When Is the Best Time to Spray Sunflowers for Head Rot?
Posted: July 29, 2014
With the registration of fungicides for Sclerotinia head rot control in sunflowers, growers have an excellent management tool for reducing the impact of an economically devastating disease.
As the products and use is new to many growers, there are a number of question on timing.
- Sunflower staging: Target the R5.1 to R5.2 stage (10-20% disk flowers open)
- Field staging: 50-80% of heads at R5.1 to R5.2
- Number of applications: Depends of product. If registered and conditions good for infection a second application can be made 12-14 days after the first application
Expert advice from Dr. Khalid Rashid, Pathologist with AAFC Morden, who has tested the head rot fungicides and sunflower staging timing for over 10 years is that:
“The growth stage of R5.1-R5.2, until end of flowering (3 week window) is the most susceptible stage. The main factors for susceptibility are the availability of ascospores from mushroom production in adjacent fields (less are produced in the sunflower fields), and there is humidity in the air and on the sunflower heads, for ascospores to germinate and infect the heads. Sometimes, a second application 2 weeks after the first application may further reduce the disease infections. In some years/some fields get high late infection after the end of flowering due to a flux of ascospores production late in the season coupled with favourable humidity/rain conditions.”
Banded Sunflower Moth counts on the rise! Time to Scout…
Posted: July 24, 2014
As a follow up to our July 17, 2014 crop report, banded sunflower moth counts have increased. Refer to the chart for counts in your area. NOTE: The threshold is 1 banded sunflower moth per 2 plants.
July 17, 2014 Sunflower Crop Report
Posted: July 17, 2014
Sunflowers in the red river valley are nearing or are in the R-1 to R-3 stage. In the SW part of the province, V8 to V12. Monitoring for banded sunflower moth continues and over the past two weeks, trap counts are nearing economical thresholds (RM of Dufferin and Woodlands). With the current staging of sunflowers in the RRV and if trap counts continue to climb, an insecticide application will be warranted. Traps will be monitored until the second week of August. Follow us on twitter for to update counts. (Table 1—Page 2)
Other insects to watch are bud moth, sunflower seed weevil, stem weevil, and lygus bug. (Figure 1) All these insects can affect seed quality, specifically in confections, and Canada Sunflower #1 standards are 2% insect damage. Continue to scout and monitor insect pressure.
Click here to read the full report.