Eradication:

• These methods aim at breaking the infection chain by removing the foci of infection and starvation of the pathogen.

a) Rouging:

• Removal of diseased plants or their affected organs from field, which prevent the dissemination of plant pathogens.
• Loose smut of wheat and barley, whip smut of sugarcane, red rot of sugarcane, ergot of bajra, yellow vein mosaic of bhendi, khatte disease of cardamom,etc.

b) Eradication of alternate and collateral hosts:

• Eradication of collateral hosts, such as Panicum repens, Digitaria marginata will help in the management of rice blast disease (Pyricularia oryzae)

c) Crop rotation:

• To reduce the incidence and severity of many soil borne diseases, crop rotation is adopted.
• Crop rotation is applicable to only root inhabitants and facultative saprophytes, and may not work with soil inhabitants.

d) Crop sanitation:

• Collection and destruction of plant debris is an important method to reduce the primary inoculum.

e) Manures and fertilizers:

• Excessive nitrogen application aggravates diseases like stem rot, bacterial leaf blight and blast of rice.
• Addition of farm yard manure or organic manures such as green manure, 60-100 t/ha, helps to manage the diseases like cotton wilt, Ganoderma root rot of citrus, coconut, etc.

f) Mixed cropping:

• Root rot of cotton (Phymatotrichum omnivorum) is reduced when cotton is grown along with sorghum

h) Soil amendments:

• Application of lime (2500 Kg/ha) reduces the club root of cabbage by increasing soil pH to 8.5
• Application of Sulphur (900 Kg/ha) to soil brings the soil pH to 5.2 and reduces the incidence of common scab of potato (Streptomyces scabies).

i) Changing time of sowing:

• Rice blast can be managed by changing planting season from June to September/October.

j) Seed rate and plant density:

• A spacing of 8’X8’ instead of 7’X7’ reduces sigatoka disease of banana due to better ventilation and reduced humidity.
• High density planting in chillies leads to high incidence of damping off in nurseries.

k) Irrigation and drainage:

• High soil moisture favours root knot and other nematodes and the root rots caused by species of Sclerotium, Rhizoctonia, Pythium, Phytophthora, Phymatotrichum, etc.