MEDICINAL AND AROMATIC CROPS (2+1)

Pests and diseases

Pests
Root-knot Nematode (Meloidogyne incognita and M. hapla): It is commonly found in tropical and subtropical regions. The nema¬tode which enters into the root by thrusting with the mouth spear, they reach the cortex, multiply and cause galls which are commonly called root-knots. Heavily infected plants show stunting of top growth and wilting symptoms. Typical symptoms of an infested plant become apparent only after 8 months. The nursery should be raised from healthy mother-stock under nematode¬ free conditions. The plot should be treated with a proper nematicide like Furadan @ of 20 kg/ha (3% a.i.) or Dasanit @ 150 kg/ha (5% a.i).

Disease
Leaf-blight (Cercospora spp.): The disease is characterized by the appearance of brown spots near the margin or at the apical region of leaves which enlarge irregularly, coalesce, cover the entire lamina and starts drying. It is seen in one ¬year-old plants and is less serious than the root-knot nematode. It can be controlled with two sprays of Dithane 2-78, (0.5%) at a one month interval.
The other diseases reported on this crop include wilt caused by Rhizoctonia solani, Fusarium solani and Pythium aphanidermatum and virus diseases of which pogostemon virus-I, yellow mosaic virus and tobacco necrosis virus (TNV) are important. Yellow mosaic virus is transmitted by white fly (Bemisia tabaci).