International Research Journal of Plant Science (ISSN: 2141-5447) Vol. 4(1) pp.12-18, January 2013
Available online http://www.interesjournals.org/IRJPS
Copyright © 2013 International Research Journals
Full Length Research Paper
Identification and control of fungal pathogens of
tectonia grandis (l.f) seedlings in Akwa Ibom State,
Nigeria
*Ukoima, HN, Akpan, EE, Pepple, GA
Department of Forestry and Environment, Faculty of Agriculture, Rivers State University of Science and Technology,
Port Harcourt
Abstract
Tectonia grandis (Teak) is perhaps best known for its long established use in the boat building
industry. It also used for decking, deckhouses, rails bulwarks, hatches, weather doors or planking,
pipes and chemical vats. However, teak is susceptible to various kinds of pests and diseases
especially in Akwa Ibom State. This study was therefore, conducted to identify and control fungal
pathogens found on T. grandis seedling in Akwa Ibom State nurseries.The experiment was
conducted in a screen house using soil samples from Ikot Abasi, Uyo, Itu and Ikono forestry
nurseries. Soil analysis, pathogenicity test, isolation and identification of pathogens were carried out
according to standard guidelines spelt out by Common wealth mycological Institute and Soil Science
H
Society. The results showed that, p values for Ikot Abasi and Ikono were 5.1 and 3.8 respectively. The
mean value for organic matter for Ikot Abasi and Ikono were 1.4 and 1.9 respectively. Exchangeable K
for Ikot Abasi was 0-18 c-mol/kg and 0.12 for Ikono. Ten fungal species were viz: Sclerotium rolfsii,
Fusarium oxysporum, Pythium debaryanum, Armillaria mallea, Rhizoctonia solani, Aspergillus niger,
Aspergillus flavus. The mortality of seedlings per nursery soil was 80%, 70% and 20% for Ikono, Itu
and Uyo respectively. The mean fungal population for Ikono was 2.1, for Itu 1.9 and 1.2 for Uyo .
Pathogenicity test confirmed that Armillaria mallea, Sclerotium rolfsii, Pythium debaryanum and
Fusarium oxysporum were pathogenic to Tectona grandis seedlings. At 500 ppm concentration of
methyl bromide, the mycelial dry weight of Fusarium oxysporum was 0.03g, sclerotium rolfsii weighed
0.02g while there was no growth at all with Pythium debaryanum. With palm bunch ash at 100ppm
Fusarium oxysporum gave mycelia dry weight of 0.02 whereas there was no growth of sclerotium
rolfsii. This result showed that methyl bromide and palm bunch ash are effective control measures
against the identified pathogens.
Keywords: Pathgenicity test, Tectona grandis, Pathogens, Agro- chemicals and Plant extracts.
INTRODUCTION
Tectona grandis is of the family Verbenaceae. It grows
well in good sites up to 45 meters and produces an
outstanding timber (Farmer, 1972).
The sapwood is white to pale yellow-brown, narrow
to moderately wide. The heartwood is a dark golden-
*Corresponding
rijmanconsult@yahoo.com
Author
E-mail:
yellow when fresh, turning to a dark golden brown,
sometimes with dark markings. On prolonged exposure
to the weather the color becomes lighter. The grain is
generally straight but may occasionally be figured.
Texture is moderately coarse and uneven due to the
presence of growth rings. It is moderately hard and
moderately heavy weighing approximately a tonne per
1.5 cubic meters of seasoned sawn timber. Teak
possesses excellent properties and as such it has a very
wide range of uses including flooring, decking, framing,
cladding, fascias and large boards. In the decorative line
Ukoima et al. 13
it can be used for lining, paneling, turnery, carving,
furniture (both indoor and outdoor) and parquetry. Teak
is perhaps best known for its long established use in the
boat building industry. It has been extensively used for
decking, deckhouses, rails bulwarks, hatches, weather
doors or planking. It is used for cooperage, pipes and
chemical vats. (Farmer,1972).
Teak is susceptible to various kinds of pests and
diseases. Generally, defoliators and skeletonnizers
cause the greatest problems. However, chemical control
except in nurseries or young plantations is not practical.
The life cycle of these pests are so short and follow each
other so rapidly that it is not considered cost-effective to
organize such remedial measures as aerial dusting or
spraying (Robertson, 2002). The root rot of teak, which
is becoming endemic in Nigeria, is caused by
Rigidoporus lignosus. A survey reported that 11 to 13
year old trees in parts of Olukemeji forest Nigeria had
fallen over from root rot. Some parasites of trees
especially fungi and bacteria, cause the development of
galls by the host tree. A notable example here is
Phytolima lata which attacks Iroko( Chlorophora excels)
in West Africa. All young trees in a nursery may be killed
within a short time. In general, plant parasites found in
forest ecosystems may attack and destroy leaves,
branches, boles, roots and even flowers and fruits of
forest trees.
Sometimes young seedlings are destroyed by
damping off parasites particularly soon after seed
germination. Damping off may also through root infection
kill a tree after its stem had become woody. (Nwoboshi,
1982).
According to Balasundaran (2002), in India Teak is
affected by a few serious diseases both in nurseries and
plantations. Leaf spot caused by Phomopsis spp,
collectotrichum gloeosporoides, Alternaria spp and
Curvularia spp, leaf rust by Olivia tectonae and powdery
mildew by Uncinula tectone are the major leaf diseases
in nurseries in Kerala. During 1993 and 1994, 95% of the
nurseries, leaf infection caused by Phomopsis spp in
combination with C. gloeosporiodes were predominant.
Phomopsis spp leaf necrosis, localized in patches
almost year-round affecting 2 to 8 month old seedlings is
more serious after the monsoon in nursery beds of high
seedlings density. The characteristic symptom is the
development of light brown necrosis at the margin of
leaves, which gradually advances toward the midrib. The
disease spreads to the upper leaves, petiole and
ultimately to the terminal bud and stem top leading to the
dying up of upper portion of the stem. At this stage a few
secondary sprouts emerge from the top of the stump.
However, in most cases the affected seedlings die in the
absence of control measures. Leaf spot caused by C.
gloesporiodes is characterized by the development by
the development of interveinal dark-brown spots which
coalesce to form large necrotic areas. The disease
occurs commonly mixed up with Phomopsis leaf
necrosis. Leaves affected by these two leaf spots get
dried up and defoliate. If timely control measures are not
taken, the diseases spread to the entire nursery,
reducing the number of healthy seedlings available for
planting, thus upsetting the planting programme
considerably. Leaf rust, generally observed in August/
February also affects the production of healthy planting
stock. A severe infection leads to extensive premature
defoliation. Leaf spots caused by the other pathogens
are of less significance, even though they are capable of
causing some defoliation in serious cases.
Other diseases which affect Teak seedlings in the
nursery include root rot caused by Polyporous zonalis.
Pink disease fungus causes cankers and bark flaking.
Powdery mildews caused by Olivea tectoriae and
Uncinula tectonae leads to premature defoliation
(Hedge, 2000).
Annual returns at Forestry Headquarters Uyo
revealed that such stations as Itu, Ikot Abasi, Ikono, Nsit
Atai and Mbo lost up to twenty percent of the seedlings
raised due to death not related to water stress or other
environmental conditions. Such deaths occurred within
the first two months of planting in the nursery. To avoid
such loses, nursery staff travel long distances to collect
top soil for broadcasting of seeds and filling of poly pots.
This is aggravated by deforestation, making Akwa Ibom
State a wood- deficit state, therefore, depending on
neighboring states for her wood needs. A study of the
wood demand and supply for Akwa Ibom State reveals a
pathetic situation for a state whose towns and cities are
fast expanding and with a great demand for wood
needed for its expansion. Currently Akwa Ibom is
2
experiencing wood deficit of about 2,445,482m which is
responsible for the high cost of wood products in the
state. By the year 2010 Akwa Ibom will have to ‘import’ a
2
total of 2,572,738m of wood to meet her domestic
requirements (Akpan-ebe ,2006).
Empirical records on pathogens which affect
seedlings in Akwa Ibom State is unavailable. This work
therefore looked into fungal pathogens which affect
Tectona grandis seedlings in the state nurseries to
forestall seedling loss and hence improve seedling
production in the state nurseries. The study also looked
at the following objectives; To conduct soil analysis at
the four locations, identification of the fungal species
present in the soil of the four nurseries, assess the
mortality of teak seedlings in four locations, conduct
comparative study on the effect of fungal population on
survival of seedlings, carry out pathogenicity test ,
control of fungal pathogens associated with teak using
synthetic chemicals and plant extracts (biocides) and
some baseline data on the area of study.
MATERIALS AND METHODS
Location/Climate
This work was conducted in Akwa Ibom State of Nigeria.
14 Int. Res. J. Plant Sci.
Four forestry nurseries were chosen and strategically
located to represent the state. Ikot Abasi is on the coast
of the Atlantic and shares the same boundary with
Rivers State, Uyo is the state capital almost centrally
located. Itu is at the bank of the Cross River, a border
town with Cross River State, Ikono is close to the
Northern boundary with Arochukwu in Abia State. Akwa
Ibom State with an estimated current population of about
3.44 million (Akwa Ibom State Government 2004) is one
of the 36 states in the Nigerian federation. It lies in the
south-south geographical zone. The state lies
o
0
approximately between latitudes 4 33’ and 5 33’ North
0
0
and longitude 7 25’ and 8 25’ East. It has a total land
2
area of 8,412km and a coastline of 129km long (AKS
Ministry of Environment 2002). It is generally flat and of
low relief with sandy coastal beaches. In the coastal
fringes are the mangrove swamps and flood plains,
which disappear imperceptibly into gentle rolling plains in
the Northern parts while undulating relief dominate the
other parts. There are two main geomorphologic units in
the state viz: the coastal sedimentary lowlands of low
relief and the alluvium mangrove and freshwater
swamps criss-crossed with lagoon water bodies. The
climate is sub equatorial with rainfall increasing from
about 2000mm in the North to about 4000mm in the
South. There are two distinct seasons – rainy season
which lasts about eight months and dry season which
lasts about four months November to March. Akwa Ibom
2
has a total forested area of 318km of forest reserve.
This forms only 4.40% of the State land area and 0.03%
of the country’s forest reserves. ( Udo 1992).
different locations 0-15cmand 15-30cm depths. This was
thoroughly mixed to ensure that all soils aggregates
were broken down. 10gm of sample was mixed with
sterile distilled water (H2O), shaken and diluted three
times. A certain quantity 10ml of the soil suspension was
poured into a sterile Petri dish containing Potato
Dextrose Agar (PDA) medium and incubated for 7 days
oC
at 28 , fungal species which sporulated were isolated
and identified. (Blazak 1981; Barnett and Hunter, 1972).
Nursery preparation in the Screen house
Pathogenicity Tests
One broadcast base 1×1×0.5m was use for the
broadcast of the Tectona grandis seeds. The soils were
sterilized in an autoclave for 30 minutes at 15p.s.i. viable
seeds were treated to break dormancy. It was watered
daily using watering cans.
To confirm that the pathogens were responsible for the
disease and death of the seedlings; healthy seedlings of
Tectona grandis were raised in soil inoculated with
isolated pathogens. Cultures for contaminating the soil
were grown on corn meal 4.0g, washed sand 195g; 20ml
of distilled water, in 150ml conical flasks. It was
-2
autoclaved for 20 minutes at 1.03kgm . This was cooled
and infected with eight discs of 5mm diameter from the
edge of 3-day old agar cultures of the isolates. The corn
meal cultures were incubated at room temperature for 2
weeks, shaken periodically to disperse mycelia (Okpala,
1975) .50g of culture was mixed with sand in each poly
pot before planting. To inoculate the seedlings, the
seedlings were washed in running tap water for 5
minutes and sterilized by soaking in 1% sodium
hypochlorite. They were rinsed with sterile distilled water
and soaked again for 30 seconds in 70% alcohol and
finally rinsed in sterile distilled water. (Onuegbu, 1997).
Each of the seedlings (root) were covered with 20gm of
the corn meal culture, transferred to the poly pots and
maintained for growth and observation. Diseased
seedlings were uprooted and the pathogens involved reisolated and identified.
Soil Analysis
Soil samples were collected randomly per location using
auger at 0-15cm and 15-30cm depth. Samples were air
dried, thoroughly mixed, sieved and divided for different
analysis. The pH, Potassium, Phosphorus and Nitrogen
were determined as described by (Doran and Jones,
1996; Bray and Kurtz, 1945).
Isolation and Identification of Fungal
Present in the Soils of the Four Nurseries
Species
The method used was the serial dilution plate method
(Hawker and Linton 1974; Akachuku and Amakiri 1992).
50 grams of soil samples were taken randomly at five
Motality of Teak Seedlings in the Four Locations
Teak seedlings at four-leaf stage were planted in poly
pots containing the four nursery soils in a screen house.
It was replicated 5 times. The seedlings were watered
daily and uniformly at the rate of 15ml water per
seedling. The set up was maintained and monitored for
12 weeks.
Determination of the Effect of Fungal Population on
T. Grandis Seedlings
This study was done in the four nursery soils; a
composite sample of the soils was used to fill 10 poly
pots in 3 replicates. Healthy teak seedlings were planted
in all poly pots, watered regularly, maintained and
th
observed for 12 weeks. At the end of 12 week the
number of dead and living seedlings was noted and
recorded.
Ukoima et al. 15
Control of Fungal Pathogens Associated with
Tectona Grandis using Chemicals and Biocides
Effect of some agro chemicals and plant extracts on
growth of fungal isolates was tested using fungicides
such as Methyl Bromide, Oxalic acid and Plant extracts
such as palm bunch ash and Garlic extract.
One hundred ppm each of the agro chemicals in 1ml
distilled water (0.1g in 1 liter of distilled water).
The solution was dispensed into 10ml capacity flask
containing sterile potato Dextrose broth. Each 5mm
fungal disc was separately inoculated into the flask and
o
incubated on the laboratory bench 28 C for 14 days.
The fungal mycelium was filtered using Whatman No 1
o
filter paper and dried to constant weight at 60 C. The
experiment which was replicated three times was
repeated using 500 and 1000ppm of each chemical.
Sterile potato dextrose broth 100ppm was used as
control. (Onuegbu, 1997).
For the palm bunch ash 50g, 100g and 200g per liter
of distilled water concentration was used. The final
weight after drying was noted and recorded. Differences
in the effect of the chemicals, on the growth of the fungal
isolates were tested by Analysis of variance.
The potency of garlic extract on the fungal
pathogens was studied in the laboratory. Three rates of
garlic extract 10g/liter, 30/liter and 60/liter was used in
the experiment. Glucose solution 10g/liter served as
control.
Procedure
The garlic extract and glucose were dropped on glass
slides and stored in sterile Petri dishes. Spores of fungi
were aseptically collected from pure cultures and
smeared on the glass slides containing garlic extract.
Each treatment was replicated 3 times. The slides were
kept in Petri dishes and incubated for 8 days in the
o
laboratory bench at 28 C. Observation was made on the
th
th
th
4 , 6 and 8 days of incubation. The germination rates
of the spores were assessed according to (Nwoboshi,
2000).
RESULTS
Fungal Species Isolated from the Four Nurseries
Table 2 shows the list of fungal species isolated from the
four nursery soils. Ten (10) species were
identified.Aspergillus
niger,
Aspergillas
flavus,
Sclerotium
rolfsii
Rhizoctonia
solani
Pythium
debaryanum, Rhizopus stolonifer, Armillaria mallea,
Penicillium spp, Fusarium oxysporum and serratia spp.
Mortality of Teak Seedlings in the Four Locations
The result on table 3 shows that at week 12, 70% of the
seedlings were dead at Itu, 80% at Ikono, 60% at Ikot
Abasi and 20% at Uyo. The highest mortality was at
Ikono and the least in Uyo 20%. This was also significant
at P < 0.05.
Coefficient of variation between
(d) and (a)
(d) and (b)
(d) and (c)
= -6
= -9
= -3
Pathogenicity Test
The result on pathogenicity test revealed that Armillaria
mellea, Sclerotium rolfsii, Pythium debartanum and
Fusarium oxysporum were pathogenic on Tectona
grandis. Symptoms such as yellowing of leaves and
rapid death were observed on infected plants. This
experiment agrees with the research done by Hawker
and Linton (1974).
Control of Fungal Pathogens of Tectona Grandis
The result on disease control is shown on table 4. Methyl
Bromide at 100ppm and 500ppm had more effect in
inhibiting mycelial growth (0.20g and 0.016g)
respectively than Oxalic acid which inhibited mycelial
growth (0.29g and 0.06g). The result also showed that
both chemicals are effective in inhibiting mycelial growth
as the control experiment recorded higher mycelial dry
weight than the treated experiment. The result is
significant at P < 0.05.Also, Methyl and Oxalic acid are
more effective on Pythium than Fusarium and Sclerotium
spp.
Soil Analysis
The result shows that pH decreases from the coast to
the hinterland. pH 5.15 at Ikot Abasi near the sea and
pH 3.8 at Ikono on the Nothern fringes. The mean value
of organic matter is 1.44 at Ikot Abasi and highest in
Ikono 1.99 (Table 1). The result also indicated that
available phosphorus , percentage organic matter and
organic carbon were higher than other soil properties
such as nitrogen and exchangeable cations.
Control of Pathogens Using Palm Bunch Ash
The result on palm bunch ash is shown in Table 5. At
200ppm concentration, there was no mycelia growth for
all fungal pathogens. However, at 100ppm fungal growth
was 0.01g mycelia dry weight; 50ppm recorded 0.28g
mycelia dry weight and the control had 0.70g mycelia dry
weight.
16 Int. Res. J. Plant Sci.
Table 1. Soil properties in selected nurseries in Akwa Ibom state
H
S/No.
LOCATION
SOIL AVAILABLE
DEPTH(CM)
SOIL P
ORGANIC)
CARBON(%)
ORGANIC
MATTER(%)
TOTAL
NITROGEN(%)
1. IKONO
0-15
15-30
Average
0-15
15-30
Average
0-15
15-30
Average
0-15
15-30
Average
3.80
3.85
3.83
5.50
4.80
5.15
4.83
4.95
4.85
4.37
4.63
4.50
1.05
1.26
1.16
1.07
0.60
0.84
0.80
1.01
0.91
0.95
1.22
1.09
1.81
1.17
1.99
1.84
1.04
1.44
1.37
1.74
1.56
1.64
1.82
1.73
0.07
0.09
0.08
0.06
0.04
0.05
0.04
0.05
0.05
0.07
0.08
0.08
2.
IKOT
ABASI
3. ITU
4. UYO
EXCHANGEABLE
MOL
KC /KG Pµ/g
0.11
29.47
58.95
0.13
0.12
44.21
0.18
45.61
0.18
0.35
0.18
22.98
0.17
9.12
0.22
2.81
0.19
5.97
0.11
87.02
0.17
70.18
0.15
78.6
Table 2. Fungal species isolated from nursery soils
ITU
Species
Aspergillus niger
Aspergillus flavus
A. flavus
Penicillium sp
Penicillium sp
Rhizopus stolonifer
R. stolonifer
Sclerotium rolfsii
F. oxysporum
Armillaria mallea
P. debaryanum
Rhizoctonia solani
IKOT ABASI
IKONO
Rhizopus stolonifer
A.
niger
stolonifer
Armillaria mallea
A. flavus
Serratia sp
Sclerotium rolfsii
Rhizoctonia solani
Fusarium oxysporum
Pythium debaryanum
Rhizoctonia solani
S. rolfsii
P. debaryanum
Penicillium sp
UYO
A. niger
Table 3. Mortality of teak seedlings in the four locations.
Location
ITU (a)
IKONO (b)
IKOT ABASI (c)
UYO (d)
No of seedling
surviving
after
week 12
3
2
4
8
LSD @ 0.5
Coefficient of variation between
No dead before
week 12
Percentage
loss
7
8
6
2
70%
80%
60%
20%
(d) and (a)
(d) and (b)
(d) and (c)
Effect of Garlic Extract on Germination of Sclerotium
spp
The result of this experiment shows that garlic extract is
= -6
= -9
= -3
effective in the control of the growth of sclerotium rolfsii.
Whereas there is 100 percent germination of sclerotia in
the control (glucose solution), there is only 20 percent
germination in 30g/lit of garlic extract and zero percent
Ukoima et al. 17
Table 4. Effect of different agro chemicals on the growth of fungal isolates
ISOLATES
Fusarium oxysporum
Sclerotium rolfsii
Pythium debaryanum
Mean mycelia dry
Weight
METHYL BROMIDE (PPM)
(a)
0
100
500
1000
0.69g
0.25g
0.03g
0.00g
0.63g
0.20g
0.02g
0.00g
0.6g
0.15g
0.00g
0.00g
0.66g
0.20g
0.016g
0.00g
0
0.75g
0.68g
0.73g
0.72g
OXALIC ACID (PPM)
(b)
100
500
0.36g
0.06g
0.39g
0.08g
0.20g
0.04g
0.29g
0.06g
1000
0.00g
0.00g
0.00g
0.00g
LSD @ 0.5
Coefficient of variation between a1 and b1 = 0.084
“
“
“
“
a2 and b2 = 0.0427
“
“
“
“
a3 and b3 = 0.038
Table 5. Effect of palm bunch ash on the growth of fungal isolates
ISOLATES
Fusarium oxysporum
Sclerotium rolfsii
Pythium debaryanun
Mean
mycelia
dry
weight
PALM BUNCH ASH (PPM)
0
50
100
200
0.70g 0.34g 0.02g
0.00g
0.69g 0.20g 0.00g
0.00g
0.73g 0.30g 0.01g
0.00g
0.70g 0.28g 0.01g
0.00g
LSD @ 0.5
germination at 60g/lit concentration of garlic extract
(Table 6).
DISCUSSION
The result showed that Aspergillus niger, Sclerotium
rolfsii, Rhizoctonia solani, Aspergillus flavus, Pythium
debaryanum, Armillaria mallea, Fusarium oxysporum,
Rhizopus, Stolonifer Penicillium sp and Serratia sp
occurred in the selected sites in Akwa Ibom State. Also,
these fungi appear to tolerate a wide range of acidic pH
of 3.80-5.15 since they were isolated from such soils.
This agrees with the findings of Wheeler, (1978) who
suggested that most fungi do occur in slight acidic to low
alkaline soils. Similarly, most fungal pathogens are
active between pH 3.8 and 8.2 (Agrios, 1969). The rise
of soil pH up to 14 drastically reduces their activity.
The result on seedlings mortality showed that fungal
population had an effect on the growth of Tectona
grandis seedlings. For example, at Ikono with the
4
highest fungal population of 2.3 × 10 per gram of soil
only two seedlings survived to week 12. While in Uyo
4
with a fungal population of 1.25 × 10 , 8 seedlings
survived to week 12. This finding agrees with what was
done by Onuegbu (1997) who opined that the fungi
isolated from T. grandis are pathogenic. The seedlings
transplanted at four leaf stage had the largest number of
deaths within the first six weeks of planting. This agrees
with the assertion by Dickerson and Lucas (1982) that
one major factor in seedling death is the relative ease
with which pathogens penetrate juvenile trees due to the
absence of well developed external structures like cuticle
on the stem and roots. The ability of the isolated
pathogens acting in isolation and combining to cause
severe damage to the seedlings confirm that Sclerotium
rolfsii and Fusarium oxysporum in the nursery soils were
responsible for the loss of the seedlings by blocking the
vessels and causing damping off and wilt. Also, the
result indicates that under favorable conditions several
pathogens can co-exist to attack susceptible hosts like
Tectona grandis seedlings. The result is collaborated by
findings of Alexopoulos (1974) and Wheeler (1969),
which identify 3 species of Fusarium and two species of
Sclerotium as parasites which cause vascular wilt of
seedlings by plugging the conducting tissues and toxin
secretions as well.
At 100ppm and 500ppm concentration, Methyl
Bromide is more potent than Oxalic acid. Palm bush ash
is the best of the three showing higher potency even in
smaller concentrations of 50ppm and 100pmm. The
actions of garlic extract on fungal spores agree with the
18 Int. Res. J. Plant Sci.
Table 6. Effect of garlic extract on germination of sclerotia of isolates
Concentration (g/litre)
Percentage germination
Sclerotia (average values)
Glucose
Solution
10g/liter
100
findings of Nwoboshi (2000) in a similar experiment.
Okpala (1974) working on organic soil amendment on
damping off lettuce commended the advantages of
biological control measures over chemical control in the
nursery. His findings were also supported by Lewis
(1991 and Tschen 1992).
Lazzen (2002) reported
the suppressive activity of Brassica plant green manure
against soil-borne phytopathogenic fungi as an
ecological alternative to Methyl bromide in horticulture.
Treatment with the green manure crop increased
Pythium propagules four-fold while after three weeks C.
hassleriana treatment reduced Pythium by 88% as
compared to untreated soil.
In summary, Armillaria mallea, Sclerotium rolfsii,
Pythium debaryanum and Fusarium oxysporum are
present in the nurseries studied and do cause young
seedlings to wilt and die. Treatment of the soil with heat,
Methyl Bromide, Oxalic acid and palm bunch ash is
recommended to reduce the effect of the pathogens on
the seedlings.
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