Tillage management: Fungicides on winter and spring barley

As we enter the middle of May fungicides on winter barley will be wrapping up, while the majority of spring barley crops will have yet to receive their first fungicide application.

Winter barley should receive its final fungicide application ideally when awns are peeping, but it may be applied before the head is fully emerged.

The timing will depend on a number of factors including disease pressure and when the crop was last sprayed. By now most winter barley crops across the country will have a fully emerged flag leaf, more are at awns peeping and advanced crops have headed out.

In general, crops are very clean, but those which are on a two-spray programme should still receive a robust final spray including a triazole, SDHI and chlorothalonil.

Chlorothalonil can be used up to and including May 19 and is important for ramularia control, but cannot be used after this date.

Farmers in a three-spray programme who have used robust rates so far may decide to cut back slightly. In this case they may decide to use a triazole/strobilurin mix, along with chlorothalonil when applied on or before May 19.

Spring barley

Once again crops are clean, but key to a good spring barley crop is disease prevention and the protection of tillers so the first fungicide should be applied between mid to late-tillering.

Treatment may include a triazole mixed with a strobilurin for net blotch control. Some may decide to use a triazole/SDHI mix at T1. Remember triazoles should be alternated at each timing to prevent resistance.

Chlorothalonil will not be available to use at T2 (after May 19) and some farmers may therefore decide to apply at T1 for prevention of ramularia.

All varieties on this year’s spring barley recommended list have a rating of 8 for mildew.

All three fully recommended varieties – Gangway, RGT Planet, SY Errigal – have a score of 5 for rhynchosporium, while Limona and Prospect have a score of 7 and SY Arderin has a score of 6. Growers may need to look out for net blotch on Planet.

Nutrition is essential

Nutrition is essential to keep plants healthy and therefore fight disease.

Any nutrient deficiencies in plants should be treated early and where plants have received foliar treatments such as manganese or magnesium with the herbicide application, a second application may be needed with the first fungicide.

Crops went through rapid growth in last week’s high temperatures. However, changes in weather to very cold temperatures this week may put stress on plants. Some bio-stimulant products may be useful here as an anti-stress strategy.