Weed & Disease Contol

1) Weed Control
Guar field in kharif season is always full with a number of weed plants, Hoeing and weeding in the initial stages of plant growth with the help of khurpi, tined harrow reduces the weed-crop competition and increases soil aeration for bacterial growth. The application of Basalin at the rate of 1.0 kg a.i. per hectare as pre- planting dose suppresses the growth of grasses and other weeds.

2) Disease Contol

The most common diseases of guar are wilt, bacterial blight, powdery mildew, and anthracnose. These diseases along with their control measures are described here.

1. Wilt
This disease is caused by Fusarium monolifonne. The pathogen is soil- borne and, therefore, its damage is of localized nature. It causes infection to the base of plants including roots and seedlings. The roots show dis-colouration and plant wilts. Poor emergence of seedlings is the first symptom of the disease. The seedlings rot before or soon after emergence.
Control

a. Mixed croping of guar with sorghum reduces the damage up to 55 per cent.
b. Addition of organic manures also reduces the disease incidence.
c. Seed treatment with Agrosan GN or Thiram or Captan at the rate 3 g/kg seed prevents the disease spread during germination and seedling emergence.

2. 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

a. Use healthy seed., b. Avoid excess watering; c. Give wider spacing; d. Use hot water treated seed ; e. Spray fungicides like Dithane M -45 or Dithane Z- 78 at the rate of 2 kg in l000 litres of water per hectare.

3. 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.
 I. Control

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

4. 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

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

5. 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 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.


 Pest Control

Guar is a rainy season crop. Therefore, a number of insect pests feed and grow on its leaves and pods. Some important ones are described here.

1. Hairy caterpillars
Ascotis imparata and Spilosoma obliqua, Amsacta lactinae and Euproctis scintilans are the insects that cause heavy damage. The adult lays eggs in clusters over the surface of the leaves. The larvae cause characteristic skeletonisation of leaves during the early gregarious stage and later they completely defoliate the plant. The pest can easily be controlled by systematic collection of larvae during the early gregarious stage or spraying with Endosulfan @ 0.07 percent.

2. Jassid
Empoasca fabae, Empoasca Kraemeri and Amrascakerri are serious pest of the crop. The nymph are wingless and found in abundance on the lower surface of the leaves. The nymph and adult pierce the plant tissues and suck the cell sap. Leaves become yellow at the margin. They can be controlled by: (i) soil application of systemic granular insecticides such as Aldicarb 10 G at the rate of 10 -15 kg per hectare. (ii) spray of Endosulphan 35 EC at the rate of 2litres in 1000 litres of water, or (iii) dusting of BHC 10% dust at the rate of 20 -25 kg per hectare.

No comments:

='footer-1'/>