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Village Agriculture, Horticulture and Sericulture Assistant · Chapter 6

Plant Protection and Integrated Pest Management (IPM)

What to remember

  • IPM is a decision-based, mixed approach. It uses cultural, mechanical, biological, resistant-variety and chemical methods together, with chemicals as the last option, and acts only when pests cross the Economic Threshold Level (ETL).
  • Know the pest group: insects (6 legs, 3 body parts), mites (8 legs), nematodes (round worms), fungi, bacteria, viruses, rodents and weeds. The control method depends on the group.
  • Safe pesticide use matters: correct dose, correct time, correct nozzle, protective clothing and the right waiting period before harvest.

Pests, diseases and basic terms

  • Pest: any organism that causes economic loss to crops.
  • Disease: a harmful change in the plant caused by a pathogen (fungus, bacterium, virus, phytoplasma, nematode) or by non-living causes.
  • Insect: body in head, thorax and abdomen; three pairs of legs; usually wings and antennae.
  • Mite: eight legs and no separate head, thorax and abdomen (not an insect).
  • Pest status: key pest (serious every year), occasional pest, minor pest and potential pest.
  • Economic Injury Level (EIL): the lowest pest density that causes damage equal to the cost of control.
  • Economic Threshold Level (ETL): the pest density at which control must be started to stop the pest reaching EIL. ETL is always lower than EIL.
  • Pest scouting: regular field observation of pests and natural enemies. It supports a decision.
  • Pesticide resistance: inherited ability of a pest population to survive a dose that once killed it.
  • Resurgence: pest population rises after spraying because natural enemies were killed. Secondary pest outbreak: a minor pest becomes major after spray removes its enemies.

Types of insect damage and mouthparts

MouthpartDamageExampleSuitable insecticide
Biting and chewingHoles, defoliationCaterpillars, grasshoppersStomach poison
Piercing and suckingYellowing, curling, sooty mould, virus spreadAphids, jassids, whitefly, brown planthopperSystemic or contact poison
BoringDead heart, white ear, fruit damageStem borer, shoot and fruit borerSystemic granules, traps
Rasping and suckingSilvery patchesThripsContact or systemic

Principles and methods of plant protection

1. Cultural methods. Deep summer ploughing (exposes soil pests), clean cultivation, field sanitation, crop rotation, timely sowing, optimum spacing, balanced fertilizer, proper water management, trap crops and intercrops, and destroying crop residue.

2. Mechanical and physical methods. Hand picking of larvae, light traps, pheromone traps, sticky traps, bird perches, bonfires, hot-water seed treatment, sun drying of seed.

3. Resistant varieties. The cheapest and safest method. Resistance may be host plant resistance by antibiosis, antixenosis (non-preference) or tolerance.

4. Biological control. Use of living natural enemies:

  • Predators: ladybird beetle, lacewing, spiders, dragonfly, Cryptolaemus.
  • Parasitoids: Trichogramma (egg parasitoid), Bracon, Apanteles, Chelonus.
  • Pathogens: Bacillus thuringiensis (Bt), NPV (nuclear polyhedrosis virus), Beauveria bassiana, Metarhizium, Trichoderma (against soil fungi), Pseudomonas fluorescens (bacterial antagonist).
  • Conservation, augmentation and importation are the three approaches.

5. Chemical control. Pesticides used as seed treatment, soil application, foliar spray, dusting or fumigation.

6. Legal or regulatory control. Quarantine and acts, such as the Destructive Insects and Pests Act, 1914 and the Insecticides Act, 1968. Quarantine stops entry of exotic pests.

7. Botanical and organic options. Neem seed kernel extract (NSKE) 5 percent, neem oil, Neemastra and Brahmastra types of farm-made sprays, cow-urine based and chilli-garlic extracts. Effects are mild; use for early or low pest levels.

Classification of pesticides

By targetNameExample
InsectsInsecticideChlorpyrifos, imidacloprid
MitesAcaricideDicofol, spiromesifen
FungiFungicideMancozeb, carbendazim
BacteriaBactericideStreptocycline
WeedsHerbicideGlyphosate, atrazine
RodentsRodenticideZinc phosphide
NematodesNematicideCarbofuran

By mode of action: stomach poison, contact poison, systemic poison (moves inside the plant), fumigant (gas) and repellent. By chemical group: organochlorine (e.g. DDT, BHC; mostly banned), organophosphate (e.g. malathion), carbamate, synthetic pyrethroid, neonicotinoid. Organochlorines persist long in the environment and build up in the food chain (biomagnification).

Common pests and diseases of major AP crops

CropPest or diseaseNote
RiceStem borer; brown planthopper; blast (fungus); bacterial leaf blight; sheath blightDead heart and white ear by stem borer
CottonPink bollworm; American bollworm; whitefly; sucking pestsPheromone traps help scouting
GroundnutLeaf miner; tikka (leaf spot); collar rotTikka is a fungal leaf spot
ChilliThrips; mites; leaf curl; anthracnoseLeaf curl is virus-like and spread by vectors
RedgramPod borer (Helicoverpa); wilt (fungus)Pheromone traps for monitoring
MangoHopper; powdery mildew; anthracnose; fruit flyHopper and powdery mildew at flowering
CoconutRhinoceros beetle; red palm weevilHooks and pheromone traps
SugarcaneEarly shoot borer; red rotUse healthy setts

Plant diseases: causes and control

Fungal diseases form spores and spread by wind, water and seed; they are controlled by seed treatment, resistant varieties and fungicides. Bacterial diseases spread by water splash, tools and seed; copper compounds and antibiotics such as streptocycline give partial control. Virus diseases spread by insect vectors (whitefly, aphid, thrips), so the vector is controlled and infected plants are uprooted. Nematodes live in soil and roots; they are reduced by crop rotation, summer ploughing and nematicides. Seed treatment before sowing is the cheapest protection: for example, seed is treated with a fungicide such as thiram at about 2 to 3 g per kg seed, or with Trichoderma or Pseudomonas as a biological option. Soil solarisation (covering moist soil with clear polythene in summer) also kills many soil pathogens.

IPM in detail

Aims: keep pest below ETL, reduce chemical use, protect natural enemies and the environment, and give farmers a better profit.

Steps:

  • 1. Prevention: healthy seed, resistant variety, clean field.
  • 2. Monitoring: regular field walk, traps and scouting (agro-ecosystem analysis).
  • 3. Decision: compare pest count with ETL and count of natural enemies.
  • 4. Action: choose the least harmful effective method, starting with cultural and biological.
  • 5. Evaluation: check the result and record it.

Tools: pheromone traps (sex attractant to catch males), light traps, yellow sticky traps for whitefly and aphids, bird perches (T-shaped), Trichocards (Trichogramma) released at egg stage, NPV for Helicoverpa and Spodoptera. A rule of thumb for pheromone traps is about 5 per hectare for monitoring.

IPM in AP is promoted through farmer field schools, Non-Pesticidal Management (NPM) and natural farming programmes, and village-level staff of the agriculture department.

Safe use of pesticides

  • Read the label: colour-coded triangle (red extremely toxic, yellow highly toxic, blue moderately toxic, green slightly toxic).
  • Wear gloves, mask and full-sleeved clothes.
  • Do not spray against the wind, do not eat or smoke while spraying, wash after work.
  • Use a recommended sprayer and nozzle: hollow cone for insecticides and fungicides, flat fan or flood jet for herbicides.
  • Waiting period: the time between last spray and harvest, so that residue stays below the maximum residue limit.
  • Calculate the dose: spray fluid = nozzle discharge rate multiplied by time of walking over the area. Dose in grams = concentration (percent) times spray volume in litres times 10 (for 1 percent = 10 g per litre).
  • Worked example: to prepare 200 litres of 0.2 percent spray, product needed = 0.2 times 200 times 10 = 400 g.
  • Store in original containers away from children and food; destroy empty containers by crushing and burying.

Exam traps

  • ETL is lower than EIL; ETL is when control starts, EIL is when loss equals cost.
  • Mites have eight legs and are not insects; they are controlled by acaricides.
  • Pheromone traps catch males of one species; they are for monitoring more than killing.
  • Trichogramma is an egg parasitoid; Bt is a bacterium; NPV is a virus; Beauveria is a fungus.
  • Systemic poison moves inside the plant; contact poison kills on touch.
  • Resurgence follows destruction of natural enemies; resistance is a genetic change.
  • Triangle colours: red is the most toxic, green is the least toxic.
  • Rodenticide, nematicide and acaricide are different groups; do not mix.

One-liners

  • IPM means using several methods with chemicals as the last choice.
  • Trichogramma parasitises eggs of borers.
  • Bacillus thuringiensis is a bacterial insecticide.
  • Trichoderma controls soil-borne fungi.
  • The Insecticides Act is of 1968.
  • Insects have six legs; mites have eight.
  • NSKE is used at 5 percent.
  • Stem borer causes dead heart and white ear in rice.
  • Pink bollworm attacks cotton bolls.
  • Rhinoceros beetle attacks coconut palms.
  • Zinc phosphide is a rodenticide.
  • Pests are scouted before any spray decision.

Practice questions

  1. IPM stands for

    1. Integrated Pest Management
    2. Improved Pesticide Marketing
    3. Intensive Plant Manuring
    4. Integrated Plant Mutation
    Answer

    A. Integrated Pest Management

    IPM combines several control methods.

  2. In IPM, chemical pesticides are used

    1. as the first and only method
    2. never under any condition
    3. only on weeds
    4. as the last option when other methods are not enough
    Answer

    D. as the last option when other methods are not enough

    IPM uses chemicals only when pests cross the threshold.

  3. Economic Threshold Level (ETL) is the pest density at which

    1. the pest is first seen
    2. control action should begin to prevent reaching EIL
    3. the pest disappears
    4. the crop is fully lost
    Answer

    B. control action should begin to prevent reaching EIL

    ETL is set below EIL.

  4. Which statement about ETL and EIL is correct?

    1. ETL and EIL are always equal
    2. EIL is lower than ETL
    3. ETL is lower than EIL
    4. ETL is higher than EIL
    Answer

    C. ETL is lower than EIL

    Action must start before damage equals the cost of control.

  5. How many legs does an adult insect have?

    1. Four
    2. Six
    3. Eight
    4. Ten
    Answer

    B. Six

    Insects have three pairs of legs.

  6. Mites differ from insects because mites have

    1. eight legs
    2. two wings
    3. three body parts
    4. six legs
    Answer

    A. eight legs

    Mites are arachnids with eight legs.

  7. Which insecticide group is meant for mites?

    1. Bactericide
    2. Rodenticide
    3. Acaricide
    4. Herbicide
    Answer

    C. Acaricide

    Acaricides kill mites.

  8. Zinc phosphide is used as a

    1. rodenticide
    2. nematicide
    3. herbicide
    4. fungicide
    Answer

    A. rodenticide

    It is a common rat poison.

  9. Trichogramma is a

    1. predatory bird
    2. egg parasitoid
    3. soil fungus
    4. larval virus
    Answer

    B. egg parasitoid

    It parasitises eggs of borers and bollworms.

  10. Bacillus thuringiensis (Bt) is a

    1. virus used against whitefly
    2. fungus used against weeds
    3. bacterium used against caterpillars
    4. mite used against aphids
    Answer

    C. bacterium used against caterpillars

    Bt toxin kills caterpillar pests.

  11. NPV used against Helicoverpa is a

    1. nematode
    2. fungus
    3. bacterium
    4. virus
    Answer

    D. virus

    NPV is nuclear polyhedrosis virus.

  12. Beauveria bassiana is an

    1. predatory bug
    2. entomopathogenic fungus
    3. herbicide
    4. egg parasitoid
    Answer

    B. entomopathogenic fungus

    It infects and kills insects.

  13. Trichoderma is mostly used to control

    1. soil-borne fungal diseases
    2. aphids
    3. rats
    4. weeds
    Answer

    A. soil-borne fungal diseases

    It is a biocontrol fungus for soil pathogens.

  14. Dead heart and white ear in rice are caused by

    1. blast fungus
    2. gall midge
    3. brown planthopper
    4. stem borer
    Answer

    D. stem borer

    Larvae bore into the stem; dead heart is seen at the vegetative stage and white ear at flowering.

  15. Pink bollworm is a major pest of

    1. groundnut
    2. coconut
    3. cotton
    4. rice
    Answer

    C. cotton

    It attacks cotton bolls.

  16. Rhinoceros beetle is a pest of

    1. mango
    2. chilli
    3. coconut
    4. redgram
    Answer

    C. coconut

    It bores into the crown of the palm.

  17. Tikka disease is a leaf spot of

    1. rice
    2. sugarcane
    3. cotton
    4. groundnut
    Answer

    D. groundnut

    It is a fungal leaf spot disease.

  18. Red rot is a serious disease of

    1. chilli
    2. sugarcane
    3. coconut
    4. tomato
    Answer

    B. sugarcane

    It is spread through infected setts.

  19. A systemic insecticide

    1. is absorbed and moves inside the plant
    2. kills only by gas
    3. only repels insects
    4. acts only on the leaf surface
    Answer

    A. is absorbed and moves inside the plant

    Systemic poisons move through plant sap.

  20. A fumigant acts as a

    1. seed colour
    2. leaf-spot dye
    3. poison in gas form
    4. soil nutrient
    Answer

    C. poison in gas form

    Fumigants kill pests through the vapour phase.

  21. DDT belongs to the group of

    1. carbamates
    2. organochlorine insecticides
    3. botanicals
    4. organophosphates
    Answer

    B. organochlorine insecticides

    Organochlorines persist and biomagnify.

  22. Heavy use of broad-spectrum sprays killing natural enemies and causing a pest rise is called

    1. resurgence
    2. quarantine
    3. antixenosis
    4. sanitation
    Answer

    A. resurgence

    Loss of natural enemies leads to pest resurgence.

  23. Pest resistance to a pesticide is

    1. a type of seed treatment
    2. a short-term rise in dose
    3. an equipment fault
    4. an inherited ability to survive the usual dose
    Answer

    D. an inherited ability to survive the usual dose

    Repeated use selects resistant individuals.

  24. A colour triangle on a pesticide label that is red indicates

    1. non-toxic
    2. slightly toxic
    3. moderately toxic
    4. extremely toxic
    Answer

    D. extremely toxic

    Red extremely toxic, yellow highly, blue moderately, green slightly.

  25. Which colour triangle shows the least toxic class?

    1. Yellow
    2. Green
    3. Red
    4. Blue
    Answer

    B. Green

    Green means slightly toxic.

  26. How many grams of product are needed to prepare 100 litres of a 0.2 percent spray fluid?

    1. 2000 g
    2. 20 g
    3. 200 g
    4. 2 g
    Answer

    C. 200 g

    0.2 percent is 2 g per litre; 2 x 100 = 200 g.

  27. How much product is needed for 50 litres of a 0.1 percent spray?

    1. 50 g
    2. 500 g
    3. 5 g
    4. 10 g
    Answer

    A. 50 g

    0.1 percent is 1 g per litre; 1 x 50 = 50 g.

  28. To make 20 litres of 2 percent solution, the product needed is

    1. 4 g
    2. 200 g
    3. 400 g
    4. 40 g
    Answer

    C. 400 g

    2 percent is 20 g per litre; 20 x 20 = 400 g.

  29. A knapsack sprayer discharges 1 litre per minute. To cover a plot in 40 minutes, the spray fluid used is

    1. 40 litres
    2. 400 litres
    3. 4 litres
    4. 14 litres
    Answer

    A. 40 litres

    Fluid = discharge x time = 1 x 40.

  30. If 5 g per litre is the dose and the tank holds 15 litres, the product needed per tank is

    1. 50 g
    2. 75 g
    3. 150 g
    4. 20 g
    Answer

    B. 75 g

    5 x 15 = 75 g.

  31. Consider the statements. 1. Light traps and pheromone traps are mechanical or physical tools. 2. Pheromone traps attract females of all insect species. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    A pheromone trap is species-specific and usually attracts males.

  32. Consider the statements. 1. Resistant varieties are a cheap and safe control method. 2. Resistance can act by antibiosis or antixenosis. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are standard facts.

  33. Consider the statements. 1. A hollow cone nozzle is usual for insecticides and fungicides. 2. A flat fan nozzle is usual for herbicides. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct nozzle choices.

  34. Consider the statements. 1. Trichoderma is a bacterium used against insects. 2. Pseudomonas fluorescens is a bacterial biocontrol agent. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Trichoderma is a fungus used against soil fungi.

  35. Consider the statements. 1. The Insecticides Act is of 1968. 2. The Destructive Insects and Pests Act is a regulatory law on pest entry. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are correct; the latter dates from 1914.

  36. Consider the statements. 1. Deep summer ploughing exposes soil pests to sun and birds. 2. Crop rotation can reduce soil nematodes. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are standard cultural methods.

  37. Match the pair: Cultural control is

    1. use of Trichogramma
    2. quarantine law
    3. spraying of pyrethroids
    4. deep ploughing and crop rotation
    Answer

    D. deep ploughing and crop rotation

    Farm practices that make the field less suitable for pests.

  38. Match: Predator example

    1. Beauveria
    2. Trichogramma
    3. Bacillus thuringiensis
    4. Ladybird beetle
    Answer

    D. Ladybird beetle

    Ladybird beetles eat aphids and scale insects.

  39. Which pair is correct?

    1. Thrips - rasping and sucking mouthpart
    2. Stem borer - sucking mouthpart
    3. Caterpillar - piercing and sucking mouthpart
    4. Aphid - biting and chewing mouthpart
    Answer

    A. Thrips - rasping and sucking mouthpart

    Thrips rasp tissue and suck sap; the other pairs are mismatched.

  40. Yellow sticky traps are most useful for

    1. rats
    2. whitefly and aphids
    3. weeds
    4. soil nematodes
    Answer

    B. whitefly and aphids

    Winged sap-suckers are attracted to yellow.

  41. Seed treatment before sowing is useful mainly to

    1. increase seed size
    2. reduce water need
    3. reduce plant height
    4. protect seed and seedling from seed-borne and soil-borne disease
    Answer

    D. protect seed and seedling from seed-borne and soil-borne disease

    It is a cheap first-line protection.

  42. Soil solarisation uses

    1. flooding for a year
    2. black soil mulch in winter
    3. fertilizer in excess
    4. clear polythene sheet over moist soil in summer
    Answer

    D. clear polythene sheet over moist soil in summer

    Trapped heat kills many soil pathogens.

  43. A key pest is one that

    1. causes serious damage every year
    2. appears once in ten years
    3. is never found
    4. is always beneficial
    Answer

    A. causes serious damage every year

    Key pests need regular management.

  44. The waiting period of a pesticide is the time between

    1. two sprays
    2. the last spray and harvest
    3. harvest and sale
    4. sowing and spraying
    Answer

    B. the last spray and harvest

    It keeps residue within permitted limits.

  45. Virus diseases of plants are mainly spread by

    1. rain on leaves only
    2. insect vectors such as whitefly and aphids
    3. soil colour
    4. fertilizer
    Answer

    B. insect vectors such as whitefly and aphids

    Controlling vectors reduces virus spread.

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