The document provides an overview of remote sensing in plant pathology. It discusses the history and fundamentals of remote sensing, including different types of platforms, resolutions, and the objectives and case studies of remote sensing in plant disease management. Key objectives of remote sensing in plant pathology include assessing diseases over large areas, understanding disease-environment relationships, detecting and identifying plant diseases, and aiding disease management. Case studies demonstrate uses of remote sensing for various crop diseases.

2. Major Advisor
Dr. J.R. Verma
(Assoc. Prof. & HoD)
Seminar In-charge
Dr. Krishna Saharan
(Assistant Professor)

3. Contents
Introduction
History of Remote Sensing
Types of remote sensing
Fundamentals of remote sensing
Types of platforms used in remote sensing
Types of resolution used in remote sensing
Objectives of remote sensing in plant pathology
Case studies of remote sensing in plant disease management
Conclusion

4. • It simply referred collection of information an object without
coming into physical contact .
• Remote sensing is defined as the technique of obtaining information
about objects through the analysis of data collected by special
instruments that are not in physical contact with the object of
investigation.
• The output of a remote sensing system is usually an image
representing the scene being observed.
(Campbell 1987)

5.  The technology of modern remote sensing began with the invention of the camera more than 150 years ago.
 The idea and practice of looking down at the Earths surface emerged in the 1840s when pictures were taken from
cameras bind with balloon for purpose of topographic mapping.
 Aerial photography is the original form of remote sensing (using visible spectrum) started in 1909.
 Colour infrared photography began 1931, and then was widely used in agriculture and forestry.
 The terms “remote sensing” first used in the United State in the 1950s by Ms. Evelyn Pruitt.
 Satellite remote sensing can be traced to the early days of the space age (both Russian and American programs)
and actually began as a dual approach to imaging surfaces using several types of sensors from spacecraft.
 After the first man-made satellite (Sputnik 1) was launched on 4 October 1957 by Soviet
 Colwell (1956) first used remote sensing technique for monitoring stem rust of wheat.
(Reid, S.H., 2020)

6. 1. Active remote sensing
2. Passive remote sensing
1. Active remote sensing :- The use of sensors that deduct reflected
responses from object that are irradiated from artificially generated energy
sources such as Radar.
2. Passive remote sensing :- The use of sensors that deduct the reflected or
emitted electromagnetic radiation from natural sources.
(Satapathy, R.R., 2020)

8. • Electromagnetic remote sensing of earth resources involves the
two basis processes viz.
1. Data acquisition
2. Data analysis

9. 1. Energy sources
2. Propagation of energy through the atmosphere
3. Energy interaction with earth surface features
4. Re- transmission of energy through the atmosphere
5. Air-borne and / or space borne sensors
6. Generation of sensor data in pictorial and / or digital form

10.  Energy source :- The first requirements for remote sensing is to have an energy source
which illuminates or provides electromagnetic energy to the target of interest. (Sun to
earth - 300000 km/Sec.)
 Propagation of energy through the atmosphere :- As the energy travels from its
sources to the target , it will come in contact with the atmosphere it passes through. This
interaction may take place a second time as energy travels from the target to the sensor.
Scattering , Reflection , Refraction, Absorption.
 Energy interaction with earth surface features:- It interacts with the target depending
on the properties of both the target and the radiation.

11.  Re- transmission :- The energy recorded by the sensor has to be
transmitted, often in electronic form.
 Air-borne and / or space borne sensors :- It use to collect and record the
electromagnetic radiation.
 Generation of sensor data in pictorial and / or digital form :- The energy
recorded by the sensor has to be transmitted, often in electronic form, to a
receiving and processing station where the data are processed into an
image (hardcopy / digital).

12. Source - J Pharma Phytochemi (2020)

13. • The processed image is interpreted, visually and / or digitally or
electronically, to extract information about the target which was
illuminated.

14. Platforms : The base on which remote sensors are placed to acquire information about
the earth surface is called platforms.
Ground based platforms - up to 50 m
Towers, Radar
Airborne platforms : up to 50 km
Helicopters, Aircrafts, Balloons
Space borne : from about 100 km to 36000 km
1. Space station : 300-400 km
2. Low earth orbit – 700- 1500 km
3. High earth orbit – about 36000

15. Ground Based Sensors Aerial Platforms Space Platforms

16. • This sensor converts these radiation into electrical signals and
presents it in a form suitable for obtaining information about the
land / earth resource as used by an information gathering systems.
• The specific parameters of sensors are -
1. Spatial resolution
2. Spectral resolution
3. Radiometric resolution
4. Temporal resolution
(Ekwal Imam 2019)

17. • The ability to distinguish small adjacent objects in an image.
• Dimensions of the smallest object or minimum detectable area
which can be resolved by the sensor.
• Large area covered by a pixel means low spatial resolution and
vice versa.
• 1 MP = 1 lakh pixel
Source - Remote Sensing & GIS Applications Directorate

18. High vs. Low?
Spatial Resolution
Source: Jensen (2000)

19. 0.6 M

23. • Spectral resolution describe the ability of a sensor to define fine wavelength
intervals.
• Is the ability to resolve spectral features and bands into their separate
components.
• More number of bands in a specified bandwidth means higher spectral
resolution and vice versa.
Remote Sensing & GIS Applications Directorate

24. <10 no. of wavebands 10-1000 no. of wavebands
Wavelength , Frequency

25. Radiometric Resolution refers to the smallest change in
intensity level that can be detected by the sensing system.
The number of gray level / values which a sensor can
difference between black and white.
The more the grey levels, the better the radiometric
resolution.
(Remote Sensing & GIS Applications Directorate)

26. (Remote Sensing & GIS Applications Directorate)
1023
6-bit range
0 63
8-bit range
0 255
0
10-bit range
2-bit range
0 4

27. • 1 bit (0-1) – it 1000 watt or not
• 2 bit (1, 2, 3, 4) – 0-250 = 1
– 250-500 = 2
– 500-750= 3
– 750-1000= 4

29. Frequency at which images are recorded/ captured in a specific
place on the earth.
The more frequently it is captured, the better or finer the
temporal resolution is said to be
For example, a sensor that captures an image of an agriculture
land twice a day has better temporal resolution than a sensor that
only captures that same image once a week.
(Remote Sensing & GIS Applications Directorate)

30. (Remote Sensing & GIS Applications Directorate)
Temporal Resolution
Time
July 1 July 12 July 23 August 3
11 days
16 days
July 2 July 18 August 3

32. Objectives of remote sensing in plant pathology
1. Assessment of disease over a vast area
2. To know the relationship of diseases and environment
3. To know the origin and development of epidemics
4. For detection, identification, of plant disease
5. Management of plant disease
6. Miscellaneous

33. 1. Assessment of disease over a vast area
• Remote sensing technology can provide spatial distribution information of diseases and
pests over a large area with relatively low cost.
• The presence of diseases on canopy surface causes changes in pigment, chemical
concentrations, cell structure, nutrient, water uptake, and gas exchange. These changes
result in differences in color and temperature of the canopy, and affect canopy reflectance
characteristics, which can be detectable by remote sensing (Raikes and Burpee 1998).
• Colwell (1956) first used remote sensing technique for monitoring stem rust of wheat.

34. 2.
Indian stem rust rules - The spread and deposition of stem rust pathogen
of wheat is influenced by definite synoptic weather conditions.
• Late blight of potato
e.g. Dutch rules in potato – Everdingen
• i) Night temp. below dew point at least for 4 hours
ii) A min temp of 10°C or above
iii) A mean cloudiness on the next day of 0.8 or more
iv) At least 0.1mm rainfall during the next 24 hours.
The sensing of the pathogen and environmental conditions is a
very promising tool to support decision-making regarding
fungicide use.

35. Sensing of Host–Pathogen Interactions
Host–pathogen relationships may be investigated using spatial
resolution for metabolic changes.
Temporal resolution use for understanding host pathogen
interactions.
High spatial resolution of imaging sensors enables time-series
measurements of host–pathogen interactions at the tissue scale.
These images may be used to visualize and quantify pathogen
effects on host metabolism with high spatial resolution, contributing
to the understanding of tolerance mechanisms in host genotypes.
(Oerke EC 2019)

36. • Infrared Thermography (IRT) assesses plant temperature and is
correlated with plant water status, the microclimate in crop stands
and with changes in transpiration due to early infections by plant
pathogens.
Monitoring of rose leaf colorization by Peronospora sp. and symptom develop. of downy mildew in early stages (5
and 7 days after inoculation) of the disease by thermographic imaging

39. • In the food industry, postharvest sensing of the quality and checking
ripeness, colour, and suitability for storage.
• Sensors of plant diseases may be used in quality control (e.g., by the food
industry or quarantine authorities) once, or they may be integrated into
autonomous systems for the continuous monitoring of crops for plant
diseases, i.e., checking and keeping a continuous record of the crop health
status.

40. (Oerke EC 2019)

41. • Remote sensing includes the sensor-based methods for the detection,
identification of plant diseases.
• Sensors are expected to be objective, accurate, precise, rapid, and
available 24 hours a day, 7 days a week (24/7).
• Systematic observation of a crop by technical sensors can allow the
operator to intervene when infections are detectable or exceed action
threshold levels.
• Its helps in Quantifying the severity of the disease.

42. The decision whether or not to apply a fungicide to control a sensitive
pathogen depends on not only the presence of a symptom but also whether the
disease severity exceeds the action threshold level calculated from economic
considerations
In Monocyclic pathogens do not need control at the time of the first
appearance of symptoms, as the damage is already done (e.g., smut fungi).
 In contrast, the frequency of first disease symptoms caused by polycyclic
pathogens is often low and the expected increase in disease severity from the
next generations of the pathogen may be controlled to prevent disease severity
from exceeding the economic threshold level, provided effective fungicides
are available.

43. Case studies of remote sensing in plant disease
management
Nilsson et al. observed that the flag leaves of oats infected by barley
yellow dwarf virus were 3-4° warmer than visually healthy leaves.
Smith et al. reported that stripe rust on wheat initially reduced stomata
closure and disrupted the cuticle.
Colwell (1956) demonstrated the potential of aerial photography using
panchromatic and infrared films to detect and quantify crop diseases such
as cereal rusts and virus diseases of citrus.
Southern corn blight watch project in the USA (Helminthosporium
maydis) demonstrated the efficacy of large-scale application of aerial IR-
photography to crop disease surveillance.

44.  Evapo - transpiration from the leaves increased and the infected leaves
were 0.2-1.0 °C cooler than the controls during early disease development.
Clark et al (68) used aerial IR-photography to estimate damage by diseases
such as spot blotch of barley, crown rust and barley yellow dwarf virus of
oats (BYDV), and powdery mildew of wheat in field plot experiments.
 In the early 1930s infrared plate-films were used in studies of virus
diseases of potatoes and tobacco (Bawden).
 Blazquez & Edwards used IR-color photography and spectral reflectance
for studies of tomato and potato diseases.

45. Remote sensing is a very useful tool for disease management. This is not
only helps in management of disease but its also prevents upcoming
epidemics in crop plant.
Plant Quarantine regulation is very important principle in plant disease
management and without remote sensing it is not possible.
Without study of host pathogen interaction we are not able to manage
disease in precise manners.
Therefore we can say in the end that without remote sensing, managements
of plant disease is not possible now a days.

47. Acknowledgements
• I would like to express my special thanks of gratitude to Dr.
Dama Ram sir, Dr. J.R Verma sir, Dr. Krishna Saharan mam
for their able guidance and support in complete my presentation.
• I gratefully acknowledge the use of some very important
information and photographs given in test book “Plant
Pathology” by G N Agrios and research paper written by Rakesh
Roshan Satapathy sir and other researchers.