Why breeding rust resistant varieties is
not sufficient to control Yellow Rust
Hans-Joachim Braun
CIMMYT
International Wheat Stripe Rust Symposium
Aleppo, Syria
April 18 – 20, 2011
Importance of wheat
• Globally the most important food crop
• Second most important food crop in the developing world after rice
• Food to 2.5 billion poor people (< 2 USD) in 89 countries
• Provides calories (20%) and protein (20%) in LDC
• Most traded food crop
Consumer price index basket weights (2009 or latest available)
0 10 20 30 40 50 60
India
China
Japan
France
Britain
USA
Food
Energy
Source: Economist, Jan 22, 2011: OECD; IMF; Chinese Nat Bureau of Statistics; Indian Labour Bureau
PM Jawahar Lal Nehru famously said in the early 1960s:
“Everything else can wait but not agriculture”
• Demand for wheat is increasing by
>40%.
• Production lags behind demand
• Further decreasing global stocks
• International markets fail the poor
• Financial realities in first world “bread
baskets” and on global financial markets
do no longer tally with what the poor in
developing countries can pay for food
• Urgent demand to increase and protect
local production in low and middle
income countries
• Genetics + Agronomy + Markets + Risk
management + Policies + Infrastructure
Red alert zone for global
food securityReal wheat prices (USD) 1960 - 2011
Estimated contribution of crop protection (mechanical, biological and
chemical) to wheat production for 2001 – 03. Modified after Oerke 2006.
Add. Production due
to crop Protection
22%
Production without
Crop Protection
50%
Losses
28%
• 1B.1R varieties dominant from Kenya to China
• Basis for Yr resistance / suscepetibility was known
• 5 – 10 years gap from Yr9 virulence occurrence in Kenya
until it reached Asia
• No (?) country has removed 1B.1R varieties from seed
production before an epidemic occurred – but then fast
reaction e.g. Iran, established first class YR facilities,
Pakistan
Losses reported from yellow rust epidemics in CWANA
Region: Central and West Asia (CWANA); Countries;
Turkey, Azerbaijan, Iran, Pakistan, Afghanistan, Syria, T
urkmenistan, and Uzbekistan
•Turkey: 25 % yield loss, in 1991, up to 50 % in 1998.
•Iran: 15 % loss in 1993, 1995.
•Pakistan very significant loss in consecutive years
1990, 1991, 1992.
•Syria and Lebanon: 30% loss in 1988 and 1994
respectively.
•Turkmenistan, Uzbekistan: severe epidemics in 1998.
•Azerbaijan: nearly every year.
•Afghanistan 1991 famine due to yellow rust epidemic
Yellow rust epidemics during last decade of last century
National average wheat yield in years with yellow rust
epidemic in % of average yield of 3 previous and 3
consecutive years
50 60 70 80 90 100 110 120 130 140 150
Tur-92
Tur-98
Iran-93
Iran-95
Pak-92
Pak-91
Pak-90
Syria-88
Syria-94
Leb-88
Leb-94
Uzbek-98
Turkmen-98
Afg-91
National average yield in % of mean yield in years with YR epidemic
National average wheat yield in years with yellow rust
epidemic in % of average yield of 3 previous and 3
consecutive years and potential losses (15%)
50 60 70 80 90 100 110 120 130 140 150
Tur-92
Tur-98
Iran-93
Iran-95
Pak-92
Pak-91
Pak-90
Syria-88
Syria-94
Leb-88
Leb-94
Uzbek-98
Turkmen-98
Afg-91
National average yield in % of mean yield in years with YR epidemic
Country and
year Year+3 Year+2 Year+1
Year with
Yr-Epidemic Year-1 Year-2 Year-3
Tur-92 94 88 106 100 104 104 86
Tur-98 91 100 86 100 89 88 86
Iran-93 106 115 107 100 99 90 86
Iran-95 113 93 92 100 94 87 86
Pak-92 105 95 98 100 92 91 94
Pak-91 103 106 108 100 99 102 94
Pak-90 107 109 101 100 103 95 86
Syria-88 90 82 44 100 74 95 72
Syria-94 72 106 107 100 110 93 71
Leb-88 112 99 108 100 98 75 66
Leb-94 73 111 112 100 103 103 100
Uzbek-98 120 104 101 100 83 82 80
Turkmen-98 101 97 101 100 57 31 64
Afg-91 100 100 101 100 103 110 115
National average wheat grain yield in % of yield in years with yellow rust epidemic
in 3 consecutive (Year +) and previous years (Year-). Source: FAO 2009
In 27 of 42 cases yield greater In 9 of 42 cases yield greater
Losses reported in 1991 from Turkey
FACTS:•Turkey: 25 % yield loss, in 1991,
•Estimates were developed for Gerek 79 by calculating
the mean yield performance of three yellow rust
resistant check cultivars commonly used along with
Gerek 79 in the regional yield trials of the Eskisehir
Agricultural Research Institute. The data from the three
proceeding years were used to compare against Gerek
79.
•Losses are expressed in potential losses
Yellow rust epidemics during last decade of last century
Why is yield in years with yellow rust epidemics not lower?
• Good year for wheat = good year for yellow rust (cool, wet)
• Farmers may apply more N to benefit from good weather
conditions
• Wheat and Yellow Rust grow better with N
• Resistant varieties benefit from climate / N and yield
increases relative to normal year (20 – 30%)
• Yield of susceptible varieties reduced by 20 – 30% =
Yield of susceptible variety like in an average year
• Farmers loose 15 - 30% in extremes up to 50% and high %
of shriveled grains
• NB: This does not apply to very severe epidemics like in
Ethiopia in 2010
Examples for drastic rust control measures
• Barberry eradication program in US
• Sowing winter barley illegal in Denmark (1968) to
prevent infection of spring barley
• Legally defined earliest sowing dates for wheat
• Australian rust control program
Rust Control Measures
• Surveillance Monitoring
• Know genetic make up of major parents in crossing programs
• Hot spot screening – do we need another Njoro?
Rust Control Measures
• Surveillance Monitoring
• Know genetic make up of major parents in crossing prrgrams
• Hot spot screening – slide -
• No release of susceptible varieties
• No seed multiplication of “Rust Suckers” – after resistance broke
down
• Use APR – no more rust suckers
• Agronomy – control volunteers
• Use BC and Modified BC to fix resistance in dominating cultivars
whose resistance broke down
• Release genetically diverse varieties – CG-centers – NARS –
Mega-varieties how to avoid / can we avoid / should we avoid
• Establish similar testing network for YR as in place for Ug99
• Establish aggressive seed multiplication programs / extension
• One of the most important conditions for an epidemic is that
timely infection can occur in susceptible varieties sown on
large areas, Lang, 1918
• An epidemic will only occur when three factors come together:
Gaeuman (1951)
Virulent pathogen
Susceptible host grown on large areas
Conducive environmental conditions -
• Yr 27 may be the most rapid spread of an important crop
pathogen on the global scale (Hovmoller, 2008).
Countries in the Africa – Asia epidemiological
zone for YR where widely grown varieties are
susceptible to YR (2010)
Major variety replacement programs in Afghanistan, Egypt, Ethiopia, India,
Pakistan, Syria, Uzbekistan - list may not be complete
Ug99 resistant wheat varieties under seed increase 2010–11
Name Sr gene Countries undertaking seed production
NPL BGL AFG EGY ETH PAK IRN YR
CIMMYT name
Danphe#1 a APR (Sr2+) `√ √ √
Picaflor#1b APR (Sr2+) √ √ √ √ √
Quaiu#1c Sr2+SrTmp √ √
Quaiu#2 Sr2+SrTmp √ √ √
Pauraque#1 APR (Sr2+) √ √ √
Becard#1 APR (Sr2+) √ √
Munal#1 APR (Sr2+) √ √ √ √
Francolin#1 APR (Sr2+) √ √ √
Chonte#1d APR (Sr2+) √ √ √
NARS name
BL 3063e APR √
Bari Gom APR √
Misr 1 Sr2+Sr25 √ √ √ √ √
Misr 2 Sr25 √ √
Kavir Unknown
Bam Unknown √
V-04178 Unknown √
Flag 5m Unknown √ √
Area planted and seed production obtained for Ug99 resistant
wheat genotypes during crop season 2008-09 in the six
countries (3 tons seed sent in 2008 from Mexico, )
Countries Area planted (ha) Seed produced
(Kg)
Nepal* 7.5 18386
Bangladesh* 7.0 12000
Afghanistan 2.0 9523
Egypt 21.1 81166
Ethiopia (summer
crop estimated)**
7.0 20000
Pakistan 9.0 23633
Total 52.6 162808* Incl. locally developed lines resistant to Ug 99; ** incl. 2 ICARDA derived lines
Provided adequate funds are available and
NARS and private companies agree and
do replace susceptible varieties