Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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%
90
80
70
60
50
40
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20
10
0
2003 2004 2005 2006 2007 2008 2009
Yellow Rust Tan Spot
Figure 3. Frequency of wheat entries in breeding nurseries damaged by yellow rust
and tan spot (i.e. moderately susceptible (MS) and susceptible (S)) in 2003–2009
In comparison with 2003, the severity of yellow rust decreased in the period
from 2004 to 2008 in all agro-ecological zones of Tajikistan, whereas the
severity of tan spot increased. The reasons for decreased yellow rust levels
were dry climatic conditions, unfavourable for the formation of yellow rust,
and the introduction of new varieties resistant to yellow rust and other
diseases.
The results from 2006 over three locations showed that the cvs most
susceptible to yellow rust were Navruz with 50% level infestation; Somoni
with 40% in Isfara and 20% at the Farming Institute; Ziroat 70 with 30% in
Isfara and no yellow rust in the farming institute and at Vakhsh. Genotypes
showing resistance to yellow rust were Alex, Kauz, Norman, TAM200/KAUZ
and SHARK/F4105W2.1.
During growing seasons 2007 and 2008, yellow rust was not observed in
Tajikistan. Even cv. Navruz, which under normal conditions is susceptible,
was not infected by yellow rust.
The humidity was very high during the spring of 2009, but still yellow rust
infestation was low, with an average of 10% of entries in breeding nurseries
being characterized as either medium susceptible or susceptible. The wheat
varieties most susceptible to yellow rust were standard cvs Navruz (50%
damage) and Eskina (80%) in all zones.
The results from 2009 demonstrate that brown rust is becoming a serious
wheat disease in Tajikistan. The most susceptible cvs and their infestation
levels were Krasnodar 99 (100%), Gelibolu (100%), Trakya Aktar (100%),
Kazakhstran 10 (70%), Navruz (60%) and Konya-2002.