What is in this article?:
- Rust diseases cut into North Carolina wheat yields
- Very warm winter
- Overcame resistance
• Warm winter and spring temperatures were the main culprits for the increased rust pressure in wheat, but the size of the crop also provided more opportunities for disease to form.
USDA PLANT PATHOLOGIST Christina Cowger shows the results of rust damage to wheat in a North Carolina field.
“Unfortunately, the abundance of rust spores meant that a number of strains could overcome built in genetic protection. With the perfect weather conditions, these rare rust strains took a toll on some of the varieties that normally have good protection against leaf rust.”
Fortunately, a number of strobilurin and triazole fungicides provide very good protection to wheat from leaf rust and stripe rust damage.
Strobilurin fungicides tend to build up in the cuticle of the small grain plant and tend to be best against the spores. Once the spores germinate and start to grow, this family of fungicides is less effective. So, in general the strobilurin fungicides are used as a preventative.
Triazole-based fungicides have more systemic activity and move more inside the plant. So, these fungicides have some activity even after infections have been established and are somewhat more effective in managing diseases after they occur on the plant.
There are also combinations of strobilurins and triazoles that work extremely well to manage wheat diseases. However, regardless of the fungicide treatment used, Cowger says it is critical to catch a rust epidemic before it goes too far. It’s always going to be best to apply fungicides before the leaf rust has gotten going on a big scale.
To move around, disease spores depend on wind to move from place to place. In the Upper Southeast, there was plenty of wind to go along with warm temperatures in the winter and spring. All in all, rust had a near perfect environment to grow, and it had a negative impact on wheat yields in the region.
A late spring freeze didn’t help and likely cut yields as much or more than the heavy rust outbreak in some areas of the Upper Southeast.
The combination of the freeze and the otherwise warm weather that produced excessive, early wheat plant growth contributed significantly to reduced wheat yields statewide, according to Extension specialists from Maryland to South Carolina.
Throw the heavy rust year into the mix and growers had a battle on their hands to keep what at one time looked like a record wheat crop in terms of yield, and keep it a good wheat yield.
Despite the setbacks on yield, North Carolina State Small Grains Specialist Randy Weisz says it appears growers are gearing up to plant even more wheat this fall.
“Seed for some of the more popular wheat varieties in the Upper Southeast may be in short supply this fall,” Weisz says.
He points out that growers would be ahead of the game to look at North Carolina State’s recently released variety performance reports and determine which varieties would work best under a number of different scenarios, including varieties with rust and mildew resistance.
The North Carolina Small Grain Growers Association recently released a video and posted it on social media in which Weisz gives an overview of wheat varieties and provides some valuable insights on how growers may go about choosing varieties based on performance, maturity date, and resistance to diseases.