperate areas than in tropical areas. The fungus is seed -borne and symptoms may start as early as in seedling stage. The most characteristic symptoms of the disease are black, sunken, crater like cankers on the pods, stem or cotyledons. The lesions remain isolated by yellow -orange margins. They give out a dull salmon conloured ooze from the centre when humidity is very high.

Control

1. Use healthy seed
2. Avoid excess watering
3. Give wider spacing
4. Use hot water treated seed
5.Spray fungicides like Dithane M -45 or Dithane Z- 78 at the rate of 2 kg in l000 litres of water per hectare.



Powdery mildew

This disease is caused by Oidium ~pp. White powdery growth occurs on leaves, spreading to cover the stem and other plant parts. In severe cases, the entire plant dries up.

Control

1. Dusting with sulphur powder
2. Spraing with systemic fungicides Benlate or Bavistin and Calixin gives effective control of powdery mildew.
3. Sowing healthy seed after treating with Thiram.
4. Follow a crop rotation to reduce the soil- borne innoculum of the fungus.




Bacterial blight

This disease is caused by Xanthomonas cyamophagus. The disease is characterized by irregular, sunken, red to brown leaf spots surrounded by a narrow yellowish halo. Several spots coalesce to from irregular patches. The spots may also develop on pods.

Control

1. Grow resistant varieties .
2. Treat the seed with thiram at the rate of 3 gm/kg seed. Also adopt hot water treatment at 560 C for 10 minutes.
3. Eradicate affected plants and burn them.



Leaf spot

This disease is caused by Myrothecium roridum. Dark brown round spots appear on leaf. In case of severe infection. Several spots merge together and leaflets become chlorotic [/B]and usually drop off. If plants are infected in the early stages of growth, there may not be any flowering.

Control

Spray with Dithane Z- 78,0.2% at the interval of 15 days, twice or thrice.

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