SPRING FROST RISK IN ORCHARDS - FORECAST AND PROTECTION METHODS CNR-Institute of Biometeorology Bologna Meteorological Service Regione Emilia Romagna Federica.

SPRING FROST RISK IN SPRING FROST RISK IN ORCHARDS - FORECAST ORCHARDS - FORECAST AND PROTECTION AND PROTECTION METHODSMETHODS

CNR-Institute of Biometeorology Bologna

Meteorological Service Regione Emilia Romagna

Federica Rossi, Franco Zinoni

Scarring, distortion, russet

Spring frosts: when temperature falls below the melting point (0°c) sensitive crops can be injured

Style, ovary, petals necrosis Dehydration, brown tissues

Whether or not there is frost damage at a particular minimum temperature

plant species, crop variety, hardening, cultural practices (pruning, fertilization, irrigation), presence of INA bacteria, weather conditions.

Most countries with temperate climates experience frost damage to crops and even tropical countries can have frost damage at high elevations.

Coffee region

Farmers have been always Farmers have been always cohabiting with such a cohabiting with such a meteorological hazardmeteorological hazard

More sensibile cvs

Cultural practices

Climate change: higher winter temperatures early blooming. Increase of low-temperature episodes in spring

Now….

Needs to protect local and traditional crops (sustainable- GAP)

Average economic losses due to the occurrence of late frosts - Emilia Romagna

300 M Euros

38% Gross Production Value

65 M Euros

50 % Gross Production Value

Define meteo & micrometeorological conditions during frost events

Develop knowledge and instruments able to evaluate the risk

Define the more appropriate methods for protection in relation to the climatic hazard and sustainable resources management

Communicate to farmers how to avoid or mitigate the detrimental effects (active-passive protection)

How to improve frost protection ?

Passive protection (low-cost – high-benefits)

Awareness of the meteorological risk

Selection of low-risk sites

Avoid low-spots, select slope orientation

Planting species and cvs blooming later in the spring

Maintain soil water content to obtain high thermal diffusitivity

Minimizing or removing cover crops

Proper pruning, nutritional management

Active protection (high costs)

Awareness of the meteorological risk

Selection of the appropriate protection method:

•Crop

•Location

•Climate

•Costs

Effectiveness

Efficiency

Risk

High effectiveness (all kind of freezing)

Low efficiency

Active protection

High consumption rates (50 % of efficiency)

Expensive to operate (2000 €/ha/night)

Total efficiency is proportional to the number of heaters and depending on the air temperature

Heaters

Active protectionBreak up of b.l. – mixing of warm air aloft with surface colder air

Effectiveness: radiative frosts

Efficiency:

low labour requirement, low operational costs (10 €/ha/h) but high capital cost and high ‘standby’ charges. Possible in every location. Environmental friend, but noise pollution

Wind machines

Active protection

Water freezing: when 1 Kg of water freezes at 0°C, the phase change converts 334 kJ of latent to sensible heat

Efficiency:

Low operational costs. High installation costs but sprinklers can be used for irrigation, fertilizer applications, evaporative cooling…Disadvantages: large amounts of water needed

Over-plant sprinklers

Under-plant sprinklers

Uniform application, continuous and adequate water amounts. Problems under windy conditions. Errors in operating (late starting, early stopping, accidental interruptions) can induce major damages

Over-plant sprinklers

Under-plant sprinklers

The goal is to maintain the wetted cover crop temperature near 0°C

Efficiency:

Intermittency low amounts of water (higher sustainability, lower costs).

The same sprinklers can be used for irrigation.

Useful to protect large surfaces

Effectiveness: Radiation frosts

Meteorological Base S.Pietro Capofiume 44°65’N – 11° 62’E 11 m a.s.l.

Test- site for microclimatic characterization to identify the atmospheric features correlated to frost events

26 January 2000 23:00 GMT

0

100

200

300

400

500

600

700

800

900

-5 -4 -3 -2 -1 0 1 2

Temperature (°C)

Hei

gh

t (m

)

22.5 cm

50 cm

100 cm

200 cm

400 cm

Radiation frosts: calm wind - clear sky: heat is lost in form of radiant energy. Temperature falls faster near the surface causing a temperature inversion

ATMOSPHERE STATUS - CLOUD COVER ARE THE MAIN FACTORS CONDITIONING SPRING FROSTS

To optimize orchard protection, it is important to understand the interaction between radiation and turbulent processes in complex canopies.

Evaluation of the effectiveness in orchards:

Micrometeorological observations - energy and radiation balances

Air and plant tissue temperatures

+ 3°C

Irrigated Non irrigated

Temperature °C

He

igh

t (c

m)

-4

-3

-2

-1

0

1

2

3

4

5

22:3023:3000:3001:3002:3003:3004:3005:3006:30

Ora solare

T (°

C)

T air at ground

T air 2 m

h= 2m

h= 1m

Under-canopy irrigation: the temperature of the lower part of the canopy becomes higher because of the release of latent heat.

-4

-3

-2

-1

0

1

2

3

4

5

22:3023:3000:3001:3002:3003:3004:3005:3006:30

Ora solare

T (

°C)

T air at ground

T air 2 m

h= 2m

h= 1m

Bud t (under-canopy irrigation

Bud t (over-canopy irrigation)

WHY FARMERS NEED PREVISIONS ?

Sensibilità al gelo - danno del 10 %

-16

-14

-12

-10

-8

-6

-4

-2

0

germogliamento fioritura allegagione frutticini

fase di sviluppo

T (

°C)

Actinidia

Albicocco

Pesco

Pero

10% damage

kiwi

apricotpeachi

peari

apricot

Awareness of the risk

Active protection

What a probability for a frost occuring tonight? Can the thermal levels predicted compromize my crops at this stage ? Shall I activate my protection devices? What will be the ratio cost sustained/cost of the possible damage?

Frost forecasting target

7 – 2 days forecast EPS

2 – 1 day EPS-Kf

< 12 hrs Nowcasting

Reclamation consortiums to make

water available

Farmers to dispose protection devices

Alert to activate and optimize protection

Rischio gelo nelle prossime nottiRiceviamo dall'ARPA-SMR e diffondiamo il seguente bollettinoARPA - Servizio MeteorologicoVenerdì 4 aprile 2003Speciale Bollettino Agrometeorologico per Rischio Gelate. A seguito della perturbazione che ha interessato la regione a partire da Mercoledì 2 Aprile e prodotto piogge  diffuse ed un notevole calo delle temperature massime, è previsto  l’arrivo di aria fredda e secca da nord-est che apporterà condizioni di cielo sereno o poco nuvoloso . Queste condizioni sono favorevoli a forti abbassamenti termici dovuti sia all’arrivo di aria fredda (avvezione) che alla perdita di calore dal terreno durante la notte (irraggiamento).Nei prossimi giorni sono quindi previste intense gelate. La temperatura dovrebbe scendere al di sotto dello zero nella notte tra Domenica 6 e Lunedì 7, ma i valori potrebbero essere ancora più bassi nella notte successiva, tra Lunedì 7 e Martedì 8

Awareness of the risk

Passive protection

Selection of low-risk sites !!!!

WHY FARMERS NEED PREVISIONS ?

Crop selection

A regional topoclimatic model including phenological and growth models is under

development to be used operationally

•Definition of the risk maps for the

different crops •Weekly agrometeorological bullettins•Climatic regional data-base for land

capability

seaznrelmin IbHaT

valley top

valley bottom

computation pointH c

H f

D c

D f

Topoclimatic analysis to create frost risk maps as a tool for agricultural land planning and site selections

Climatologic component Geographical component

Spatial interpolations of previsional data from meteo

models

Frost index values for the different species

Generation of DEM:

Plan & hill domains

Correlation analysis between orography and climatic variables

Minimum temperature prediction maps

Correlation between frost indexes and minimum temperatures

Biological component

Needs:

•to improve accuracy and resolution of DEM

•take into account other meteo variables affecting frost

•more and proper distributed meteo stations

•remote sensing imagery to retrieve night surface temperature maps

Thank you