BASF launches PGR Caryx for oilseed rape

BASF received approval for PGR Caryx (metconazole 30g/L+ mepiquat chloride 210g/L), which is the first to be developed specially for oilseed rape and is claimed to help to create an improved plant canopy to maximise yields. It will be available from Agrovista this season.

BASF's Caryx is claimed to reduce lodging and promote rooting as well as promoting a better canopy, especially useful in this difficult cold spring.

"Crops are much more variable, some are forward and will need holding back while most are backward," says Mark Hemmant, technical manager at adviser Agrovista.

"But some of these backward crops are nicely set to produce reasonable yields. How often do you see a poor crop go on and produce some of your best yields," he adds.

BASF field crops manager Will Reyer explains the new product was specifically developed for oilseed rape instead of being an existing cereal fungicide that has had the label extended for use on oilseed rape.

It contains the familiar fungicide PGR metconazole (30g/litre) plus mepiquat chloride (210g/litre), and is applied from stem extension stage to yellow bud in oilseed rape.

"This combination has been widely used on the continent for a few years and is now available for the first time to UK growers," Mr Reyer says.

For top yields, crops need managing to maximise the number of seeds/sq m and BASF argues this requires regulating growth to achieve the ideal plant canopy.

"It reduces apical dominance in the primary stem, reducing overall crop height, and promoting growth and the number of the secondary branches," says Mr Reyer.

Over-large canopies tend to shade the lower part of the canopy, but the regulator can create a more open canopy, stronger lower branches and more light to these lower levels.

In addition, using the regulator increases the number of chloroplasts (parts of a cell containing chlorophyll) resulting in increased photosynthesis and delayed senescence, keeping crops greener for longer.

"Compared with straight metconazole, trials show greater consistency, particularly when crops are under stress," says Mr Hemmant.

Reasons for this increased consistency is the improved take-up of metconazole due to an improved formulation plus the complementary effects of the two actives, says Mr Reyer.

Metconazole has a shorter duration of activity, rapid onset of effects and has an optimum temperature of 12-18C.

In contrast, mepiquat has a relatively slower onset of effects, relatively short duration and optimum activity at colder temperatures, he adds.

Pete Berry, principal research consultant at ADAS, has carried out nine complex trials to help determine how the new product partitions yield in the plant.

"Using the product resulted in a greater number of secondary branches. We measured the contribution and found altogether the secondary branches yielded about 1t/ha. We were surprised they contributed this much," says Dr Berry.

"The terminal raceme gets most attention, but generally only accounts for 20% of the total. Maximising secondary branching can make a meaningful contribution to overall yield," he adds.

Mr Hemmant agrees that this approach to managing canopies delivers more seeds/sq m rather than just lodging control.

With this in mind, Mr Hemmant is looking at combining its use with wide rows. He believes it could increase further the contribution from secondary branches, thus pushing oilseed rape yields even higher.

Further trials with the new regulator showed that using it at half rate (0.7 litres/ha) reduced lodging from 48% (untreated) to 12% and applying the full rate reduced it further to 4%.

Lodging can result in large losses and even leaning crops lose yield. According to a recent ADAS report, for every 10% of an area lodged, yields fall by 0.07 to 0.16t/ha.

Several trials carried by ADAS found that applying Caryx resulted in 20% greater height shortening than full-rate metconazole.
"The difference was noticeable," says Dr Berry.