Plant diseases

The soil borne fungus Monilochaetes infuscans causes Black Scurf disease in sweet potatoes, which can cause significant crop damage. The disease infects tubers and causes raised, dark-colored scabby lesions on the surface. 

This not only changes the appearance of the tubers, but also makes them more susceptible to secondary infections, which can reduce the crop’s quality and marketability even further. The fungus can also infect the plant’s stems and leaves, causing stunted growth and decreased yields.

Fusarium mainly effects on sweet basil varieties; it is vascular wilt caused by a fungus. Symptoms of this disease include wilted leaves, stunted plants, and vertical brown stripes on the stem. These appear late in the growing season and are first noticed on the older leaves.

The fungus infects the young flower buds. The infected buds shrivel and become dark brown in colour. The pathogen also infects leaves causing blight. The infection is visible in the form of brown necrotic spots on margins and tips of older leaves.

Brown necrotic spots develop on leaves, which get enlarged at the later stage of infection. The entire foliage gets damaged and results in poor vegetative growth. Spraying of fungicides is helpful in controlling the disease.

The symptoms are in the form of black lesions developed on the main stem. Rotting at the collar regions causes death of the plant. Soil sterilization and controlled watering help in reducing the disease incidence.

The fungus affects the collar portions of the plants. In nursery the infection results in damping-off and is aggravated by soil moisture. In the field the infected plants show wilting. French marigold and dwarf varieties are less susceptible whereas the African types are highly susceptible to the disease.

Root galls on carnation are caused by parasitic root nematodes, Meloidogyne spp. The most characteristic symptom of this disease is the profuse root swellings that assume innumerable shapes. The microscopic eel-shaped larvae of the nematode infect roots at the tip, where the tissue is soft and cell division is occurring. Symptoms of nematode-infected plants are lack of Vigour, stunting, and pale green to yellow leaves that tend to wilt in warm weather.