Hisar, Aug 18: Alarmed over the harmful effect of diseases on 'guar' crop, scientists of Chaudhary Charan Singh Haryana Agricultural University (HAU) here have issued advisory measures for the farmers to save the crop.
According to HAU's, Director of Research, BS Chhillar, the incessant rains and humid conditions have caused a number of diseases in guar crop. To ascertain the impact of the diseases, he directed the scientists to conduct survey in guar cultivation areas.
In the survey report, the scientists confirmed the harmful effect of Bacterial Leaf Blight (BLB), Alternatia Leaf Spot, root rot and wilt on guar crop. Guar is used both as cattle fodder as well as its beans, which have a very high nutritional value are consumed in many parts of Haryana and other states.
According to the scientists, the BLB disease causes loss in clusterbean upto 50-70 per cent under severe conditions. They have stated that scattered rains, high humidity and warm temperature (28-30 degrees C) favours BLB development during monsoon months.
Positive and significant correlation has been obtained between disease severity, rainfall and relative humidity during July to October. BLB disease appears both as leaf spot as well as blight simultaneously.
The spots are intraveinal, round, water soaked or oily in appearance and well defined on the dorsal surface of the leaf. The spot enlarges to cover large areas and make V- shaped structure on leaves. The blight phase develops in the form of necrotic areas mostly from the leaf margin and the streaks get blackened and lead to cracking of stem.
The farmers have been advised to spray streptocycline. The spray
should be repeated after 15 days.
Another disease also known as Alternaria leaf spot has also been observed in farmlands. In this, small water soaked, dark brown, circular to irregular spots varying from 2-10 mm in diameter speards on the leaves. These spots on leaves increase in size, multiply rapidly forming dark brown concentrating rings. Circular to linear, dark brown lesions on stem and pods are formed which elongate an late stage.
Blighting and defoliation also takes place. For the control of Altenaria leaf spot, farmers have been advised to spray Mancozeb (400g/acre) in 200 litres of water. This spray should also be repeated after 15 days.
Care should be taken that the rain should not occur atleast 6 hours of the spray otherwise it would be washed away.
In root rot, at early stage the seedling mortality take place.
In later stages the decomposition of tissue takes place as a result the normal development of the plant is prevented.
In wilt, the leaves and other green parts of the plant loss their turgidity and become flaccid and drop out. In later stages, the whole plants die suddenly and get dried up.
The Director of Research has appealed to the farmers to apply the recommendations as suggested by the scientists for controlling the disease. Appropriate crop rotation can be yet another an effective measure to control the disease.