PLANT DISEASE MANAGEMENT PRINCIPLES AND ITS IMPORTANCE

The concepts of plant disease management are primarily centered on identifying the disease and reducing damage or loss below the threshold of economic detriment. Whetzel (1919) was the first to define disease control approaches as Exclusion, Eradication, Protection, and Resistance, with two more methods added later: Avoidance and Therapy (National Science Academy, 1968). Thus, management methods refer to steps done to lower the incidence and intensity of the illness, limit the number of inoculums that originate and propagate the disease, and, eventually, minimize the disease's losses.

1. MASTER’S SEMINAR (PL.PATH-591) Research Scholar: Supervisor: Talapati Aruna Chenna Vydyanad Assistant professor M.Sc Agri (Plant pathology) Dr. Neelam Maurya MPPN1AG20009 Dept. of. Plant Pathology Plant Disease Management Principles

2. Contents Introduction Definition Avoidance Exclusion Eradication Protection Disease resistance Therapy Conclusion

3. Introduction: Information on etiology, symptoms, pathogenesis and epidemiology of plant diseases are intellectually interesting and scientifically justified but most important of all they are useful as they help in formulation of methods developed for successful management of disease and thereby increasing the quantity and improving the quality of plant and plant products. Methods for plant diseases control were first classified by Whetzel (1929) into exclusion,eradication , protection and immunization. Further advances in plant pathology leading to development of newer methods. Two more principles - avoidance and therapy were created (NAS, 1968).

4. Disease : A disease is the impairment of the normal and physiological functioning of a plant or plant part, caused by continued irritation of primary factors. Management : It conveys a concept of continuous process which is based not only on the principle of eradication of the pathogen but mainly on the principle of minimizing the damage or loss below economic injury level. Disease management : It is the practice of  minimising disease in crops to increase quantity or quality of harvest yield.

5. Source: ANGRAU Notes General principles of plant disease management : 1. Avoidance 2. Exclusion of inoculum 3. Eradication 5. Disease resistance 4. Protection 6. Therapy

6. I. Avoidance of the pathogen: These methods aim at avoiding the contact between the pathogen and susceptible stage of the crop. a) Proper selection of geographical area: Many fungal and bacterial diseases are more severe in wet areas than in dry areas. Cultivation of bajra in wet areas is not profitable due to the diseases, smut ( Tolyposporium penicillariae ) and ergot ( Claviceps microcephala ). b) Proper selection of the field: It in the management of many diseases, especially the soil borne diseases. Raising of a particular crop year after year in the same field makes the soil sick, where disease incidence and severity may be more. Ex: Wilt of redgram

7. c) Time of sowing: Generally pathogens are able to infect the susceptible plants under certain environmental conditions. Alteration of date of sowing can help in avoidance of favourable conditions for pathogen. Ex: Infection of black stem rust of wheat is more in late sowing, hence, early sowing helps in reduction of stem rust incidence. d) Proper selection of seed and planting material: Selection of seed and seedling material from healthy sources will effectively manage the diseases such as loose smut of wheat, bunchy top of banana

8. II. Exclusion of the pathogen : Preventing the inoculum from entering or establishing in the field or area where it does not exist. Different methods of exclusion like- seed inspection & certification and plant quarantine. a) Seed inspection and certification: Crops grown for seed purpose are inspected periodically for the presence of diseases that are disseminated by seed. Necessary precautions are to be taken to remove the diseased plants in early stages, and then the crop is certified as disease free. b) Plant quarantine regulation: “ It is a legal restriction on the movement of agricultural commodities for the purpose of exclusion, prevention or delaying the spread of the plant diseases in uninfected areas”.

9. * Plant quarantine laws were first enacted in France (1660) * In India, plant quarantine rules and regulations were issued under Destructive Insects and Pests Act (DIPA) in 1914. Plant quarantine measures are of 3 types. 1. Domestic quarantine: 2. Foreign quarantine: 3. Total embargoes:

10. Domestic quarantine: Prohibiting the movement of insects and diseases and their hosts from one state to another state in India is called domestic quarantine. Domestic quarantine in India exists for two pests (Rooted scale and Sanjose scale) and three diseases (Bunchy top of banana, banana mosaic and wart of potato). 5 Regional plant quarantine station :- A. Amritsar B. Kolkata C. Bengaluru D. New Delhi E. Mumbai Head quarter of plant quarantine station :- Faridabad ( Haryana). 2. Foreign quarantine: Rules and regulations issued prohibiting the import of plants, plant materials, insects and fungi into India from foreign countries by air, sea and land.

11. a. Airports: Bombay, Calcutta, Madras , New delhi and Tiruchurapally . b. Sea ports: Bombay, Calcutta, Vishakapatnam , Trivandrum, Madras, Tuticorin , Cochin and Dhanushkoti . c. Land frontiers: Hussainiwala ( Ferozpur district of Punjab), Kharla (Amritsar district of Punjab) and Sukhiapokri (Darjeeling district of West Bengal) 3. Total embargoes: Total restriction on import and export of agricultural commodities

12. III. Eradication: Reducing, inactivating, eliminating or destroying inoculum at the source, either from a region or from an individual plant in which it is already established . It is achieved by - a) Rouging: Removal of diseased plants or their affected organs from field, which prevent the dissemination of plant pathogens. Ex: Loose smut of wheat and barley, whip smut of sugarcane . b) Eradication of alternate and collateral hosts: Eradication of alternate hosts will help in management of many plant diseases. Ex: Barbery eradication programme in France and USA reduced the severity of black stem rust of wheat

13. c)Crop sanitation: Collection and destruction of plant debris from soil will help in the management of soil borne facultative saprophytes as most of these survive in plant debris. Collection and destruction of plant debris is an important method to reduce the primary inoculum . d) Mixed cropping: Root rot of cotton ( Phymatotrichum omnivorum ) is reduced when cotton is grown along with sorghum. Intercropping sorghum in cluster bean reduces the incidence of root rot and wilt ( Rhizoctonia solani ) e) Summer ploughing : Ploughing the soil during summer months expose soil to hot weather which will eradicate heat sensitive soil borne pathogens.

14. IV. Protection: It is the use of some protective barrier between the host and the pathogen. - In most cases, a protective spray applied to the plant in advance of the arrival of the fungus spores. - Fungicidal sprays that act as protectants in those fields where inoculum has carried over from the previous year. - The principle of protective fungicides is to disrupt the natural sequence of infection . - Sulphur is used as a protectant fungicide to control powdery mildew.

15. V. Disease resistance : Disease resistant and tolerant varieties are the cheapest and most efficient way to reduce disease losses. For some diseases, such as the soil-borne vascular wilts and the viruses, the use of resistant varieties is the only means of ensuring control. When such varieties become available, they are then tested for resistance against some of the most important pathogens present in the area where the variety is developed and where it is expected to be cultivated. Modern DNA technology has made it possible to engineer transgenic plants that are transformed with genes for resistance against specific disease, for tolerance of adverse environmental factors or with nucleic acid sequence that lead to gene silencing of the pathogen.

16. VI. Therapy - It is used on individual plants and can not be used on a large scale. - It is achieved by inoculating or treating the plant with something that will inactivate the pathogen. - Chemotherapy is the use of chemicals to inactivate the pathogen, whereas heat is sometimes used to inactivate or inhibit virus development in infected plant tissues so that newly developing tissue may be obtained which is free of pathogen. - Thermotherapy involves the exposure of diseased plants or parts of them to hot water or high air temperature for different periods of time

17. Conclusion : Practices of disease management vary considerably from one disease to another depending upon the type of pathogen, the host and the biotic and abiotic factors involved. Contrary to management of human and animal diseases where every individual is attended, the plants are generally treated as populations and measures used as preventive rather than curative.

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