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African Journal of Plant Science Vol. 6(13), pp. 337-345, October 2012
Available online at http://www.academicjournals.org/AJPS
DOI: 10.5897/AJPS12.040
ISSN 1996-0824 ©2012 Academic Journals
Full Length Research Paper
Distribution, incidence, severity and effect of the rust
(Puccinia abrupta var. partheniicola) on Parthenium
hysterophorus L. in Western Hararghe Zone, Ethiopia
Zelalem Bekeko1*, Temam Hussien2 and Taye Tessema3
1Haramaya University, Chiro Campus, P O Box 335, Chiro, Ethiopia.
2Haramaya University, P O Box 138, Dire Dawa, Ethiopia.
3Ethiopian Institute of Agricultural Research, P O Box 3002, Addis Ababa, Ethiopia.
Accepted 10 September, 2012
Parthenium is an exotic invasive weed that originated in South America, and has formed severe
infestations in Ethiopia. This weed is known to be host to various micro-organisms such as the rust
pathogen Puccinia abrupta var. partheniicola that may be used as a component of integrated
parthenium weed management. Field surveys were conducted in 2008 and 2009 cropping seasons in
eastern Ethiopia to determine distribution, incidence, and severity of the rust (P. abrupta var.
partheniicola) on this weed. In addition, the effect of this pathogen on morphological parameters of
parthenium was studied both in the field and in the greenhouse at the Plant Protection Research
Center, Ambo. A total of 218 fields were surveyed in four districts (Chiro, Gemechis, Kuni and Tullo) of
Western Hararghe Zone, eastern Ethiopia. All the fields surveyed were infected with the pathogen,
indicating that the disease was widely distributed in the zone. The incidence of rust in the surveyed
area ranged from 25 to 74% while severity ranged from 18 to 55%. The highest (74%) and the lowest
(25%) disease incidence were recorded in Tullo and Chiro, respectively, while the highest (55%) and the
lowest (18%) disease severities were encountered at Gemechis and Chiro, respectively. Altitude had
significant effect on both disease parameters (p ≤ 0.05). The effect of this pathogen on morphological
parameters of parthenium under field conditions was found to be significant (p ≤ 0.05) at all locations.
The effect of the rust on parthenium dry matter and seed production was significant (p ≤ 0.05) at all
locations. Also, the effect of the rust on morphological parameters of parthenium in the greenhouse
was significant (p ≤ 0.05). In addition, there was significant variation in the number of rust pustules per
leaf, leaf senescence, and number of leaves attacked per plant, disease incidence and severity both at
14 and 21 days after inoculation. In the greenhouse, comparison of isolates from Ambo, Kuni, and Tullo
showed significant effect while isolates from Chiro and Gemechis performed poorly for all the studied
morphological parameters of parthenium. This study indicated that P. abrupta var. partheniicola has the
potential to reduce morphological parameters as well as dry matter and seed production capacity of
parthenium weed. It also elucidated the presence of variation in aggressiveness of the isolates.
However, more extensive studies need to be undertaken at molecular level to utilize this pathogen in
combination with other host-specific insects and pathogens after importation and release, as a
component of integrated parthenium weed management in Ethiopia.
Key words: Parthenium hysterophorus, Puccinia abrupta var. partheniicola, aggressiveness, biological control,
disease incidence, disease severity, epidemiological factors.
INTRODUCTION
In Ethiopia, disease, insects and weeds contribute to a
loss of 42% yield reduction in field crops (Tamado et al.,
2002). Especially, weeds are one of the biotic stressors
which have contributed to the low level of grain yield,
quality of fruits, vegetables, cereals, and incurred high
level of herbicide cost. Hence, they have a strong share
338 Afr. J. Plant Sci.
in the stagnation of the country’s national economy (Taye
et al., 2004). One of the weed species which is becoming
serious in Ethiopia is Parthenium hysterophorus L., which
affects range lands, forest lands, crop lands, gardens,
orchards, and has a significant role in yield reduction
(Taye et al., 2004).
Parthenium, an invasive herbaceous weed that is
believed to have originated in tropical Americas, now
occurs widely in Asia, Australia Southern and east Africa.
It is an annual procumbent, leafy herb, 0.5 to 2 m tall,
bearing alternate, pinnatified leaves, belonging to the
family Compositae. The major ecological and
morphological characteristics that contribute to severe
invasiveness might be its adaptability to wide climatic and
soil conditions, production of allelopathic chemicals and
the ability to produce large number of seeds (10,000 to
25,000 per plant) which are small in size (1 to 2 mm
diameter) and light in weight (50 µg) to travel long
distances through wind, water and other means (Navie et
al., 1996).
It is believed to have been introduced into Ethiopia in
the 1970s during the Ethio-Somali war and has become a
serious weed both in arable and grazing lands (Berhanu,
1992; Fasil, 1994; Frew et al., 1996; Tamado, 2002).
Parthenium can cause severe crop yield losses. In India,
a yield reduction of 40% in agricultural crops (Khosla and
Sobti, 1981) and 90% reduction in forage production
were reported. In eastern Ethiopia, parthenium is the
second most frequent weed (54%) after Digitaria
abyssinica (63%) (Tamado and Milberg, 2000) and
sorghum grain yield was reduced from 40 to 97%
depending on the year and the location (Tamado et al.,
2002). Other than direct competition with crops,
parthenium poses allelopathic effect on different crops
and other plants (Mersie and Singh, 1988; Evans, 1997a;
Adkins, 2002; Wakjira et al., 2005; Adkins and Naive,
2006).
Although several methods have been developed for the
control of parthenium, each has its own limitations. For
instance, removing parthenium by slashing or mowing as
soon as or before it flowers, though it prevents seed
production, results in regeneration of new shoots leading
to a repeated operation. Manual and mechanical
uprooting also prove to be of limited value owing to
enormous amount of labour and time required (Berhanu,
1992) and vulnerability of workers engaged in the
operation to the various kinds of allergies caused by the
weed (Kololgi et al., 1997). Chemical control, though
effective, is temporary and needs repeated application,
besides it has problems of residues, selectivity,
availability and cost of application (Singh, 1997). Hence,
the use of biocontrol agents including insects, pathogens
and strong interfering smoother crops are recommended
*Corresponding author. E-mail: zelalembekeko@yahoo.com.
Tel: +251911810622.
for the long-term management of parthenium (Adkins,
2002).
Parthenium management through biological method
can be made by using different pathogens (fungal and
bacterial agents) and insects (Zygogramma bicolorata).
Use of fungal species especially P. abrupta var.
partheniicola helps in reducing parthenium morphological
parameters, seed production capacity and biological
aging or leaf senescence (Evans, 1987b; Evans 1997a;
Parker et al., 1994). Except the investigation made by
Taye (2002), so far, comprehensive study on parthenium
biological control using the rust was not made in Ethiopia.
Also, the presence of variation in aggressiveness of the
isolates of this pathogen was not studied. Therefore, the
objective of this study was to evaluate the distribution,
incidence, severity and effect of parthenium rust on
parthenium morphological parameters under field and
greenhouse conditions in Western Hararghe Zone,
Oromia Regional State, Ethiopia.
MATERIALS AND METHODS
Field study
Description of the study area
Field surveys were conducted in major parthenium infested areas of
Western Hararghe Zone in four districts (Chrio, Gemechis, Kuni and
Tullo) during September to December 2008 and October to
December 2009. W est Hararghe is located between 7° 55′ N to 9°
33′ N latitude and 40° 10′ E to 41°
39′ E longitude. The major crops
grown in the study area are sorghum, maize, chat, field beans,
potato and tef. The area is characterized by Charcher Highlands
having undulating slopes and mountainous in topography. The
mean annual rainfall ranges from 850 to 1200 mm/year with
minimum and maximum temperatures of 12 and 27°C, respectively.
Survey on the distribution, incidence and severity of rust on
parthenium
Field surveys from September to December 2008 and October to
December 2009 were made in four districts (Chrio, Gemechis, Kuni
and Tullo) of W estern Hararghe Zone, where parthenium infestation
was found to be high and exhaustive inventory of parthenium
infestation with rust was made (Taye, 2002).
Assessment of rust on parthenium was conducted in different
habitats: cultivated (80%), vacant (10%) and grass lands (10%), to
study the distr ibution, incidence, severity and effect of the rust (P.
abrupta var. partheniicola) on morphological parameters of
parthenium. Rust incidence and severity were recorded and its
effect on morphological parameters was evaluated by comparing
diseased and healthy parthenium plants.
Assessment of rust disease incidence
Percentage of parthenium plants with disease symptoms over the
total plants in a 1 m × 1 m (1 m2) was assessed. In each locality,
five c ounts were taken per field and 3 to 5 fields per location were
assessed at an interval of 8 to 10 km per location as indicated on
the car speedometer. Rust incidence was calculated using the
following formula:
Number of parthenium plants with disease
Rust incidence = × 100
Total number of parthenium plants/m
2
Assessment of rust disease severity
Rust severity (% leaf area covered by rust) was ass essed on twenty
plants per field by moving in each field in a zigzag manner. The 1 t o
5 disease scoring scale suggested by Ambo (PPRC, 2000) was
used to assess the rust severity level.
Assessment of parthenium dry matter production
Dry matter production was assessed at flowering stage on five
diseased and five healthy plants. The plants were harvested,
weighed and kept in an oven dry at a temperature of 105°C f or 72
h. Then the proportion of the weight loss was assessed:
W
eight of dry parthenium
plants
% Dry matter production = × 100
Weight of fresh parthenium plants
Determination of the effects of rust on parthenium
morphological parameters and seed production
Effect of rust on parthenium morphological parameters and seed
production capacity were studied under field condition by
comparing healthy and rust infected plants. Samples were collected
from parthenium infested areas at flowering stage. The
morphological parameters considered were plant height, number of
leaves per plant, leaf length, leaf width, leaf area, number of
branches per plant and dry matter weight. Two separate samples
were collected; one for t he determination of the effects of rust on
morphological parameters, and the other for the determination of its
effects on seed production.
Effect on morphological parameters
Forty plants (20 healthy and 20 diseased) were observed by
moving diagonally in crop fields and non-crop lands in Chiro,
Gemechis, Kuni and Tullo districts in 2008 and 2009 main crop
seasons. Morphological data and sample collection were made late
in the evening to avoid drying of plants. Finally, data from different
locations were analyzed using Chi-square (x2) test, and percentage
proportion of the effect were used to test the presence of significant
difference within locations and among districts (Gomez, 1984; Taye
et al., 2004).
Effect on seed production
Forty matured plants (20 healthy and 20 diseased) were c ollected
by diagonally moving in the fields at Chrio, Gemechis, Kuni and
Tullo districts, and comparison on the effect of the pathogen on
seed production was made between Chrio and Tullo districts
representing mid altitude and high land areas, respectively. The
dried plants were threshed and clean s eeds were weighed.
Laboratory and greenhouse studies
Greenhouse studies
Greenhouse studies were conducted at Ambo PPRC located 125
km west of Addis Ababa. Seeds were collected from matured
Bekeko et al. 339
parthenium plants in September 2009 from western Hararghe zone
and seedlings were raised. To avoid surface c ontaminants, seeds
were disinfected with 5% NaOCl for 2 min and soaked in a sterile
distilled water to remove excess NaOCl. Pots having 25 cm × 15
cm × 30 cm volume were filled with garden s oil, sand and manure
in the ratio of 2:1:1. Seeds were sown on this prepared media.
Assessment of aggressiveness of rust isolates
Collection of spores: Rust spores were collected from different
districts of W est Hararghe Zone fr om September to October 2009
from leaves and stems of diseased parthenium plants. Collected
plants were pressed, sun dried and transported to Ambo PPRC.
Rust pustules were scratched off from these materials and kept in
vials and placed in refrigerator at 4°C until used for aggressiveness
test. Fresh spores were collected from Ambo and used as a
reference test because their pathogenecity was already known
(Taye et al., 2004).
Multiplication of rust on parthenium seedlings: Isolate viability
was tested by carrying out spore germination test in the laboratory.
Briefly, spores were thinly spread over a wet filter paper in a Petri
dish and incubated at room temperature and germination
percentage was determined after 24 h and inoculated to parthenium
seedlings for mass multiplication.
Inoculation of spores
Inoculum was prepared by mixing rust spores in sterile distilled
water and a drop of 0.01% Tween 80, and the concentration was
adjusted to approximately 105 spores per ml using
haemocytometer. The suspensions were sprayed with hand sprayer
on the leaves at 4 to 6 leaves stage (Parker et al., 1994).
Inoculated plants were sprayed with fine droplets of water to
create dew and kept in plastic chamber to maintain maximum
humidity (≥85%). The plants were maintained at about 17°C for 24
h. After inoculation, the plants were placed in standard greenhouse
condition. Multiplied spores were inoculated to fresh seedlings on
pots to assess aggressiveness of each isolate.
Comparison of aggressiveness of rust isolates
Studies on aggressiveness of four rust isolates collected from
western Hararghe Zone and a reference isolate from PPRC area
were carried out in greenhous e at Ambo during October to
December 2009 using a randomized block design (CRD).
Data collected in the greenhouse and analysis of data
Data on the number of leaves on each plant attacked by rust and
number of pustules developed on each leaf were recorded. Effect of
the disease on plant height, leaf length, leaf width, leaf area,
number of leaves per plant, disease incidence, and disease severity
were assessed. And, analysis of variance was made using SAS
software version 9.0.
RESULTS AND DISCUSSION
Distribution, incidence and severity of the rust
(Puccinia abrupta var. partheniicola) in Western
Hararghe Zone
Field surveys on the distribution, incidence and severity
340 Afr. J. Plant Sci.
Table 1. Incidence and severity (mean value) of P. abrupta var. partheniicola on parthenium at Chiro, Gemechis, Kuni and
Tullo districts of West Hararghe Zone, under field condition.
Location Altitude (m.a.s.l) Mean of disease incidence (%) Mean of disease severity (%)
Chiro 1850 - 2300 30.00 (25.0)a 25.10 (18.0)a
Gemechis 1700 - 1950 56.17 (69.0)b 47.8 (55.0)b
Kuni 2150 - 2460 50.77 (60.0)c 40.40 (42.0)c
Tullo 1850 - 2200 59.34 (74.0)d 45.57 (51.0)d
Mean 49.02 (57.0) 39.82 (41.0)
CV 26.30 32.30
LSD 15.47 14.00
Table 2. Effect of Puccinia abrupta var. partheniicola on morphological parameters of parthenium at flowering at Chiro, Gemechis,
kuni and Tullo districts, Western Hararghe Zone.
No. Parameters Percentage reduction in size of morphological parameters
Chrio Gemechis Kuni Tullo
1 Mean plant height (cm) 10 11 8 15
2 Mean number of leaves per plant 10 12 8 23
3 Mean leaf length (cm) 31 34 26 50
4 Mean leaf width (cm) 19 21 14 40
5 Mean leaf area (cm2) 32 36 28 26
6 Mean number of branches/plant 40 46 32 33
of parthenium rust were conducted in Western Hararghe
Zone. A total of 218 fields were surveyed in four districts
(Chiro, Gemechis, Kuni and Tullo). In all the surveyed
fields parthenium weed was affected by rust and the
pathogen was widely distributed in the fields. Mean rust
incidence varied from a minimum of 25% at Chiro to
maximum of 74% at Tullo. Similarly severities of 18 and
55% were noted at Chiro and Gemechis, respectively
(Table 1). The pathogen was found to be infecting leaves,
stems, and floral parts of parthenium plants in the studied
area. Also the disease was distributed in all parts of the
studied locations ranging from an altitude of 1700 to 2460
m.a.s.l (Table 1).
The analysis of variance for both disease incidence and
severity showed that there is no significant difference
within location; but there existed a significant difference
among locations (Table 1). This might be due to the
variation in epidemiological factors (environmental
conditions, stages of the parthenium plants and
differences in aggressiveness of rust isolates) as well as
the variation in time of sampling during the survey (p ≤
0.05). Similarly, an investigation conducted by Taye et al.
(2004) showed the presence of a significant difference in
the level of rust disease incidence and severity in
different parts of Ethiopia. Location effects were highly
significant (p ≤ 0.05) for mean plant height, number of
leaves per plant, leaf width, leaf length, leaf area and
number of branches per plant. This is owing to the fact
that spore dispersal, germination and the response of the
plant to the disease vary with location and meteorological
parameters (Chemeda, 2001). Similar studies undertaken
by Parker et al. (1994) and Taye et al. (2004), showed
the existence of a significant difference among locations
both in Australia and Ethiopia, respectively.
Effect on morphological parameters
The effect of rust disease on morphological parameters
of parthenium was assessed by comparing healthy and
diseased plant samples collected from Chiro and Tullo
districts under field condition. The result showed the
disease has reduced mean plant height, number of
leaves per plant, leaf length, leaf width, leaf area and
number of branches per plant by 10, 10, 31, 19, 32 and
40%, respectively for Chrio, and 15, 23, 50, 40, 26 and
33%, respectively for Tullo (Table 2). Similarly, the results
from the Chi-square (x2) analysis of variance for
parthenium morphological parameters showed the
presence of significant difference among locations (p ≤
0.05). This might be owing to the existence of variation in
the epidemiological factors of the locations which has a
profound effect on the amount of the disease and its
effect (Appendix Tables 1 and 2).
Similarly, rust infected parthenium plants were
subjected to stress which can reduce the competitive
ability of the weed. Similar study undertaken by Parker et
al. (1994) and Taye et al. (2004), showed closer results in
utilizing this pathogen as a classical biological control
agent which is eco-friendly and economically feasible.
Bekeko et al. 341
Table 3. Effect of Puccinia abrupta var. partheniicola on dry matter and seed production capacity of parthenium
plant in Western Hararghe Zone.
No Parameter Percentage reduction in size of morphological parameters
Chiro Gemechis Kuni Tullo
1 Dry matter 35.0 45.0 38.0 36.3
2 Seed weight 50.0 42.0 42.0 72.0
In the study area, the effect of P. abrupta var.
partheniicola was more severe at Tullo than Chrio for all
parameters. This might be due to the temperature and
relative humidity variations at Chiro and Tullo as well as
the variation in the level of aggressiveness between the
isolates from both locations. That is, Tullo is cooler than
Chiro which is highly favorable for the epidemics of
parthenium rust. In an investigation conducted by Taye et
al. (2004), it was demonstrated that rust has reduced
plant height and leaf area by 11 and 25%, respectively at
Debrezit and Ambo. Thus, the present finding is in line
with their report.
As Tamado et al. (2002) reported, parthenium has
severely invaded the eastern parts of Ethiopia. Currently,
the status of the weed in both east and west Hararghe
Zones of Oromia Regional State is highly severe and its
impact has caused tremendous yield reduction and
economic loss. No matter how, there exists a varied
distribution among different locations the invasiveness of
parthenium at high altitude areas is low this might be due
to the presence of P. abrupta var. partheniicola which has
limited its further expansion in those high land areas.
Effect of rust on dry matter and seed production
The result from the Chi-square (x2) analysis of variance
for dry matter production and seed weight in the study
area showed, there is a significance difference among
locations for all parameters. This is owing to the
difference in epidemiological factors of the locations
(environmental factors, level of aggressiveness of the
pathogen and the growth stage of parthenium plant).
Dry matter production at maturity and mean seed
weight per plant were significantly reduced at Tullo
resulting in 36 and 72% reduction, respectively as
compared to diseased plants at Chrio. Similarly, 35%
reductions in dry matter production as well as 50%
reduction in seed weight were observed at Chrio, Table
3. In 2008, as the meteorological data showed, the
monthly rainfall and temperatures in the months of
October and November at the study areas were favorable
for the rust epidemics than similar study in 2009
(Appendix Table 3).
Comparison of aggressiveness of P. abrupta var.
partheniicola isolates
In the greenhouse study, nine days after inoculation, the
symptom of rust and development of pustules were
observed on Ambo, Kuni, Gemechis and Tullo isolates,
and the area and number of pustules were relatively
increased from the 9th day till the 23rd day. After the 23rd
day, all the infection has stopped and the progress of the
disease was localized. Starting from the 14th day to 23rd
day, all the leaves infected by uredinio spores of P.
abrupta var. partheniicola were subjected to rapid leaf
senescence and total defoliation was observed after 28
days. In addition, it was observed that all the leaves
which emerged after the inoculation were found to be
healthy.
In comparison to the field study, in the greenhouse, the
dispersal and auto-infection capacity of P. abrupta was
limited, owing to the absence of wind and other dispersal
agents in the greenhouse as compared to the wide
exposure of parthenium plants to many spore dispersal
agents which help in increasing the cyclic infection of the
plant. In the field study, the effect of the rust on all
morphological parameters was found to be severe than
the greenhouse study and as a result the biological age
of the weed was so short. This is owing to the landing of
larger number of spore population carried by wind to the
plant parts which can attack all organs simultaneously
and cyclically.
In the greenhouse, 14 days after inoculation the effect
of P. abrupta var partheniicola isolates showed marked
variation on morphological parameters of parthenium
(Table 4) in which the effect of Ambo isolate on plant
height, leaf length, leaf width, number of leaves per plant
and leaf area was superior to other isolates followed by
Kuni isolate. In Tullo and Gemechis isolates, there was
no significant variation for all parameters and the isolate
from Chiro showed poor performance for all parameters
(p ≤ 0.05).
Similarly, at 21 days after inoculation, the effect of P.
abrupta isolates showed significant difference on
morphological parameters of parthenium (Table 5). Under
all parameters, the effect of Ambo isolate showed a
significant effect followed by Kuni (p ≤ 0.05). At this day,
disease severity for Ambo, Kuni, Gemechis and Tullo
isolates have showed a marked increase which is in line
with the fact that disease development and effect
advance for certain period of time and relapses when the
affected areas are totally consumed (Van der Plank,
1963). From the analysis of variance, it can be seen that
the Ambo isolate was found to be the most aggressive
one while the aggressiveness of the Chiro isolate was
found to be the poorest (p ≤ 0.05).
342 Afr. J. Plant Sci.
Table 4. Effect of Puccinia abrupta var. partheniicola at 14 days after inoculation on parthenium weed. Plant height, leaf length, leaf width,
number of leaves per plant and leaf area (mean value), were evaluated in greenhouse at Ambo, 2009.
Isolate (treatments) Plant height (cm) Leaf length (cm) Leaf width (cm) Number of leaves per plant Leaf area (cm
2
)
Ambo 13.33a 12.50a 5.50a 2.34a 12.00a
Kuni 14.16ab 12.66a 5.50a 2.44a 12.00a
Gemechis 14.83b 13.46b 6.83b 2.61b 12.83b
Tullo 14.80b 13.50b 7.16b 2.78b 12.83b
Chiro 14.96c 13.83bc 7.50c 2.74b 13.46c
Control 15.00c 13.85bc 7.83c 2.80bc 13.50c
CV 4.44 3.51 7.25 3.57 4.44
LSD 1.10 0.72 0.89 0.16 0.96
*Means with same letter are not significantly different.
Table 5. Effect of Puccinia abrupta var. partheniicola at 21 days after inoculation on parthenium weed. Plant height, leaf length leaf width
number of leaves per plant and leaf area (mean value), were evaluated at Ambo, 2009.
Isolate
(treatments)
Plant
height (cm)
Leaf
length (cm)
Leaf
width (cm)
Number of leaves
per plant
Leaf
area (cm2)
Ambo 15.00a 15.00a 7.50a 2.74a 12.13a
Kuni 15.00a 15.00a 7.56a 2.75a 12.5a
Tullo 16.60b 15.00a 7.80b 2.78b 12.50a
Gemechis 17.33b 15.66ba 7.80b 2.78b 12.83c
Chiro 18.66c 16.66b 8.00bc 2.83c 13.00c
Control 20.66d 16.66b 8.33c 2.88c 13.50c
CV 6.29 6.77 9.75 5.08 4.30
LSD 1.96 1.87 1.35 0.25 0.97
P. abrupta in the experiment was observed colonizing the
whole leaf and stem surface of parthenium (Figure 1)
which hinders gaseous movement and light interception
which are helpful in undertaking carbohydrate production
(photosynthesis) and also helps in increasing the rapid
oxidation of carbohydrate reserve in the plant body, thus
the parthenium plant growth will be suppressed, its
competitive ability is reduced, its seed production
capacity is reduced and the overall impact of the weed on
native plants and soil resource (growth resource) will be
reduced and hence, the present finding is in line with
Evans (1987b).
Conclusions
Parthenium is an exotic invasive weed that originated in
South America now causing severe infestation in
Ethiopia. This weed is known to be infected by various
micro organisms such as the rust pathogen that may be
used as a component of integrated weed management. A
total of 218 fields were surveyed in 2008 and 2009
cropping seasons in four districts (Chiro, Gemechis, Kuni
and Tullo) of west Hararghe zone. And result from the
present study showed that P. abrupta var. partheniicola
was widely distributed in all of the surveyed areas
covering different altitudes which range from 1700 to
2460 m.a.s.l. During the study, it was found that the
distribution of rust varied among locations, and higher
rust incidence and sev erity were observed in areas where
the altitude is higher and the temperature was cooler.
Rust disease incidence varied from 25 to 74% at Chiro
and Tullo, respectively. And 18 to 55% severities were
noted for Chiro and Gemechis, respectively. From the
analyzed result, there was no significant difference within
location but significant differences were observed among
locations (p ≤ 0.05). Similar study conducted by Parker et
al. (1994) in Australia and Mexico showed the same
result. The effect of rust on plant height, leaf area, leaf
length and leaf width was significant, and the pathogen
has reduced the morphological parameters significantly
under field conditions (p ≤ 0.05). The effect of P. abrupta
on leaf senescence was also significant and the
pathogen had a potential in reducing the photosynthetic
part of the parthenium weed. With regard to seed
production, it was noted that the pathogen also had a
potential in minimizing the seed producing capacity of
parthenium and a reduction of 0.015 to 0.04 g was
recorded during the study at Chiro and Tullo,
respectively.
In the greenhouse study, at 14 and 21 days after
inoculation, it was found that the isolates had different
degree of aggressiveness in which Ambo isolate became
the most aggressive followed by Kuni for all parameters.
Bekeko et al. 343
Figure 1. The effects of Puccinia abrupta var. partheniicola on parthenium weed under greenhouse condition 21
days after inoculation at Ambo Plant Protection Research Center, 2009. The leaves were subj ected to r apid leaf
senescence as a result of the disease (Ambo isolate, the most aggressive one).
In the study, it was observed that there is no significant
difference between Gemechis and Tullo isolates but
Chiro isolate showed poor degree of aggressiveness (p ≤
0.05). With regard to disease severity and leaf
senescence all the inoculated leaves were severely
infected and the leaves were subjected to rapid leaf
senescence 21 days after inoculation. From this finding, it
can be concluded that P. abrupta v ar. partheniicola
isolates had different degrees of aggressiveness.
However, further studies have to be conducted to confirm
the presence of genetic diversity among the population of
this pathogen at molecular level.
ACKNOWLEDGEMENTS
The authors are grateful to the Ministry of Agriculture and
Rural Development of the Federal Democratic Republic
of Ethiopia for funding this research project, Ambo Plant
Protection Research Center in providing the greenhouse
facilities, the Haramaya University, Plant Pathology Staff
members in critically commenting the findings, Professor
Steve Adkinsfrom the University of Queensland, Australia
for his sound comments on the article, Tadele Gudeta,
Ararsa Gudissa, Tadesse Bedada and Fisiha Zeleke for
their assistance during the field data collection and
greenhouse experiment.
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APPENDIX
Table 1. Element monthly mean maximum temperature of Chiro Station.
Year Jan. Feb. March April May June July Aug. Sep. Oct. Nov. Dec.
2003 28.0 29.4 28.7 28.9 30.6 29.8 27.0 27.2 28.5 29.6 29.2 27.4
2004 28.4 27.5 28.3 28.7 30.5 29.3 29.3 29.5 29.5 29.3 27.2 24.9
2005 28.3 30.1 29.4 28.7 29.0 29.3 29.3 29.5 29.3 29.3 27.2 21.9
2006 28.5 29.5 28.6 28.1 29.0 29.1 28.2 27.4 27.9 28.5 27.1 25.2
2007 25.0 29.5 30.4 28.1 28.7 29.4 28.5 27.2 26.8 27.8 27.3 NA
2008 27.2 28.4 29.3 28.4 27.5 28.3 28.2 28.8 25.8 27.4 28.0 26.4
2009 28.4 30.5 30.0 29.4 28 28.5 28.5 28.6 25.5 27.6 28.5 26.4
Table 2. Element monthly mean minimum temperature (°C) of Chiro Station.
Year Jan. Feb. March April May June July Aug. Sep. Oct. Nov. Dec.
2003 16.5 17.6 15.4 16.1 16.2 16.8 15.1 15.9 16.6 17.1 15.7 13.8
2004 14.3 14.0 14.0 15.2 16.4 15.2 13.2 14.1 15.2 15.1 14.9 15.8
2005 15.8 16.4 16.3 15.7 15.8 16.3 15.9 16.0 15.8 16.4 15.0 10.4
2006 15.4 18.1 12.4 15.8 16.6 15.5 14.9 14.9 15.1 14.7 13.8 13.0
2007 13.0 17.2 16.4 14.8 15.0 16.0 14.9 15.6 14.8 13.3 11.0 NA
2008 14.5 17.0 16.2 14.4 15.2 16.0 14.6 15.0 15.2 15.0 14.8 14.2
2009 15.4 17.6 15.5 15.7 15.0 16.5 14.5 15.0 15.5 15.0 14.0 14.5
Table 3. Element monthly total rainfall (mm) of Chiro Station.
Year Jan. Feb. March April May June July Aug. Sep. Oct. Nov. Dec.
2003 3.2 29.4 74.7 111.6 25.2 96.6 215.4 225.0 141.4 0.0 40.8 15.8
2004 51.5 0.0 73.4 164.8 2.4 36.1 125.6 145.9 446.8 99.0 17.0 28.0
2005 0 14.8 107.6 173.6 208.8 98.4 215.6 87.6 171.0 4.8 12.4 0
2006 12.0 33.4 130.0 88.0 63.4 47.0 140.8 243.3 103.1 133.0 0 73.2
2007 18.2 0 150.0 285.4 43.4 96.8 186.3 195.9 147.2 16.2 0 NA
2008 15.0 15.6 130.0 264.8 40.4 82.8 168.4 214.0 105.0 112.0 128 65.0
2009 12.0 6.5 108.0 182.0 26.0 15.0 120.0 108 120.0 96.0 85.0 90.0
