Dry Bean Rust Found in North Dakota
January 12, 2009
Rust started showing up late in the season this year around northern Trail County, mostly in the Buxton/Hatton area and in some small areas in Grand Forks County. Even though it was localized, it was severe in some areas. That is not unusual to have rust show up late in the season, but what was interesting was that it was showing up on rust resistant varieties, says Sam Markell, Extension Plant Pathologist at NDSU.
Rust can progress quickly in fields when temperatures are moderate, and when heavy dews occur in the mornings. When it comes late, growers usually dont lose yields. It is when rust shows up in the early stages of the plant that there could be a problem.
Why Trail County?
The disease is most commonly found where lots of beans are grown in the previous year. The rust pathogen can overwinter in residue from beans planted last year, and when there is lots of residue, it is more likely that you see rust again. However, if in fact we do have a new race of rust, when and where a race change occurs is often a fairly random event. When breeders release varieties, those varieties have all sorts of traits, usually including a resistance gene to rust. But the rust pathogen is variable and changes through mutation or genetic recombination. Sooner or later, through this change, one of the spores may overcome the genetic resistance in some varieties. This could happen anywhere, says Markell
Rust can be controlled with fungicides, including Folicur, which recently received a Section 3 full registration for management of rust on dry beans. These are added inputs to the growers, but are a very useful tool when necessary. Additionally, as beans mature, rust is less detrimental to yield, and thus, fungicides are not as economical. We have had rust issues in the past and may have rust showing up in the future.
Fortunately, we have good control tools. Rust is a manageable situation but growers always have to be on the ball. They will have to be prepared to scout their fields this upcoming year, says Markell.
Markell will be presenting more on dry bean rust and his new findings at Bean Day on January 16, 2009.
Dr. Sam Markell