The first autumn-applied PGR for rape
Oilseed rape growers are much more aware of how damaging lodging can be in the crop. “Lodging in rape can causes significant crop losses, just as it does in cereals, by reducing the amount of light getting into the canopy, by restricting essential assimilate supply and so reducing seed fill. Two springs ago the first true plant growth regulator (PGR) specifically developed for rape was registered, Caryx. Now Caryx has received a new approval for autumn applications, allowing crop manipulation to start much earlier in forward crops at high risk of lodging,” says BASF business development manager Clare Tucker.
She explains that its autumn registration was granted on the premise that in some autumns where crops are advanced, a single spring application of a PGR may be insufficient to give full lodging control, whereas improved lodging can be achieved by a programme of autumn followed by spring application.
The autumn recommendation is for Caryx at 0.7 l/ha applied to forward crops at the 4 to 6 leaf stage. “It is important not to let the crop get too big. The usual window would be September and October when the crop is still actively growing. Well established crops sown in August are likely to benefit from the sequence, particularly if sown at higher than normal seed rates,” she says.
“With early drilling and more crops being planted at higher seed rates to try and foil cabbage stem flea beetle, if the pest doesn’t turn up in the expected numbers, we could be seeing some very advanced, larger crops this season – ideal for the PGR sequence.”
Clare Tucker explains that autumn Caryx works in a number of ways.
“It prevents early elongation of the stem; it also increases root mass & and root collar diameter. Reducing early elongation of the stem minimises the ‘helicopter effect’ where the wind can twist and damage the top of the plant and pull out its anchorage. Reducing the stem growth also helps prevent premature shoot development and associated frost damage. Importantly it also minimises exposed tissue vulnerable to Phoma stem canker infection.”
“Increasing the root mass and root collar diameter increases the plant’s tolerance to waterlogging and cold conditions. It also improves anchorage of the plant, so reducing root lodging risk. Autumn Caryx will also 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 autumn PGRs can affect this,” she says.
She Clare reminds growers that Caryx contains two actives, metconazole and mepiquat chloride. "These actives have complementary modes of action. Metconazole starts off quickly but has a short duration of activity. Mepiquat chloride is the opposite; being slow at the onset of activity but with a longer duration. Temperature requirements for each active are also different, with metconazole being optimal at between 12º to 18ºC and mepiquat active down to 5ºC. This means that Caryx can cope with variable growing conditions experienced in the autumn. It is important that products are reliable in unpredictable weather.”
