SOIL INOCULUM LEVEL OF ROOT ROT PATHOGENS IN
LEGUMES AND MANAGEMENT USING DIFFERENT
SEED DRESSING APPLICATIONS IN NANDI SOUTH
ANNE KADAARI
A56/80093/2012
MSC. CROP PROTECTION
SUPERVISOR: DR.MUTHOMI
INTRODUCTION
 Legumes are among the most important food crops in
Kenya
 They play an important role on farms, human diet and
sustainability of agriculture.
 Mostly grown as risk reducing crop
 However, yield decline has been reported due to their
susceptibility to environmental stress, diseases, pests and
low soil fertility.
Problem statement and justification
 Root rot diseases are a major limiting factor in legume production
 Several factorsfavor their establishment in a crop
 Root rot diseases suppress seedling germination and cause
emergency damping off resulting in poor yield of legumes
 Major losses have been reported in western Kenya
 This study will be carried out to determine the soil inoculum levels of
root rot pathogens with appropriate seed dressing application as a
management tool
Objective
Broad objective
To determine soil inoculum levels of legume root rot pathogens and their
management using different seed dressing applications
Specific objectives
1.
Determination of the level of root rot pathogen of legumes
2.
To evaluate different seed dressing application on the management of
root rot pathogens of legumes using different regimes
Materials and methods
1. Determination of the level of root rot pathogen of legumes
Study sites
 The sites will be in Nandi South; Kapkerer, Kiptaruswo and
Koibem.
 Each site will consist of 3 farms selected randomly
Experimental design
 The design will be a complete split plot with 3 replications
 Grain legumes to be used include common beans, dolichos
lablab, groundnuts, soy beans, field peas & cow peas. Each
legume will consist of 3 varieties.
Materials and methods cont..
 The legume species will form the main plot while the varieties form





the sub plot.
The plot will be 2x2m size.
The legume varieties will be planted in 3 rows per sub plot.
3 seeds per legume species will be sown 5cm deep and 10-30cm
spacing within plants.
The experiment will be carried out for two rainy seasons.
18 treatments
Sample collection and isolation
 100g of soil will be collected randomly on each plot before the onset
of rainy season, at planting time and prior to harvesting
 A composite will be made from soil sample collected from one site
and labeled appropriately.
Materials and methodology cont..
Isolations of root rot pathogens & identification
 Soil sample will be grounded and soil suspension made from each of
the 3 composite samples per site.
 Serial dilutions will be made by diluting 10g to 100ml sterile distilled
water
 1ml of 10-4 to 10-6 dilutions will be plated and replicated thrice on
petridishes containing PDA and incubated for 5-7days at 250c
 Colony numbers will recorded and total number of colony forming
units per grams in soil calculated.
 Hyphal tip transfer will be done and sub cultured to PDA at 26-280C
for 5 days . Fungal isolates from the pure culture will be identified by
morphological and cultural features
Materials and methodology cont..
Assessment of root rot incidence
 All legumes species showing root rot disease symptoms per plot will be
counted in the 2nd ,4th ,6th and 8th week after seedling emergence and
total incidence determined by calculating the total no of plants showing
disease symptoms over total no. of plants in a plot.
To determine nodulation ,yield , growth and yield parameters
 Nodules will be determined by washing the harvested plants roots and
the total no. of nodules counted on entire root system.
 Growth parameters will consist of biomass and root mass
measurements.
 Individual legume species will be selected randomly ;roots and shoots
will be separated from the plant , washed and blot dried.
 Fresh weight will be determined by weighing freshly harvested plant and
weights recorded.
 The roots and shoot will be dried in an oven at 1000c for 48hrs and
weighed to determine dry weight and total biomass calculated.
Materials and methodology cont..
 Yield: calculating individual plant yield on each harvesting date by
dividing total yield per plot by no.of plants in each plot
 Yield parameters will constitute mature pods and seeds. Total no. of
pods and seeds per pod at harvest time from randomly selected
plants will be recorded and weighed and total no. of seeds per pod
recorded.
2. To evaluate different seed dressing application on the
management of
root rot pathogens of legumes using different
regimes
Study area , experimental design and treatments
 There will be two experiments; a field experiment in Nandi south and
a greenhouse experiment at the University of Nairobi, Upper Kabete
Field Station
 The experiments will be complete split plot design with 3 replications.
 Main plot will consist of legumes species and subplot consist of 3
legumes varieties.
Materials and methodology cont..
 Treatments will include seeds dressed in portassium sorbate, Neem
extract, a mixture of potassium sorbate and neem and a control.
Greenhouse experiment
 Legumes exhibiting root rot symptoms will be collected, roots will be
cut into small portions which will be washed in running water and
surface sterilized using 1% Naocl ,rinse in distilled water thrice and
blot dried.
 Aseptically the root segments will be plated on PDA and incubated for
7-14 days at 250c and identification will be by morphological and
cultural features.
 Pure culture will be obtained by hyphal tip transfer into fresh PDA.
 Inoculum will be prepared whereby colonies will be flooded with
sterile distilled water and gently scraped off from the surface of the
media to make a slurry. Sterile soil on each set of plastic pots will
then be inoculated with the inoculum through spraying.
Materials and methodology cont…
Chemical seed dressing and botanical seed dressing
 Prior to seed dressing seeds will be surface sterilized using 1%Naocl and rinsed three
times.
 Sterilized seeds (3) of all legume species will be individually soaked separately for 1hr
in potassium sorbate solution
and Neem extract concentration at varying
concentrations then sown in sterile soil in a set of arranged plastic pots.
 Seeds will be soaked in a mixture of
potassium sorbate and neem extract
solutions will be planted.
Field experiment
 A field experiment will be carried out consisting of the 6 legume species on a 2x2m
plots in a complete split plot design. 3 Seeds dressed with potassium sorbate and
Neem extract at varying concentration and in a mixture of the two applications will be
sown on each plot. Untreated seeds will be planted as controls.
Assessment of root rot incidence
All legumes species showing root rot disease symptoms per plot will be counted in the 2nd
,4th ,6th and 8th week after seedling emergence and total incidence determined by
calculating the total no of plants showing disease symptoms over total no. of plants in a
plot.
Materials and Methodology cont…
To determine nodulation ,yield , growth and yield parameters
 Nodules will be determined by washing the harvested plants roots and the
total no. of nodules counted on entire root system.
 Growth parameters will consist of biomass and root mass.
 Individual legume species will be selected randomly ;roots and shoots will be
separated from the plant , washed and blot dry.
 Fresh weight will be determined by weighing freshly harvested plant.
 The roots and shoot will be dried in an oven at 1000c for 48hrs and weighed
to determine dry weight and total biomass calculated.
 Yield: calculating individual plant yield on each harvesting date by dividing
total yield per plot by no.of plants in each plot.
 Yield parameters : Total no. of pods and seeds per pod at harvest time from
randomly selected plants will be recorded and weighed and total no. of seeds
per pod recorded.
Statistical Analysis
 Data will be analyzed using analysis of variance (ANOVA) Genstat
software and means distinguished using Tukey LSD test at 5%
Expected results
 Soil inoculum level of root rot pathogens in legumes will be




determined.
Seed treatments as a suppression method of root rot pathogens in
legumes will be incorporated as management tool
Increase in yield due to seed treatments.
Msc. Thesis
Publication in scientific journal.
Work plan
Activity
2013
Jun
e
Proposal
development
Planting
and
sample collection
Pathogen
isolation
and
identification
Data Analysis
Thesis
Write
and submission
up
2014
July
AugOct
Sep- JanDec
Feb
MarApril
May- June
Budget
Item
Cost (K sh)
Sample collections
20,000
Laboratory analysis
70,000
Variety evaluations
60,000
Thesis development
20,000
publication
20,000
Total
190,000
THANK YOU