Forskolin obtained from its roots has been used for preparation of drugs against hypertension, glaucoma, asthma and obesity.
Increased export
On account of increased exports, cultivation of Coleus is expanding in Tamil Nadu, Karnataka, Andhra Pradesh and the present area is about 5,000 acres. In Tamil Nadu, it is cultivated in Salem (Attur), Erode (Sathyamanagalam), Dindugal districts in about 2,000 acres under contract farming.
The productivity of coleus has been hampered by its susceptibility to nematode, root rot and wilt disease. Pathogens associated with wilt and root rot are Fusarium chlamydosporum, Macrophomina phaseolina, Rhizoctonia solani and Sclerotium sp and the root knot nematode Meloidogyne incognita .
Severely affected areas were Salem, Attur and Rasipuram. Due to this disease complex the yield loss was ranged up to 50 to 60 per cent. Therefore, it is necessary to take effective control measures to save the crop from complete devastation.
Management strategies
Select the coleus cuttings from disease free plants.
Coleus cuttings should be treated with Carbendazim solution (0.1 per cent). Soil drenching with Carbendazim (0.1 per cent) or propiconazole (0.1 per cent)
Soil application of FYM at 12.5 ton/ha + Trichoderma viride at 2. 5 kg /ha before planting is effective for biomanagement of nematode fungal disease complex involving Meloidogyne incognita and Macrophomina phaseolina
Application of chemical nematicide Carbofuran 3G at 1 kg/ha before planting for control.
Stem cuttings
Stem cuttings to be dipped in 0.1 per cent Pseudomonas fluorescens at the time of planting and growing.
Marigold (Tagetus erecta) as intercrop in between the rows of medicinal coleus and
uprooting cum in-situ incorporation of their biomass during earthing up at 60-70 days after
planting can be followed for the management of root-knot nematodes. It reduces root knot
nematode population by 66.7 per cent and also decreases the incidence of Macrophomina phaseolina root rot disease up to 50 per cent.
Use drip irrigation to minimize the spread of pathogens from infected plants to healthy plants
Dr. K.Rajamani
Prof and Head, Department of Medicinal and Aromatic CropsHorticultural College and Research Institute, TNAU, Coimbatore
