Key banana pests and diseases and their mitigation in Africa

Eldad Karamura et al

Presentation outline

• Banana systems characteristics in Africa

• Key banana pests and disease in Africa

• Risks associated with key pests and diseases

• Mitigation strategies

Banana systems characteristics in Africa

Region Year

2009 2010

Africa 40,158,682 tonnes 39,653,941 tonnes

Eastern Africa 22,073,329 tonnes 21,533,708 tonnes

Middle Africa 6,288,916 tonnes 6,361,672 tonnes

Northern Africa 1,984,793 tonnes 1,993,270 tonnes

Southern Africa 376,505 tonnes 399,021 tonnes

Western Africa 9,435,139 tonnes 9,366,270 tonnes

Banana Production in Africa: Systems characteristics

FAO production data, 2012

AAA-EAHB

PLANTAINS

Cavendish

Cavendish

31%

49%

17%

3%

Plantains AAB

East African highland bananas + ABB,AAB,AA

Cavendish AAA

Gros Michel & other AA,AAA,AAB,ABB

Main banana production systems in Africa

Lescot, 2010

Systems characteristics cont’d

Systems Characteristics cont’dBanana in diets in Africa

D R C on go

U ganda

K en ya

Tanzania

R w an da

B urun di

Ba n a n a d ie t s h are (% )N o d ata0 - 55 - 1 010 - 2020 - 3030 - 5050 - 10 0

7

0

50

100

150

200

250

kg /

capi

ta /

yr

Sour

ce: F

AO

STA

T

Systems Characteristics cont’d:

Consumption in eastern and southern Africa

Cameroon South Nigeria

Children 182 8

Mothers 362 212

Ref: Honfo FG, et al, 1996

Systems Characteristics cont’d:

Annual per capita plantain consumption in Nigeria and Cameroon (Kg)

0 100 200 300 400 500 600

Sugar

Poultry

Beans_Peas

Wheat_Barley

Rice

Potatoes_Sweetpotatoes

Coffee_Tea

Bananas

Maize

Beef

Vegetable_Fruits

Sorghum_Millet

Cassava

Oilseeds

Milk

Regional Regional GDP Gains to 2015 from Growth in Selected GDP Gains to 2015 from Growth in Selected Commodity SubCommodity Sub--Sectors (US$ million)Sectors (US$ million)

Systems’ characteristics cont’d

• Especially in eastern and west Africa, the banana systems are • slow-changing and rural-based economies

• under stress due to population pressure/decreasing farm size; decreasing land fallow periods and production progressively unable to meet household needs.

• facing additional stresses, including climate change, characterized by increasing temperatures and greater rainfall variability; and

• changing social structures due to HIV-AIDS, rural-to-urban migration and declining returns from agriculture.

Systems’ characteristics

• Smallholder banana production as a system in Africa is built to a large extent on an informal seed system with minimum attention to quality.– Informal seed systems account for 95-98% of the seed

exchanges– lacks a well organized seed system to subtend sustained

production– Planting material is the principle mechanism for disease

transmission between farms and landscapes• Banana stands in smallholder systems are perennial for

certain production systems, spanning over 5>150 years– Steady build up of pests and diseases, leading to

productivity declines

Systems Characteristics cont’d: Farm sizes

05

101520253035404550

>0-2 >2-4 >4-6 >6-8 >8-10 >10-15 >15-20 >20-40

Perc

enta

ge

AcresUganda Tanzania Kenya

Low input – Low output systems

Systems Characteristics

Small; low input subsistence/semi-commercial systems

Key banana pests and disease in Africa

BXW symptoms Foc Wilt Nematodes

BBTV

Black leaf streak

Weevil infestation

Banana Steak Virus?

Biotic stresses range from viruses, fungi, bacteria and nematodes to insects

Key pests and diseases cont’d

• In general highlands and sub-tropical regions have very less pest and disease pressure resulting into better productivity than in the equatorial humid lowlands;

• The equatorial belt has the highest pest and disease intensity which progressively reduces towards the subtropical regions;

• There is a need to systematically rank banana pests and diseases in Africa in order to guide research investment.

Suggested Ranking Criteria for pests and diseases in Africa

1. Number of countries affected. (Reference Gowen, 1995; Jones 2000; Blomme, et al, 2012)

2. Number of banana genotypes (Stover, 2000; Jones 2000; Blomme, 2012)

3. Yield loss attributed to each pest or disease ( Jones, 2000; Gold et al, 2001, )

4. Ease of control (Robinson, 1996; Gowen, 1995; Jones 2000)

5. Ease of eradication or probability of permanent control6. Estimated costs of control (High, medium, low?)7. Short-term impact on communities (high, medium, low?)8. Long-term impact on communities (high, medium, low?)

Staver (2000) Viljoen (2010) Blomme et al 2012

Black leaf spots (M.fijiensis & Cladosporium)

Xanthomonas Banana Weevil

Nematode Fusarium wilt Nematodes

Weevil Black leaf streak BBTD

Fusarium Nematodes BSV

Viruses Banana Weevil Mycosphaerellaleaf spots

Viruses Viruses Xanthomonas wilt

Fusarium

Key banana pests and diseases have not changed over the last decade

Risks associated with key pests and diseases

20

• Some diseases are spread by vectors over short and long distances accidentally and/or intentionally (BXW BBTD, BSV, etc)

• Most are moved in planting material in the informal seed systems (BBTV, BSV, BBrMV, CMV, BMMV, weevils, nematodes,Foc, BXW); ubiquitous plantings of bananas provide reservoirs of pests/diseases making it difficult to control

• Weak and/or non-existent quarantine services linked to lack of surveillance and limited information exchange within and between countries and regions.

• Limited capacity for efficient/effective pest and disease detection in support of quarantine

Risk 1. Potential for rapid dispersal by natural means

Region

Year

2009 2010

Africa 14.164 tonnes/ha 14.53 tonnes/ha

Eastern Africa 12.010 tonnes/ha 12.21 tonnes/ha

Middle Africa 16.290 tonnes/ha 16.30 tonnes/ha

Northern Africa 38.322 tonnes/ha 37.53 tonnes/ha

Southern Africa 44.557 tonnes/ha 44.81 tonnes/ha

Western Africa 17.183 tonnes/ha 19.33 tonnes/ha

A major yield gap exists especially in tropical Africa

FAO production data, 2012

Risk 2. Extensive yield losses threatening food security

1. Yield is a product of complex interactions between, the genotype, soil fertility, pests and diseases;

2. Methods are very variable, making comparisons difficult.

3. For some regions/countries, studies on yields attributed to pests and diseases are very limited

4. Nevertheless, pests and diseases probably contribute a significant proportion of the yield gap;

Risk 2. Extensive yield losses cont’d

Risk 3. Environment damage

• Use of chemical control is still limited in smallholder systems but may increase with changing farming objectives;

• Wide spread adoption of resistant varieties recommended to manage pests and diseases; but this may lead to monoculture and loss of diversity;

• Extensive rouging may lead to loss of associated biodiversity.

BXW management effects on environment

Parameter Macrofauna Mean number/trap/sample

Abundance Control (0 % rouged)

100%Rouged

Hymenoptera (ants) 20.2 14.6

Isoptera 11.8 6.2

Coleoptera 2.5 1.8

Orthoptera 1.4 1.1

Araneida 3.7 3.4

Others 5.4 3.2

Diversity Number of orders 24 15

100 % rouged

Control (0% rouged)

Mitigation

STRATEGY PRODUCTION SYSTEMS IN AFRICA REMARKS REFERENCE

1. Host plant resistance by convectional

EAHB & plantainIITA in Nigeria for plantains NARO/IITAin Uganda for EAHB; several varieties released in both regions

Tushemereirwe et al 2009

2. Host plant resistance by biotechnology

EAHB & plantain

IITA(NARO) has successfully transferred the sweet pepper gene against BXW; plants in CFT. More work in progress with cystatin genes against weevil borer in EAHB

Tripathi, 2011

3. Clean planting material linked to formal seed systems

EAHB, Plantain, cavendish

South Africa, Ivory cost, Ghana, Kenya driven y profit by tc companies; more informal systems linked to macro propagation in East and Central Africa. Quality control remains a challenge.

Viljoen, 2010

4. Cultural controls EAHB & Plantain in small holder systems

Systems dependent; affordable though labour intensive e g BXW Mgt in central Africa

Ssekiwoko 2010

5. Biological control All systems targeting weevils and FoC

No significant field application but may be applied as part overall IPM

6. IPDM All systems

Accepted by most as the way forward but information and technology gaps linked to weak policies constrainapplication.

Stover 2000; Viljoen 201; Blomme 2012.

MITIGATION STRATEGIES RECOMMENDED

What can and can not be done is influenced by a host of interactive factors:

• Limited collaboration within and between countries and regions, resulting in disfunctional management strategies and unchecked movement of pests and diseases across boundaries.

• The agro-ecologies, farming systems (cultivar sets in various food systems) and farming objectives, all influence management options and decisions

• Particularly in Africa smallholder systems dominate banana production and the socioeconomic setting; resources, labour, knowledge and information, infra-structure and local policy environment will interactively determine what can/can not be done.

• The agro-ecology in question and how the biophysical systems respond and/or impact on the crop and associated biodiversity

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