Agronomy Blog

Drilling and Early Soil Conditions

Soil conditions at the start of the month have encouraged growers to finish drilling the last combinable crops. This brings the 2020/21 eight-month drilling window to a close.

Cereal Crop Development

Cereal growth stages feel slightly behind expectations. Most winter cereals went in later than planned, and cooler March air and soil temperatures slowed development. Winter wheat now ranges from emerging (2-leaf after sugar beet) to GS31. Winter barley is receiving T1 fungicide and has only recently begun to move after the wet winter. Winter rye on lighter land has accelerated, while winter oats remain lacklustre.

Forward wheat crops with established yellow rust have received, or will receive, a T0 of tebuconazole plus a growth regulator. In some cases, we are testing varietal rust resistance and applying only a regulator or herbicide.

Nitrogen Applications

Nitrogen applications have progressed well. The trend of front-loading higher early rates continues. Oilseed rape, winter barley, and rye have all received final splits. Total N rates remain as planned, with small adjustments of ±20 kg/ha depending on crop establishment.

Winter wheat planted before January has had two N applications totaling around 150 kg/ha. Ideally, the final dose will land with rain later this month. Total nitrogen remains close to plan. Stronger crops will be pushed harder, especially where late-planted wheat may underperform. First and second feed wheats typically receive 230–240 kg/ha total N. Milling wheats receive similar totals, but rates may increase by 30–60 kg/ha before any late foliar nitrogen if yield and protein potential justify it.

Post-January-planted wheats are in a similar position but may not have received as much nitrogen yet. There is also a longer window for the final dose. Again, timing close to rainfall will be reassuring. Final rates will depend on rainfall and crop potential.

T0–T1 Growth Regulation

After two dry springs that limited biomass growth, T0 growth regulator rates remain cautious. Many crops receive very low Moddus/3C doses or 3C alone. Late-planted, unrolled crops that were rolled at the end of March will show reduced apical dominance and will not need strong regulation now.

While dry weather persists, it is safer to hold back at T0 and increase rates at T1 if conditions turn warmer and wetter. Winter barley and rye often react badly to low early-season regulator rates, so plan for an extra pass before T2 if needed.

T0–T1 Fungicide Applications

Varying Growth Stages and Disease Pressure

Growth stages, disease levels, and crop potential vary widely, so fungicide decisions hinge on appropriateness.

Skipping T0 and Early Yellow Rust Risk

Crops that miss a T0 may move quickly to leaf-three emergence. If they avoid yellow rust, they may go straight to T1. However, many January–March-planted wheats are Skyfall, so yellow rust will likely need treatment before leaf three emerges.

Septoria Risk in Earlier-Emerged Crops

Wheats that emerged before late October show high Septoria levels on both frost-killed lower leaves and surviving green leaves. With established inoculum, these crops carry reasonable disease risk. T1 fungicide dose depends on varietal Septoria resistance and rainfall exposure before treatment. Because most fungicides move toward the leaf tip, leaf three should be 75–80% emerged before spraying.

Spray Timeliness and Weather Outlook

Dry weather should limit disease spread and allow timely spraying. Leaf three is now emerging in forward wheat crops, and T1 sprays will likely begin around 19 April.

Choosing T1 Products and Managing Rust

Most T1 choices rely on Prothioconazole, which offers strong stem-based disease control. Ascra Xpro at 1.0 l/ha remains a solid default for early-drilled susceptible wheats, costing around £35/ha and providing robust Septoria protection plus some eradication. If yellow rust remains a concern at T1, Prothioconazole mixes such as Elatus, Firefly, or Sparticus can enhance rust control, although they slightly reduce Septoria eradication. Alternatively, 85–125 g/ha tebuconazole will clear active rust, leaving Ascra to protect the plant through flag leaf.

Adjusting Rates for Resistant Varieties

These benchmarks help compare other treatment options. KWS Extase is unlikely to need this level of control, so cheaper options or reduced rates may be suitable.

Considerations for Late-Planted Wheat

Late-planted wheats have less biomass and therefore carry lower early Septoria risk, though conditions can change with a wet end to April or delayed T1s. Yield potential is also lower in some of these crops, so while costs must be watched carefully, uncontrolled disease will not help margins.

The Folpet Debate

Debate continues over Folpet (Arizona). It is less active on Septoria than chlorothalonil and costs 50% more. It also has little effect on other wheat diseases. However, it brings a different mode of action, and during high-pressure, wet seasons, its inclusion—especially at T2—may offer reassurance. Trials rarely show negative effects, but yield benefits in dry seasons are often unclear. A pragmatic approach is best this year. With weather extremes, evolving resistance, and new actives arriving, having options is generally better than not.

New Tools for Assessing Disease Risk

Disease risk and fungicide planning can feel subjective. Bayer Crop Science’s new in-season Rapid Disease Detection service provides early insight into leaf disease levels. This may prove useful, especially for understanding varietal resilience in local conditions. Registration details are available via the provided link – https://cropscience.bayer.co.uk/registerinterest/

Broad-Leaved Weed Control

Crops that received a pre-emergence spray and an autumn residual follow-up are generally clean at T0. Occasional charlock, fumitory, and volunteer rape are appearing, while cleavers are mostly yet to emerge. If weeds are visible before the first growth regulator, they should be treated then to reduce T1 tank-mix size. If few weeds emerge by T0, control can wait until T1 in wheat. In other cereals where T0 is unnecessary, broad-leaved weed sprays must fit around other passes. Keeping tank mixes light helps protect stressed crops in dry conditions.

Wild Oat, Brome, and Volunteer Cereal Control

Thorough field walking will reveal patches of winter-germinated brome, and spring-germinating species have appeared since early March. Once found, accurate species identification is essential, as not all treatments work on every brome species. Most SU herbicides for brome also control wild oats, except Monitor. Brome herbicides can be harsh even when applied within label limits, so assess cost versus benefit carefully. No options exist for controlling emerged brome in winter or spring barley or oats. Rye and spring wheat can use Broadway Star with reduced rates.

Axial Pro now provides the most reliable control of winter- and spring-emerging wild oats, generally outperforming Topik. Smaller oats are easier to control, and results improve with early-season applications when soil moisture is higher. Always watch intervals with SU herbicides and aim for smaller tank mixes in dry conditions.

SU herbicides used to suppress barley volunteers in wheat have slowed barley growth, aided by frost, allowing wheat to get ahead. The barley is not killed and will regrow unpredictably, so follow-up treatment may be needed.

Barley Yellow Dwarf Virus (BYDV)

BYDV is visible in early-emerging cereals, particularly unsprayed crops. Winter barley shows the most symptoms, as it is typically drilled earlier than oats and most wheats.

There is little to be done now. Zinc applications may reduce virus multiplication, but at this stage the benefit is uncertain. The main practical step is to monitor crops regularly. If symptoms are widespread, yield will be affected, and late-season inputs should be adjusted accordingly. Avoid stressing the crop through unnecessary spraying or delayed inputs.