A race against time is developing as agronomists and seed breeders adapt to increasingly frequent extreme weather.
Wetter winters and warmer summers are forcing a rethink in UK agronomy. Crop performance is shifting. So too are pest and disease risks. The challenge now is adapting management and variety choice fast enough to protect yield.
The situation was highlighted by ADAS senior crop research scientist Christina Baxter at the recent Association of Independent Crop Consultants (AICC) annual technical conference near Towcester.
Clear trends can be seen clearly by comparing average on-farm wheat yields with AHDB Recommended List (RL) trial yields. It shows marked seasonal volatility from around 2006 onwards.
“The fact that both datasets show the same pattern of fluctuation tells us that they are dealing with the same limitations coming from the environment and changing weather patterns,” she said.
A four-year rolling average from 2002 to 2025 shows RL yields rising by about 0.5t/ha. On-farm yields have remained static or declined slightly. The result is a yield gap of roughly 2.5t/ha.
“Some of this can be attributed to changing weather patterns and the fact that we may not be adapting our management to these changes.”
Central England temperatures have risen by about 1°C. Rainfall totals are less clear, but the trend towards drier summers, wetter winters and heavier rainfall events is strengthening.
Crop response
Yield Enhancement Network (YEN) data show maturity is closely linked to yield. Varieties maturing two days earlier than the control yield around 1t/ha more; those three days later yield about 1t/ha less.
“Maturity is closely linked to flowering time,” said Dr Baxter. “What we believe is happening is that earlier varieties are flowering and filling their grains earlier in the season, under cooler temperatures when more water is available. This raises the question of whether we should be considering growing more earlier flowering varieties in the future.”
Mean growing season temperatures in the first decade of YEN data increased by about 0.5°C, with June and July rising by 0.8°C. The grain fill period has shortened by around 10 days.
“The production phase is influenced by degree days. Therefore, temperature increases are resulting in a grain fill period that is around 10 days shorter, which has a negative impact on thousand grain weight.”
Management still matters. Good soil water capture, robust fungicide timing at flowering and adequate canopy nutrient levels are critical. Nitrogen, phosphorus, sulphur and zinc deficiencies can accelerate senescence.
Nutrient effects
Grain nutrient concentrations now fluctuate more sharply between seasons. In 2025, grain nitrogen was higher because uptake occurred earlier and was concentrated by lower yields. Grain phosphorus was lower after a dry spring.
“When rainfall data was compared with grain nutrient concentrations, phosphorus, manganese and sulphur were all strongly influenced by spring rainfall,” said Dr Baxter.
“Greater rainfall from April to June increased phosphorus and manganese uptake. For sulphur, which is highly soluble, higher early spring rainfall reduced concentrations due to increased leaching, particularly when sulphur fertiliser is applied early.”
Establishment is increasingly important. Strong root biomass supports nutrient uptake in the topsoil and water extraction later in the season. Drilling just two or three days earlier can significantly increase root length in warm soils.
But early drilling can raise disease and lodging risk. Flexibility is essential.
Future suitability
Process-based models developed by the UK Centre for Ecology and Hydrology estimate climate-constrained yield potential at 1km? resolution.
Professor Richard Pywell said modelling under +2°C and +4°C warming scenarios shows wheat yield potential increasing in northern regions but declining in parts of southern England by mid-century.
Under +4°C warming towards 2080, wheat becomes more questionable in southern England. Oilseed rape also begins to suffer.
A digital tool allows farmers to input postcode and farm data to assess climate risks and adaptation options, including soil organic matter improvements to increase water-holding capacity.
“It tracks performance over time so farmers can see how things are changing and improving,” said Prof Pywell.
Crop suitability may shift. In some southern areas, modelling suggests reduced wheat and oat suitability but improved prospects for durum wheat, chickpeas or soybean. Trials will be essential.
Climate change will also reshape pest and disease pressure. Research at Exeter University shows pathogens adapting. Yellow rust populations are adjusting to warmer conditions.
Fusarium species composition is shifting. Septoria, which thrives in warm, wet weather, may become more problematic in parts of the UK.
“Predicting and mitigating disease risks under climate change requires understanding pathogens as well as plants,” said Dr Helen Fones. The message is clear: variety choice, drilling date, nutrition and disease control must adapt to the new reality.