The problem is so severe in Belgaum district that farmers clean up their fields
Belgaum: The growers of this district called “sugar bowl” of Karnataka are worried with the infestation of their standing crop by Root Grub.
After the ‘Woolly Aphid’ infestation, the Root Grub in sugarcane is a major problem confronting growers in sugarcane belts in the district this year. Patches of sugarcane crop are drying up even on irrigated land in Kadapur, Naslapur, Nandikurli, Kerur, Ankli in Chikodi taluk and Hire Bagewadi in Belgaum taluk. In certain areas, the menace is severe forcing the growers to uproot the crop and clean the field.
For instance, Sambe Pawar is clearing his five acres of sugarcane crop attacked by the Root Grub. Since the crop is not mature, it can only be fodder for the cattle.
According to S.S. Hiremath, Assistant Professor in K.L.E. Society’s School of Agricultural Training and Research, Belgaum, the Root Grub, which is called “White Grub” occurring in northern Karnataka are “holotrichia serrata”, “holotrichia consanguinea” and “lecuopholis lepidophora”.
The beetles emerging from pupae remain in the soil till the first heavy summer rains in April and by that time their productive system fully matures. At day break, they move back to the soil to lay eggs. The egg period varies from 8 to 30 days, larval from 56 to 292 days and pupal from 10 to 35 days. The lifecycle is completed within 96 to 357 days.
The pupation takes place around October-November, the beetle emergence occurs only after the next first heavy summer showers. The first instar grubs on hatching from these eggs feed on organic matter in the soil and small roots of grasses or other plants.
The second and third instar grubs feed voraciously on the roots and underground portion of the sugarcane drying up the clumps. The symptoms can be seen only when sufficient damage is done to the roots and underground portion of the sugarcane. The sugarcane leaves in a clump, a part of the row or patch of the field starts slowly yellowing and drying and ultimately the entire crop dries up.
The affected clumps can be pulled out without much effort and grown up grubs can be seen below the clumps.
Although several pest management practices are available to combat root grubs, there is need for integrated approach to prevent this dreaded pest from attacking sugarcane.
The infestation is more when farmers practise mono cropping.
Integrated pest management calls for adopting various tactics as mechanical, cultural, biological and chemical methods in a compatible manner where each complements the other to keep pests at manageable levels.
While adopting IPM, growers are required to take up following measures before raising the sugarcane crop:
Summer ploughing which helps exposure of the grubs and beetles which could be handpicked and destroyed; beetles emerge only after the first summer rains. They should be collected from the host trees by using light traps and killed by kerosene.
Crop rotation with paddy every alternative year would reduce the problem. Application of Metarrigium (bioagents) power 3-5 kgs per acre may reduce infestation.