At BASF’s recent technical conference, Claire Tucker explained how important canopy management is for oilseed rape yields.

On any crop, green leaf allows crops to maximise sunshine and photosynthesis to produce food for the plant and ultimately a high yielding crop. Oilseed rape is no different.

This is why Claire spoke about green leaf area duration (GLAD) on oilseed rape. She said that every area of green leaf that stays in your crop affects your yield, so we should aim to maintain green leaf area for as long as possible.

Clare referred to a GLAD unit and explained that for every unit of green leaf that the crop holds on to, it can result in 0.13t/ha in yield. However, once the plant has enough green area this levels off.


There are plenty of management practices to help this.

Nitrogen application is one and on oilseed rape crops, farmers should be measuring green leaf area to decide how much nitrogen the crop has taken up and how much it needs.

Wet weather has severely delayed fieldwork this season, so many oilseed rape crops have not received a herbicide, fungicide or growth regulator and are still waiting on nitrogen.

Claire explained that if you put down a quadrat to measure 1m2 or you use an application on your phone to measure your oilseed rape crop’s green area and half of the space is covered with green leaf, then this gives a GAI of about 0.8.

Growth regulator

At a GAI of 0.8, she said it makes economic sense to use a growth regulator.

To increase yield, you need to increase seed number and a growth regulator will help to improve how the crop grows.

You can’t get all of the yield from the main stem, so you need the plant to increase branch number and make branches stronger.

Applying a growth regulator will also help the plant to grow in a way that allows the light through the plant to help all parts of the plant to get light and provide seeds and yield.

Light leaf spot should be controlled early in the season, but recent weather has not allowed for this, so a fungicide such as prothioconazole should be applied with a growth regulator application.