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What does your drill timing mean for your spring barley crop?

Agronomy Issues
06.04.2021

This season spring barley drilling has been a drawn-out affair, with some crops going into the ground in December and many towards the end of March and into April.  With these differences in drilling dates, there are big differences in the risks to the crop in the coming season.

Drilling plots at Barton Black grass Focus Site

EARLY DRILLED

In general, the earlier spring barley is drilled the more time the crop will have to tiller.  This can also result in good rooting structure and a higher yield potential.  However, early drilled crops will also be exposed to more frosts which may result in winter kill of some tillers or, in harsh conditions full plant death. Lodging resistance is generally better in early drilled crops, due to greater rooting and slower growth, although a PGR programme may be advisable in very lush crops or when seed rates and nitrogen rates are high. 

The longer the crop is in the ground, the more time disease infections have to cycle; so higher levels of disease such as Brown rust, Rhynchosporium and Net blotch may be common in December drilled crops.  T0 applications are not usually required in crops drilled after January, however they may be necessary in early drilled spring barley if overwintered disease is there.  An early application of a triazole or strobilurin can be used if rust infections are high, alternatively cyprodinil is effective against both Rhynchosporium and Net blotch.

The time between growth stages may be extended in an early drilled crop as it grows more slowly in cooler temperatures.  Growth stage rather than calendar date should guide spray application timings. The target growth stages for T1 and T2 are different for wheat and barley, aiming for GS30-31 at T1 and GS37-49 for T2.  In general, regular monitoring of early drilled crops is advisable to check the growth stage of the crop and control disease before levels get too high.

Independent of drill date, disease pressure can still be high at T1 and T2.  For broad spectrum control of Rhynchosporium and Net blotch, an SDHI + triazole combination such as ELATUS Era, would be suitable at either timing, it is also class leading in terms of brown rust control.  Ramularia is a late season disease, which often appears after the last fungicide application has been made.  Chlorothalonil used to give the most effective protection against Ramularia, but with the loss of this chemistry, there are now limited methods of control available.  Folpet, although not as effective as chlorothalonil, is the next best option as a multi-site fungicide, and gives a reduction in Ramularia, especially when included in a full programme.

Whilst there is still moisture in the ground and growing conditions are good, weeds will be growing rapidly within the crop and early control always gives the best control.  Early drilled spring crops should be monitored for spring emerging weeds as soils start to warm up and growth rates increase. 

AXIAL Pro is a great tool for wild oat control, no matter the drill date, as it gives rate flexibility depending on the size of the weed.  When targeting spring germinating wild oats while they are still at the tillering stage, if conditions are good then AXIAL Pro rates can be flexible; once wild oats are at stem extension or beyond higher rates of at least 0.6 l/ha will be required for robust control

When the spring barley crop is still below GS30 and the small wild oat targets are exposed, a nozzle with good coverage such as the 3D nozzle is the best choice providing spray conditions allow.  As crops get larger, through stem elongation, and the grass weeds are more shaded under the canopy, the angled Amistar nozzle is a better option to increase penetration and allow more droplets through the crop canopy to reach the target weed.

Remember the mixing and sequencing rules for use of hormones (especially the older generation of this MOA) and SU products. For sequencing: AXIAL Pro first, wait 7 days. SU/hormone first, wait 21 days.

Spring barley seedlings

 

LATE DRILLED

Crops drilled late March to April, have a much shorter growing season, and will have less time to put down roots and tiller before the crop reaches stem extension.  This may result in less ears overall and therefore a lower number of grains produced.  The flip side of this is that specific weight is often high in lower tillering crops as grain fill can be better.  If the season turns dry, tiller losses to drought can have a large impact on yield to a crop which is already low yielding.  Early nitrogen can help to feed and strengthen tillers, improving tiller survival, which will be especially important in low tillering crops. 

As late drilled crops have a shorter growing season, they are fast growing.  When stem extension occurs, more energy is diverted above ground, giving late frilled crops less opportunity for rooting.  For this reason, late drilled crops tend to have less anchorage and are more prone to lodging than earlier drilled spring barley.  One MODDUS application between GS30-32 will give the crop a good foundation, strengthening straw early on.  In high-risk areas, a follow up ethephon-based application may be needed, to reduce height and the risk of lodging later in the season. In dry seasons drought can act as a natural PGR and so rates and applications should be adapted to avoid over-regulation.

Unlike autumn drilled barley, it is the later drilled spring barley crops that will suffer more from BYDV.  BYDV infection is more serious to spring barley that has not yet reached GS31, later drilled crops are more likely to be below this stage at the time of aphid flight, and therefore yield losses can be significant.  In spring cereals only one aphicide is needed at initial aphid invasion to gain control of primary infections, so monitoring late drilled spring barley crops regularly for aphids is important to get the timing right.  Aphid flights start at ~11 degrees C, and you can use the AHDB website for predictions on aphid flights in your area