AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA
ISSN Print: 2151-7517, ISSN Online: 2151-7525, doi:10.5251/abjna.2013.4.4.476.484
© 2013, ScienceHuβ, http://www.scihub.org/ABJNA
Etiology and assessment of leafspot disease of sweet potato (Ipomoea
batatas (L.) Lam) in selected farms in Delta State, Nigeria
Ilondu, E.M.
Department of Botany,
Delta State University, PMB 1, Abraka, Nigeria.
Mobile: +2348036758249, E-mail: [email protected]
ABSTRACT
A multilocational study was conducted to investigate the associated mycoflora of leafspot disease
of sweet potato (Ipomoea batatas) and evaluate the extent of leafspot damage in selected farms
in the central District of Delta State. The disease assessment in four locations of study (Abraka,
Sapele, Oghara and Ughelli) was based on two criteria: Number of leafspot lesions per plant and
percentage area of leaf surface covered by leafspot lesions. The result indicated that leafspot
lesions were greatest on the older leaves and decreased progressively to the apex. The
percentage leaf area damaged followed the same trend ranging from 1-48% in various locations.
The leafspot disease in Sapele was significantly (P<0.05) greater than those found in Oghara,
Abraka and Ughelli. The pathogen isolation study was conducted in the laboratory in potato
Dextrose Agar medium with diseased leaf specimens from the study locations. Cochlobolus
lunatus, Fusarium solani, Fusarium lateritium, Non-spolulating isolate EMI-E and Mucor hiemalis,
F. luteus were found associated with leafspot disease of sweet potato at percentage ferequency
of 57.71, 21.71, 10.86, 6.29 and 3.43 % respectively. C. lunatus, F. solani and F. lateritium were
pathogenic. C. lunatus was the most frequent and pathogenic of all the isolates. The significance
of these findings has a great implication on the food security and income of resource-limited
families in the central district of Delta State.
Keywords: Etiology, Leafspot disease, assessment, Ipomoea batatas and pathogenecity
Sweet potato is vulnerable to many diseases which
INTRODUCTION
have been grouped by Arene and Nwankiti (1978)
into foliage, stem (vines), root or tubers for
Sweet potato (Ipomoea batatas (L.) Lam) a member
convenience. Leafspot diseases predominates all
of the family Convolvulaceae, is a spreading and
other diseases, hence a close look at any plant
prostrate herbaceous plant mostly propagated
reveals that it expresses leafspot disease symptoms
vegetatively from vines (Onwueme, 1978; Hahn and
at all stages of plant growth (Bilgrami and Dube,
th
Hozyo, 1984; Kaitisha and Gibson, 1999). It ranks 7
1976). There is a dearth of information on the
th
in World Food production, 4 in the tropics (Clark and
leafspot disease of sweet potato. However, Van
rd
Moyer, 1988), 3 within sub-saharan Africa after
Brugen (1984) and Lopes and Boiteux (1994), have
th
cassava and yam (Njoku et. al., 2001) and 4 among
reported that leafspot disease of sweet potato in
the root crops in Nigeria (Onwueme, 1978; Emehute
Ethiopia and South America has been attributed to
et. al., 1987). It is regarded as “live saver” because it
Alternaria bataticola. In Nigeria, the disease
is usually a reliable crop to depend on in times of
incidence so far reported is caused by various fungi
disaster, war, drought and famine (Woolfe, 1992;
which include the species of Alternaria, Cercospora,
Akoroda, 1995; Nwokocha et al., 1999). It also
Phyllosticta, Septoria (Arene and Nwankiti, 1978),
complements other food crops and serves to bridge
Fusarium culmorum (Amienyo and Ataga, 2008) and
periods of food shortage before the next harvest of
Cercosporella (Ilondu et al., 2010).
other staple crops (Emehute and Usua, 1989;
Jeremiah et. al., 1999). Traditionally, it is a food
The leaves of sweet potato are the main source of
security item and dependable source of income for
assimilate for dry matter production and increase
resource-poor families in Africa (Kaitisha and Gibson,
(Hahn and Hozyo, 1984). Leafspots reduce the
1999) and Nigeria.
photosynthetic area of the plants and consequently,
impair the amount of assimilate that goes into the
One of the major constraints to increased sweet
sink (Bilgrami and Dube, 1976; Hahn and Hozyo,
potato production is the high incidence of disease.
Agric. Biol. J. N. Am., 2013, 4(4): 476-484
1984). Severe leafspot infections sometimes result in
total defoliation and hence crop failure (Alabi and
Waliyar, 2004). Similarly, many of the leafspot
causing organisms are capable of killing the host
partially or totally not only by direct destruction of the
tissues but also by systemic dispersal of the toxic
substances far beyond the original region of infection
(Bilgrami and Dube, 1976). This reduces the quality
and quantity of the leaves for use as vegetable and
forage for man and livestock respectively. An
investigation into the etiology of the leafspot diseases
of sweet potato is therefore necessary. This study
was designed to isolate, identify and establish the
pathogenicity of associated organisms and assess
the extent of leafspot damage on sweet potato under
natural infection in selected farms with a view to
providing baseline information on the strategies for
the management of leafspot diseases of sweet potato
in the central district of Delta State.
Assessment of Leafspot Disease in Study
Locations: The location is the factor and the
experiment was replicated three times in each
location in a Randomized Complete Block Design
(RCBD).
MATERIALS AND METHODS
Location of the study: A multilocational study was
conducted for naturally occurring leafspot disease of
sweet potato (Ipomoea batatas (L.) Lam) in various
farms (which included Abraka, Ughelli, Sapele and
Oghara) in Central Senatorial District of Delta State.
The method of Ilondu and Ayodele, (2003) was
adopted for the assessment. Two criteria were used:
(a) Number of leafspot lesions per plant, and (b)
Percentage area of the leaf surface covered by
leafspot lesions. A visual observation indicated that
disease severity was greatest on the older leaves
hence the study was limited to 10 oldest leaves on
each plant. The leaves were numbered 1 to 10
according to the position of the petiole. The oldest
(lowest) leaf was labelled as number 1. Where the
plants were branched, the most prominent branch
was selected for the study. Leafspot lesions on each
leaf were counted. Similarly, the areas of both
diseased and unaffected (healthy) portions were
determined using a graph paper
Abraka (Ethiope East Local Government Area) lies
0
0
within latitude 05 47˝N and longitude 06 06˝E of the
Equator with an annual rainfall of 3,097.8 mm, annual
relative humidity of 83 % and annual mean
0
temperature of 30.6 C, Sapele (Sapele Local
0
Government Area) lies within latitude 06 20˝N,
0
longitude 05 38˝E of the Equator with an annual
rainfall of 3,835mm, annual relative humidity of 85%
0
and annual mean temperature of 30.6 C, Ughelli
(Ughelli North Local Government Area) lies within
0
0
latitude 05 30˝N and longitude 05 58˝E of the
Equator with an annual rainfall of 3500mm, mean
annual relative humidity of 80.1% and annual mean
0
temperature of 28.5 C and Oghara (Ethiope West
0
Local Government Area) lies within latitude 05 56˝N
0
and longitude 06 39˝E of the Equator with an annual
rainfall of 3,528 mm, mean annual relative humidity of
0
81 % and annual mean temperature of 30.2 C (Efe,
2007) (Fig. 1).
Isolation and Identification of Fungi from
Leafspot Lesions: The sweet potato leaves showing
characteristic leafspot symptoms were collected from
each location into paper bags and taken to the
Department of Botany laboratory, Delta State
University, Abraka for isolation of the associated
mycoflora.
Four millimeter long sections excised from the
margins of necrotic leafspot with sterile razor blade
were surface-sterilized for 2 minutes in 2 % aqueous
solution of commercial bleach (Sodium hypochloride
solution) and rinsed in two changes of sterile distilled
water. The disinfected tissue pieces were blotted
477
Agric. Biol. J. N. Am., 2013, 4(4): 476-484
between sterile Whatman No. 1 filter papers and
aseptically plated in 9 cm diameter Petri-dishes
o
containing Potato Dextrose Agar (PDA) at 30±2 C on
a laboratory bench in a completely randomized
design (Wokocha and Okereke, 2005).
No. of times a fungus is encountered
Observed fungal growth was transferred to fresh PDA
plates and sub-cultured repeatedly until pure cultures
of the isolates were obtained.
Percentage frequencies of isolation (PFI) of all the
fungi were calculated by the formula:PFI
=
x
100
Total no. of times all fungi were encountered
1
The upper and lower surfaces of the leaves were
sprayed to run-off point with the spore suspensions
5
(85x10 spores/ml) from each of the isolates using a
hand sprayer. There were three replicates for each
organism. Three control plants were sprayed with
sterile distilled water. The screen house was lined on
the outside with transparent polythene sheets and
sprayed with sterile distilled water twice daily to
maintain a humid atmosphere. The leaves were
inspected daily for symptom development up to 21
days after inoculation. The experiment was repeated
twice.
Identification of isolates was by microscopic
observation with standard mycological manuals by
Barnett and Hunter (1999) and Alexopoulos et al.
(2002). Confirmation of the identities of all isolated
fungi was done by International Mycological Institute,
Egham, Surrey, U.K. Isolates were maintained on
PDA slants in McCartney bottles and sub-cultured at
bi-weekly intervals until needed.
Pathogenicity of Isolates: This experiment was
conducted in the screen house of Department of
Botany, Delta State University, Abraka. Top garden
soil (of 0-20 cm in depth) collected from the
Department of Agricultural Education Teaching and
Research Farm, Delta State University, Abraka was
used for the pathogenicity tests. The soil was
collected in 45 x 38 x 0.4 cm black polythene bags
2
and sterilized by autoclaving at 1.1 kg/cm pressure
o
and at a temperature of 121 C for 1 hour, then
repeated after 24 hours for 1hour and left to cool for 2
days before use.
Number of leafspot lesions on the plant were counted
and used as a criterion for virulence of each isolate.
The fungi were re-isolated from the inoculated
diseased leaves and cultured in PDA plates. The
morphology of each pathogenic fungus was
compared with that of original cultures.
Data Analysis: Data obtained were subjected to
Analysis of variance (ANOVA) using Statistical
Package for Social Science (SPSS) version 17.0 and
means were separated according to Duncan’s
Multiple Range Test (DMRT) at 5% probability level.
Three-node vine cuttings of sweet potato (Sapele
local) obtained from a farm at Ogorode, Sapele were
planted in the black polythene bags each containing
5 kg of the sterile soil and maintained in a screen
house under prevailing conditions of temperature
o
(30±2 C) and light for three weeks before inoculation.
RESULTS
Assessment of the Leafspot Disease of Sweet
Potato in Study Locations: Leafspot lesions were
observed in every sweet potato farm visited, with varied
severity ranging from a few to numerous spots in all the
plants at different locations which included Abraka,
Oghara, Sapele and Ughelli. The lesions were
characterized by round to irregular shaped brown spots
measuring about 2-19 mm across the longer axis,
shining on the abaxial surface of the leaf but dull on the
adaxial surface with white spots cluster in the centre.
The lesions frequently exhibit concentric rings and have
well-defined margins. In some leafspots, the central part
of its lesion had often cracked leaving a shot-hole effect.
In some cases where the disease was severe, lesions
had coalesced to give extensive leaf necrosis.
The preparation of inocula and their application to the
test plants were carried out according to the method
of Okigbo and Osuide (2003). Cultures of the isolates
were incubated in PDA for 10-15 days on the
o
laboratory bench at a room temperature (30±2 C). To
prepare the spore (conidial) suspension, the agar
surface of 10-day old culture was flushed with three
changes of 20 ml of sterile distilled water and with the
aid of sterile glass rod, the conidia were dislodged
from the mycelium. The suspension was made up to
100 ml before filtering through four-fold cheesecloth
to remove the residual hyphae and centrifuged for 20
minutes at 250 rpm. The concentration was
determined by haemocytometer counts.
The leafspot disease in Sapele was significantly
(P<0.05) greater than those found in Oghara, Abraka
478
Agric. Biol. J. N. Am., 2013, 4(4): 476-484
and Ughelli. Although Abraka had more number of
leaf surface covered by the lesion (Table 2) based on
leafspots than Ughelli, there was no significant
the data obtained from the oldest ten leaves of the vine
difference between them (Fig. 2). The results obtained
was greatest on the lowest leaves (leaf position 1) and
from the number of leafspot lesions per plant and the
decreased progressively towards the apex.
The
percentage area of the leaf surface covered by the
percentage leaf area diseased ranged from 4.00 –
leafspot lesions followed the same trend. The number of
48.33 in Sapele; 1.67 – 41.100 in Oghara; 1.3 – 31.00
lesions per leaf (Table 1) and percentage area of the
in Abraka and 2.00 – 27.33 in Ughelli.
Table 1: Association between the number of lesions per leaf damaged by leafspot disease and the stalk
positions of leaves on the vine
Stalk position
Abraka
Oghara
Sapele
Ughelli
a
22.00a
a
18.00b
a
16.67c
a
14.33d
a
12.33e
a
8.33f
a
5.67g
c
a
5.00h
d
on the Vine
b
24.00a
a
21.67b
a
18.00c
a
17.00d
15.33e
a
a
a
1
24.00a
2
22.00b
3
18.33c
4
17.33d
5
6
12.67f
7
11.00g
8
6.67h
9
4.67i
10
3.67j
c
b
35.00a
a
23.00b
ab
18.67c
a
16.67d
13.00e
b
15.00e
12.00f
a
12.33f
8.67g
b
11.67g
8.33h
b
11.33h
b
4.67i
b
8.00i
b
3.67j
b
6.33j
c
b
b
b
b
a
4.33i
a
4.00j
b
b
b
Values with the same subscript(s) in the same column and superscript(s) in the same row are not significantly
different at P>0.05 by DMRT
120
a
100
No. of leafspots
80
ab
b
b
60
40
20
0
Abraka
Ughelli
Sapele
Oghara
Locations
Fig. 2: Frequency of occurrence of fungal leafspot disease of sweet potato (Ipomoea batatas (L) Lam) in
the four study locations in Delta State Locations with the same alphabet are not significantly different at
5 % level of probability by DMRT
479
Agric. Biol. J. N. Am., 2013, 4(4): 476-484
Table 2: Association between the percentage leaf area damaged by leafspot disease and the stalk
positions of leaves on the vine
Stalk
position
Abraka
Oghara
Sapele
Ughelli
a
27.33a
a
22.67b
a
18.67c
a
16.00d
a
10.33e
a
5.33f
a
4.00g
c
a
2.67h
c
on the Vine
1
31.00a
c
41.00a
b
48.33a
2
23.33b
c
36.33b
b
42.00b
3
17.67c
c
28.33c
b
35.33c
4
16.67d
c
22.00d
b
31.00d
5
13.67e
c
17.33e
b
23.33e
6
11.00f
c
13.33f
b
17.33f
7
7.00g
b
8.67g
b
11.67g
8
3.67h
bc
4.00h
b
11.00h
9
2.67i
10
1.33j
b
2.33i
b
6.00i
b
1.67j
b
4.00j
d
c
c
c
d
d
a
2.00i
b
a
2.00i
b
Values with the same subscript(s) in the same column and superscript(s) in the same row are not significantly
different at P>0.05 by DMRT
Table 3:
Fungi isolated
Fungi isolated from leafspot lesions of sweet potato collected from four locations
and their frequency of isolation
International
Mycological
Institute
Identification
number
Presence or Absence of Fungi at different locations
Abraka
Ughelli Sapele Oghara
Total
no.of
times
isolated
Isolation
frequency
(%)
F. lateritium
394869
-
-
+
+
19
10.86
M. hiemalis f.
luteus
C. lunatus
394870
+
-
-
-
6
3.43
394871
+
+
+
+
101
57.71
F. solani
394872
+
+
+
+
38
21.71
EMI-E
(Unidentified)
394873
-
+
+
-
11
6.29
+ = Fungi present
- = Fungi absent
480
Agric. Biol. J. N. Am., 2013, 4(4): 476-484
Table 4:
Symptom induction and re-isolation
of fungal isolates from sweet potato leaves 3
weeks after inoculation
Fungal inoculum
Re-isolation from
leaf tissues
3weeeks after
inoculation
leaves of Sapele local were inoculated with their spore
suspension. The leafspots closely resembled those
developing from natural infection in the farms but were
smaller in size than the naturally-induced spots. The
spots were usually visible as water-soaked lesions after
day 7 of inoculation and were well- developed by day 14
to 21. They appeared chlorotic at first, but later turned
brown. The fungal isolates were consistently re-isolated
from the lesion which developed following inoculation.
M. hiemalis, f. luteus and isolate EMI-E were nonpathogenic as the leaves inoculated with their spore
suspension did not show any lesion development
(Table 4). Similarly, the leaves sprayed with sterile
distilled water as control did not show any sign of
infection throughout the period of observation.
No. of spots
per leaf
b
Fusarim lateritium
+ve
65.33
Mucor hiemalis f.
luteus
-ve
0.00
C. lunatus
+ve
78.00
a
Fusarium solani
+ve
51.00
c
EMI-(Unidentified)
-ve
0.00
d
Control
-ve
0.00
d
d
DISCUSSION
Leafspot disease of sweet potato was observed in
the four study locations in Central Senatorial District
of Delta State. Amienyo and Ataga (2008) reported
that leafspot disease of sweet potato occurred in all
locations sampled in Rivers state. Similarly, Uma and
Damagun (1989) reported an extensive leafspot
disease of cassava in many farms in Lagos state.
According to Arene and Nwankiti (1978), leafspot
diseases are favoured by cool humid weather when
they destroy a greater portion of the foliage. The high
humidity of Sapele compared to other locations must
have contributed to greater leafspot disease
development there.
Values within columns followed by the same
superscript(s) are not significantly different at P>0.05
by DMRT
+ve = Fungus re-isolated
-ve = Fungus not re-isolated
Fungi Isolated from the Leafspot Lesions of
Sweet Potato: The fungi isolated from the diseased
sweet potato leaves were Cochliobolus lunatus R.R
Nelson & F.A. Haasis. Anamorph: Curvularia lunata
(Wakker) Boedgin (1M1394871); Fusarium lateritium
Nees. Teleomorph: Gibberella baccata (Wallr.) Sacc.
(1M1394869); Fusarium solani (Mart.) Sacc. (1M1
394872); Mucor hiemalis f. luteus (Linnem) Schipper
(1M1 394870) and a non-sporulating isolate of EMI-E
(1M1 394873) which could not be identified.
The leafspot lesions were found more on the older
leaves than on the younger leaves. This could be due
to the presence of high levels of phenolic
compounds, phenol oxidases and phytoalexins in the
younger leaves, which contributes to disease
resistance mechanisms in sweet potato foliage as
reported by Clark and Moyer (1988). Similar
observations were made by Okigbo (2001) with
respect to infections by Macrophoma mangiferae, the
causal agent of mango blight; Ilondu and Ayodele
(2003) on leafspot disease of tobacco and
Maduewesi (1980) on white leafspot disease of fluted
pumpkin (Telfairia occidentalis Hooke).
Of the 175 fungal isolates made from sweet potato
leafspots in an attempt to isolate the organisms
associated with the disease, 101 (57.71 %) were C.
lunatus; 38 (21.71 %) were F. solani; 19 (10.86 %)
were F. lateritium; 11 (6.29%) were non-sporulating
EMI-E isolate while 6 (3.43 %) were M. hiemalis f.
luteus (Table 3). C. lunatus and F. solani were
isolated from all the locations under study, while F.
lateritium was isolated from Sapele and Oghara
locations only. Similarly EMI-E (unidentified) was
isolated from leafspots leisons in Ughelli and Sapele
while M. hiemalis f. luteus was isolated only from
Abraka.
Leafspot lesions on sweet potato are easily defined
and can be counted with considerable ease even on
severely diseased leaves. Leafspot count from the
lowest ten leaves per plant was found to be a quick
and reliable criterion for assessing comparative
susceptibility of sweet potato plants to the leafspot
fungi. The use of local lesion counts or percentage of
diseased leaf area as assessment of fungal infections
have been employed by various researchers
Pathogenicity of the Isolated Fungi:
Curvularia
lunatus, Fusarium lateritium and Fusarium solani
produced leafspot lesions when healthy sweet potato
481
Agric. Biol. J. N. Am., 2013, 4(4): 476-484
including (Ilondu and Ayodele, 2003; Oke, 1990;
Okigbo and Osuide, 2003). The determination of the
percentage leaf area damaged by the disease
showed that up to 37 % of the total leaf area was
destroyed in all the locations. Previously, Maduewesi
(1975) reported that about 22 % of the total leaf area
of cassava was destroyed by Cercospora leafspot
disease in naturally infected fields at Nsukka. In a
similar development, Ilondu and Ayodele (2003)
reported that about 16 % of the total leaf area of
tobacco was damaged by leafspot disease at Sapele,
Nigeria.
were among the pathogens of leafspot disease of
tobacco (Nicotiana tabaccum) and phylloplane
mycoflora of fluted pumpkin (Telfairia occidentalis)
respectively. Ewekeye and Odebode (2008) reported
Fusarium as one of the causal pathogens of leafspot
disease of Croton (Codiatum variegatum L. Blume).
Amienyo and Ataga (2008) reported that the leafspot
disease of sweet potato was caused by Fusarium
culmorum. The chlorotic leaf distortion disorder of
sweet potato was reported by Clark and Hoy (1994)
to be caused by Fusarium lateritium.
There is a dearth of information on the pathogenicity
of F. solani on leafspot disease of sweet potato.
However, F. solani is a filamentous fungus known to
be the most destructive form-species on potato,
producing mycotoxin called Naphthoquinones and
Fusaric acid as well as inducing accumulation of
Furanoterpenoids in sweet potato (Clark et al., 1981).
It is cellulolytic causing root rots, spoilage of foods,
fruits and vegetables (Mongar and Grover, 1991;
Suberu, 2003).
The implication of the increasing foliar diseases of
sweet potato is obvious. At gross morphological
level, photosynthesis may be drastically reduced by
pathogens growing or killing areas of the green leaf
(Parry, 1990). The physiological changes which
commonly occur in plants under pathogenic inversion
include: increased respiration rates and reduced
photosynthesis leading to possible yield losses
(Bilgrami and Dube, 1976). The quality and quantity
of the leaves used as vegetables and fodder will be
reduced (Amienyo and Ataga, 2008).
There was no previous report implicating M. hiemalis
f. luteus as a leafspot pathogen. Possibly it acted as
a secondary invader of the leafspot lesions caused
by C. lunatus, F. lateritum and F. solani singly or in
combination, since it was occasionally isolated in
association with them, but could not reproduce the
leafspot symptoms on sweet potato. Thus as pointed
out by Ilondu and Ayodele (2003), such organism
when tested against the host in the absence of the
primary pathogen would have no effect. According to
Ilondu and Ayodele (2005), pathogenic fungi on the
leaf surface may provide nutrient directly for the
saprophytes either through the decay of the tissue or
liberation of nutrient from their teleospores.
Of all the fungi reported in this study as associated
with leafspot disease of sweet potato in all the
locations, only Cochliobolus lunatus, Fusarium
lateritium and Fusarium solani were shown through
inoculation tests to produce leafspot disease
symptoms in sweet potato. These results indicated
that leafspot diseases of sweet potato in Central
District of Delta State, particularly at Abraka, Oghara,
Sapele and Ughelli under natural conditions were
caused by either of these fungi or a combination of
them. The involvements of Curvularia lunata, the
Cochiliobolus lunatus anarmorph in leafspot disease
of crop plants have been reported by researchers.
Maduewesi (1977) implicated Curvularia spp (C.
fallax; C. brachyspora and C. verruculosa) with the
white leafspot disease of Telfairia occidentalis in
Nigeria. Leafspot symptoms on Dioscorea rotundata
has been attributed to infections by Curvularia
eragrostidis (Green 1995). C lunata (Wakk) Boed
was reported to induce leafspot and head blight
symptoms on wheat grown under rain-fed condition
(Enikuomehin et al., 1999). Similarly, Okoi and Ataga
(1999) reported that C. lunata caused leafspot
disease of Okra while Odigie (2000) reported that
leafspot disease of oil palm (Elaesis guineensis
Jacq.) was caused by C. clavata. On the other hand,
Fusarium species are ubiquitous and have been
associated with various leaf diseases. Ilondu and
Ayodele (2003, 2005) reported that Fusarium species
CONCLUSION
From this study, it has been found that the leafspot
disease of sweet potato in Central District of Delta
State, especially at Abraka, Oghara, Sapele and
Ughelli are caused by C. lunatus, F. lateritium and
F.solani. The isolation study also showed that C.
lunatus was the most frequently isolated and most
pathogenic among the leafspot fungi. The percentage
leaf area damage vary in different location with a
maximum of 48.33% in Sapele. With the knowledge
of etiological agents of leafspot disease of sweet
potato, this study has provided baseline information
on the strategies for the management of leafspot
diseases of sweet potato. Consequently, this will
contribute to food security and poverty alleviation to
resource-limited families in the district.
482
Agric. Biol. J. N. Am., 2013, 4(4): 476-484
Enikuomehin, O. A., L.A. Kahinde, and O. Shokalu, (1999).
Pathogenicity of fungi associated with rain-fed wheat
(Triticum aestivum L.) in South-western Nigeria. Niger.
J. Plt. Prot. 18: 67-74.
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