How are your crops looking? Are your fields all at the same stage? Do you need to speed up dry down to get in the field? Are you bored with summer and need to get in the combine? How important is combine efficiency? What is the frost forecast? These are all things to consider when deciding to preharvest or not.
First thing is first, what are your fields looking like? Pre-harvest products do not hasten maturity, they simply stop the plant dead in its tracks. Take a walk (or we can do it for you). Be sure to evaluate the difference in crop staging throughout the field and base your decision on the least mature areas.
W H E A T
If you are looking at wheat, start with the peduncle. A ped-a-what? Peduncle, the small area between the head and the stem. If it has turned from green to yellow this means the plant is physiologically mature and no longer translocating energy from the stem into the head. Why is this important? A pre-harvest glyphosate application is only safe if done once the crop is mature to avoid chemical translocation into the kernels. Glyphosate residue in kernels is NO GOOD FOR ANYONE. Keep it clean!
Next up, the kernel thumbnail test – if the kernel squishes between your fingers, it is obviously not mature enough. Moisture in the head should be less than 30%, if your thumbnail leaves a dent (that stays), the kernel is at the hard dough stage and it’s GO time!
C A N O L A
For canola, varieties with pod shatter or pod integrity traits are improving every year. Swathing at the 60% seed color change on the main stem is one way to bring on harvest. If you are into straight cutting (or want to try it) you have options with canola.
Glyphosate. Same with wheat, seed moisture should be less than 30%. Take a look at your main stem and apply the rule of thirds – in the top third seeds should be green and firm to roll, second third seeds are mostly brown with some speckling and in the bottom third seeds are completely brown-black. ETA on dry down will be 7-21 days.
DYK: Seed colour change advances up the stem at about 10% every 2 to 3 days!
Diquat. If you want faster dry down, this is your product. Apply at 90% seed color change – seeds should rattle in the pods, open seed pods on the main and secondary stems to verify 90% brown seeds. This is a contact product and water volume is key (think 15 gal minimum!) to penetrate the canopy and hit green tissue. Pay attention to the forecast. Diquat is activated immediately by sunlight. Apply in the evening or on a cloudy day to allow the herbicide to spread slightly from the droplet contact point to promote better uptake for when the sun shines! Plant dry down can be as fast as 5 days so have combines ready to move on that field to avoid shatter loss.
Heat LQ. Number one rule, Heat likes heat! Best when applied at 80% seed color change, tank mixed with your glyphosate and throw in some Merge. You are looking at a dry down interval of 7-21 days, pending weather conditions but you can get some effective perennial weed control.
I N G E N E R A L
Adjuvants enhance spray performance. Add Crimson NG (water conditioner) to your glyphosate for faster activity. For best canopy penetration, use a deposition / adhesion /drift agent such as Interlock or Masterlock. You will not regret it.
No matter what product you decide to go with, watch your seed moisture and color change, don’t skimp on the water volume (water is free!), talk to your grain buyer on market access, keep it clean and watch your pre-harvest interval timing.
Your last decision with preharvest applications will be to apply with a ground rig or aerial. Consider your crop price, in-field equipment costs, loss due to trampling and if you can spare an operator to run the sprayer.
These are the days to work around the clock and get the crop in the bin! We are happy to help in any way we can!