Jim Rennie, Technical Director for CSC, is advising the use of the BASF GAI Tool this spring to help with the practical canopy management of the many advanced oilseed rape crops growing in Scotland.
"Oilseed rape was well established this year into good quality seedbeds with good moisture levels. Crops grew well throughout the autumn and became very advanced. Although many oilseed rape have gone backwards in their biomass since Christmas due to leaf loss and pigeons, most are physiologically very much more advanced - completely different to rape crops at the same time last year. Currently soils are still cold and quite saturated. But as soon as the temperatures begin to climb, the crops will start to grow away and they will be in need of nitrogen as well as a PGR.
This is where the use of the BASF GAI tool comes in. Found on the www.totaloilseedcare.co.uk web site, this tool allows you to upload a digital photograph and get back immediately an accurate assessment of the GAI of that crop. It is probably an idea this year to go to the best part of the field to take your photograph. This approach is used to help with both nitrogen and PGR usage," explains Jim.
In Jim’s view the majority of oilseed rape crops in Scotland will need canopy manipulation this spring in order to optimise canopy size and maximise yield potential. "Metconazole (Sunorg Pro) has the best PGR effect and works very well, not just reducing height but also improving rooting and branching. It also has good disease activity on Phoma and Sclerotinia and some effect on Light Leaf Spot."
Jim Rennie points out that Light Leaf Spot is the most important and frequent disease in rape in Scotland and may need treating at the same time as the PGR. "I have had very good results mixing metconazole with another triazole such as prothioconazole or flusilazole that are more effective on this disease. The concept of triazole stacking works well in rape as well as in other crops, balancing out the dose rates according to the need for growth regulation and/or disease control."
BASF point out that the main timing for protecting against yield loss from Light leaf Spot in the spring is before the stem extension stage, when a triazole without any growth regulating activity should be used. For PGR triazoles such as metconazole it is recommended that when the GAI of the rape crop is greater than 1 in mid-March or greater than 2 in April, then an application of 0.8 l/ha of Sunorg Pro would be beneficial. Applying metconazole at mid-stem extension maximises stem shortening, reduces lodging risk and improves rooting. Used at late green bud onwards Sunorg Pro will maximise canopy effects, reduce lodging risk, improve rooting and contribute to Sclerotinia control.
