SUSTAINABLE MANAGEMENT OF SOIL-BORNE DISEASES

1. SUSTAINABLE MANAGEMENT OF SOIL-BORNE DISEASES Oleh: Irda Safni

2. INTRODUCTION • Sustainable management to be defined as the application of sustainable practice in the category of agriculture, business, society, environment and in personal life by manage them in the way that will be benefit current and future generation. • It create the ability to keep a system running indefinitely without depleting resources the decision of making sustainable management help to sustain our immediate surrounding and environment. • One important result is that farmers are able to minimize their use of pesticides and fertilizers, thereby saving money and protecting future productivity, as well as the environment.

3. Intensive production in agriculture, horticulture or forestry increases the opportunity for disease to develop comparing to other ecosystem. • As plants and soils become sickers, growers have responded with newer and more powerful chemicals in an effort to kill off the pathogens, chemical intervention only serves to make things worse over time. • In this condition sustainable management of soil borne plant disease is very important to minimize the activity that cause damage to our environment .

4. PREDOMINANT SOILBORNE PATHOGENS: Fungi: Sclerotium rolfsii,Rhizoctonia solani,Fusarium sp, Pythium, Phytophthora, etc. Bacteria: Erwinia, Raltsonia, Rhizomonas, Agrobacterium, Streptomyces etc. Virus: Wheat soil borne Mosaic virus Nematodes: Meloidogyne, Heterodera, Longidorus, Paratrichodorus , Trichodorus, etc. Parasitic plants: Orobanche, striga

5. Disease Triangle

6. PRINCIPLES OF PLANT DISEASE MANAGEMENT • Avoidance of pathogen • Pathogenexclusion • Pathogen eradication and reduction of inoculum • Plantprotection • ResistantVarieties • Therapy

7. Practices for sustainablemanagement ofsoil -borneplant disease 4% Culturalmethod 8% 28% 15% Physicalmethod Biologicalmethod Chemical method Host resistance 45%

8. 1) CULTURAL METHOD • It is an integral part of subsistence agriculture in developing countries. • Cultural practices are now being consider as essential back up procedure for management of resistant varieties and also for chemical protected crops. • Cultural practices involves the principles of : • Avoidance • Eradication • Exclusion

9. Cultural methodsincludes Crop rotation Depth of sowing Management of top soil Dateof sowing Covercops Organic amendment Nutrient management

10. CROP ROTATION AND DISEASE SUPPRESSION • Many diseases build up in the soil when the same crop is grown in the same field year after year. Rotation to a non-susceptible crop can help break this cycle by reducing pathogen levels. • The susceptible crop, related plants, and alternate host plants for the disease must be kept out of the field during the rotation period. • It helps control pathogens that can survive long periods in the soil without a host • Example : Fusarium sp t.

11. Rotation periods to reduce vegetable soil-bornediseases

12. Effect ofshort term rotation on somepathogens

13. PLANT NUTRIENT AND DISEASECONTROL • All essential plant nutrients influence the health of plants and their susceptibility to disease. Plants suffering a nutrient stress will be more susceptible to diseases, while adequate crop nutrition makes plants more tolerant of or resistant to disease. • The nutrient status of the soil and the use of particular fertilizers and amendments can have significant impacts on the pathogen’s environment.

14. One of the most widely recognized associations between fertility management and a crop disease is the effect of soil pH on potato scab. • Potato scab is more severe in soils with pH levels above 5.2. Below 5.2 the disease is generally suppressed. • Sulfur and ammonium sources of nitrogen acidify the soil, also reducing the incidence and severity of potato scab.

15. Example • Fungi penetrate the surface cells (epidermis), by passing between the cells or through them. The cell walls present a physical resistance to the fungus and stronger cell walls can prevent the infection. Certain nutrients, like Calcium, play a major role in the ability of the plant to develop stronger cell walls and tissues. • Bacteria invade the plant tissue through wounds, sucking insects and through the stomata. Then they spread within the intercellular spaces. The bacteria release enzymes that dissolve the plant tissue. Calcium is known in its ability to inhibit such enzymes.

16. How can mineral nutrition prevent plantdisease? Mineral nutrition can affect two primary resistance mechanisms: A) Formation of mechanical barrier(eg. thickness of cell wall ) B ) Synthesis of natural defence compounds (eg: phytoalexins , antioxidants and flavanoids)

17. EFFECTOFNUTRITION IN PLANT DISEASE SUPPRESSION

18. COMPOST and DISEASESUPPRESSION Compost encourages healthy plants that are better equipped to fight off disease and increase in yield are often an added benefit of improving soil and plant health.

19. HOW DOES COMPOST SUPPRESSDISEASE? • Adding compost to soil improves soil physical and chemical properties and increases the number and diversity(different types) of bacteria and fungi in soil. • Root rots caused by Pythium and Phytophthora are generally suppressed by the high numbers and diversity of beneficial microbes found in the compost.

20. Compost Treatment and DiseaseManagement

22. Management of topsoil • Covering of soil with organic residue helps in reducing plant diseases ,but it should be unrelated material to the host’ • Shaping the top soil into ridges will be helpful to keeping the soil dry which is in direct contact with collar region it help to reduce the pathogens like sclerotium rolfsii, pythium fruit rot and sclerotiana sclerotium

23. Covercropping • They are non-host crops sown with the purpose of making soil borne pathogens waste their infection potential before the susceptible main crop is grown. • Growing of cover crops: • Mustard and Brassicasp (Broccoli) helps to reduce the load of soilborne pathogens. • Cover crops will increase soil microbial diversity by enhancing the soil microflora. • Create unfavorable conditions.

24. Depthof sowing: The depth of sowing has important effect on pathogen that attack seedling . By delaying the emergence of seedling ,deep sowing may help to increase the resistance of a susceptible crop to pathogen . Example : Deep sowing is advisable, in case of diseases caused by Fusarium and Rhizoctonia sp.

25. 2) PHYSICAL METHODS • It aims to eradicate the pathogen propagules. It causes the inactivation and immobilization of the pathogen • The physical agents used most commonly in controlling plant diseases are temperature (high or low), dryair,unfavorable light wavelengths, and various types of radiation. • With some crops, cultivation in glass or plastic greenhouses provides physical barriers to pathogens and their vectors and in that way protects the crop from some diseases. • Plastic or net covering of row crops may protect the crop from infection by preventing pathogens or vectors from reaching the plants.

26. Soilsolarization Soilsolarizationisamethodofheatingsoilbycoveringitwith transparent soilborne polythene sheeting diseases. The during hot periodsto control technique has been commercially exploited for growing high-value crops in diseased soils in environments with a hot summer (maximum daily air temperatures regularly exceeding 35°C). Examples include control of verticillium and fusarium diseases in vegetable crops in Israel, control of Verticillium dahlias in orchards in California, USA and control of chickpea and pigeonpea wilt in India.

27. Heatsterilization It is a process of heating up of soil. It can generally achieved by heat produced electically than supplied by steam or hot water. Example: At 50°C – Nematodes and some oomycetes are killed At 60- 70°C – most plant pathogenic bacteria and fungi. It is a process of heating up of soil . It can generally achieved by heat produced electically than supplied by steam or hot water Example: At 50°C – Nematodes and some oomycetes are killed At 60- 70°C – most plant pathogenic bacteria and fungi.

28. Flooding • Flooding the field to eliminate soil borne plant pathogen is both a physical and cultural method. • Prolonged water logging leads to lack of oxygen and accumulate of CO2. • Example : panama wilt of banana can be effectively controlled by flooding for 4 -6 weeks prior to planting.

29. 3) BIOLOGICALCONTROL Two waysofdiseasesuppression: By Antagonistic association By Symbiotic association

30. Antagonisticassociation • Bio control agents suppress disease causing organism in four main ways: • Competition :Beneficial organism out-compete disease causing plant pathogens in the search for nutrients or colonization space in specific habitats such as the root zones. Increased competition prevents pathogens from becoming established and multiplying to levels that cause plant disease. • Antibiotics and secretions : produced by some • microorganisms inhibit the growth of plant pathogen. • Predation and parasitism of plant pathogen by bio control agents (where beneficial microbes use pathogen as a food)

31. Hyphae of the beneficial fungus Trichoderma wrap around the pathogenic fungus Rhizoctonia.

32. SymbioticAssociation In this association beneficial microorganism protect the host plant from pathogen by keeping an association with the host plant of pathogen. Example: Mycorrhiza

33. MYCORRHIZAL FUNGI AND DISEASE SUPPRESSION MYCORRHIZA : consider to be an association between fungi and root of higher plants It is considered as the most beneficial root-inhabiting organisms, which forms a fungal mat over the root and protect the root of plant from the attack of soil borne pathogen.

35. Itprotect the plant by : • It act as a barrier for invading pathogen. • By providing antagonistic chemicals. • By competing with the pathogen. • By increasing the nutrient uptake ability of plants. • By changing the amount and type of plant root exudates.

36. EXAMPLE: • Protection from the pathogen Fusarium oxysporum was shown in a field study using a cool-season annual grass and mycorrhizal fungi. In this studythe disease was suppressed in mycorrhizae- colonized grass inoculated with the pathogen. • In field studies with eggplant, fruitnumbers went from an average of3.5 per plant to an average of • 5.8 per plant when inoculated with Gigaspora margarita mycorrhizal fungi. Average fruit weight per plant went from 258 g to 437 g.

37. 4) Chemicalmethod • Chemical pesticides are generally used to protect plant surfaces from infection or to eradicate a pathogen that has already infected a plant. • A few chemical treatments, however, are aimed at eradicating or greatly reducing the inoculum before it comes in contact with the plant. They include soil treatments (such as fumigation),disinfestation of warehouses, sanitation of handling equipment, and control of insect vectors of pathogens

38. Chemicals in plant disease are used to create the toxic barrier between the host surface and pathogen. • These are applied in the soil as pre and post plant applications. Generally these treatments are being given in high value cash crops. • Applied as soil fumigation, soil drenching and seed treatment. • Fungicides like prothiocarb, propamocarb and metalaxyl are useful to control the Oomycetes pathogens. • Fosetyl – Al is the fungicide which controls the soilborne pathogens when it is used as foliar spray.

39. Suppressivesoil • Suppressiveness is linked to the types and numbers of soil organisms, fertility level, and nature of the soil itself. • The response of plants growing in the soil contributes to suppressiveness. This is • known as “induced resistance“ • The level of disease suppressiveness is typically related to the level of total microbiological activity in a soil.

40. limiting available nutrients is a key for general suppression . • Virtually any treatment to increase the total microbial activity in the soil will enhance general suppression of pathogens by increasing competition for nutrients.

41. 5) Host PlantResistance • Growing of resistance plants is one of the most effective and economical method. Host plant resistance not only reduces the crop losses but lessens the expenditure incurred on disease control as well as reduces the pollution hazards. • Resistance is of two types: • Monogenic (Vertical) • Polygenic (Horizontal):

42. General preventive measures to restrict soil-borne diseases occurrence • Select resistant plant cultivars and certified disease- free stock, then plant them at the right time of year. • Avoid mechanical damage to plants • Do not over-fertilize; doing so inhibits proper root development • Management of soil pH—raising the soil pH to 6.5–7 by using nitrate nitrogen in place of ammonical nitrogen, for example will decrease the development of Fusarial wilt. • Avoid contamination of the growing medium and purchase quality seed

43. Avoid use of low, poorly drained areas for nursery production • Restrict use of machinery in infested areas, particularly when soil is wet • Prevent movement of soil from infested to non- infested areas of nursery • Avoid over watering to puddle or run-off point • Avoid movement of infected trees within and between nurseries

44. Conclusions • Management of soil-borne disease is most successful and economical when all the required information pertaining to the crop, disease affecting it, history of these in the previous years, resistant levels of the host and environmental conditions to prevail is available. • Combination of disease management practices may have additive or synergistic effects and such an approach is especially desirable in the case of soilborne diseases which are entirely different epidemiologically. • Hopefully, the present situation, which emphasizes the use of integrated disease management practices, will stimulate the development of non-chemical methods of disease management to better manage the soilborne pathogens.

45. TERIMA KASIH