Yet another new race of downy mildew in spinach has been identified.
The 14th race was first confirmed in November 2010 in a Ventura County, Calif., field, according to a grower newsletter report by University of California Cooperative Extension farm advisor Steven Koike and University of Arkansas plant pathologist Jim Correll.
The new race was initially designated UA4410.
The International Working Group on Peronospora has designated the isolate as race Pfs: 14. UA4410 will be the official isolate of Pfs: 14.
Subsequent testing identified the race in several locations in California and Arizona in 2011 and this year. It has not been reported in Europe.
This newcomer poses a threat to the spinach industry because it's well adapted to hybrids that are resistant to races 1-13.
The discovery should encourage breeders to develop varieties resistant to races 1-14, according to the newsletter.
A group of researchers from the international group, the University of Arkansas and University of California is monitoring the development of new spinach downy mildew races globally and will continue to collect and test suspected new isolates.
Correll and Koike's work is being supported by the California Leafy Greens Research Board as well as allied industries in California and Arizona.