This document discusses major diseases that affect common bean and faba bean production in Ethiopia. It identifies 25 common bean diseases reported in the country, with the top 5 most important and widely distributed being anthracnose, rust, common bacterial blight, halo blight, and angular leaf spot. It provides details on symptoms, management strategies like host resistance and fungicides, and the disease cycle for each of these top 5 diseases. It also discusses 3 major faba bean diseases - chocolate spot, rust, and black rot - and provides details on chocolate spot symptoms and impacts.

1. 3.5. Major haricot bean diseases and their Management
 A total of twenty five common bean diseases were recorded in Ethiopia.
 Fungal disease such as Anthracnose, Rust, Web blight, Angular leaf spot, Leaf blight,
Floury leaf spot, Rhizoctonia spp, Fusarium wilt and Sclerotium spp;
 Bacterial disease such as Common bacterial blight and Halo blight;
 Common bean mosaic virus and Root rot nematode are among frequently reported
diseases on common bean.
 Among these in Ethiopia; Anthracnose, Rust, Common bacterial blight, Halo blight and
Angular leaf spot are more important and widely distributed in the country
 while the remaining are also important in some areas and much more restricted in their
distribution.
 Among these diseases the major one is Anthracnose, Rust, common bacterial blight and
Halo blight causing 100%, 85%, 62% and 45% yield loss respectively.

2. Common name Causal agent Status
Leaf Spot Ascochyta phaseolorum Sacc. Minor
Angular Leaf Spot Isariopsie sriseola Sacc. Major
Leaf Spot Ceraoapora zurunaris Ell.Sev Minor
Anthracnose Colletotriohum lindermthiamm Major
Stem Anthracnose C. trunatamm (Schw.) Minor
Leaf Spot Phyllosticta phaseolina (Sacc.) Minor
Powdery Leaf Spot Mycospaerella phaseoli Intermediate
Root-Rot Saterotiwn rofsii Sacc. It Intermediate
Rust Uromyces phaseoli Major
Common Bacterial Blight Xanthompnas campastria pv phaleoli Intermediate
Halo Blight P. syringae pv. Phaseolicola Intermediate
Leave/Leaf Spot Ceroosporidium spp. Minor
Leaf Spots Mycosphaerella pinodea Minor
Leaf Spots Periconia byssoides Pers. ex. Merta. Minor
Leaf Spots Phoma exigua Desm. Major
Leaf Spots P. phoselina Pass. Major
Pot Spots P. sorghina (Sacc.) Unknown
Mosaic Virus/BCMV Major
Root Rot Sclerotinia sclerotiorum (Lib) Minor
Wilt Fusarium solani (Mart.) Intermediate
Ashy Stem Blight Macrophomina phaseoti(maub1.) Minor
Leaf Spot Ascochyta sojicola Abaram off. Minor
Charcoal Rot Macrophomina phaseoli Minor
Leaf Spot Mycosphaerella creuenta (Sacc.) Minor
Bacterial Blight P. syringae pv glycinea Major
Table : Common bean diseases status in Ethiopia.

3. 1. Common bean Anthracnose: Colletotrichum lindemuthianum
Symptoms
Symptom
Bean pods with black, sunken lesions or reddish-brown blotches
most likely have anthracnose, a fungal disease caused by
Colletotrichum lindemuthianum.
Black, sunken lesions about ½ inch in diameter develop on
stems, pods and seedling leaves (cotyledons) but are most
prominent on pods.
A salmon colored ooze on lesions and the veins on lower leaf
surfaces turns black.
Anthracnose develops primarily during the spring and fall when
the weather is cool and wet, and not during our hot, dry
summers.
Lima beans are particularly susceptible.
 The pathogen is distributed worldwide including Ethiopia and affects all vegetative anatomy as
well as seeds.
 The fungus C. lindemuthianum can attack all aerial plant parts and may cause yield losses as high
as 100%.
 In seed multiplication program on farmers’ field, the released variety Roba-1 failed to give seed
due to anthracnose in 2002 cropping season

4.  Anthracnose symptoms on bean pods
 Symptoms on Infected leaf
Anthracnose symptoms on beans and pods
Mode of spread and survival
The fungus is seed borne and can survive from one season to
another in debris from infected plant as well as in diseased seed.
The fungus can remain alive in seeds even after the seeds are dead.

5.  The fungus survives the winter primarily in bean seed.
 Survival in soil or in plant residue varies greatly, depending on
environmental conditions.
 Moisture is required for development, spread, and germination
of the spores as well as for infection of the plant.
 A prolonged wet period is necessary for the fungus to establish
its infection
 The time from infection to visible symptoms ranges from 4 to
9 days, depending on the temperature, bean variety, and age of
the tissues.
 The fungal spores are easily carried to healthy plants in wind-
blown rain and by people and
 Machinery moving through contaminated fields when the plants
are wet.
 Frequent rainy weather increases disease occurrence and
severity.
Bean anthracnose Disease Cycle

6. Cultural method:
 Growing common bean in cultivar mixture is one strategy of controlling anthracnose.
 Remove bean debris to reduce winter survival and inoculum level.
 Crop rotation for two years with non-host crop can reduce inoculum source and inoculum load.
 Do not plant bean seeds in an area that had disease for two to three years.
 Avoid overhead watering and avoid splashing soil onto the plants when watering.
Management of bean anthracnose
 Fungicide sprays of fixed copper are the only recommended chemical that can be used on lima
beans for anthracnose control.
Host resistance: the use of anthracnose resistant variety is one management measure that
is effective, safe and cheap in dealing with the disease.
 In Glasshouse and field experiments the haricot bean genotypes Widusa, GLP X 1132, A482,
HAL 5 and G 2333 were identified resistant to the Ethiopian isolates of C. lindemuthianum.
 In addition, genotypes RAZ-18 and REN-20 possess field resistance to Anthracnose and
Angular leaf spot.

7. 2. Bean Rust: Uromyces appendiculaters
 Bean Rust (BR) caused by Uromyces appendiculaters, syn Uromyces
phaseoli has a wide geographical distribution and one of the major common
bean diseases occurring in most parts of Ethiopia.
 Although it can infect many species of Phaseolus it has been particularly
damaging to haricot bean in this country.
 Common bean rust causes yield loss up to 85-100% in susceptible cultivars.
Symptom
 Rust spots (pustules) appear on all parts above the ground.
 They are most numerous on leaves, particularly on the
underside.
 Severely infected leaves turn yellow, wilt, and then drop off
of the plant.
 Stems and pods may also be infected.
 It affects most types of beans under humid conditions.
 They are less abundant on stems and occur sparingly on
pods.
 Initial symptoms are minute, slightly raised yellow
pustules, which later become distinct circles, reddish
brown in color and surrounded by a yellow halo.

8. Management of common bean rust
A. Cultural practice:
 Common bean rust can be managed by cleaning the field and removing alternate host
grown around the field.
 Crop rotation.
 Intercropping with other crop may reduces the infection.
For example in the Hararghe highlands, rust incidence and severity, respectively, are
reduced by about 25% and 16% in intercropping bean sorghum and maize.
B. Host resistance: Rust resistant bean varieties such as ‘‘Yocto Negro’’ are available in Ethiopia.
C.Chemical control: Fungicides such as Tebuconazole, Chlorothalonil, Propiconazole, Mancozeb
and Maneb are effective in controlling rust.
Mode of spread and survival
 The rust fungus is not seed borne, but can be disseminated locally by farm tools, insects,
animals or other moving bodies.
 However wind is the principal agent for long distance spore dissemination.

9.  Angular leaf spot(ALS) is one of the most destructive diseases of
common bean in tropical and subtropical regions of the world.
 Yield losses due to ALS was reported 50–60% were reported during
epidemics in the world while in Ethiopia 47% yield losses were
reported so far.
3. Angular leaf spot (Phaeoisariopsis griseola)
Symptom of ALS.
 Spots are usually seen first at flowering.
 Two types of symptoms occur depending on the leaf type.
 On the trifoliate(3 leaflets) leaves, angular spots up to 3 mm
wide, grey and then light brown, some times surrounded by
a yellow halo, but limited by the veins.
 On the primary(single) leaves, the spots are up to 15 mm
diameter and are often with rings, like a target.
 On the pods and stems, dark, sunken, oval to circular spots
of varying size occur.
 Spot On the trifoliate (3 leaflets) leaves
 Large oval to circular spots on pods of bean caused by P. griseola.

10. Management of bean ALS
CULTURAL CONTROL
 Before planting, make sure that the seed is certified free of the fungus.
 After harvest, collect and burn or bury as much of the crop as possible after harvest.
 Do not plant one crop of bean after another in the same land; use a rotation of at
least 2-years.
RESISTANT VARIETIES
 There are resistant bean and cowpea resistant varieties.
 However, in some varieties resistance to spots on the leaves and spots on the fruit
may differ.
CHEMICAL CONTROL
 Treat seed with carbendazim.
 If fungicides are needed for control of leaf or pod spots, use a copper product or
mancozeb.

11. 4. Bacterial Blight
 There are two widespread bacterial blights that affect most types of
beans, these are:
 Common blight (Xanthomonas campestris pv phaseoli) and
 Halo blight (Pseudomonas syringae pathovar phaseolicola).
A. Common blight (Xanthomonas campestris pv phaseoli)
 Common bacterial blight is first reported in 1893, and the causal
agent was named Bacillus phaseoli by Smith in 1897.
 The pathogen was observed during 1967 in Ethiopia as as
intermediate disease.
 However starting from 1997 Common bacterial blight re-emerge
and categorized as major disease causing agent.
 Since then this pathogen is major constraint in all common bean
producing areas of Ethiopia.
 It is the most destructive disease of bean causing up to 62% yield
losses.
 Yield reduction of up to 35% recorded by common bacterial blight
in susceptible varieties of beans.
 In eastern Hararghe, loss of 21% was reported due to Common
bacterial blight in the 1999 and 2000 cropping seasons.

12. Mode of spread and survival
The pathogen is seed borne and the disease spread through wind
splashed rains from diseased to healthy plants.
 In new area disease spreads through infected seeds.
Management
Cultural practice: Common bacterial blight management
options include components that reduce initial inoculum source
such as
Field sanitation, crop rotation whenever feasible, Early
incorporation of bean debris into soil, Burning of crop
residues, Use clean seed and Keeping the field free of weed
to reduce field are effective.
Host resistance: In Ethiopia, variety Gofta (G-2816) have
resistant gene against CBB.
Chemical control methods: Copper containing pesticide such
as Copper sulphate, Copper hydroxide, and Potassium methyl
dithiocarbamate can control leaf infection
A. Common blight (Xanthomonas campestris pv phaseoli)
 Symptom of common bacterial blight taken
from Boset, during 2016.

13. B. Bacterial Halo blight on common bean
 Halo blight is caused by Pseudomonas syringae pv. phaseolicola and the
pathogen is a strict aerobe, and is rod shaped with a gram negative
 Halo blight is major pathogen causing economic significance that can
plague common bean production worldwide.
 This pathogen is seed-borne and is a major in common bean growing
areas of Ethiopia.
 Recent study reported causes common bean yield losses of up to 45%.
SYMPTOM
 The most characteristic halo blight symptoms occur on bean foliage.
 Initially, small water-soaked spots resembling pin pricks appear on the lower
leaf surface.
 These spots turn brown in a few days and the surrounding tissue gradually
become yellow-green.
 This zone of yellowed tissue around the spot resembles a halo (the name of
the disease).
 Pod lesions first appear as small water-soaked pin pricks on the pod surface.
 These lesions gradually enlarge to form dark sunken spots of various sizes.
 White bacterial ooze appears on the spots when wet.
 Halos do not develop around pod lesions

14. Management of common bean halo blight
 Cultural practice:
Field sanitation,
Crop rotation,
Planting healthy seed,
Removing debris and
Seed treatment and planting disease free seed and
Avoiding disease by suitable choice of planting date are
effective.
 Host resistance: Various sources of tolerance to Halo blight
have been identified,
 But breeding is complicated due to wide genetic variability of
the pathogen that have different reactions in pods and leaves.
 Halo blight is cause by nine races, however race 1, 2, 5, 6 (the
most common), and 7 are distributed worldwide.
 Designation of races has been defined by differential cultivar
that means the reaction of specific bean cultivars to specific
race.
 Chemical control: Copper based pesticides such as Kocide
2000, Copper hydroxide and seed treatment with antibiotics
streptomycin.

15. 5. Bean common mosaic virus
Symptoms
 Symptoms of bean common mosaic virus (BCMV) are cupping
and twisting of leaves with a light and dark green mosaic pattern.
 The dark green tissue is often bubbled and/or in bands next to the
veins.
 Affected plants produce smaller, curled pods with a greasy
 the leaves show sharply defined patches of unusual coloration
may occur in beans.
 The causal agents of these symptoms may be nutrient imbalance
or herbicide injury or result from infection by one of several
viruses.
Pathogen
 Cucumber mosaic virus

16. Management of common bean mosaic virus:
 Use certified and disease-free seeds
 Plant resistant varieties (e.g. French bean variety 'Paulista')
 Control attacks of aphids
 Remove infected plants from the field.
Mode of spread and survival:
 The virus occurs worldwide in many agricultural
crops, ornamentals and weeds which serve for
season to season survival of the virus.
The virus is transmitted mechanically with ease as
well as in seed and by aphids, especially Myzus
persicae and Aphis gossypii.

17. 3.6. Major Faba bean diseases and their management
 Diseases are among the most important biotic factors, causing faba
bean yield reduction.
 More than 17 pathogens have been reported so far on faba bean,
from different parts of the Ethiopia .
 The most important yield limiting diseases that contributes to the
low productivity of the crop in Ethiopia are:
 Chocolate spot (Botrytis fabae),
 Rust (Uromyces vicia-fabae),
 Black rot (Fusarium solani),
 Aschochyta blight (Ascochyta fabae),
 Faba bean necrotic yellow virus and
 A newly emerging disease known as “faba bean gall”.

18. 1. Faba bean Chocolate Spot
 Chocolate spot of faba bean caused by Botrytis fabae occur where ever
faba beans are grown and is capable of devastating unprotected crops
up to 67%.
 It is a major limiting factor in the main faba bean growing regions of
Ethiopia and yield losses vary from 34 to 61 % was reported.
Symptoms
 Symptoms of chocolate spot occur on leaves, stem, flower and pod
tissues.
 Infection starts as small reddish-brown circular spots on leaves, stems
and flowers.
 The spots on leaves and stems enlarge and develop a grey, dead center
with a red-brown margin.
 Often, two stages of the disease have been observed.
 The non-aggressive stage known by the small circular and discrete
reddish spots with darker margins visible on one side of leaf; and
 The aggressive stage where the small spots merge and coalesce to
form irregular larger dark-brown lesions involving the entire leaf
surface.
 Damage from stem infection often results in serious crop lodging in
susceptible varieties.

19.  Chocolate spot, caused by Botrytis fabae can survive either as
sclerotia in the soil or on crop debris, in infected seed, or on self-sown
volunteer plants.
 In subsequent years, the initial infection usually occurs when spores
formed on old bean trash are carried by wind into new crops.
 Once the disease becomes established it rapidly spreads within a crop,
and within 4-5 days of infection spores can be formed on infected
tissue and initiate secondary spread of the disease.
Disease cycle and favorable condition
 Environmental conditions usually determine the
severity of a chocolate spot epidemic.
 The fungus is most aggressive under cool, humid
conditions, particularly at flowering time.
 Aggressive development of stem infection late in
the season can cause the crop to lodge.
 The optimum conditions are temperatures
between 15 and 22°C with at least 90 per cent
relative humidity.
 However, infection will develop slowly at lower
temperatures.

20. Chocolate spot disease Management
Cultural practice:
 The use of low seeding rates,
 The choice of the planting date to avoid extended periods of wet
weather conditions.
 Removal of infected and infested plant debris from the field that may
harbor hyphae or sclerotia of B. fabae,
 Rotating faba bean with non-host crops such as cereals to reduce
sclerotial population and chances of primary infections
 Use of clean, blemish-free seed and wide row spacing can play an
important role in reducing disease severity.
 The use of fungicides like vinclozoline 50 WP as a foliar spray, once every
two weeks, mancozeb, chlorothalonil, carbendazim or procymidone are also
better options for the management of this disease.
 Three faba bean lines viz; BPL 1179, 710 and 1196 as durable sources of
resistance to B. fabae.

21. 2. Faba beans Rust (Uromyces vicia-fabae)
Symptoms of faba bean rust
 Rust symptom first seen on leaves as rusty red small powdery lesion densely cover the surface,
and later to develop on the stems (see next figure A-C on next page).
 Early in the season, the aecial stage of the rust produces creamy-yellow spots or pustules on leaves
(figure A)
 Aecia are soon replaced by the more common uredinia on leaves and stems .
 On the leaves these are orange-brown pustules surrounded by a pale halo (figure B)
 Later in the season, rust infections on the stem appear as black-brown masses or pustules usually
surrounded by a pale halo(figure C)
 This is the telial stage of the fungus that contains resting spores which allow survival over
summer.
Faba bean rust is one of the most widely distributed diseases of faba bean around the world, but
severe in humid tropical and subtropical areas.
Normally, rust epidemics begin late in the season, when pod filling has started and yield losses
usually range from 5 to 30%.
When the infection starts early in the season, severe epidemics can occur and yield losses can be as
high as 70%.
Faba bean rust is widely distributed in Ethiopia and causes yield losses of up to 27%.

22. Symptoms of faba bean rust………
A. Early stages of infection, creamy-yellow pustules
(aecia) full of spores on leaves B. Orange-brown pustules (uredinia) surrounded by a pale
halo on leaves
C. Black-brown pustules (telia) surrounded by a pale
halo on stem
Definition
 Aecia = the fruiting body of a rust fungus in which the first binucleate
spores are usually produced.
 Uredopsores and teliospores= are fungal spores that spread fungal
diseases on plants. However, the key difference between uredospore and
teliospore is the spore cell wall.
 Uredospores have thin walls, whereas teliospores have thick walls.

23. Uromyces viciae fabae Disease cycle
 The fungus survives on infected debris of faba bean crops.
 The teliospores produced can infect volunteer bean plants directly without the need for an alternate
host.
 Rust spores from stubble and volunteers are blown onto new crops by the wind.
 Infection of volunteer faba bean is thought to be an important factor in the early development of rust
epidemics.
 Subsequently, rust pustules form on the infected leaves and stems.
 Spores are released from these pustules and are spread by wind, insects, farm implements etc.
 Rainfall or dew is necessary for spores to infect after landing on a susceptible plant (see the next figure
A-H)

24. A. The resting stage (telia) survives in a semidormant
state over summer in crop residues and on seed.
B. Teliospores produced on residues are blown by wind
and infect volunteer plants and Seedlings
C. Aecia are produced on seedlings.
D. Aeciospores spread rust within the crop and to other
faba bean crops.
E. Uridinia is produced on stems and leaves.
F. Urediniospores spread the disease through the crop
canopy.
G. Telia form on stems and leaves late in the season.
H. Disease infested stubble remains after harvest, and
some dust and trash is taken with the harvested seed.
Uromyces viciae fabae Disease cycle
Fig. Generalized life cycle of Uromyces viciae-fabae
 The disease is favored by high humidity, cloudy and warm weather conditions.

25. Management of the disease
 Cultural practices such as
 Appropriate crop rotation with non host crop,
 Removal of weeds and volunteer plants
 Removal of infected bean plant debris
 Use of clean, contaminant-free seed is also recommended.
 Several fungicides give satisfactory control of faba bean rust.
 Fungicides found effective against the pathogen are:
 Mancozeb (0.2%),
 Bayleton (0.05%) and
 Calixin (0.2%).
 First spray is given as soon as the disease is detected in the field and three
more sprays are given at 10 days interval.
 Use of resistant variety
 The faba bean lines BPL 1179, 261, 710, 8, 406, 417, and 484 have been
found to be resistant.

26. 3. Aschochyta blight (Ascochyta fabae)
Ascochyta blight is a major disease of faba bean, widely
distributed throughout the world.
 Its severity varies considerably between seasons.
Yield losses of 10-30 per cent can occur in seasons favorable for
the disease.
However, in mid and highlands of Ethiopia yield loss up to 90 to
100% was reported in highly susceptible faba bean varieties.
 They become irregular in shape, often zonate, and may coalesce to cover most of the leaf surface.
 Leaf tissue next to the lesions may become black and necrotic.
 Within the lesions, numerous pin headsized black fruiting bodies (pycnidia) of the fungus develop
only under moist conditions( as seen on Figure A above).
.
Fig A. Leaf lesions caused by ascochyta on faba bean
Symptoms of faba beans Ascochyta blight
A. Symptoms occur on leaves
 On leaves, small, circular, dark-brown spots appear
first which are visible on both sides of the leaves.
 As the disease develops, lesions enlarge and turn light
and then change to dark grey in color.

27. Symptoms of faba beans Ascochyta blight…..
Symptoms occur on the stem:
 On the stem, lesions are More elongated,
 Sunken and darker than leaf lesions and re usually covered
with scattered pycnidia (as seen on Figure B below).
 These lesions may girdle the affected portion.
 Stems may split and break at the point of infection causing
plants to lodge.
Symptoms occur on the pod:
• On pods, lesions are sunken and have a pale centre
and dark margins; they can be covered by numerous
pycnidia.
• Well developed lesions can penetrate the pod and
infect developing seeds causing them to be shrunken
and discolored.
• Badly infected seeds have yellowish brown stains on
the outer seed coat, which considerably reduces its
market value (as seen on Figure C below).
Figure B. Stem cankers caused by Ascochyta on faba bean
Figure C. Faba bean Pod and seed discolored by late infection of Ascochyta blight

28.  Field sanitation to destroy crop debris is very important for reducing losses from the
disease.
 Crop rotation, suitable spacing and proper placement of seed help in avoiding the
disease.
 Pathogen is externally and internally seed-borne and the only satisfactory preventive
measure is to use clean seed harvested from healthy crops.
 Seed treatment with copper sulphate, thiram, benomyl or calixin M.
 The last named fungicide (calixin M) is reported to completely eradicate the inoculum
from the seed.
 Seed treatment with carbendazim + thiram in 1: 3 ratio at the rate of 2.5 g/kg seed
followed by 3 sprays of carbendazim (0.5kg/ha) at 10 days interval when the disease
appears is important option.
Management of the Ascochyta blight disease

29. 4. Faba beans Black rot (Fusarium solani)
 Black root rot caused by Fusarim solani is one of the most important biotic
stresses in the major faba bean growing areas of the world.
 When favorable conditions prevail and sever infections occur, the disease
can cause complete crop loss.
 In Ethiopia it cause loss of up to 45 to 70% on farm yield in severe
conditions
 Damage caused by the emergence of the disease is worsened by warm,
compacted soils, limited soil moisture and poor soil fertility
Symptoms
 Stunted plant growth;
 Yellowing,
 Necrotic basal leaves;
 Brown-red or black streaks on roots that coalesce as they mature;
 Lesions may spread above the soil line

30. Management faba beans black root rot
 Control relies on cultural practices e.g. do not plant broad bean in same area more than once in any
5 year span; treat seeds with an appropriate fungicide prior to planting.
 Integrated management is the most promising alternative to control faba bean black root rot .
 Soaking faba bean seeds in biocontrol agents (Bacillus megaterium and Trichoderma viride) and
chemical inducers [salicylic acid and hydrogen peroxide (H2O2)] individually or in combination
significantly reduced root rot either under green house or field conditions.
 Fungicidal seed treatments with Apron Maxx (Fludioxonil + Metalaxyl) and Vitaflo 280
(Carbathiin + Thiram) consistently improved emergence and seed yield in trials inoculated with
Fusarium avenaceum and Rhizoctonia solani.
 the integration of varietal resistance (either Wolki or Wayu), drainage method and sowing date’s
adjustment are important for effective management of faba bean root rot.