Keeping on top of disease in spring barley

With spring barley crops sown so much earlier this year, there’s inevitably a greater exposure time to foliar disease and a few early disease risks to watch for this season. The SRUC crop clinic has seen more loose smut and net blotch in recent years. This may relate to the fact that many of the seed treatments that previously managed the diseases have been removed. There are only one or two  remaining treatments that manage these diseases, while the majority target seedling blights and leaf stripe. This indicates the importance of testing seed and selecting seed treatments based on the disease detected if you are home-saving seed. If you buy in certified seed it is guaranteed to be low in these seed borne diseases. So a few simple measures around seed health and seed treatment can take out an early net blotch risk straight off. Net blotch is also suffering multiple resistance issues around azoles, SDHIs and strobilurins so that if used individually we see reduced efficacy. The better news is that when used in mixtures, as would be normal practice anyway, efficacy is good.

Early control

Early control (timed from mid tillering before the start of stem extension) of damaging diseases such as rhynchosporium can be crucial in some of the outclassed and weaker varieties of spring barleys but many of the current lead varieties have improved levels of rhynchosporium resistance – Laureate scores a 7 as does KWS Enduris, and SY Arrow for example. And with the development of more disease resistant varieties of spring barley we are in the happy position of being able to dial back some of the fungicide inputs on spring barley where other risks are low.

SRUC trials show that it is only the weaker varieties that tend to give a yield response to the T1 timed fungicides, over and above the standard T2 fungicides applied at booting /ear emergence, and then only in years and at sites where there was rainfall in the weeks around T1. Using more resistant varieties means there is a reduced risk that disease will establish early, especially if the weather is dry following T1.

Spring barley grows rapidly so the gap between T1 and T2 can be short which also helps reduce the period where the crop is unprotected. When drilling early the gap to the T2 sprays at booting is slightly longer so there is slightly more risk that there will be a period of wet conditions and disease can nip in.

Think about whether your farm history of disease and the varieties you have drilled will let you reduce or take out the T1 fungicides, and factor in the weather at the time.

Ramularia is best dealt with at T2 and is driven by factors such as wet weather and stress – but a crop in a better seed bed with better roots will be less prone to early spots than a crop established in a poor seed bed with limited rooting.