Forecasting Chilling Accumulation, Rest Completion,

and Crop Development in the Southeastern U.S.

John G. BellowAgrometeorologist – Extension

Specialist

Center for Ocean-Atmospheric Prediction StudiesThe Florida State University

Tallahassee, FL

Meetings withstakeholders and advisorsindicated a need for additional climate variablesemphasizingdevelopment andphenology

Methods NWS Coop Data Data cleaning Calculation of hourly temp Calculation of daily, monthly,

and seasonal thermal units ANOVA and Tukey in 293

counties

• Hourly temperature estimation from: Lat., Long., Max T, Min T•Non-linear fit using FAWN hourly data for 9 sites (3 coastal 6 inland)•Tested on independent FAWN sites: R2 =0.92 (n = 6)

Hourly temperature estimation from daily Tmax and Tmin

A.M. Time of Day P.M.0 3 6 9 12 3 6 9 12

Tem

per

atu

re °

F

60

65

70

75

80

85

Observed TemperaturePredicted Temperature

ROJAS AND MARTINEZ, 1990

0 3 6 9 12 15 18 21 24 27 30

2

1

1

Temperature

CU

Coeff

icie

nt

1

2

f 9 t( )

300 t

Chill units accumulated a 1 CU per hour at optimal temperatureand 0.0 CU per hour at Tmax and Tmin

The loss of chill units with diurnal warming was not included in the present analysis

ANDERSON AND SEELEY , 1992

Derived forecast productsChilling accumulation

Blueberries Chill hours Chill Units

T < 7.2 °C Tmax:15.0 °C; Topt:7.2 °C; Tmin: -2.5 °CSHINE AND BUCHANAN 1982

Strawberries Tmax:20.0 °C; Topt:7.2 °C; Tmin: 0 °CBIGEY 2002

Peaches T < 7.2 °C Tmax:14.0 °C; Topt:6.0 °C; Tmin: -2.0 °C

Growing degree days

GDD Hourly GDD Daily Mean EREZ ET AL 1990

Wheat THour > 0 °C Tmean > 0 °C (T-Tbase)

Rest Completion

Subtropicals Rest hours

Avocado -1.1 < T < 15.0 °C

Mango 4.4 < T < 15.0 °C

Lychee 10 < T < 15.0 °C

CRANE AND SHAFFER 2004

Blueberries Range of chill required 150 – 800 hrs Anthesis Feb-Mar; Harvest Apr-Jun Integration from Oct through Feb. Role of cool temperatures on floral bud

initiation and maturation.

El Niño CU Oct-Apr method 3

bb_ensomeans_oct_apr.no3

421 - 500

501 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

2501 - 3000

El Niño CU Oct-Apr method 5

bb_ensomeans_oct_apr.no5

60 - 500

501 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

2501 - 3000

Chill units estimation Chill hours estimation

CU provide a higher estimation of chilling than chill hours.

La Niña CU Oct-Apr method 5

bb_ensomeans_oct_apr.na5

52 - 500

501 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

2501 - 3000

La Niña CU Oct-Apr method 3

bb_ensomeans_oct_apr.na3

292 - 500

501 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

Chill units estimation Chill hours estimation

El Niño Chill Units Anomolies

nino_3

-109.6780 - -100.0000

-99.9999 - 0.0000

0.0001 - 100.0000

100.0001 - 200.0000

200.0001 - 300.0000

300.0001 - 400.0000

El Niño Chilling hour anom.

nino_5

-114.4531 - -100.0000

-99.9999 - 0.0000

0.0001 - 100.0000

100.0001 - 200.0000

200.0001 - 300.0000

300.0001 - 400.0000

Chill units anomalies Chill hours anomalies

El Niño signal is an increase in chill

La Niña Chill Units Anomolies

nina_3

-193.2572 - -100.0000

-99.9999 - 0.0000

0.0001 - 100.0000

100.0001 - 200.0000

200.0001 - 300.0000

La Niña Chilling hour anom.

nina_5

-331.7363 - -300.0000

-299.9999 - -200.0000

-199.9999 - -100.0000

-99.9999 - 0.0000

0.0001 - 100.0000

100.0001 - 200.0000

200.0001 - 300.0000

Chill units anomalies Chill hours anomalies

La Niña brings reduced chilling

Strawberry

•Chill requirements from 700 to 1300 hours•Responses to inadequate chilling include artificial chilling and photoperiod treatments

El Niño chill

nino

606 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

La Niña Chill

nina

540 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

Movement of chill isotherms south in C Fl during El Niño.

La Niña Anomolies

ninaanom

-306 - -300

-299 - -200

-199 - -100

-99 - 0

1 - 100

101 - 200

El Niño Anomolies

ninoanom

-78 - 0

1 - 100

101 - 200

201 - 300

Signals weak or non-existent in N GA & AL.

Increase in chill with El Niño and decrease in chill with La Niña.

Peach Alabama peach growers are facing a serious crisis as a result of the 1998-99 winter weather

pattern that has resulted in what may prove to be a record shortage of chilling.  Georgia, South Carolina and Alabama have made application for state labels (24C) for application of Dormex on peaches, nectarines and blueberries to help overcome the shortage of chilling hours being experienced this winter.  It is hoped the Alabama label will be issued by January 21, 1999.  Georgia and South Carolina have already issued their state labels.

Chill requirements 150 – 1050 hours Anthesis Jan – Feb; Harvest May -July

El Niño Means

snhr_no

191 - 500

501 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

El Niño Means

_45mn_no

7 - 500

501 - 1000

1001 - 1500

1501 - 2000

2001 - 2500

2501 - 3000

CU methods estimates greater chill accumulation compared with Chill hours using daily mean values.

El Niño Anomolies

noan_snhr

-42 - 0

1 - 100

101 - 200

201 - 300

301 - 400

El Niño Anomolies

noan_45mn

-46 - 0

1 - 100

101 - 200

201 - 300

Clear increase in chill for peaches with El Niño

La Niña Anomolies

naan_snhr

-226 - -200

-199 - -100

-99 - 0

1 - 100

101 - 200

201 - 300

La Niña Anomolies

naan_45mn

-409 - -400

-399 - -300

-299 - -200

-199 - -100

-99 - 0

1 - 100

Wheat

Winter forage grass October establishment – Jan – Mar use. Biomass development and timing are

principal concerns.

El Niño anomolies Mean

noan_1

-370 - -250

-249 - 0

1 - 200

La Niña anomolies Mean

naan_1

-78 - 0

1 - 250

251 - 500

501 - 750

GDD anomalies for wheat consistent with known ENSO signals, El Niño cooler and La Niña warmer.

Anomalies broadly significant across tri-state region.

Wheat La Niña GDD Hourly

na_2

3004 - 4000

4001 - 5000

5001 - 6000

6001 - 7000

7001 - 8000

8001 - 9000

Wheat La Niña GDD Daily Mean

na_1

3205 - 4000

4001 - 5000

5001 - 6000

6001 - 7000

7001 - 8000

8001 - 9000

Little impact of hourly vs. daily estimation, both appear satisfactory.

Subtropicals

180 to 400 hours of rest

Rest hours for subtropicals reduced during La Niña and increased during El Niño.

Enso anomalies small within S FL Differences not significant in region

Avocado La Niña anomolies_N_M

naan_avoc

100.1 - 200.0

0.1 - 100.0

-99.9 - 0.0

-199.9 - -100.0

-299.9 - -200.0

-314.5 - -300.0

Avocado El Niño anomolies_N_M

noan_avoc

3 - 100

101 - 200

201 - 300

301 - 400

Mango El Niño anomolies_N_M

noan_mang

22.9 - 100.0

100.1 - 200.0

200.1 - 300.0

Mango La Niña anomolies_N_M

naan_mang

-278.1 - -200.0

-199.9 - -100.0

-99.9 - 0.0

0.1 - 100.0

Lychee El Niño anomolies_N_M

noan_lych

-54 - -50

-49 - 0

1 - 50

51 - 100

101 - 150

151 - 200

Lychee La Niña anomolies_N_M

naan_lych

-148 - -100

-99 - -50

-49 - 0

1 - 50

Conclusions

Prediction of thermal units for development and phenology based on ENSO climatology seems robust for deciduous fruits and wheat, however results were somewhat weaker for subtropical rest completion.

Signal is consistent with previous knowledge

All forecasts will be enhanced by the integration of ‘season to date’ data.

Weakness from the integration dates range

Further directions

Reanalysis for ‘days to completion’ for threshold accumulations for specific cultivars or varietals?

Phenology models for budbreak and anthesis incorporating CU to dormancy and HU to budbreak?

Deployment as probabilistic forecast through agclimate