With most oilseed rape now in the ground, establishment is mixed. Some crops drilled in late July or early August caught rain and got away quickly. Others drilled into dry seedbeds have struggled, while some were only drilled after the recent rainfall. As a result, crops are now at very different stages.

There are pros and cons to drilling later, but it is important to remember that cooler conditions can quickly slow establishment and early growth. Early drilled crops have not been without challenges either: flea beetle pressure was high in July, as shown by Agrii’s 17 Bayer Magic Traps, and many crops took a hit. Whatever the challenge, the focus now must be on establishing a robust crop before winter and maximising root and top growth ahead of pigeon grazing and cabbage stem flea beetle (CSFB) larvae pressure.

Nutrition plays a vital role in this process. Crops short of key nutrients are more vulnerable to larvae, disease and environmental stress. The ideal OSR canopy at flowering should carry a Green Area Index (GAI) of 3.5 and set 6-8,000 pods/m². The target is to reach a GAI of 1.0-1.5 by Christmas, providing enough canopy to support overwinter survival while reducing spring N demand. Achieving this helps build resilience while locking more nitrogen in the crop, reducing spring fertiliser requirements.

Later drilled crops have less opportunity to build biomass, so NDVI scores will typically be lower. Later-drilled crops typically show NDVI readings 20-30% lower by mid-November compared with earlier-sown crops, highlighting the challenge in building canopy biomass. Where the initial 30 kg/ha N allowance has already been used, bagged fertiliser is no longer an option. 

Quark: Supporting Rooting Early

Quark, a soluble liquid zinc technology, is one option to support rooting. Applied from emergence but before strong vegetative growth, the zinc improves root foraging and root development across a range of soil conditions.

Trials show Quark can enhance early rooting capacity, helping crops withstand establishment stress.

The image and graph below show the benefit Quark has on root growth. 

Phosphites and Nutri-phite PGA

Phosphites also encourage root development and can be applied at any crop growth stage. Using phosphites in sequence with other biostimulants has shown additional benefits.

Nutri-Phite PGA is one such option. It contains stabilised potassium phosphite, chelated manganese, zinc, and PGA (pyroglutamic acid). PGA improves carbon fixation and nitrogen efficiency during plant growth, further boosting nutrient uptake and root development.

Applied as a foliar treatment at 0.5-2 L/ha, Nutri-Phite PGA stimulates both root and shoot growth, strengthening crops against CSFB larvae, stress and disease. This is particularly useful for backward crops or those under pest pressure, where stimulating growth helps plants better withstand larval feeding.

Agrii trials have shown Nutri-Phite PGA can increase NDVI (a measure of canopy size and greenness) by up to 43% (figure 1 above). Higher rates (1.0 L/ha) produce stronger effects than lower doses (figure 2), particularly when applied in both autumn and spring. 

These sequenced applications (figure 3) have also delivered the highest yields and spring vigour scores.

Proven benefits include:

• Increased nitrogen utilisation (up to +48%)
• Improved nitrate reductase activity → better N assimilation
• Enhanced photosynthetic activity and water use efficiency
• Greater root and shoot biomass (+18-58% root growth depending on variety)
• Up to +30% carbon sequestration
• Stronger tolerance to abiotic stresses (heat, water, nutrient limitations)

Lono Multi: Improving Nitrogen Efficiency

Oilseed rape is a high-N-demand crop, but regulations and variable weather have made N management more difficult. Lono Multi, a stabilised amine nitrogen formulation from Levity Crop Science, offers a proven way to improve nitrogen use efficiency (NUE).

Unlike nitrate, which requires significant plant energy to convert, stabilised amine nitrogen is readily available and 12 times more efficient in protein assimilation. 

This leaves more energy for crop growth and yield.

Key benefits in OSR include:

• Better early establishment and seedling vigour
• Stronger root biomass for water and nutrient uptake
• Optimised nitrogen partitioning towards biomass and seed production
• Higher yield and oil content (trials report +0.3-0.6 t/ha)

Application is typically at 2-5 L/ha, post-emergence at the 2-4 leaf stage, or in early spring. Trials across the UK and Europe consistently show improvements in canopy structure, biomass, and nitrogen retention.

An Agrii nutrient use efficiency trial compared winter OSR with and without Lono Multi. Standard farm practice yielded 4.0 t/ha.

With Lono included, yield rose to 4.6 t/ha. Even at reduced fertiliser rates, the inclusion of Lono maintained yield increases of 0.6 t/ha - more than covering treatment cost.

Physio-N: Foliar Nitrogen for Stress Situations

Physio-N is a 28% N foliar polymer nitrogen containing methylene and ureic nitrogen with added amino acids. The amino acids help prime the crop and improve tolerance under stress. Physio-N releases N steadily over 6-8 weeks and is not prone to leaching or volatilisation.

Because it is slow-release, Physio-N is best applied earlier in the season to oilseed rape crops to provide a consistent N supply.

Agrii strip trials indicate that Physio-N applied at early stem extension improves canopy greenness and supports biomass under stress. While yield responses in OSR require further replicated testing, results in cereals suggest improved NUE and yield stability.