Greater timing flexibility and improved root anchorage are two reasons growers might choose to use BASF’s new plant growth regulator Canopy this spring. It also offers the opportunity to reduce chlormequat inputs in crops where residues may be an issue.
Containing a completely new active ingredient, prohexadione-calcium, in combination with mepiquat chloride, Canopy is likely to be a direct competitor for Moddus (trinexapac-methyl) in mixtures with chlormequat, although it can also be used as stand-alone product from GS30 to GS39.
Its effectiveness at lower temperatures is a key attribute, according to Dick Dyason, a BASF agronomist. Unlike Moddus, which is dependent on light intensity and temperature to activate it in the plant, Canopy is in the active form once dissolved in the spray tank, he explains. It means Canopy starts working as soon as it’s applied, while the activity of Moddus can be delayed in cooler conditions. “It might be 10 days before trinexapac-ethyl has any effect, which could be why you can sometimes get a ragged crop effect with Moddus.”
It also should prevent over-regulation of crops if the weather turns cold, as Moddus is prone to do, Hutchinson technical manager Dick Neale believes. “Canopy could be useful if we have another cold season or as an alternative to ethephon if we have a cold May.”
Once inside the plant Canopy works similarly to Moddus by inhibiting gibberellin production and causing cell walls to thicken. In particular, it encourages an increase in stem dry matter and lignin, Mr Dyason says. “Effectively it adds more steel and concrete to the structure.” It could also improve resistance to eyespot.
A second effect of Canopy – increased root growth – should also help protect against root lodging through better root anchorage, he suggests. In laboratory tests 0.6 litres/ha of Canopy increased root growth by 20%, compared with only 10% from 0.4 litres/ha of Moddus, and 0% from the commercial use rate of 0.2 litres/ha. “It’s a key feature of the product. In wet summers the whole plant can come out of the ground.”
In addition, applying Canopy could also have physiological benefits, including a greening effect and better drought tolerance, BASF claims.
Typically Canopy should be used at 0.6 litres/ha in mixture with chlormequat at GS30/31, Mr Neale suggests. “Our trials suggest you’re not gaining anything from increasing the dose when mixed.”
But if chlormequat residues prove to be an issue for processors in the future then higher rates could be an option. “You would need 0.8-1 litre/ha alone.”
The product also has potential to replace Terpal (2-chloroethylphosphonic acid + mepiquat chloride) as a late season growth regulator. “It has proved equally effective,” Mr Neale says. That could be good news on light land where growers are sometimes nervous about applying ethephon, he suggests. “Canopy is far softer on the crop.”