Oilseed rape growersare much more aware of how damaging lodging can be in the crop, according to BASF. Lodging in rape can causes significant croplosses, just as it does in cereals, by reducing the amount of light gettinginto the canopy, by restricting essential assimilate supply and so reducingseed fill,” says BASF business development manager Clare Tucker. “Two springs ago the first true plant growth regulator (PGR) specificallydeveloped for rape was registered, Caryx. Now Caryx has received a new approvalfor autumn applications, allowing crop manipulation to start much earlier inforward crops at high risk of lodging.”
She explains that its autumn registration wasgranted on the premise that in some autumns where crops are advanced, a singlespring application of a PGR may be insufficient to give full lodging control, whereasimproved lodging can be achieved by a programme of autumn followed by springapplication.
The autumn recommendation is for Caryx at 0.7 l/haapplied to forward crops at the 4 to 6 leaf stage. It is important not to let the crop get toobig. The usual window would be September and October when the crop is stillactively growing. Well established crops sown in August are likely to benefitfrom the sequence, particularly if sown at higher than normal seed rates, shesays.
With earlydrilling and more crops being planted at higher seed rates to try and foilcabbage stem flea beetle, if the pest doesnt turn up in the expected numbers,we could be seeing some very advanced, larger crops this season ideal for thePGR sequence.
Clare Tucker explains that autumn Caryx works in anumber of ways.
It prevents early elongation of the stem; it also increasesroot mass and root collar diameter. Reducing early elongation of the stemminimises the helicopter effect where the wind can twist and damage the topof the plant and pull out its anchorage. Reducing the stem growth also helpsprevent premature shoot development and associated frost damage. Importantly italso minimises exposed tissue vulnerable to Phoma stem canker infection.
Increasing the root mass and root collar diameterincreases the plants tolerance to waterlogging and cold conditions. It alsoimproves anchorage of the plant, so reducing root lodging risk. Autumn Caryx willalso encourage more branch initials leading to more branching in the spring.Physiology shows us that the primary branches of rape form early on and so autumnPGRs can affect this, she says.
Clare reminds growers that Caryx contains twoactives, metconazole and mepiquat chloride. “These actives have complementary modes of action. Metconazolestarts off quickly but has a short duration of activity. Mepiquat chloride isthe opposite; being slow at the onset of activity but with a longer duration.Temperature requirements for each active are also different, with metconazolebeing optimal at between 12 to 18C and mepiquat active down to 5C. Thismeans that Caryx can cope with variable growing conditions experienced in theautumn. It is important that products are reliable in unpredictable weather.