Is rye worth a try?

Hybrid rye is a relatively new crop to Ireland but its area has been increasing over the last number of years albeit from a low base.

In 2019, just over 460ha of rye were grown in this country. In 2024, almost 2,650ha were planted.

Many growers who have grown it once are happy to grow it again.

As with any ‘new’ crop it is important that growers are aware of the agronomy of that crop to get the most out of it and avoid costly mistakes.

Research at Teagasc Oak Park over the last number of years, funded by a Department of Agriculture, Food and the Marine Research Stimulus grant, has sought to optimise the agronomy of rye under Irish conditions and some of the main findings are summarised here.

Rye has a number of advantages that make it an attractive proposition. Firstly, it has been shown to have the potential for high grain yields.

In Oak Park trials it has usually out yielded September sown winter barley, particularly in a take-all situation, and in many instances given similar yields to winter wheat even in a first wheat slot.

Although experience on farm suggests that its yield is often somewhat lower than high-yielding winter wheat.

It has a good disease profile with the main foliar diseases being brown rust and mildew and to a lesser extent rhynchosporium, meaning less robust fungicide programmes than for winter wheat are required.

It has a very high straw yield compared to wheat or barley although this does mean that progress with the combine will be slower

It is much less affected by take-all than wheat or barley meaning that it can be a good option for high take-all risk slots in the rotation. It is important to note that it does get take-all and it does not act as a break crop for take-all so crops sown after rye are at risk of take-all.

It does get barley yellow dwarf virus (BYDV) but Oak Park work has shown that it is much less affected by BYDV than barley; typically the yield response to insecticide application for rye is about half that of winter barley when both are sown in mid-September (ie. a high BYDV risk situation).

Both these factors mean that it is better suited to earlier sowing (ie. from mid September) than either wheat or barley, particularly where take-all is likely to be an issue.

It also has good drought tolerance and has a lower requirement for nitrogen than winter wheat at similar yield levels. It has a very high straw yield compared to wheat or barley although this does mean that progress with the combine will be slower.

Disadvantages of rye

The key disadvantage currently is that the market for rye grain is limited.

Any grower contemplating growing the crop should ensure that they have a market for the grain before sowing the crop as not all merchants are willing to accept rye and it may attract a price discount.

It can be used for wholecrop silage which may be another avenue worth exploring. It is also very attractive to slugs and the crop can be severely damaged or lost if slug numbers are high.

Slugs will continue to graze on rye right through the winter period to a greater extent than for other cereals but rye has a tremendous ability to recover from this damage. It is best to avoid fields with high slug populations if planning to sow rye as control of high slug populations in rye with molluscides can be challenging.

Rye is also more susceptible to ergot than wheat or barley but the incidence of ergot in modern hybrid varieties is normally very low.

Rye is taller than either wheat or barley but has stiff straw so lodging is not as big an issue as its height might suggest.

From a rotational point of view rye could be grown at any point in the rotation but slots with high take-all risk are particularly suited. Ideally rye shouldn’t be grown on the same ground in successive years to reduce the risk of ergot.

Rye volunteers will be very visible in the next crop so ideally rye would be followed either by a non-cereal crop such as OSR or by a spring crop to allow any grains left in the field to germinate over the winter period.

If rye is to be followed by a winter cereal crop a good stubble cultivation soon after the crop is harvested is advised.

Autumn management of the hybrid crop

The ideal sowing window is mid-September to mid-October with late September probably being the optimum date. Sowing in late October or later, particularly on heavier soils, is likely to lead to reduced yields and, particularly on heavier soils, to poor establishment.

That said crops sown in mid-to late-November have established and performed well in Oak Park trials where conditions after sowing were reasonable.

Where crops are being sown into good conditions during the optimum sowing window, and slug risk is low, a seed rate of 200-230 seeds/m2 is usually sufficient. For less than ideal conditions, or where slugs may be an issue, the rate may need to be increased to 230-250 seeds/m2.

For sowing dates after mid-October seed rate will generally be in the range of 250-300 seeds/m2 depending on conditions and slug risk.

Rye should not be planted deeply and the ideal sowing depth is 2-4cm. Rolling after sowing is strongly advised particularly where slugs are likely to be an issue.

In terms of variety there are a number of hybrid varieties available commercially and experience at Oak Park would suggest that agronomic differences between the varieties are relatively small and all are capable of giving high yields.

The number of herbicides approved for use on rye are limited so care should be taken to ensure any products used are approved for rye.

Pre-emergence or post-emergence herbicide programmes can be used but as rye germinates and emerges more quickly than other cereals pre-emergence treatments should be applied as soon as possible after sowing and ideally on the same day.

Even though rye is less affected by BYDV than barley, work at Oak Park has shown that it does respond to insecticide application, particularly when sown in September.

Initial work indicates that one insecticide spray in early November is sufficient even for early sown crops.