The ‘right’ time to desiccate sunflowers is when the back of the head looks banana yellow and the bracts are brown up to and past the shoulders. This visual combination equates to R9 or typically around 30% seed moisture. You want to visually check out different parts of your fields, looking at the areas that you know advance faster and the ones that advance the slowest. Try to aim that the majority of you field is at the R9 stage.
Reasons to desiccate would be that even though seed moisture is drying down, to properly thresh out the seeds, the head material and stalk material need to be dry as well. Desiccation speeds up time to harvest meaning seeds are off the field faster, which can mean less losses from head rot damage, stalk breakage and bird feeding. National Sunflower Association of Canada has just released a bulletin explaining more on timing and products at http://www.canadasunflower.com/
Sclerotinia in sunflowers can be frustrating and devastating, especially in the form of headrot. Headrot is very weather related. It needs rainfall to wet soils stimulate sclerotia to produce apothecia mushrooms and ascopores. Ascospores once on disk petals, need prolonged wetness to allow the infection and growth of the fungus on the petals and spread into the sunflower head tissue.
It takes approximately 14 days after a “ground soaking” rainfall for the mushrooms to appear and produce ascospores. In 2016, most areas in Manitoba have saturated soils, making an ideal environment for apothecia emergence, which could be the start of the lifecycle to cause sclerotinia head rot in sunflowers.
It has only been in the past couple of years that sunflower growers have had fungicide registered to control headrot. With limited use of use, control has been not always been what was expected. The fungicides available are protectant and work to protect plant when disease infection potential present. If there was infection prior to application, or, if pressure remains high after application, control may be less than expected.
Manitoba Agricultural Services Corporation (MASC) has released an early version of the 2014 yield report with 99.8% of the Harvest Production Reports (HPRs) keyed in. The table below summarizes the 2014 average yield by crop type based on the harvested acres, as well as comparisons to 2013 and a 5-year average (2009 to 2013).
In February 2015, MASC will release their annual Yield Manitoba publication and update their Manitoba Management Plus Program (MMPP) website (http://www.mmpp.com/mmpp.nsf/mmpp_index.html) where further information on yields and acres by variety will be released. Additionally, the data will be more complete in February as all HPR’s will be keyed in.
Submitted by: Pam de Rocquigny, Anastasia Kubinec & Dennis Lange, Crop Specialist with MAFRD
Special Thanks to Doug Wilcox, MASC, for providing the 2014 data!
Sunflowers can be safely combined when the seed moisture is below 18-20%. However, allowing sunflowers to dry-down to a moisture content of 9.5 -12% reduces the need for drying on-farm. At 12% moisture content, seed can be stored in bins with aeration. Any moisture content over 12% will require drying to avoid spoilage. Oil-type sunflowers can be dried with temperatures of 71º to 104º C (160ºF to 220ºF) but confection-type sunflower seed may scorch or wrinkle with these temperatures. Sunflower seed should be cooled before storage, since even sunflowers at 8.5% moisture can spoil if stored when warm.
Frost anytime before the sunflower crop reaches physiological maturity (R9) can cause damage. Once sunflowers reaches the R7 stage (ray petals have dropped, back of head starting to turn yellow), sunflower can withstand temperatures as low as -4° C, but temperature, duration and crop stage will influence the type and amount of damage.
A killing frost in sunflowers is considered to be -4 to -5° C for 6 or more hours, as this low temperature for the extended period is required to penetrate the thick layer in the back of the sunflower head and start the dry down process. See attached bulletin for more details
Prepared by Anastasia Kubinec, MAFRD Oilseed Crop Specialist
Sunflower planting was spread out in 2014, which means flowering and dry-down will be as well. The chart below gives and indication to the amount of time it will take the crop to reach R8 to R9. This is a guide only. Sunflower development and dry down is based on temperature. If August is all above 25C during the day and doesn’t go below 10C at night, the sunflower crop will develop much faster than this!
From August 5th to 31st, regardless of location, there is typically 275-320 Sunflower GDD accumulated in Manitoba. To get from R5.1 to R9 the crop needs 393 GDD.
Sunflower GDD (Celcius)
*Sunflower GDD= (Tmax+Tmin)/2 – 6.7C
Example = ((25+10)/2)-6.7=10.8
For more information, contact NSAC agronomist at (204)750-2555 or MAFRD Oilseed Crop Specialist at (204) 750-2717
Standardized Growth Stages described by Schneiter and Miller. 1981. Description of Sunflower Growth Stages. Crop Science 11: 635-638
With the registration of fungicides for sclertotinia 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 weeks 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.”
One of our most used extension messages is seed early!
In a year that is later, this may cause some concern that seeding into the second half of May is not going to have good crop yields. Typically seeding earlier does normally translate into higher yields, but good yield potential remains when seeding throughout the month of May, provided you don’t compromise the seeding operation.
Things Other than Seeding Date That Influence Yield:
Using clean seed with high %germination
Applying the appropriate fertilizer nutrients and rates to support yield goals
Seeding for a good plant stand – taking in account TKW, %germination and seed mortality!
Seeding into a firm seedbed
Seeding into soil warm enough to result in quick germination and emergence
Timely weed control
Timely fungicide application if needed
Appropriate harvest operation timing
Table 1: Crop Yield Response to Seeding Date (2005-2013)