Parthasarathy Seethapathy.Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore – 641 003. Email:email@example.com.
Neem has demonstrated antifungal activity and is very successful against fungi that cause certain plant diseases viz., rots, smuts, wilts, mildews, diebacks and other plant diseases. Field and laboratory experiments have indicated considerable results against several diseases. Neem products are very useful against diseases of field crops, vegetable crops and fruit trees.
Neem oil can protect the seeds of chickpeas against the serious fungal diseases Rhizoctoniasolani, Sclerotium rolfsii, and Sclerotinia sclerotiorum. It also slows down growth of Fusariumoxysporum, but does not kill it. In addition, neem cake incorporated into the soil completely blocks the development of the resting forms of R. solani there by interfering with the long-term survival of this devastating fungus.
Three sprays of 1% neem leaf extract have been recommended for effective and economical management of tikka disease of groundnut and three sprays of 2% neem leaf extract for effective control of the mustard powdery mildew. Nimin and neem cake were also found best against severity of club root disease of yellow sarson. Alternaria blight and white rust infection in mustard can be controlled by two applications of ethanol extract of neem. The treatment checked the stag head formation and percent severity on leaves. Neem extract can also be included in soil treatment for the management of soil borne pathogens. Leaf extract of neem was tested for control of stem rot of mustard as application. The treatment was found superior in controlling the disease and increasing percent plant stand over the control. The treatment has also exhibited increased germination of seeds.
Among the neem-based compounds, repelin was significantly superior over control to reduce rice blast disease. Picnidial formation was not observed in treated condition. The neem leaf extract and neem seed extract were found most effective in checking mycelia growth of fungus Sclerotinia sclerotiorum and Phomopsis vexans
To manage disease of vegetable crops, usage of neem products may prove safe and eco-friendly. Extracts of neem provided sufficient protection against clump rot of small cardamom. Application of neem cake in soil may act as useful amendment in soil. In addition to that, soil application of neem cake @ 1 tons per hectare was effective as drenching of carbendazim against Rhizoctonia root rot disease of fenugreek. The derivatives of neem including aqueous extract of neem leaf and neem oil 3% provided suitable protection against powdery mildew disease and die-back or fruit rot disease of chili. The extract was also found effective for inhibiting sporulation of the pathogen. Neem leaf extract can be used as fungicide against brinjal stem and branch blight caused by Sclerotium rolfsii and collar rot disease caused by Phomopsis vexans.
The extract inhibits mycelia growth and fungal development. Damping off of tomato seedling caused by p.aphanidermatum can be managed by the application of aqueous extract of neem leaves. The results of laboratory experiment revealed maximum inhibition of mycelium.
Neem leaf extract 10% was found effective against basal stem rot of coconut. The treatment was effective against basal stem rot of coconut. The treatment was effective in suppressing the mycelial growth of G. lucidum in vitro by recording 67% reduction of mycelial growth over control. In field condition, the treatment was effective in control disease. Mango wilt caused by Fusarium solani can be managed by adding organic amendment like neem cake in the soil. The population of wilt pathogen was reduced in pot culture and resulted in maximum control of wilt.