Find out about Bayer’s advice for these nine agronomic decisions in April

Crop Progress

After good establishment and an open autumn, crops look good across the board as we enter spring – so a different starting place for a few years.

Sam’s agronomy tips for April

1. Be careful around your timings of early fungicide sprays in wheat

As I write T0s in wheat crops will soon be with us in early April as yellow rust rears its ugly head. T0 application date inevitably impacts on when pressure mounts to apply the T1 – and it is the latter timing that it is critical to apply to the correct leaf layer (L3) to ensure a sound foundation for the whole fungicide programme.

Going too earlier for either or both timings can be a recipe for getting it wrong for the T2. This was evident last year with the stop-start spring meaning leaf emergence was all over the place. It was partly the reason why some T1 and T2 intervals became stretched with consequences for overall disease control and fungicide resistance stewardship. Avoiding an interval of no more than three weeks between T0 to T1 is important.

Not all crops will need a T0 but I expect most will. Take the usual factors such as varietal disease susceptibility, drilling date and weather into account. Yellow rust susceptible varieties will be a certainty, and perhaps other forward crops where you need some extra Septoria protection.

Remember in an era post chlorothalonil, Septoria management requires greater attention to detail. All crops will get a growth regulator at GS30, so there will be the opportunity to put something in if necessary, although there are fewer obvious options now.

2. Target leaf three fully emerged for T1s

Later in the month the key for T1s is to target leaf three when it’s fully emerged rather than leaf four which is what happened in some cases last season. The only way to identify which leaf layer has emerged is to dissect plants – get it wrong and disease control will be compromised later if pressure is high.

At this timing you’re looking for broad-spectrum activity to cover Septoria, yellow rust, mildew and eyespot. Ascra Xpro (bixafen + fluopyram + prothioconazole) at 1L/ha minimum provides yellow rust control alongside strong Septoria activity through its dual complementary SDHI loading. In addition, it will also give good protection against stem-based diseases and mildew to complete its all-round broad spectrum profile resulting in best return on investment.

As with all the Xpro range the Leafshield formulation gives excellent rainfastness in minutes – useful in catchy conditions – and alternatively physiological benefits if it is dry.

There’s plenty of understandable discussion about nitrogen rates depending on price purchased, percentage of current crop sold and at what price as well as next year’s pricing and availability. Early trials of the Xpro range demonstrated that using bixafen (in Ascra Xpro or Aviator Xpro) can increase nitrogen use efficiency producing higher grain protein and therefore yields from reduced nitrogen input.

3. Maintain tiller numbers in winter barley with a T1 fungicide

Winter barley crops vary in potential depending on when they received their first dose of nitrogen, but most will be at GS31/32 in early April.

In winter barley maintaining tiller number is more important than wheat. Maximising the number of ears is what drives yield, and disease infection at this stage will cause the plant to abort tillers limiting yield.

Some crops may well have had a T0 of prothioconazole, but in any-case T1 gives the biggest response to fungicides. This season Ascra is also available for use in barley crops, including those destined for malting. But it can only be used once, so there is a choice between T1 for broad spectrum disease control adding to in particular improved net blotch control or T2 where its additional benefit against Ramularia comes into play.

In the most part, I would suggest using it at T1 at 0.9 L/ha, where it’s superior net blotch control over the usual high standard Siltra (bixafen + prothioconazole) is most useful. Having said that Siltra is still the market leader with its relative ratio of prothioconazole to bixafen combined with the Leafshield formulation providing rainfast in minutes in catchy conditions as well as physiological benefits in the dry.  

If you opt to save Ascra for awns emerging T2 sprays, then Siltra at 0.6 l/ha followed by Ascra at 0.7 L/ha is an excellent programme.

4. Watch weather to help decide spring barley fungicide strategy

Spring barley crops will have been drilled from December to March. How to approach disease control in the crop will depend on what weather we have in the next month to six weeks.

If it is dry or crops were planted later then a one-spray strategy may well be popular, while wetter weather or earlier drilling will favour two sprays.

In contrast to winter barley, the later timing is more important given speed of development and Ramularia tends to be the greatest threat to the crop depending on stress conditions. Bearing that in mind it could make sense to save Ascra for a second spray, or as the only spray in the crop, to take advantage of its better suppression of that disease. However, remember Ramularia control must first and foremost focus on cultural practice and hygiene to mitigate stress.

5. Use CropCheck to help fine tune decisions

In winter wheat and winter barley our CropCheck service, which uses qPCR analysis to detect pathogen DNA in leaf samples can be useful to help understand Septoria and yellow rust levels ahead of key timings on specific leaf layers.

It provides a useful additional piece of information that can be used in conjunction with all key factors, such as variety, drilling date, weather etc to help fine tune inputs.

6. Protect oilseed rape crops during flowering

Oilseed rape crops took off and by the end of March will have had a yellow tinge assuming it stayed warm.

While Sclerotinia isn’t a big problem most years, when flowering and petal fall coincides with optimum conditions for the pathogen infection it can be a big yield robber, and at current prices this probably isn’t the year to take the risk.

An application of Aviator (0.75 L/ha) is the best all round option from green bud through to mid-flowering, covering not only Sclerotinia but also light leaf spot. It also provides physiological benefits to the crop in the absence of disease, prolonging flowering. In farmer strips trials it has increased yield by 0.25 t/ha on average versus the farm standard consistently over the past few years.

7. Earlier is better with weed control applications in sugar beet

It has been a steady start for sugar beet drilling in East Anglia, with many crops having been drilled during the second half of March. Early weed control will be a priority, although careful weed management is also required to not check crop growth, especially given the chemistry available to us now.

Betanal Tandem (phenmedipham + ethofumesate) is a good broad spectrum option that can be used from expanded cotyledon stage of the beet with a suitable residual. Take care as warm days and cool nights with large diurnal swings can predispose the crop to herbicide damage.

If you’re growing Conviso Smart varieties, remember earlier as opposed to late is generally the right thing - consider the use of a pre-emergence herbicide to buy a little bit of flexibility over the timing of your one and only Conviso One (foramsulfuron + thiencarbazone-methyl) application. Finally, implementing Conviso stewardship is a must.

8. Consider these two early season potato products

The low dose, operator friendly liquid nematicide Velum Prime (fluopyram) provides good yield protection and PCN population management and is a useful starting point for all programmes. In low pressure sites it can be used alone as an affordable option, while under higher pressure use in conjunction with a granular nematicide at either half or full rate of the granule.

With application either on-planter in-furrow or as an overall spray and then incorporated it can fit into most systems without too much hassle.

Pre-emergence product Emerger (aclonifen), which provides a strong backbone for weed control in potatoes, ideally should be applied at least seven days before the crop emerges. It gives good all-round weed control, especially of Polygonum, Chenopodium species and nettles. Add a partner, such as Artist (flufenacet + metribuzin) to provide robust grassweed control.

9. Use FieldView to monitor and measure on-farm trials

It’s probably never been more pertinent to do some of your own on-farm trials than the current season, most obviously would be nitrogen rate trials to help inform 2023 decisions. Our digital platform FieldView makes that easy. FieldView brings all your data under one umbrella to enable better analysis and interrogation of data for better more informed decisions. If you’re interested in a free trial, please get in touch.