This document presents the background and methodology for a study investigating the susceptibility of different Irish potato varieties to bacterial wilt caused by Ralstonia solanacearum. The study aims to identify high-yielding varieties that are less susceptible to bacterial wilt. The experiment will use a randomized complete block design with four potato varieties (Kenya karibu, Shangi, Dutch robijn, Tigoni) and five replications. Data on days to wilting onset, tuber numbers, weights, and proportion of symptomatic tubers will be collected and analyzed. The results are expected to help breeding programs identify resistant varieties and advise small-scale farmers on high-yielding, less susceptible varieties.

1. BY
MANJALE M. J
SUSCEPTIBILITY OF DIFFERENT IRISH POTATO
VARIETIES TO BACTERIAL WILT (Ralstonia
solanacearum)

2. Potato plant affected by bacterial
wilt
Potato tuber affected by bacterial
wilt
Cross sectional tuber affected by
bacterial wilt
Healthy Potato plant.
Healthy Potato plant.
Healthy potato tuber Cross sectional healthy tuber

3. BACKGROUND INFORMATION
• Potato, Solanum tuberosum, is ranked as the world's fourth
important food crop after maize, wheat, and rice.
• Kenya is ranked as the fifth-largest potato producer in sub-Saharan
Africa with an output of 790000 metric tons from about 108, 000 ha
of land.
• There is a gap of 10% to 75% between the actual and potential yield
of potatoes due to various biotic and social-ecological problems both
worldwide and in Kenya.
• Low soil fertility, poor seed quality, and bacterial wilt have been
identified as the leading yield gap drivers
2

4. • to improve and expand the countries potato production,
there is a need to identify solutions to biotic and social-
ecological problems such as bacterial wilt.
• Bacterial wilt caused by a soil-borne bacterium Ralstonia
solanacearum is the second most damaging Irish potato
disease and thrives well under conditions of low PH,
malnourished soils, and low moisture.
• It inhabits roots and enters the root system at points of
injury caused by farm tools, pests, and breakages,

5. • The disease exhibits some symptoms like wilting,
stunting growth, dieback, yellowing of the leaves. These
symptoms mimic water shortage symptoms which
makes the disease spread without the consent of
farmers.
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6. STATEMENT OF THE PROBLEM
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• Bacterial wilt affects more than 77% of potato farmers in the
country.
• Research has been done and proven that bacterial wilt is a major
threat to potato production.
• Different management practice strategies have been adopted to
curb the disease they include cultural practices, quarantine,
chemical control, and crop rotation.
• Chemicals manufactured to control bacterial wilt are found to be
expensive and non-selective to the pathogen thereby killing
important and beneficial organisms in the potato plant.

7. • Breeding of different varieties has been done but only
aims in the improvement of different traits such as yield
and maturity duration.
• These traits make farmers adopt them and eventually
make losses due to bacterial wilt.
• This study will address these problems by identifying less
susceptible varieties to bacterial wilt which will later be
used by plant breeders while choosing the best parents
during breeding for resistance to bacterial wilt.’

8. OBJECTIVES
MAIN OBJECTIVE
• To contribute to the identification of high yielding potato
varieties that are less susceptible to bacterial wilt.
SPECIFIC OBJECTIVES
• To identify a high-yielding potato variety.
• To establish a potato variety that is more resistant to
bacterial wilt.

9. HYPOTHESES.
• Bacterial wilt has no significant effect on the yield of Irish
potato.
• There is no significant difference in the susceptibility of
different potato varieties to bacterial wilt

10. JUSTIFICATION OF THE STUDY
• For improved potato production in Kenya, strategic plans to
control pest and diseases should be improvised.
• This will help the country to realize its full potential in potato
production.
• Bacterial wilt control through use of resistant varieties will be the
best strategic plan to fully combat the disease by a good
percentage.
• This study will therefore contribute to this strategic plan by
establishing the less susceptible Irish potato variety to bacterial
wilt and also offer grounds for breeders to choose the best two
less susceptible varieties as parents for breeding

11. MATERIALS AND METHODS
Experimental Site
• This research project is to be carried out at FIELD 7,
Egerton University.
• The field is located on a latitude of 2200M ASL and
annual rainfall of 1800mm.
• The area experiences temperatures of between 220C-
230C. The soil type is deep volcanic soils having a PH
range of between 5.5- 6.5

12. Experimental Treatments
• Kenya karibu.
• Shangi.
• Dutch robijn.
• Tigoni.
• which will be secured from ADC Molo.

13. Experimental Design
• The experiment will adopt a Randomized Complete Block
Design (RCBD) with four (4) treatments and five (5)
replications.
• Statistical model : Yijk=µ + Fi + Bj +£ijk.

14. Experimental Layout, land preparation
and planting.
• The exponent layout will be laid on the land measuring 13X13M.
• A path of 1M will be left in between the blocks and the border.
• The field will be ploughed early to allow time for the debris to
decompose.
• Secondary cultivation will be done to achieve required tilth and
then ridges made.
• Planting will then be done at a spacing of 75cmx30cm.

15. Inoculation of Experimental Field.
• The field will be inoculated with Ralstonia solanacearum. Tubers having
bacterial wilt symptoms will be washed under running water to remove
attached soils on them.
• They will then be immersed in ethanol (70%) for 3 minutes. The tubers will
then be soften and immersed in distilled water to obtain bacterial wilt
suspension according to Kinyua et al. (2014).
• The bacterial suspension will then be streaked on agar medium at 28oC for
48minutes.
• Virulent colonies will then be harvested and suspended in Casamino acid
and glucose liquid medium and grown for three days.
• Bacterial pellets will then be suspended in distilled water and the suspension
sprayed in the field.

16. Data Collection and Data Analysis
• Days to the onset of wilting (DTOW)
• Total tuber numbers (TTN)
• Total tuber weights in kg/ha (TTW),
• Proportion of symptomatic tubers base on the total
number of tubers (PSTTN).
• ANOVA will be performed on DTOW, TTN, TTW and
PSTTN using Genstat and SPSS statistical softwares.
.

17. EXPECTED OUTPUT
• Get outstanding results from our field experiment which
will help us to graduate as per the requirements of the
university.
• Help in bridging the knowledge gap about bacterial wilt
that exists among small-scale farmers.
• Breeding centers e.g. KALRO to use data from our
experiment in their programs for breeding resistant
varieties.
• Small-scale farmers to adopt high yielding and resistant
variety identified from the project.

18. WORKPLAN
Month
Activity
March April May June July August September November
Project title selection
Proposal writing
Proposal defense
Materials collection.
Land preparations
and soil sterilization
Inoculation of
bacteria to soil.
Planting
Agronomic practices
and data collection
Data analysis and
report writing.

19. BUDGET
Materials Budget
ITEM COST PER NUMBER COST
Planting materials
Shangi 70 1kg 5 350 /=
Tigoni 70 1kg 5 350 /=
Karibu Kenya 70 1kg 5 350 /=
Dutch robijn 70 1kg 5 350 /=
fertilizers
DAP
planting
1000 5kg 1 1000 /=
17.17.17 NPK
Topdressing.
100 1kg 5 500 /=
Transport 1000 /=
Data bundle 500 /=
TOTAL 4400.

20. BUDGET
Labor Budget
LABOUR COST PER
PERSON
NUMBER COST
Planting 200 4 800 /=
weeding 200 6 1200 /=
Topdressing 100 4 400 /=
watering 100 4 400 /=
Data collection 300 4 1200 /=
Data analysis 300 2 600 /=
harvesting 200 6 1200 /=
TOTAL 5800 /=
Materials budget 4400 /=
Labor budget 5800 /=
TOTAL 10,200/=
TOTAL

21. THANK YOU.