PESTS AND DISEASES

MANAGEMENT IN

KADAHENDA, RWANDA

Kadahenda, 29 April 2016

Dieudonné Harahagazwe

1Integrated potato crop management course

Outline

�Disease triangle

�Potato fungal diseases

�Major bacterial diseases

�Major potato pests

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I. DISEASE TRIANGLE

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Disease Triangle = Basis of Control Strategies

Pathogen

Host

Environment

DISEASE

Example of Potato Late Blight

Phytophthora infestans

Susceptible variety

Weather conditions

DISEASETemp. < 22°C

RH: 90-95%

II. POTATO FUNGAL

DISEASES

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1. LATE BLIGHT

(Miridiyu)

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Symptoms on leaves

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Common Control practices

• Resistant/tolerant varieties

• Chemicals:

– Dithane (Mancozeb): at plant germination

(around 30DAP) and then after Ridomil at 2-

week interval

– Ridomil: 2 weeks after the first Dithane.

The second spray would occur upon onset

of LB symptoms.

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2. ALTERNARIA

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Symptoms

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The disease can be very severe especially in

subtropical lowlands

Chimoio, Mozambique

• Fortunately it

appears late in the

crop cycle

• Therefore yield

incidence is little in

tropical highlands

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3. FUSARIUM

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Symptoms mainly on tubers in storage

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Symptoms on leaves as well but not

common in tropical highlands

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III. POTATO BACTERIAL

DISEASES

MAJOR BACTERIAL DISEASES

�Bacterial Wilt (BW)

�Blackleg/Soft Rot

(KIRABIRANYA)

1. BACTERIAL WILT

Typical symptoms

Host plants

Chili pepper (Urusenda) Sweet pepper (Puwavuro)

Eggplant (Intoryi) Tomato (Inyanya)

Water test: Unique for BW

Rotanda, Mozambique

Rotanda, Mozambique

2. BLACKLEG/SOFT ROT

Symptoms on tubers

Chimoio, Mozambique

3. Integrated Control for bacterial

diseases

• Use of seed

• Plant in a healthy field

• Crop rotation with non-host plants

• Removal of diseased plants

• Removal of plant volunteers

• Application of other sanitation and cultivation

practices

Wilting

plant

Removal of wilting plants

and its neighbors for clean

seed production.

Affected soil

and plant out

of the field

(Farmer of

Kayanza,

Burundi)

Rotanda, Mozambique

Angonia, Mozambique

I am so sorry ladies!

There is no chemical

control for Bacterial

Wilt!

4. Latent Infection

• No apparent symptoms

• Tubers carry diseases from one land to

the other

• Tolerant varieties are more prone to

latency than the sensitive ones

• Need to test seed tubers prior to planting

IV. MAJOR POTATO PESTS

1. Agrotis (INANDA)

• Cutworms normally appear in

the field at young age of the

potato crop (20 – 40 DAP).

• Smallholder farmers are

encouraged to visit their fields

on a daily basis in a bid to

detect, collect and kill any

cutworms that show up.

2. Aphids

The pest

3. Leafminer

The pest, abundant in Kadahenda

Severity in the field

Sussundenga, Mozambique

Even wild plants are affected

Symptoms (continued)

4. PTM(Potato Tuber Moth)

The pest

Lichinga, Mozambique Symptoms on tubers

When the tuber is cut….

4. Insecticides for aphids and

leafminer control

As recommended by the National Potato Sub-

Program, RAB-Rwanda:

• Imidachloprid 200 SL: systemic insecticide for aphid control

• CYPRO 44 EC (Profenofos 40% + Cypermethrine 4% EC)

• Jackpot 50 EC (Lambda-Cyhalothrin 50g/l): broad spectrum

insecticide for the control of biting and sucking insect pests

• Romectin 18 EC (Abamectin 18% ): Insecticide/miticide for the

control of spider mites and leafminers

Acknowledgements

We would like to acknowledge Humidtropics and the CGIAR Fund Donors

for their provision of core and project-specific funding without which this

research could not deliver results that eventually positively impact the lives

of millions of smallholder farmers in tropical Americas, Asia and Africa.

This presentation was made at a training workshop on Integrated Potato Crop

Management organized by the International Potato Center (CIP) for Innovation

Platform (IP) members of Kadahenda, Rwanda.

MURAKOZE

Contact: dharahagazwe@yahoo.fr