Harvest, hail and winter wheat disease
SCOTTSBLUFF, Neb. – Wheat producers whose crop was damaged or destroyed by hail this year need to take special precautions soon to prevent viruses such as wheat streak mosaic and high plains virus from damaging the 2011 winter wheat crop, according to University of Nebraska-Lincoln specialists.
Wheat producers in western Nebraska received ample precipitation this spring, leading to some of the largest yields reported in quite some time. However, for some, this precipitation also fell in the form of destructive hail.
Regardless of how severe the hail damage was, it is critical to plan now to control volunteer wheat before sowing next year’s wheat crop, says Dr. Jeff Bradshaw, extension entomology specialist at the UNL Panhandle Research and Extension Center in Scottsbluff. Here is why:
During wheat harvest some grain always falls to the ground to produce volunteer wheat. However, this isn’t the volunteer wheat that raises concerns about viruses in the following crop. Rather, Bradshaw said, it is the volunteer wheat produced by hail damage, because it has had much more time to grow and serve as habitat for wheat curl mites.
These mite-infested plants will be a source for viruses such as wheat streak mosaic virus and high plains virus in the 2011 winter wheat crop, according to Dr. Steven Wegulo, UNL Extension Plant Pathologist at Lincoln. Wegulo added that the two viruses act synergistically, in the sense that one virus is harmful to the wheat plant, but two are even worse.
Bradshaw explained how volunteer wheat fits into the mites’ life cycle: Prior to harvest, mites will begin to move as they are carried by the wind out of the old wheat and will establish on green volunteer plants. If these volunteer plants are not controlled, they will serve as a host for infestations and viruses for seedling winter wheat.
However, timing is crucial, he stressed. It is important to control volunteer wheat early, before next year’s crop emerges. Applying herbicide to volunteer wheat adjacent to newly-emerged wheat will only result in mites moving off of dying volunteer wheat and onto young wheat seedlings.
“This is a situation to avoid because the inoculation of seedling wheat by wheat streak mosaic and high plains viruses can cause significant damage to the wheat crop,” he said.
Two management strategies can effectively manage this disease, Bradshaw said:
Control. Be sure to control volunteer wheat after harvest. This is particularly important this year because many fields suffered from hail damage.
Avoidance. Do not plant winter wheat too early for your growing area. It is crucial to allow time for herbicides to effectively kill off volunteer wheat, to prevent the spread of wheat curl mites into the new crop.
Additionally, avoid planting winter wheat next to late-maturing, green corn. This is important since corn is also a host for the mite as well as wheat streak mosaic virus.
Another reason to avoid early planting is to reduce the risk from Hessian fly and to reduce winter kill, according to Greg Kruger, cropping systems specialist at the UNL West Central Research and Extension Center at North Platte.
For more information on wheat production and management please go to: cropwatch.unl.edu/web/wheat/
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