Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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11th FAWWON
The 11th FAWWON consisted of 146 entries and was distributed for planting
in 2001/02 to around 80 co-operators from more than 40 countries. Most lines
developed by the IWWIP programme show good levels of resistance, while the
majority of lines from other areas of the world are highly susceptible to YR
(Figures 3 and 4). The figures show the maximum YR score from evaluation of
11th FAWWON across 9 locations, namely Azerbaijan (1 location), Iran (5
locations), Syria (1 location), Tajikistan (1 location) and Turkey (1 location).
Entries within each group of origin (Checks, IWWIP, CAC [Caucasian and
Central Asian Countries], Eastern Europe, USA, Western Europe, China and
Iran) are sorted by ascending susceptibility. The number on the X-axis refers to
entry number in 11th FAWWON. However, since many of these are excellent
lines with highly favourable characteristics, it is important that such
information is shared with all co-operators in order to more efficiently utilize
these lines in breeding programmes. Otherwise, they may be at risk of being
discarded by breeders due to YR.
4th WWEERYT
The 4th WWEERYT consisted of 64 genotypes submitted by breeding
programmes from twelve countries, and YR data was reported from three
locations: Turkey, Iran and Tajikistan (Table 1). Highest disease pressure was
observed in Turkey under artificial inoculation, where susceptible checks
reached levels of 80S and 90S. High levels of susceptibility to YR were
observed for most lines submitted by the majority of the breeding
programmes, although a limited number of lines were found to have
acceptable levels of resistance to YR.
Discussion
YR has long been a major threat to winter wheat producers in CWANA, and
with the disease recently moving into areas (such as the USA) where it has
become an important constraint, even more focus is now placed on the
development of resistant cultivars. The majority of the lines and cultivars
submitted by breeding programmes to be included in the international
nurseries (FAWWON and WWEERYT) are high yielding lines and potential
candidates for release in several countries. However, if these countries are
lacking the facilities for artificial inoculation and other facilities necessary to
assure a high degree of disease pressure, and natural epidemics do not occur
on a regular basis, then breeding programmes in these countries may run the
risk of releasing cultivars that will be highly susceptible under conditions that
permit natural epidemics. Having an international testing network, like the
one facilitated by IWWIP, where promising lines can be evaluated under
conditions assuring good artificial epidemics, reduces this threat.