DISEASE MANAGEMENT

   1.    Prophylactic Approach

Ø  Practices management that protect the host from pathogen or from environment that may encourage the development of disease.

                      i.        Quarantine

·     Regulations controlling the import and export of plants to prevent spread of disease and pest.

·    Plant quarantine centre – airport, port harbor and state boundary town.

·    This center determine the foreigner do not bring in the plant material into the country.

·     Example: AKTA KUARANTIN TUMBUHAN 1976

                    ii.        Eradication

·   Elimination of pathogen after it has established in the region of host plants.

·       Examples:- sanitation, eradication of plant parts

                   iii.        Prevention

·         crop rotation

·         chemical treatment

   2.    Host Plant Resistance

                      i.        Horizontal resistance

·         against all races of pathogen

·         Controlled by many genes (polygene) (>1 gene)

·         Non race specific

·         Unstable resistance- affected by environment.

·         Slower the infection and epidemic progress

·    Example: A very vigorous tomato plant will have some tolerance to nematodes just because the plant can grow new roots to replace infected roots.

                    ii.        Vertical resistance

·         Plant host is resistent to some races of a pathogen

·   Controlled by one or two genes (1 gene) ( ‘monogene / oligogene’ resistance)

·         Race specific

·         Stable resistance - Non affected by enviromental factors

   3.    Integrated Disease Management

Ø  Combination of all control methods to protect the host plant effectively

Ø  Example: biological control + cultural control + physical control.

                      i.        Biological control

·         The process to reduce or control the pest level by using another micro-organism.

·         Use antagonistic microorganism, microorganism that antagonist to the pathogen.

·         The microorganism will destroy and inhibit the growth of pathogen.

·         Environmentally friendly method.

a)    Antagonistic microorganisms

-       Usually a parasite to pathogen.

-       Compete to get food and space.

-       Remove toxin that give negative effect to pathogen.

-    Example: Plant legume cover crop (LCC) to prevent root disease in oil palm and rubber which enhance the growth of antagonist pathogen like Tricoderma spp in the soil.

-   Coffee rust disease cause by Hemileia vastetrix can be control with Verticilium psaliotae

b)    Intercropping/mixed cropping

-       To reduce pathogen attack the main crop

-       Example: corn was planted together with peanut to avoid disease by virus.

-       Vector/insect (aphid) more interested with higher crop.

-       So, virus disease in peanut can be reduced because corn is mores higher than peanut and easy to attract the vector.

                    ii.        Cultural control

a)    Host eradication

-       Removed or burned all infected host plant

-       Example: paddy virus – destroy weed

b)    Crop rotation

-    To prevent the build-up of pathogens in one area by rotating the types of crops grown.

-     Some pathogen will die if the specific host are not available in certain period of time.

-       Bacteria (Pseudomonas) - southern wilt can be control by planting the unaffected host.

-       Example: pea nut-corn-onion-chilli-corn

c)    Sanitation

-       A process to eliminate or to reduce the level of inoculum in a field or plant.

- Make a space/planting density to reduce the moisture/temperature especially in nursery.

-       Liming the soil to reduce fungi Plasmodiophora brassicae

d)    Eliminate alternate host

-       Viral diseases of rice – Eliminate weeds

-       Wheat rust by Pucccinia - eliminate barberry crops

e)    Environments unstable for pathogen

-       Create unfavourable conditions for pathogen life

-   Planting distance to reduce moisture, especially in the nursery

-  Fungal root disease  - reduce fungal Plasmodiophora brassicae by liming the soil

f)     host resistance

-       Vertical resistance (resistance genetic)

-       Horizontal resistance

                   iii.        Physical control

a)    Heat treatment

-    Suitable for soil sterilization, which is usually used in the greenhouse / small beds

-   50 C: for fungi and nematode, 60 C – 72 C: for fungi, bacteria

b)    Drying

-       Control pathogen in cereals/fruits in storage

-       Reduce rot disease if proper drying at 12% moisture.

c)    Cooling

-       Disease control after harvesting

-       Example: fruits and vegetables

-  Lower temperature cannot kill pathogen but inhibit the growth/ pathogen activity.

d)    Radiation

-       UV (ultra violet) like laminar flow

-       X radiation

-       Gama radiation

                   iv.        Chemical control

·         Quick effect to reduce disease

·         Problems:-

-       environmental pollution

-       health effect to human

-       pathogen resistant to chemical/toxin

·         Mostly focused on the use of fungicides disorder on vegetables, fruits and plantation such as rubber, oil palm and cocoa

·         Provide phytotoxicity to plants

·         Types of pesticides: fungicides, bactericides, nematicides, insecticides.

                         

                                                                      
                                                                         Pesticides

                                                       

                                                     Fungicides 

   

                                                      

                                                       Insecticides

                          

References,

                              https://www.nda.agric.za/docs/et/plant_pathology.htm

                              https://en.m.wikipedia.org/wiki/plant_pathology

Prepared by, MOHAMAD SAUFIUDDIN BIN SHAMSUDIN