Plant Disease Forecasting

1
Plant Disease Forecasting Plant Clinic
By Dr. S.M. Prasad,
Chief Scientist cum
University Professor, Department of Plant
Pathology, Birsa
Agricultural University,
Ranchi-834006
2
Plant Disease Forecasting
3
Introduction

• Plant diseases vary in consistency of occurrence
  and Severity
• The growers are often faced with the dilemma
  whether to spray or wait?
• Disease forecasting or warning systems are boon
  to growers as it encourages judicious, need based
  use of pesticides
• This not only saves the money and energy of the
  growers without risking crop health, but also
  avoids the environmental pollution.

4
Definition

• Forecasting involves all the activities in
  ascertaining and notifying the growers of
  community that conditions and sufficiently
  favorable for certain diseases, that application
  of control measures will result in economic gain
  or on the other hand, and just as important that
  the amount expected is unlikely to be enough to
  justify the expenditure of time, energy and money
  for control.

5
Positive and Negative Forecast
Positive Forecast

• Positive forecast employs need based chemical
  sprays, provides adequate protection to crop and
  reduce damage to environment

Negative Forecast

• Negative forecast avoids unnecessary chemical
  sprays, no risk to the crop health and and no
  disruption of environment

6
Prerequisites for developing a forecast system

• The crop must be a cash crop (Economic value)
• The disease must have potential to cause damage (
  Yield losses)
• The disease should not be a regular feature
  (Uncertainty)
• Effective and economic control known (Option to
  the growers)
• Reliable means of communication with farmers
• Farmers should be adaptive and have purchase power

7
Basis of forecasting

• Forecasts based on assessment of amount of
  initial inoculum
• Forecasts based on weather conditions favoring
  development of secondary inoculum
• Forecasts based on amounts of initial and
  secondary inoculum

8
Forecasting Late blight of potato
The Dutch Rules

• Night temperature below dew point for atleast 4
  hours
• Minimum temperature of 100C or slightly above
• Clouds on the next day
• Rainfall during next 24 hours for atleast 0.1 mm
  (Van Everdingen, 1926)

9
Late blight forecasting in India
Non-rainy years 7-day moving graph

• RH gt 85 for gt 50 hrs and temp.7.2-26.60C for gt
  115 hrs.
• (If above conditions prevail for 7 consecutive
  days blight would appear within 7-10 days)

10
Late blight forecasting in India
Rainy years 7-day moving graph

• Measurable rain (0.1-0.5 mm) for two consecutive
  days
• Five-day moving RH gt 85 gt 50 hrs
• Five days moving congenial temperature (7.2-26.6
  0 C) for gt 100 hrs.
• (If above conditions prevail for five consecutive
  days blight would appear within 7-10 days)

11
Computer based forecasting programmes

• BLITECAST-Late blight of potato
• EPIDEM-Early blight epidemics in tomato
• EPIMAY-Southern maize leaf blight
• EPIVEN-Apple scab

12
Plant Clinic
13
Purpose

• Examination of soil health
• Identification of disease /pest problems
• Recommendations (Remedial measures)

14
Experts

• Soil health (Soil analyst, Soil microbiologist)
• Disease problems (Plant Pathologist)
• Insect-pest problems (Entomologist)
• Weed menace (Weed Scientist)

15
Facilities

• Soil testing laboratory
• Disease diagnosis laboratory
• Entomological laboratory
• Weed herbarium

16
Functions

• Advisory services including forecasts on disease
  and pest outbreaks through media (Print, Radio,
  TV)
• Availability of inputs (Fungicides,Pesticides,
  Weedicides etc.)
• Services(Equipments like sprayers,dusters etc. on
  hire, undertaking spraying operations etc.)

17
Thank you!