The document discusses various cultural methods for managing plant diseases, including avoidance, exclusion, and immunization, with a focus on practices that reduce pathogen presence and promote beneficial microorganisms. It details specific techniques like soil solarization, crop rotation, and the use of organic and inorganic amendments to enhance soil health and control diseases. Additionally, it outlines how practices such as fallowing, green manures, and irrigation can further support disease management in agricultural settings.

2. M.RAMAIAH
RAM/16-39

3. Management of plant diseases
The principal methods of controlling plant disease
are:
1.Avoidance
2.Exclusion
3.Eradication
4.Protection
5.Immunization

4. Cultural Methods of Disease Control
Definition:
 Manipulation of cultural practices at an appropriate time for reducing
or avoiding disease damage to crops
 The cultural practices make the environment less favorable for the
plant pathogen and or more favorable for its bio control agents.
 It is the cheapest of all methods.

5. • According to Stevens(1960) , the cultural methods of disease control
involve agricultural cropping, harvesting and storage, tillage, crop
rotation, soil management, growing of resistant varieties, planning of
land use, and other related practices.
• Cultural disease management practices are the measures undertaken by
humans to prevent and control disease by manipulating plants.

6. Effect of cultural practices on
disease control
Direct effects
 By reducing the amount of
inoculum and reducing the
spread of an established
pathogen.
Indirect effects
 By increasing the
population of microbial
agents in the soil which will
be helpful in controlling the
pathogens

7. List of Cultural practices
1.Soil solarization
2.Deep summer ploughing
3.Organic and inorganic amendments
4.Fallowing
5. Crop rotation
6. Green manure crops
7.Irrigation practices

8.  Roughing
 Strip farming
 Trap and decay crops
 Burning crop residue
 Fertilizers usage
 Time of sowing
 Sanitation
Other cultural practices

9. 1.Soil solarization
The covering of soil with material which raise the surface
temperature above ambient.
Using plastic sheet does soil solarization.
Transparent polythene sheets laid over the soil during
periods of high air temperature.
It can reduce or eradicate a variety of pathogens and
pests, including soil-borne fungi and nematodes, as well
as weed seeds.

10. Reason
Most of pathogen propagules are unable to withstand
temperatures of 50 degree celcius for more than a few hours,
and longer periods at low temperatures may also be lethal.
The soil temperature rise to above the critical threshold
levels, where actually pathogen propagules killed.
The method has proved most successful in regions with
hotter climate.

11. Example
1. Onion white rot,
Sclerotium cepivorum
2. Many soil borne
plant pathogens..

12. 2.Deep summer
ploughing
• Ploughing the land
during hot summer
periods in early
monsoon period.(crop
residues).
Advantages:
Exposing of resting
spores to the sun
thermosensitive pathogens
die.
Eg;Nemawool, sclerotial
bodies etc.

13. Soil borne fungi

15. 3.Organic and inorganic amendments
Definition:
Any substance added in to soil to improve its physical
properties is called” AMENDMENT”.
Types of amendment:
1.Organic amendment
2.Inorganic amendment

16. 1.Organic amendment
Eg; oil cakes, crop residues, saw dust, compost and green
manures.
ROLE OF ORGANIC AMENDMENTs:
Enhance physical properties- soil structure, soil color, pH, porosity
and water holding capacity.
Enhance biological properties- microbial activity.
Balanced availability of nutrients.
Reduces plant diseases by microbiological means such as
antagonism.
Rapid root extension and better plant growth.

17. Example of diseases controlled by organic
amendment
Application of castor cake and neem leaves- foot and root rot of
wheat, Sclerotium rolfsii.
Use of mustard cake- root rot peach, Aphanomyces eutichus.
Pseudomonas, Bacillus, and Streptomyces etc. were collected from
these soils.

18. 2. Inorganic amendments
Eg; fertilizers and chemicals.
• The major role of the fertilizers is to supply essential
nutrients for the growth of the plants.
• They may also help in reduction of disease incidence by
fungistasis mechanism.

19. Examples of diseases controlled by in organic
amendments
Rot of citrus caused by Phytophthora citrophthora
Ammonium form N enhances the rot while it is decreased by
nitrate form of N.
Root rot of Avocardo reduced by drenching the soil with
calcium salts.
Application of single super phosphate- reduced root rot and
increased plant growth.
Application of elemental sulphur to soil was effective in
control of root rot. The population of Trichoderma spp
exploded in sulphured soils.

20. Mechanisms involved in suppression of
diseases by addition of amendments
1.Antagonism
2.Change of soil pH
3.Saprophytic activity
4.Host nutrition

21. 4. Fallow land
• Keeping of land vacant with out any crop is known as
“fallowing”
• During fallowing debris and plant pathogen inoculum are
destroyed.
• Eg; panama wilt of banana controlled by 6 years fallow land.

22. 5.Crop rotation
Definition
• Growing of different crops in a specific piece of land in a year
after year.
• On a certain land , repeated cultivation of different crops or
fallow land in certain sequence.
Purpose
• To control the soil borne pathogens.
• To control the obligate pathogens, where pathogen can not
survive away from the suitable host.
• To improve the biocontrol agents in the soil.

23. Satisfactory control through crop rotation is possible with
pathogens that are soil invaders
i.e.,survive only on living plants or only as long as the host
residue persists as a substrate for their saprophytic existence.
When the pathogen is a soil inhabitant
i.e., produce long lived spores or can live as a saprophyte
for more than 5 or 6 years, crop rotation becomes less
effective or impractical.

24. Difference between soil invader and soil
inhabitant

25. Examples of diseases control by crop rotation
• Potato cyst nematode:mashua (Tropaeolum tuberosum), tarwi
(Lupinus mutabilis) these plants contains nematicidal
properties.
• Soil borne pathogens: such as Macrophomina can controlled
by growing smoothering crops.
• Fusarium wilt in redgram by sorghum.

27. 6.Green manures
Definition
• Green undecomposed plant material used as a manure” green
manure”.
• Green manures are nothing but organic amendments.
• Potentially control strategy for soil borne pathogens.
Eg; Pythium, Phytophthora, Rhizoctonia etc.

28. It is obtained in two ways
GREEN MANURING:
• By growing green manure crops in the field and incorporated it in its
green stage in the same field.
Eg: Sunhemp, Daincha etc.
GREEN LEAF MANURING:
• It is the application of green leaves and twigs of trees, shrubs and
herbs collected from elsewhere especially waste land fields, bunds
and forests to the field.
Eg: Neem, Subabul, Glyrisidia etc.

29. Mechanism involved
1.Direct;
Due to break down of glucosinolates which were present in
crops
Releasing fungi toxic compounds like Avenasin, Saponin and
Allysothiocyanates.
2.Indirect;
By influencing the native microbial populations.
eg; Increase the population of Trichoderma, Pseudomonas
and Actinomycetes etc.

30. Advantages of green manure crops
• Supply food material to beneficial microbes in soil.
• Improve soil fertility.
• Bring aeration, drainage and granulation of soil.
• Increase the water holding capacity of soil.
• Supply nitrogen to soil.
• Increase biochemical activity and increase crop yield.

32. 7. Irrigation practices
Definition:
Artificial application of water to the soil is called “Irrigation”
Factor effecting the disease incidence:
Method of irrigation
Irrigation frequency
Number of irrigations

33. Examples
Flood irrigation-due to this the spores spread from one to other
field in citrus orchards and in paddy.
Sprinkler irrigation-it favors foliar diseases because of high
humidity.
• It also spread the foliar diseases like colletotrichum.
Double ring method- it is reduces the gummosis disease in
orchards.
It is also reduce the certain diseases like root rot caused by
rhizoctonia bataticola.
Drainage can reduce the inoculum of propagules in soil.

34. Drip irrigation system

35. ROUGHING
 The removal and destruction of alternate hosts and collateral host,
diseased plants, or rogues.
 It can prevent further spread of disease, but is labour intensive.
 For that reason, it is practicable only in small plantings, or
where labour is cheap or if the crop is very valuable.

36. • Some pathogens require two alternate hosts to
complete their full life cycles.
For example :
• Puccinia graminis tritici requires wheat and barberry.
• Cronartium ribicola requires pine and currant
(Ribes).
• Gymnosporangium juniperi-virginianae requires
cedar and apple.
 In these cases, eradication of the wild or
economically less important alternate host interrupts
the life cycle of the pathogen and leads to control of
the disease.

37. Different between collateral host and alternate host
Collateral host/alternative host
Wild host of same family.
For off season surviving of
pathogen.
To bridge the gap between two
crop seasons.
Eg; paddy blast-panicum
repens.
Alternate host
Wild host of other families.
For completion of the life cycle
of pathogen.
Host compulsory required.
Eg; wheat black stem rust-
barbary leaf.

38.  Strip farming is a similar practice to intercropping.
 Where areas of one crop are separated from each
other with strips of another crop.
 The rationale being that the two different crops are
unlikely to share the same pathogens, thus reducing
the rate of spread.
 The main disadvantage of strip farming is the fact
that it is relatively labour intensive.
Strip farming

39. Principal findings

40. • In two years of field experiments, maize/soybean
intercropping suppressed the occurrence of soybean red
crown rot, a severe soil-borne disease caused
by Cylindrocladium parasiticum (C. parasiticum).
• The suppressive effects decreased with increasing distance
between intercropped plants under both low P and high P
supply, suggesting that root interactions play a significant
role independent of nutrient status.
• Further detailed quantitative studies revealed that the
diversity and intensity of root interactions altered the
expression of important soybean PRgenes, as well as, the
activity of corresponding enzymes in both P treatments..

41. • Furthermore, 5 phenolic acids were detected in root exudates of
maize/soybean intercropped plants.
• Among these phenolic acids, cinnamic acid was released in
significantly greater concentrations when intercropped maize
with soybean compared to either crop grown in monoculture,
and this spike in cinnamic acid was found dramatically
constrain C. parasiticum growth in vitro

42.  Trap crops of susceptible plants are grown on land known to
contain pathogens.
 They become infected and are then destroyed before the
pathogens' life cycles are complete, thus reducing the amount
of inoculum in the area.
 Decoy crops stimulate the hatching or germination of
pathogen eggs or propagules, but the pathogens are unable to
establish and infection of the decoy host and die, again
reducing the amount of available inoculum.
 Eg;sunhemp.
TRAP or DECOY CROPS

43. • It has been discouraged because of destruction of
valuable organic matter and creation of an air
pollution problem.
• The fact remains, however, that it is a highly effective
means of eradicating some disease causing organisms
associated with crop residue.
Burning of crop residue

44.  Fertilizer usage may have some bearing on development of
certain diseases.
 It differs with each crop and each disease.
 In general, nitrogen out of balance with other nutrients enhances
foliage disease development and predisposes some plants to
other diseases.
 Potash, on the other hand, helps reduce disease development
when it is in balance with other elements.
Fertilizer usage

45.  Time of seeding has an important bearing on disease
prevention in many cases.
 Delayed planting of wheat will help escape the chances
of wheat streak mosaic virus.
 Early spring planting of cotton may effectively help
escape cotton root rot.
Time of seeding

46.  Many plant viruses, such as cucumber mosaic virus, are brought
into crops, such as Hoppers, by air borne aphid vectors.
 When vertical, sticky, yellow polyethylene sheets are erected
along the edges of susceptible crops, a considerable number of
aphids are attracted to and stick to the plastic.
Polythene sheet and mulches

47. if reflectant aluminum or black, whitish-gray, or colored
polyethylene sheets are used as mulches between the plants or rows in
the field, incoming aphids, thrips, and possibly other insect vectors are
repelled and misled away from the field.

48. Sanitation consists of all activities aimed at eliminating or
reducing the amount of inoculum present in a plant, a field, or a
warehouse and at preventing the spread of the pathogen to other
healthy plants and plant products.
SANITATION

58. My personal experience in RAWEP
• Mixed cropping by farmers.
• Application of Trichoderma to the soil, which is multiplied in
FYM.
• Spraying of vepa kashaum on field.
• Applying red mud to the cutting portion of citrus branches.
• Green manuring.

59. Conclusion:
Practising of all methods we can support the bioagents in soil.
These methods providing the opportunity to the bioagents to
multiply and to care of plant pathogens.
These methods are more favourable to the bioagens than the
plant pathogents.

60. References
 R S Mehrotra. Plant Pathology. Tata mcgraw- hill
publishing company limited, New Delhi.
 George N. AGRIOS. Plant Pathology. Elsevier academic
press.
Ashoke. K. Mishra and A. Bohra and Akhilesh Mishra.
Plant Pathology: Disease and Management.
R. D Sharma. Microbiology and plant pathology.