ABSTRACT
A field trial was conducted at the University of Uyo Teaching and Research Farm to assess the effect of some botanical foliar sprays in the control of leafspot disease of mungbean. The plant extracts used were: leaves of neem, tassel flower, Moringa and candle stick. The experiment was a randomized complete block design (RCBD) and replicated three times. The result of the disease survey on mungbean 10 weeks after application of 70% of each of extract showed that neem had the least incidence of 0.0 and 38.89% at 2 and 10 weeks after treatment respectively. The result also showed that, the level of infection increased with increased crop age. The result of isolation showed that four different fungi were isolated from diseased mungbean leaves. They were; Brachysporium nigrum, Dactylaria leptospermi, Gliocladium roseum and Aspergillus niger with Gliocladium roseum showing the highest percentage frequency of occurrence of 70.58%, while Dactylaria leptospermi had the least percentage frequency of occurrence of 11.76%. Results of pathogenicity test showed that Gliocladium roseum was pathogenic on mungbean seedling 28 days after inoculation. The result of experiments in which extracts were sprayed on inoculated mungbean plant showed that neem extract had the least disease incidence of 10%, four weeks after inoculation, while candle stick, moringa and tassel flower had 30% disease incidence four weeks after inoculation. Neem extract showed the least severity at four weeks after inoculation. The highest disease incidence 100% was observed in the control treatment four weeks after treatment. The results of laboratory test for mycelial growth inhibition showed that the highest inhibition of the pathogen, 0.04cm, was observed from Senna alata, while the least inhibition of 0.33cm was observed from Moringa oleifera. The results also showed that Neem, moringa, senna and tassel flower were highly effective against the incitant, Gliocladium roseum.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables ix
List of Figures x
Abstract xi
CHAPTER 1:
INTRODUCTION 1
1.1
Origin and Distribution 2
1.2
Botany of Mungbean 2
1.3
Ecological Requirement of
Mungbean 3
1.4
Uses of Mungbean 4
1.5
Justification of the
Study 5
1.6
Objectives of the Study 6
CHAPTER 2:
LITERATURE REVIEW 7
2.1 Major Diseases
of Mungbean 8
2.1.1 Cultural
practices for the control of mungbean disease 9
2.1.2 Effect
of crop rotation 9
2.1.3 Chemical
control with fungicides 10
2.1.4
Biological control methods 10
2.1.5
Botanical control method
11
CHAPTER 3:
MATERIALS AND METHODS 13
3.1 Study
Area / Experimental Site 13
3.2 Land
Preparation 13
3.2.1 Experimental
design 13
3.2.2 Experimental plot size 13
3.2.3
Collection and analysis of soil sample 13
3.2.4 Source
of planting materials 13
3.3 Planting 14
3.4 Experimental
Treatments 14
3.5 Soil Collection
and Sterilization 14
3.5.1 Raising mungbean
seedling in the greenhouse 14
3.5.2 Survey
for the incidence and severity of leaf spot disease of mungbean
in the field 15
3.6 Isolation
and Identification of the Isolates Associated with Leaf Spot
Disease of Mungbean 15
3.6.1 Collection
of leaves samples 15
3.6.2 Preparation
of growth media (PDA) 16
3.6.3 Identification
of isolates 16
3.6.4 Preparation
of inoculum suspension 17
3.7 Pathogenicity
Test 17
3.8 Preparation
of leaf Extracts 17
3.8.1 Effect
of leaf extract on fungal growth 18
3.8.2 Preservation
of isolates
18
3.9 DATA ANALYSIS
19
CHAPTER 4: RESULT
AND DISCUSSION 20
4.1 Result
of the Analysis of Soil of the Experimental Site 21
4.2 Incidence and Severity of the Leaf-Spot
Disease of Mungbean 10 Weeks
after Inoculation
with 70% Concentration of Extracts of Neem, Drum
Stick, Candle
Stick and Tassel Flower 22
4.3 Fungi
Associated with Leaf-Spot of Mungbean and their Percentage
Frequencies of Occurrence 24
4.4 Pathogenicity
Test 26
4.5 Green
House Experiment 28
4.6 Effect of Four Plant Extracts on the
Radial mycelial Growth of
Brachysporium
nigrum, Aspergillus
niger, Gliocladium roseum and
Dactylaria
leptospermi at 250C-
280C Seven Days After Inoculation
on PDA 31
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 40
References 42
LIST OF TABLES
4.1 Soil physical and chemical properties of
experimental site 21
4.2: Percentage
field incidence of mungbean leaf spot disease at 2-10 weeks
after
treatment with extracts of neem, moringa, senna and emilia in the field 23
4.3: Disease
severity Index of mungbean leaf spot disease at 2-10 weeks
after treatment
with extracts of neem, moringa, senna and emilia in the
field 23
4.4: Percentage
frequencies of occurrence of fungi associated with leaf spot
disease of mungbean 25
4.5: Results
of the inoculation of Fungi associated with the leaf spot disease
of mungbean leaves
in the field on healthy mungbean leaves 28 days
after inoculation
in the greenhouse at 280c 27
4.6 Percentage
Disease Incidence and Disease Severity indices of leaf spot
Disease of mungbean 4 weeks after inoculation
in the greenhouse 27
4.7: Percentage
disease incidence, recorded 4 weeks after treatment of
Mungbean seedlings
with different plant extracts at different
concentration of
each in the greenhouse at 280c and 70% Relative
Humidity 29
4.8: Disease
severity index recorded 4 weeks after treatment of mungbean
seedlings with
different plant extracts at different concentration of
each in the
greenhouse at 280c and 70% Relative Humidity 30
4.9: Effects
of four plant extracts on the radial mycelial growth of four
different Fungi at
room temperature (250 -280C) seven days after
inoculation on PDA 33
LIST OF FIGURES
1: Healthy
Mungbean plant in the field 34
2: Diseased
Mungbean plant in the field 34
4: Brachysporium nigrum
spores 35
5: Aspergillus niger spore 36
6: Gliocladium roseum spores 37
7: Dactylaria leptospermi spores 38
8: Effect of spraying Gliocladium
roseum spores on the leaves of 3 week
old mungbean
seedling, 28 days after treatment in the greenhouse at 250c 39
CHAPTER
1
INTRODUCTION
Vigna radiata
L. (Wilczek) is a legume cultivated for its edible seeds and sprout across
most part of the world (Akpan and Andrew, 2018). There three are (3) subgroups
of Vigna radiata; one is cultivated (Vigna radiata subspecies radiate), and
two (2) are wild (Vigna radiata
subspecies. Sublobata and Vigna radiata
subspecies. glabra).The mungbean plant is annual, erect or semi- erect, dwarf height of 0.15- 1.25m (FAO, 2012; Lambrides et al., 2006).The stems are mainly
branched, sometimes twining at the tips (Magotsi, 2006). The ``leaf ranges from
alternate to trifoliate with elliptical to ovate leaflets, 5- 18cm long by 3 -
15cm broad. The flowers (4- 30) are papillonaceous, pale yellow or greenish in
color. The shapes of the pods are long, cylindrical, hairy and pending. They
contain 7- 20 ellipsoid or cube- shaped seeds. The seeds are of different colors;
usually green, but can also be yellow, olive brown, purplish brown or black,
mottled and or ridged seed color .The presence or absence of a rough layer are
used to differentiate types of mungbean (Lambrides et al.,2006; Mogotsi, 2006).
Cultivated types are generally green,
golden, shiny or dull depending on the presence of a texture layer (Lambrides et al., 2006). Golden gram which has
yellow seeds with low seed yield and pods which shatter at maturity thus, they
are often grown for forage or green manure. Green gram with bright and green seeds
is more productive and ripens more uniformly, with reduced shattered pods. Mungbean
is a major edible legume seed in Asia, Europe and in Southern USA. The mature
seeds provide a good source of digestible protein for humans where meat is
lacking or where people are mostly vegetarian (AVDRC, 2012). Mungbean is cooked
fresh or dry. They can be eaten whole or made into flour, Soups, Porridges,
snacks, bread, noodles and ice- cream. Mungbean can be processed to make starch
noodles (bean thread noodles and cellophane noodles) or soap. The sprout seeds
are relished raw or cooked throughout the world. The immature pods and succulent
leaves are eaten as vegetable (Mogotsi, 2006).
1.1 ORIGIN AND DISTRIBUTION
The mungbean originated from the
Indian subcontinent (Lambrides et al.,
2006; Mogotsi, 2006; AVRDC, 2002). It is now widespread throughout the tropics
and is gradually cultivated in humid tropical ecology of south- eastern Nigeria
(Lambrides et al., 2006; Mogotsi,
2006; 1996; AVRDC, 2002).
Mungbean is fast growing, warm season
legume. It reaches maturity very quickly under tropical and subtropical
conditions where optimal temperatures are about 28- 300c and always
above 150c (Agugo and Opara, 2004). The mungbean is grown on a wide
range of soils but prefer well- drained sandy loams, with a PH range
of 5 - 8. It is tolerant to saline soils (Mogotsi, 2006). Mungbean production
is mainly 90% situated in Asia; India being the largest producer with over 50%
of the world’s production and consumes almost its entire production. China
produces large amounts of mungbeans, which represent 19% of its legume
production. Thailand is the main exporter and its production increased by 22% between
1980 and 2000 (Lambrides et al.,
2006). Though mungbean is produced in many African countries, it is not a major
crop in Africa and Nigeria in particular (Mogotsi, 2006; Tomooka, 1991).
1.2 BOTANY OF MUNGBEAN
Mungbeans are in the legume family of
plants and are closely related to cowpea (in the same genius but different
species (Tomooka, 1991).They are branch, warm season annuals with trifoliate
leaves like the other legumes. (Tomooka, (1991) showed that both upright and
vine types of growth habit occur in mungbean, with plant varying from one to
five feet in length. The pale yellow flowers are borne in a clusters of 12- 15 at
the top of the plant.
1.3 ECOLOGICAL REQUIREMENT OF MUNGBEAN
Mungbean is a warm season crop and
grows mainly within a mean temperature range of 20- 40o c, the
optimum being 28- 30oc.( AVRDC, 2002). It can therefore be grown in
summer and autumn in warm temperate and subtropical regions and at altitude
below 2000m in the tropics. According to Tomooka, (1991) mungbean is sensitive
to frost. It requires an average annual rainfall of 600- 1000mm, but it can do
with less. Mungbean withstand drought well, by curtailing the period of
flowering and maturation, but it is susceptible to water logging.
High humidity during maturity causes
seeds damage leading to discoloration or sprouting of seed while still in the field.
Mungbean requires phosphorus, potassium, calcium, magnesium and sulphur similar
to other legumes which must be met by fertilizer additions if the soil is
deficient in these elements (Tomooka, 1991).
1.4 USES OF MUNGBEAN
Mature mungbean seed or flour enter a
variety of dishes such as soups, porridge, snacks, breads, noodles and even
ice- creams.( Agugo and Okpara, 2008). In Kenya mungbean is most commonly
consumed as whole seeds boiled with cereals such as maize or sorghum (Mogotsi,
2006). The mungbean is a major edible legume seed in Asia, Europe and USA. The
mature seed is a good source of digestible protein for humans in the absence of
meat or where people are mostly vegetarian (AVRDC, 2012) mungbean are cooked
fresh or dry. The immature pods and succulent leaves are eaten as vegetables
(Mogotsi, 2006). Mungbean can be used as livestock feed (FAO, 2012). It can be
used for hay making, when it should be cut as it begins to flower and then
quickly dried for storage. Mungbean can be used as a cover before or after
cereal crops. It makes good source of green manure. It is an N- fixing legume
that can provide large amounts of biomass (7.16t biomass/ha) and N to the soil
(ranging from 30 to 251kg/ha (Hoorman et
al., 2009; Devendra et al.,
2001). Green manure is ploughed in when the plant is in full flower (FAO, 2012).
Mungbeans are rich in protein (20-
30% DM) and starch (over 45% DM) with a low lipid content(less than 2% DM), and
variable but generally low amount of fiber (crude fiber 6.5% DM on average).
The amino acid profile of mungbean is similar to that of soybean (Amber, 2000).
Bye- product of mungbean vermicelli processing contains 11- 23% crude protein,
0.4- 1.8% ether extract, 13- 36% crude
fiber, 0.30- 0.68% calcium and 0.17- 0.39% phosphorus depending on the mungbean
materials.(Sitthigripong et al.,1998).Mungbean
contain anti-nutritional factors (potential constraints) such as; (trypsin inhibitors,
chymotrypsin inhibitor, tannins and lectins). The amount of nutritional factors
depends greatly on mungbean types and can be reduced via processing such as
soaking, cooking or extruding (Lambrides et
al, 2006; Mogotsi, 2006). However, in some cases, this metabolite were
found to have no negative effect (Creswell, 1994).Plant residues and cracked or
weathered seeds are fed to livestock without any adverse effect (Amber, 2000;
Eusebio et al, 2000; Robinson et al, 2001).
1.5 JUSTIFICATION FOR THE STUDY
Mungbean
(Vigna radiata) is a food legume that
is very rich in protein and essential amino acids with the exception of sulphur,
amino acids, methionine and cysteine which may be nutritional limited (Opara
and Agugo, 2014). It is a good source of soluble carbohydrate, and contains
very high amount of crude fibre (Akpan and Andrew, (2018; Onimawo and Egbekun,
1998).Mungbean as a crop is little known on the African continent and in
Nigeria in particular.Mungbean is a short season crop that flowers in thirty
days, it can as well be cultivated in a very small land size. Its short
maturing period can help to ensure an all year round supply of this all
impotant food crop and this will assist in alleviating food challenges in
Nigeria. One of the reasons for conducting this research was to record what
diseases and fungal pathogens attack the crop in Nigeria and in particular in
the moist rainfall ecological zone of south eastern Nigeria. Regrettably, this
important food crop is beset by a number of fungal diseases which result in
yield loss and extremely low production in Nigeria; especially in humid
ecological zone of south eastern Nigeria. According to Akpan and Andrew, 2018),
the most important and widespread
fungal diseases of mungbean include; Cercospora leaf spot (Cercospora canescens) (Cercospora
cruenta) and powdery mildew (Erysiphe
polygoni). Less serious are; scab (Elsinoe
iwatae), Anthracnose (Collitotichum lindemuthianum)
and rust (Uromyces species).
According
to Lawn, (1995), average low yield of mungbean could be due to low inherent
yield potential, but majority of the factor is attributable to its
susceptibility to diseases. Leaf spot diseases caused by Cercospora canescens is a serious disease in the mungbean growing
areas, especially, areas with high relative humidity during the growing
periods. Cercospora leaf spot is one of the most important diseases that cause
serious loses in mungbean crop. Opara and Agugo,(2014) reported up to23% losses
in yield of mungbean to leaf spot disease, but Iqbal et al,( 1995)observed loss of up to 61% in grain yield. The disease
start appearing about 30 -40 days after planting, however, depending on the
temperature and humidity; its spread rapidly in susceptible varieties causing
premature defoliation and reduction in size of pods and grains (Iqbal et al, 2004). Several researchers have
reported the effective control of the disease with the application of fungicides.
However, according to Iqbal et al.,(1990)
and Iqbal et al(,2004), Akpan and
Andrew(2018) the cheapest, practical and economical control of the disease can
be achieved by using integrated pest management strategy via the incorporation
of crop rotation, crop hygiene, adequate spacing, adjustment in sowing date,
use of pathogen free seeds, application of foliar fungicides and chemical seed
treatment.
The
need for increasing food production in developing countries, especially where
substantial level of production comes from the resource poor farmers has
encouraged more researches in the principal of disease control in crops.
The
aim of this study was to assess the effectiveness of some plant extracts from Moringa oleifera (Moringa), Senna alata (Senna), Azadirachta indica (Neem), and Emilia
coccinea(Tassel flower) in controlling the fungal leaf spot disease of mungbean.
1.6 OBJECTIVES OF THE STUDY
The objectives of this
study were to;
1.
Determine the incidence
and severity of the fungal leaf spot disease of mungbean in the green house and
in the field.
2.
Identify the causal
organisms associated with the disease symptoms
3.
Conduct pathogenicity
tests to identify the incitant organism of leaf spot disease of mungbean.
4.
Assess some plant extracts
for effectiveness in inhibiting the growth of the pathogen in vivo and in vitro
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