OWBM Flashcards
Last major outbreak of OWBM
3-5 year outbreaks but the last one was in 2004, where 1 million tonnes of wheat was lost
Out breaks are…
Serious but sporadic, they’re sporadic due to specific growth stages.
Crops are at most risk if..
Peak adult emergence coincides with GS53-59
What crops can OWBM be found in
Wheat, barley, oats, sometimes in grass, often occurring with leather jackets
Sprayed?
They’re prophylactically sprayed but problematic with non targets
3 reasons of Importance
- Larvae feed on developing grain- grain shrivelling although signs of other problems it’s a good indication of OWBM.
- Poor germination
- Impacts of grain yield and quality
Importance with secondary problems
Grain lost through secondary problems- damage to outer grain layer, facilitating water entry and causes sprouting and secondary fungal attacks
3 examples of prevention
Crop rotations
Break crops
Resistant varieties
Crop rotations
Problematic since impractical to have 10 year rotations due to survival of larvae as cocoons in the soil
Break crop example
OSR can reduce soil population
Resistant varieties examples
From group 1: Skyfall
New ones include: Prince, merit or illuminate
Localised pest
They fly but not far, females can fly into nearby fields so treatment should include surrounding wheat fields
Identify OWBM
Both adult/larvae are orange
What are adult OWBM similar to
Yellow blossom midge
What are OWBM larvae similar to
Sandal gaul midge larvae
How do you know it is OWBM and not sandal gaul midge
Sandal haul midge is more sporadic (not had an outbreak for 30 years) so assume it’s OWBM
Correct identification is…
Crucial to IPM success
4 examples of detection
- Pheromone trapping
- Crop inspections
- Sticky traps/spider webs
- Sample when cultivating
Pheromone trapping
Placed in fields where OWBM was recorded the previous year. Most recommended
How often should you change pheromone traps
Replace every 3 weeks for efficiency
When should pheromone traps be set out
Set traps at GS 45 which is the flag leaf sheath swollen, leave trap in situ until GS 61 (flowering)
How often should you check pheromone traps
Cheeky daily
Crop inspections should be done at
On the evening when they are more active and flying, but this is impractical and you can double count individuals
Sampling benefits
Targets larvae and pupae, provides info on pest development, provides early warning
Sampling drawbacks
Expensive to conduct
Stick traps info
Put out at the start of ear emergence, does not monitor pupae or larvae, unreliable, targets adults not larvae
Action thresholds: soils sample
Pupae recorded- more than 11/kg soil
Action thresholds: sticky traps
Adults recorded: more than 10/trap/day
Action thresholds: crop inspection
Adults recorded: more than 1/6 ears sampled
Action thresholds: pheromone trapping
Adults recorded: more than 30/trap/day - present a general risk- monitor
More than 120/ trap/ day presents high risk- treat susceptible crops
What are the 4 natural enemies of OWNM
Dance flies
Spiders (webs)
Ground beetle
Parasitic wasp
What do the 4 natural enemies target
Dance flies- feed on adults
Spiders- webs traps adults
Ground beetle- feed on larvae
Parasitic wasp- attack larvae+ prevent pupation
What should we promote for natural enemies
You can’t buy, but promote naturally occurring: beetle banks, avoid bros spectrum pyrethroids, flower rich margins good for all but especially for ground beetles- providing pollen and supplementary nutrition
Chemical controls for OWBM
Chlorpirifos which is an organophosphate and targeted eggs, larvae and adults but no longer approved for use in the UK. Now the most commonly used one is Lamda-sialothrin which is a purethroid and grafted adults
Problem with natural enemies
Incompatible with one another
Favourable temperatures for OWBM
Warmer temps, 10 degrees plus, generally humid for pupae to emerge into adults.
Problems with wild flower margins
They’re effective but costly, there’s not much information on species of wildflower promoting natural enemies, most of the current effort is on bees, won’t find many pre made mixes for natural enemies
What might you do if action threshold is detected ?
If you grow a resistant variety, no action is required an no need to monitor or apply insecticide, otherwise….
set up traps prior to ear emergence as these are the sources of pests…..
If wheat is at ear emergence stage check traps, the crop is no longer vulnerable when flowering starts…
What might you do if action threshold is met… continued
If ear is at emergence.. if catches are over 30 trap/day continue to check but if over 120 trap/ day treat wheat and surrounding fields
Action threshold for feed wheat
1 midge on three ears
Action threshold for milling wheat/seed crop
1 on 6 ears
Problems with beetle banks
Beetles move into headlands of field but not that effective in the centre- talk on beetle banks in the middle- problems with spraying- equipment sizes, cost etc
