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Plant
2014; 2(1): 1-5
Published online February 20, 2014 (http://www.sciencepublishinggroup.com/j/plant)
doi: 10.11648/j.plant.20140201.11
Importance of wheat stem rust (Puccinia graminis f.sp.
tritici) in Guji zone, Southern Ethiopia
Tolessa Taye
1
, Chemada Fininsa
2
, Getaneh Woldeab
3
1
Oromia Agricultural Research Institute Yabello Pastoral and Dry Land Agricultural Research Centre, Yabello
2
Haramaya University, Dire Dawa, Ethiopia
3
Ethiopia institute of Agricultural research Ambo Plant Protection Research Centre, Ambo Ethiopia
Email address:
tolessataye1@gmail.com (T. Taye), chefigu@yahoo.com (C. Fininsa), getanehwoldeab@gmail.com (G. Woldeab)
To cite this article:
Tolessa Taye, Chemada Fininsa, Getaneh Woldeab. Importance of Wheat Stem Rust (Puccinia Graminis F.Sp. Tritici) in Guji Zone,
Southern Ethiopia. Plant. Vol. 2, No. 1, 2013, pp. 1-5. doi: 10.11648/j.plant.20140201.11
Abstract:
Wheat (Triticum spp) is the most important cereals in Ethiopia, is threatened by abiotic and biotic constraints.
Among the biotic, stem rust (Puccinia graminis f.sp. tritici) is one of the major limitations of wheat production. Information on
the occurrence and reaction of cultivars to stem rust in Guji zone was unknown. Survey was conducted in Bore, Damma and
Ana Sora districts of Guji zone to assess the prevalence, incidence and severity of wheat stem rust in 2011 growing season.
During the survey work, 77 wheat fields in 17 Peasant associations of the three districts of Guji zone were assessed. The result
of survey revealed that all the wheat fields were affected by stem rust in all the surveyed area. Incidences greater than 22.72%
and lesser than 20% were recorded in Damma and Bore districts, respectively. Stem rust severity ranged from 18.16 to 27.39%
in all the surveyed districts. The survey work showed that wheat stem rust was serious disease of wheat in the zones and may
cause high economic loss if the susceptible local cultivars and Kubsa were continued to be grown in the area.
Keywords:
Wheat Stem Rust Bore, Damma and Aana Sora
1. Introduction
Bread wheat (Triticum aestivum L. em. Thell) is the
world’s leading cereal grain where more than one-third of
the population of the world uses as a staple food (Curtis,
2002). It is one of the most important cereal crops of
Ethiopia (Hailu et al., 1991; Bekele et al., 1999). It ranked
third in land coverage and total production after tef and
maize and in productivity after maize and sorghum (CSA,
2010). Wheat is produced across a wide range of agro-
ecological and crop management regime (Belay and
Tanners, 1999). The most suitable area for wheat
production falls between 1900-2700 m.a.s.l (Hailu et al.,
1991). Despite the large area under wheat in Ethiopia the
national average yield is 1.83 t/ha (CSA, 2010), which is
far below the average of African and world yield
productivity. This probably wheat is attacked by a number
of diseases that cause great losses to the quality and
quantity of produce. Among this rusts are the most
important disease of wheat worldwide, inspite of great
progress made in their control in many countries (Saari and
Prescot, 1985). Rusts are the major disease of wheat since
no other wheat disease could result in greater loss over
large area in a given year (Loegering et al., 1967; Amanuel,
1994). Rusts can cause up to 60 percent of yield loss for
leaf or stripe (yellow) rust and 100 percent loss for stem
rust (Park et al., 2007). The persistence of rust as a
significant disease in wheat can be attributed to specific
characteristics of the rust fungi. These characteristics
include a capacity to produce a large number of spores
which can be wind-disseminated over long distances and
infect wheat under favorable environmental conditions and
the ability to change genetically, thereby producing new
races with increased aggressiveness on resistant wheat
cultivars.
Stem or black rust of wheat caused by the fungus
Puccinia graminis f. sp. tritici Ericks and Henn (Pgt) is an
important disease on wheat worldwide. It is an obligate
biotroph, heteroceous in its life cycle and heterothallic in
mating type (Alexopoulos et al., 1996). It is known to bear
many physiologic races generated mainly by mutation
(Roelfs, 1985).
Ethiopia is one of the hot spot areas for the
development of the present wheat stem rust complex
(Leppik, 1970). In Guji highland wheat is highly exposed
to wheat stem rust damage. This most probable farmer of
the area is used the most susceptible wheat cultivar like
2 Tolessa Taye et al.: Importance of Wheat Stem Rust (Puccinia Graminis F.Sp. Tritici) in Guji Zone, Southern Ethiopia
Kubsa and most of the farmer use the late sown season this
usually coincide with condition suitable for wheat stem rust
and currently the barley will replacing the farm in most of
the case.
Therefore, in the present work, wheat stem rust was
studied in a more specific and intensive way in three
districts of Guji zone of southern Oromia Regional State.
These districts represent potential wheat production areas
in the zone. So far little or no efforts have been made to
identify the most affected areas in the zone, and quantifying
of the disease occurrence, hence this work gears the
information gap of stem rust that remains unknown for a
long period of time in the zone. Therefore, the present
research aims:
To asses’ distribution, incidence and severity of wheat
stem rust in Guji, Oromia.
2. Materials and Methods
2.1. Description of the Study Area
This study consisted of wheat stem rust (Puccinia
graminis f.sp. tritici) survey and evaluation of wheat
cultivars for slow rusting resistance. The wheat stem rust
assessment survey was conducted in three districts of Guji
zone namely Bore, Ana Sora and Damma. The annual mean
minimum and maximum temperature of the area is 15
0
C and
25
0
C, respectively, while, the minimum and the maximum
annual rainfall is 1450 mm and 2900 mm respectively. The
minimum and maximum temperature recorded during
growing season of 2011 was 16.5
0
c and 20.3
0
c, while the
minimum and maximum rainfall recorded in Bore during this
season was 4.2 mm and 239.8mm respectively.
2.2. Wheat Stem Rust Survey
Stem rust survey was conducted in three districts of Guji
zone during main seasons of 2011 and short season of 2011
in few districts of southern oromia regional state. The three
districts had mid highland (1500-2300 m.a.s.l) and highland
(2301-3200 m.a.s.l) agro-ecologies. This makes the area
suitable for wheat production. Unfortunately altitude below
2300 m.a.s.l was not covered during the survey work. The
survey was conducted in 17 peasant associations (PA) and
77 fields in the three districts of the zone. Stratified
sampling technique was applied in the survey. PAs were
randomly selected from each district and based on the
representativeness of wheat production of the area. As a
result, 6 PAs were assessed from each district except in
Bore district where 5 PAs were assessed because in the 6th
PA there were no wheat fields available. In this area wheat
production was stopped due to the occurrence of heavy rust
epidemics which result in high yield loss for the last three
consecutive years. The stem rust assessment was made
along the two diagonals (in an “X” pattern) of the field
from five points using 0.5mX 0.5m (0.25m2) quadrants. In
each field plants within the quadrates were counted and
recorded as diseased/infected and healthy/non-infected and
the different parameters were measured as follows.
Disease incidence (DI) was the proportion of stem rust
infected plants to the total number of plants in the quadrate
and it is calculated as:
100
Disease Severity
:
was expressed as the percentage or
proportion of plant area affected by wheat stem rust disease.
More often, disease assessment scales were used to express
the relative proportions of affected tissue at a particular
point in time. The disease severity under field conditions
was recorded as percentage of leaf/stem area covered by
rust following modified Cobb's scale as developed by
Peterson et al. (1948). According to this scale, at 100 %
disease severity, the actual leaf area covered by rust
pustules is 37 % .Disease severity was assessed by
selecting 10 plants from a single quadrate and five
quadrates were used for the estimation of disease severity
from a single wheat field, finally the average severity was
taken for the analysis
.
Percentage of severity index (PSI) was calculated by
using the following formula Wheelers (1969).
Other independent variables collected were
Altitude of the field in meters was estimated by using
GPS
Date of planting was obtained by asking the farmer
Growth stage of the crop at time of assessment was
obtained by visual observation using Zadoks scale.
Types of variety: was obtained by asking the farmers.
Agronomic practices such as number of cultivation,
frequency of weeding, fertilizer use were collected by
asking farmer.
All the parameters measured were analyzed by using
descriptive statistical analysis over peasant associations,
districts and altitude ranges.
3. Results and Discussion
3.1. Importance of Wheat Stem Rust in Guji Zone
Field survey was conducted in Guji zone in southern
Oromia during 2011 main cropping season to assess the
prevalence, incidence and severity of wheat stem rust and
to determine the importance of the disease in the zone. In
most of the areas, the survey was conducted at flowering to
maturity growth stages of wheat. The survey work was
conducted from 15-25 December 2012. The geographical
locations of the surveyed areas were located in a range of
longitude and latitude of 060.13865-06.27998N and
038.73659-0380.83739E respectively.
3.2. Disease Prevalence
Prevalence of wheat stem rust was 100% in all the
districts (Table 2). The most probable reasons for this might
be the frequent use of local and susceptible improved
cultivars in all of the surveyed areas. In addition to this,
Plant 2014; 2(1): 1-5 3
environmental condition may be suitable especially for late
sown cultivars where early sown crops may serve as
inoculum source in the areas. In all the surveyed areas the
rainfall distribution was wide and bimodal near the
surveyed area in the Borana lowlands and mid highland
where the wheat planted two times in a year. This condition
played significant role for continuous supply of inoculum
for the Guji areas. If susceptible improved and local
cultivars continue to grow it may not take a long time for
the farmer to stop wheat production in the area. Currently
in Bore and Damma wheat production was reduced from
previously used area by 13.7% and 6.02%, respectively
because of the rust disease ( predominantly stem rust and
yellow rust) causing high devastation on wheat (District
office of Agriculture and Rural Development report) in the
surveyed districts. In the majority of surveyed districts
barley was replacing wheat.
3.3. Disease Incidence
The incidence of wheat stem rust in the fields was
estimated for peasant associations (PA), districts and for the
entire study area (Table 1 and 2). A total of 77 fields were
surveyed in three districts of Guji zone. Incidence was
ranging from 16.70-22.70%. Incidence of 22.7% was
recorded in Damma, followed by Ana Sora 17.5% (Table 2).
More than 56% of surveyed areas were categorized under
low wheat stem rust incidence which was below 20%. At
PA level, the highest incidence of 30% was recorded in
Eshidho Alleyo in Bore and Areda bala in Damma districts
(Table 4), while the lowest incidence of 9.5% was also
recorded in Lettu PA in Bore district. About 57% of the
fields in Damma district, followed by 21.42% of the fields
in Ana Sora district and 20.83% of the fields in Bore
districts had incidence greater than 20% (Table 2). This
study showed that wheat stem rust in all the districts was
grouped under low incidence category which ranging from
0%-20% while severity was grouped under medium disease
category which ranging from 21-40% disease severity
(Table 2).The stem rust incidence of the zone showed that
disease was relatively higher in damma district because in
this area most of fields planted latter than the two districts.
Table 1. Wheat stem rust incidence and severity in the peasant
associations of three districts of Guji zone during main season of 2011
Districts
PA No field assessed
Incidence
Severity
Bore Sorgo Baricha 5 11.8 14.06
Eshidho Alleyo
5 30 31.25
Kerra kepanno
5 20.23 24.33
Anno Kerrensa 5 11.94 11.64
Lettu 4 9.54 9.52
16.70 18.16
±8.47 ±9.26
A.Sora
Raya Boda 5 20.5 31.23
Roba Dabaye 5 19.5 17.66
Kelle 4 23.3 26.24
G/Gejaba 4 15.9 35.9
Hirba Bulliyo 5 16.4 15.8
Bube Korsa 5 10.3 14.95
±17.5 ±22.8
±4.3 ±8.3
Damma
Hada Gurrati 3 18.3 15.1
Anole Sodo 5 14.1 17.1
Areda Bala 5 30.0 21.7
Duda Dera 5 27.2 35.7
Dugo Gutticha
4 26.6 29.8
Anfele 3 20 45.1
22.7 27.4
±8.9 ±10.3
Table 2. Disease prevalence, incidence and severity of wheat stem rust in three districts of Guji zones during main season of 2011
Districts
Prev (%)
Inci (%)
Sev (%)
Disease category class Disease severity class
L % M % H
L L % M
% H
%
Bore 100 16.70 18.16 15 62.5 5 20.83 4 16.7 14 58.3 7 29.16 3 12.5
A.Sora 100 17.48 23.63 19 67.85 6 21.42 3 10.7 20 71 6 21 2 7.14
Damma 100 22.72 27.39 7 33.37 12 57.12 3 14.3 3 12 19 76 3 12
Prev = Prevalence, Inci = incidence, Sev = Severity, L=low disease class designated 0_20% Incidence and Severity), M =medium disease class designated
from 21-40% (Incidence and Severity), H=high disease class is greater than 41% (Incidence and Severity).
3.4. Disease Severity
Severity of wheat stem rust was recorded and found to
vary from low to high at district and PA levels (Table 1 and
2). The highest average severity of 27.4% was recorded in
Damma, followed by average severity of 22.8% at Ana
Sora district (Table 2). The lowest severity both at district
(18.2%) and peasant association level (9.5%) was recorded
in Bore and lettu peasant association respectively. Severity
was below 20% for majority PA’s in Bore districts.
Similarly, severity of the disease was between 15.1% - 45%
at PA level in Damma district. The overall wheat stem rust
severity mean was 22.8% for the three districts in Guji zone
indicating wheat stem rust was important in the all
surveyed areas. Salman et al., (2006) reported that yield
losses increase proportionately with an increase in severity
of the disease. According to their investigations, varieties
like Morocco, WL-711, SA75, SA42 and Chakwal
exhibited maximum losses of 52-57% against the leaf rust.
In all the survey areas of Guji zones wheat stem rust may
reach the highest epidemic level if it get susceptible and
late maturing cultivars along with favourable
4 Tolessa Taye et al.: Importance of Wheat Stem Rust (Puccinia Graminis F.Sp. Tritici) in Guji Zone, Southern Ethiopia
environmental conditions that for the pathogens.
3.5. Date of Planting and Wheat Stem Rust
Twenty-three (29.80%) fields in surveyed area were
planted in July and had a wheat stem rust incidence of 23.3%
and severity of less than 15%. On the other hand, 50
(64.93%) fields in surveyed area were sown in August.
Fields planted during this time had stem rust incidence of
28.05% and less than 25% of disease severity. Only 4 fields
were planted in September. This had wheat stem rust
incidence of greater than 30.6 and less than 30% disease
severity. Based on these findings, it appeared that incidence
of wheat stem rust was higher in August sown wheat fields
than in July sown. Usually August sown wheat reach
flowering or grain filling in November. This period usually
coincides with warmer and humid weather (not sown)
which favours growth, reproduction and spread of the rust
pathogen. It may the most devastating and yield loss may
greater 50% for rust disease in the case of early onset of the
disease (Yaqoob, 1991). Losses of 100% can occur with
susceptible cultivars. In the surveyed area both late and
early sowing was practiced for the several reasons. Most of
the farmers use early planting to escape their crops from
frost damage and sometimes they also use for stem rust as
it is happening in the area at the end of October. Late
planting also practiced to minimizing the effect of rain that
was happened at the time physiological maturity. Wheat
stem rust is more important in late growing period, on late
sown and late maturing cultivars.
Table 3. Planting date, disease incidence and severity for three districts of
Guji zone during main season of 2011
Month of
planting
Number of
fields Incidence (%) Severity (%)
25 July 23 23.30±6.5 12.88±4.25
01 August 50 28.05±7.93 24.00±10.17
01 September 4 30.6±12 28.00±15.4
3.6. Cultivars Grown and Wheat Stem Rust
The growers in the surveyed areas use five different
kinds of wheat cultivars namely, local, Kubsa, Digalu,
Merero, Kakaba. The most widely grown cultivar Kubsa
occupied 39 (50.64%) fields in the surveyed three districts
of the zones. Local and Digalu follow Kubsa, each
covering 31.5% and 9.5% of the surveyed fields,
respectively. Merero and Kakaba cultivars were currently
introduced by Bore Agricultural Research and they were
under field evaluation on research plots and on farmers’
fields. These two cultivars covers only 2.7% and 1.4% of
the fields surveyed in the area, respectively. Incidence of
wheat stem rust was greater than 23% in 39 (50.64%) out
of 77 fields sown with Kubsa and 19 fields out of 39 had
greater than 25% of wheat stem rust severity indicating that
this cultivar was attacked by the disease in most areas of
the surveyed districts. Likewise, local was sown in 28
fields, of which 16 fields had wheat stem rust severity of
greater than 25%. In contrast, 7 fields were sown with
cultivar digalu which had incidence less than 15%, while
only 3 fields (3.89%) showed less than 10% severity of
wheat stem rust in Bore district. The study showed that
different levels of wheat stem rust incidence and severity
was observed on different cultivars grown indicating that
some cultivars were less affected by the disease than others;
this may be due to the genetic makeup of cultivars which
confer difference in resistance under different
environmental condition to the Pgt (Table 4).
Table 4. Wheat stem rust incidence, severity by cultivars grown in the
three districts of Guji zone during the main season of 2011
District Cultivar
Number of
field
Incidence
(%)
Severity
(%)
Bore Digalu 7 15.7 12
Kakaba
1 7.3 7.7
Kubsa 10 28.70 30.85
Local 4 33.3 32.15
Merero 2 5.56 4.25
Aana Sora
Kubsa 21 23.5 18.90
Local 7 12.61 10.10
Damma Kubsa 8 23.4 23.36
Local 17 29.8 24.43
3.7. Altitude and Wheat Stem Rust
Simple regression analysis was done for disease
incidence and severity as response and altitude as predictor
variable showed that highly significant (p<0.01) of the
overall probability of the equation. For disease incidence
and severity the fitted regression equation using at single
model revealed that every 100m increase in altitude at
(flowering and maturity) in the surveyed areas resulted in
reduction of incidence and severity by 0.033% and 0.030%
respectively (not shown). The R-square value of the
equation explained about 6.4% and 9 % for disease
incidence and severity respectively. This is low probable
for disease incidence and severity altitude may not be a
single major factor for the variation of wheat stem rust in
the surveyed districts of the Guji zones. There should be
other factor like favourable environmental condition and
the level of host resistance grown also play a significant
role.
3.8. Fungicide Use and Wheat Stem Rust
From 77 fields only 11 (14.28%) fields were applied with
fungicides once or twice in the growing season when stem
and stripe rusts became prevalent in the area. Bayleton was
the fungicide used for the control of rusts in the area. The
incidence and severity of stem rust in the fields which did
not use any of the fungicides was less than 23% and 22%,
respectively. In contrast to this, 11 (14.28%) of the fields
which use fungicides exhibited average incidence of less
than 19% and severity of less than 12% for the three
districts (Table 5). These findings showed that fungicides
Plant 2014; 2(1): 1-5 5
use in the surveyed area was not widely popular for the
control of wheat stem rust and other rust disease. It is
important for the grower to be able to identify the disease
early; however, this is not always possible without relevant
skills for the correct disease identification, and rust severity
assessment that are prerequisite to informed decisions on
fungicide use. Even in the sprayed fields, the incidence is
almost the same as that of unsprayed fields in the surveyed
area of the Guji zone. This might be because the farmer
may start spraying too late when the disease has well
established in the fields or neighboring fields. As it well
known rust diseases are wind borne, so repeated
applications and regular monitoring is indispensible
because stem rust is easily introduced to the health fields
from their neighboring by winds.
Table 5. Mean stem incidence and severity (%) on fungicide sprayed and
non-sprayed fields
District
Number
of fields Sprayed field Non sprayed
Incidence
(%)
Severity
(%)
Incidence
(%)
Severity
(%)
Bore 6 18
13.67 13.3 23.0 22.1
Ana
Sora 4 24
16.4 11.4 18.1 18.5
Damma 1 24
26.3 10.5 26.45 23.5
Total 11
66
56.4 35.1 67.6 64.2
Mean - - 18.8 11.7 22.5 21.4
4. Conclusion and Summary
Results from wheat rust survey in three Guji zones
reveals that stem rust was prevalent everywhere wheat is
grown during main and short rainy seasons with varying
degree of incidence and severity. However, the disease
prevalence was 100% in all of the surveyed area of the
zones that means all surveyed peasant associations in
districts were infected. The disease was severe in Damma
district, even though with less than 30% of severity. Most
probably in the near future the severity may increase
because of very few improved cultivars that are susceptible
to disease become common and no chemical control was
practiced in the areas.
Bore district suffers least from stem rust threat. In this
district use of improved cultivars and chemical spray was
practiced better compared to other two districts. The study
also indicated that fungicides were used only by few
farmers, probable because of unaffordable prices, low
access to get good and fresh fungicides and lack of
awareness on how to use. On the other hand, 10 years
weather data of the area showed that a moderately
favorable environment for the development of stem rust
prevalent in most of the districts. Generally in the Guji
zones where survey were conducted 39 (50.64%) and 28
(36.36%) of the fields were planted by highly susceptible
reaction Kubsa and local respectively. Few improved
cultivars were recently introduced by Bore Agricultural
Research Center for the enhancement of the wheat yield in
the study area.
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