Presentation to the Philippines DA

1. Julian'Ramirez-Villegas,'Patricia'Moreno'
and'Kris'Wyckhuys
Modelling)the)future)of)
cassava)cultivation)in)Asia

2. 50'%
30'%20'%
Latin'America Africa Asia

3. 10'
t/ha
19
t/ha12'
t/ha
Latin'America Africa Asia

4. CIAT)crop)and)pest)modelling)
activities
1. Suitability+modelling+(20086present)+using+niche6based+
models+(EcoCrop).
2. Process6based+modelling+(20126present):+develop+and+
maintain+cassava+model+in+DSSAT.
3. Suitability+modelling+of+pests:+greenmite,+mealybug,+
whitefly+(201162015)
4. Towards+mechanistic+simulation+of+crop6pest6
management+interactions

5. The EcoCrop)model
It+evaluates+on+monthly+basis+if+there+
are+adequate+climatic+conditions+
within+a+growing+season+for+
temperature+and+precipitation…
…and+calculates+the+climatic+suitability+of+the+
resulting+interaction+between+rainfall+and+
temperature…
Ramirez6Villegas+et+al.+(2013)+Agr.+For.+Met.

6. Current)suitability
Growing(season((days) 240 Killing&temperature&(°C) 0
Minimum&absolute&
temperature&(°C)
15.0
Minimum&optimum&
temperature&(°C)
22.0
Maximum&optimum&
temperature&(°C)
32.0
Maximum&absolute&
temperature&(°C)
45.0
Minimum&absolute&
rainfall&(mm)
300
Minimum&optimum&
rainfall&(mm)
800
Maximum&optimum&
rainfall&(mm)
2200
Maximum&absolute&
rainfall&(mm)
2800
Ceballos+et+al.+(2011)

7. Future)suitability)and)change)(2020s)
Ceballos+et+al.+(2011)

8. Why)a)processBbased)approach?
! Cassava+does+not+have+a+robust model+(Legg+et+al.,+2014)
! Short'list'of+models+describing+the+basic+processes+of+growth+
and+development+(Cock+et+al.+1979;+Manrique 1992;+Matthews+&+Hunt+1994;+Gray+2000,2003;+Mithra+et+
al.2013;+Gabriel+et+al.+2014;+Gutierrez+et+al.+1988).
! Models+answer+what%if?%%questions+! Ex6ante+evaluation+of+
technologies+and/or+environmental+conditions+expensive+or+
impossible+to+evaluate+(Cock+&+Moreno,+2013).+

9. A'robust'
cassava'model
Moreno+et+al.+(unpublished)

10. A)processBbased)cassava)simulation)model
! From+phenological+phases+
to+an+indeterminate+crop
! Node+cohorts+(leaf+and+
stem+growth,+leaf+life)
! Different+Tbase for+leaf+
development+and+
branching
! Spillover+model
Leaf'appearance Branching
Leaf'size
Moreno+et+al.+(unpublished)

11. Moreno+et+al.+(unpublished)
(DSSAT+v4.5)

12. 0
2000
4000
6000
8000
10000
12000
14000
0 50 100 150 200 250 300 350
Harvest(product(wt((kg([dm]/ha
Days(after(start(of(simulation((#)(Chart21
C1*E1+MCol622;Control measured+C1*E1+MCol622;Control
C1*E2+MCol622;Reduced+rai measured+C1*E2+MCol622;Reduced+rai

13. •CIAT’s+1980s+and+1990s+physiology+trial+data,+for+
365+LAC+cultivars.
•2+new+field+trials+in+Vietnam+(northern,+
southern)+with+12+fertilizer+(N,+P,+K)+treatments,+2+
cultivars,+2+years.+
•IITA6led+cassava+agronomy+project+in+Nigeria+and+
Tanzania+with+100++trials.
Experiments)to)develop,)calibrate)
and)validate)the)model

14. Regional)importance)of)pests)and)
diseases
*+Dry+season+data+only+ Data:+K.+Wyckhuys

15. Adapted+from+Guisan,+Broennimann,+ Di+Cola+and+FBM+team+(https://goo.gl/5KS4E8)
Ecological)niche)modelling)of)pests)and)
diseases
CLIMEX,)MaxEnt,)Support)Vector)Machines,
Climate)Spate)Model,)GARP,)Env.)Distance,)etc.

16. P.%manihoti
Potential)distribution)of)cassava)mealybug
Parsa et+al.+(2012)+PLoS+ONE

17. M.%tanajoa
M.%mcgregori
Potential)distribution)of)cassava)greenmite
Parsa et+al.+(2015)+Exp.+Appl.+Acarol.;+Herrera+Campo+et+al.+(2011)+Food+Sec.

18. Towards)a)mechanistic)simulation)of)
cropBpestBmanagement)interactions
Gutierrez+et+al.+(1988)

19. Towards)a)mechanistic)simulation)of)
cropBpestBmanagement)interactions
Gutierrez+et+al.+(1988)

20. Nothing)new…)simulating)pest)dynamics)in)
1982B1984)experiments)in)Nigeria
Mealybug with'
biological'control
Gutierrez+et+al.+(1988)
Gutierrez+et+al.+(1988)
Uncontrolled
mealybug
Root+
weight
Mealybug
number
Coccinellid
A.#lopezi
Uncontrolled
greenmite
Leaf+
weight
Root+
weight
Greenmite
number

21. • Group+spatio6temporal+variations+in+pest+dynamics+and+
yield+impacts+to+prioritise interventions+and+breeding+
efforts+(cf.+Target+Population+of+Environments)
• Develop+management+recommendations+(e.g.+best+
planting+periods,+N+application)+to+reduce+pest+damage…+
and+estimate+tradeoffs.
• Early+warning+systems+–for+timely+release+of+parasitoids+
(e.g.+A.#lopezi),+or+other+type+of+control.
• Understand+crop+&+associated+pest+expansion+patterns
What)can)we)do)with)this)type)of)
approach?