एग्रो-इकोसिस्टम विश्लेषण पर आधारित पादप स्वास्थ्य प्रबंधन

Agricultural crops are widely distributed in different agro-ecological regions and thus in different regions the pest management practices differ on various crops. Decision making in pest management requires an analysis of the agro eco system. During the late 90s, FAO started advocating Agro-Ecosystem Analysis (AESA) based IPM (Gurr et al., 2004).

Agro Ecosystem Analysis (AESA) is an approach, which can be employed by extension functionaries and farmers to analyze the field situations and monitor the population of pests, defenders, soil conditions, plant health and the influence of climatic factors to make informed decisions for growing a healthy crop. In AESA, farmers observe the crop, analyze the field situation and take decisions for crop management based on field observations.

Focus in AESA based IPM is on pest-defender dynamics, abilities of plants to compensate for the damage caused by pests and the influence of abiotic factors on pest build up. The health of a plant is determined by its environment which includes abiotic factors (sun, rain, wind, soil nutrients etc.) and biotic factors (i.e. pests, diseases, weeds etc.).

These factors play a role in the balance which exists between insects and their natural enemies. Understanding these interactions can help in pest management. The activity takes place in the farmer field.

It is season-long so that it covers different developmental stages of the crop and their related management practices. The process is learner-centered and necessitates active participation of farmers and promotes decision making based on experiential learning and discovery by farmers.

Experiences show that AESA has resulted in reduction in chemical pesticide usage and in cost of production, increase in yields and also conserves the agro-ecosystems.

AESA involves three steps

 Observation → Analysis → Decision making

Methodology of AESA to manage plant health

A) Field Observations

a) Enter the field at least 5 ft. away from the bund. Select a site with a dimension of 1 sq. mt. randomly

b) Record visual observations in following sequence:-

• Flying insects (both pests and defenders)
• Close observation on pests and defenders which remain on the plants.
• Observe pests like  lituraand defenders like ground beetle/ rove beetle/ earwigs by scrapping the soil surface around the plants.
• Record insect damage in percentage.

c) Record parameters like number of leaves, branches, plant height and reproductive parts of the selected plants which should be flagged for making observation in the following weeks.

d) Record the types of weeds, their size and population density in relation to crop plant.

e) Record soil conditions viz. flooded, wet or dry.

f) Observe rodent live burrows.

g) Repeat the step (a) to (f) in four sites randomly selected.

h) Record the climatic factors viz. sunny, partially sunny, cloudy, rainy etc. for the preceding week.

B. Drawing:

First draw the plant with actual number of branches/ leaves etc. at the centre on a chart. Then draw pests on left side and defender on the right side. Indicate the soil condition, weed population, rodent damage etc. Give natural colours to all the drawing, for instance, draw healthy plant with green colour diseased plant/ leaves with yellow colour.

While drawing the pests and the defenders on the chart care should be taken to draw them at appropriate part of the plant,where they are seen at the time of observation. The common name of pest and defenders and their population count should also be given along with diagram.

The weather factor should be reflected in the chart by drawing the diagram of sun just above the plant if the attribute is sunny. If cloudy, the clouds may be drawn in place of sun. In the case of partially sunny, the diagram of sun may be half masked with clouds.

C. Group Discussion and Decision making:

The observations recorded in the previous and current charts should be discussed among the farmers by raising questions relating to change in pest and defender population in relation to crop stages, soil condition weather factors such as rainy, cloudy or sunny, etc.

The group may evolve a strategy based upon weekly AESA, ETL and corresponding change in P: D ratio and take judicious decision for specific pest management practices.

D. Strategy for decision mating:

i) When large number of egg masses and early instar larvae are observed, the group may advocate application of NPV.

ii) Some of the defenders like lady bird beetles, groundnut beetles, rove beetles and wasps play useful  role in arriving at P: D ratio.

Principles of AESA based integrated pest management (IPM)

Grow a healthy crop

Select a variety which is resistant/tolerant to major pests. Treat the seeds/seedlings/planting material with recommended pesticides, especially bio pesticides Select healthy seeds/seedlings/planting material.

Apart from this, soil health can be improved by nutrient management especially organic manures and bio fertilizers based on soil test results. If the dosage of nitrogenous fertilizers is too high the crop becomes too succulent and susceptible to insects and diseases.

If the dosage is too low, the crop growth is retarded. So, the farmers should apply adequate amount for best results. Phosphate fertilizers should not be applied every season as the residual phosphate of the previous season will be available for the current season also.

Furthermore, proper irrigation and crop rotation can also be helpful in this regard.

Regular field observation

Farmers should monitor the field situations at least once a week (soil, water, plants, pests, natural enemies, weeds, weather factors etc.); make decisions based on the field situation. The Pest: Defender (P: D) ratio must be estimated to take necessary action.

Plant compensation ability

Compensation is defined as the replacement of plant biomass lost to herbivores and has been associated with increased photosynthetic rates and mobilization of stored resources, for e.g. From roots and remaining leaves.

Understand and conserve defenders

Know about natural enemies to understand their role through regular observations of the agro ecosystem and avoid use of chemical pesticides.

Insect zoo

Various types of insects are present in the field where some are beneficial some may be harmful. Generally farmers are not aware about this. The concept of Insect zoo can help in enhancing farmers ‘skill to identify beneficial and harmful insects.

In this method, unknown predators are collected in plastic containers from the field. Each predator is placed inside a plastic bottle together with parts of the plant and some known insect pests.

Insects in the bottle are observed to determine whether the test insect is a pest (feeds on plant) or a predator (feeds on other insects).

Pest: defender ratio (P: D ratio)

The natural enemies of crop pests include parasitoids, predators and pathogens. Identifying the pests and beneficial insects helps farmers make appropriate pest management decisions. Sweep net, visual count etc. can be adopted to arrive at the numbers of pests and defenders.

The P: D ratio can vary depending on the feeding potential of natural enemy as well as the type of pest. The general rule to be adopted for management decisions relying on the P: D ratio is 2:1. However, some of the parasitoids and predators can control more than 2 pests.

Whenever the P: D ratio is found to be favorable, there is no need for adoption of other management strategies. In cases where the P: D ratio is found to be unfavorable, the farmers can be advised to resort to release of parasitoids/predators depending upon the type of pest.

In addition, bio pesticides such as insect growth regulators, botanicals etc. can be used before resorting to chemical pesticides.

AESA through Farmers Field Schools

Adoption of AESA based IPM through Farmers Field School (FFS) programs encouraged reliance on biological control agents as well as substantial reduction in use of chemical fertilizers and pesticides and consequently reduction in cost.

The National Institute of Plant Health Management (NIPHM) and Directorate of Plant Protection, Quarantine & Storage (DPPQ&S) have revised IPM packages for different crops by incorporating agro ecosystem analysis, ecological engineering and other IPM options in association with State Agricultural Universities and ICAR institutions.

Conclusion

The health of a plant is determined by its environment. This environment includes abiotic factors (i.e. sun, rain, wind and soil nutrients) and biotic factors (i.e. pests, diseases and weeds). All these factors can play a role in the balance, which exists between herbivore insects and their natural enemies.

If we understand the whole system of interactions, we can use this knowledge to reduce the negative impact of pests and diseases. Farmer’s participation in adoption of Integrated Pest Management (IPM) is a crucial tool.

Agro Ecosystem Analysis (AESA) is an approach, which can be employed by extension functionaries and farmers to analyze the field situations and monitor the population of pests, defenders, soil conditions, plant health and the influence of climatic factors to make informed decisions for growing a healthy crop.

Thus IPM is acting as an interdisciplinary approach that starts from monitoring to decision making for a successful outcome.

AESA is a group oriented approach that requires group participation of farmers for the IPM programme to be implemented successfully, thus extension functionaries act as most important factor in the dissemination of knowledge from scientists to farmers through AESA by using FFS.

References

Gurr, G.M., Wratten, S.D., Altieri, M.A., 2004. Ecological Engineering for Pest Management: Habitat Manipulation for Arthropods. CSIRO Publishing, Collingwood, ISBN 0 643 0990223.

Kampe, T. U., B. R. Johnson, M. Kuester, and M. Keller. 2010. NEON: the first continental-scale ecological observatory with airborne remote sensing of vegetation canopy biochemistry and structure. Journal of Applied Remote Sensing 4:043510.

Rocchini, D., et al. 2015. Potential of remote sensing to predict species invasions: a modeling perspective. Progress in Physical Geography 39:283–309.

Authors:

Sushila Choudhary^1*, Dr. R. K. Bagri² and Ramniwas Yadav¹

¹Research Scholar, Division of Plant Pathology, RARI, Durgapura

²Associate Professor, Division of Plant Pathology, RARI, Durgapura

 SKN Agriculture University, Jobner- Jaipur

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