In 3 trials in spring barley different fungicide solutions using half rates were compared for control of specific diseases in 2017. Results from the 3 trials are shown in Table 20. One trial was carried out in the mildew susceptible cultivar Milford, which developed a moderate attack of powdery mildew (Blumeria graminis). Two trials developed very severe attacks of brown rust (Puccinia hordei) and a minor attack of net blotch (Pyrenophora teres), and all 3 trials developed relatively late attacks of ramularia leaf spot (Ramularia collo-cygni). As shown in Table 20, most of the tested solutions provided very similar and good control of all assessed diseases, with the exception of Propulse SE 250 for control of rust. How-ever, adding Comet 200 to Propulse SE 250 improved the control of rust significantly (Figure 15). The control of Ramularia showed only moderate control from all treatments – partly caused by the long time between application and the development of this disease. To some extent it was difficult to separate the effect on brown rust from the effect on Ramularia, which is most likely why Propulse SE 250 was giving relatively poor control. The new test product Elatus Era overall provided the best disease control and also the best yield with an increase of 19.3 hkg/ha, which reflects that severe brown rust mixed with ramularia leaf spot can reduce yields significantly (Figure 16).
Table 21 summarises the efficacy data on brown rust and yield data from trials carried out in both 2016 and 2017. With the exception of Propulse SE 250 used alone, all treatments have provided very similar control and yields.
Brown rust, net blotch and ramularia leaf spot are the most severe diseases in spring barley. Many combinations of fungicides using triazoles and strobilurins provide similar control and yield respon-ses. In most seasons one treatment at GS 37-39 will provide sufficient control using approximately 33-50% rates. In case of early and severe attacks of net blotch, scald and brown rust and late attack of Ramularia two treatments might be profitable.
Table 20. Disease control using different fungicides applied at GS 33-37 in spring barley. 3 trials 2017 (17361).
One other trial was carried out (Table 22) comparing control of mainly brown rust using different com-binations of new SDHI fungicides now available on the Swedish market. The different solutions gave good control of all diseases and also very high yield increases in the range of 13–19 hkg/ha.
Figure 15. Control of brown rust in spring barley (17361). Average of 3 trials with 47% attack of brown rust in untreated.
Table 21. Disease control using different fungicides applied at GS 33-37 in spring barley. Average of 6 trials from 2016 (16343) and 2017 (17361).
Treatments
6. Untreated 36.7 8.5 34.6 61.1
-No. of trials 6 6 6 6 6
LSD95 3.6
Table 22. Disease control using different fungicides applied at GS 37 in spring barley. 1 trial 2017 (17356).
Treatment, l/ha %
Priaxor 0.75 0.5 5.5 0.7 4.5 16.8 48.6
Priaxor 1.5 0.3 5.0 0.4 4.5 17.3 49.7
Imtrex + Proline EC 250 0.5 + 0.2 0.4 7.3 1.5 5.8 14.3 48.4
Librax + Comet 200 0.5 + 0.5 0.6 6.8 1.2 4.5 17.3 48.8
Figure 16. Average yield response in 3 spring barley trials following 1 treatment at GS 37-39 (17361).
47.6 dt/ha in untreated.
Table 23. Disease control using different fungicides applied at GS 37 in spring barley (17357).
Treatment with 2 x 1.0 Aviator Xpro provided a yield increase of 33 hkg/ha.
Untreated Chapeau with lots of net blotch.
Treatment, l/ha %
barley rust %
barley rust %
net blotch %
Ramularia Yield and increase hkg/ha
yieldNet hkg/ha
TGW(g)
GS 65 GS 75 GS 73 GS 75
Proline EC 250 0.8 GS 39 1.4 20.8 16.9 18.7 13.0 8.5 43.4
One or two sprays
Four specific trials were carried out comparing one- and two-spray strategies in spring barley using 3 different fungicides (Table 23). Two sprays generally provided a better control, which was most pro-nounced for control of brown rust and ramularia leaf spot. Yields were also improved significantly from the two-spray strategy compared with one-spray strategies. The weaker product Proline EC 250 im-proved yield by 1 tonne per ha when spraying twice compared with once, while the more potent products Aviator Xpro and Siltra Xpro increased yields by half a tonne per ha, when going from one to two treat-ments. Aviator Xpro and Siltra Xpro were both providing equal control and yield, although Aviator Xpro was slightly better on net blotch.
Control of Ramularia
Several trial plans aim at testing the efficacy of specific products against ramularia leaf spot. Two of the trials are summarised in Table 23. In these trials a cover spray was applied at GS 33-37 using 0.5 l/ha Comet 200. The trials indicate that azoles only provide moderate control of ramularia leaf spot (Table 24), which is seen as a reflectance of increasing problems with Ramularia resistance. Samples from Flakkebjerg have shown 30-86% presence of the mutation I325T and 28-78% presence of I328L. The mutations having impact on SDHI fungicides are still present at relatively low frequencies of 8-28%, which might not have much impact on the efficacy. As shown in Figure 17 the resistance of the cultivars is quite unclear and not very stable across years (data from observation plots).
Table 24. Average effect of Opus, Proline EC 250 and Adexar Extra for control of ramularia leaf spot using full rates applied at GS 50. Data were extracted from different trial plans (17363 + 17355) in which the three products were included.
2017 trials % control of Ramularia Yieldincrease, hkg/ha
Opus 1.0 35.5 5.3
Proline EC 250 0.8 44.5 8.6
Adexar Extra 2.0 70.2 11.4
No. of trials 2 2
Figure 17. Per cent attack of ramularia leaf spot in spring barley cultivars assessed in observation plots across the country (TystofteFonden). The attacks vary significantly between different cultivar and be-tween different sites and years.
Untreated plot in the cultivar Soulmate with lots of brown rust.
Plot treated with 0.5 l/ha Elatus Era applied at GS 37 providing good control of both brown rust and
Brown rust, net blotch and Ramularia are the most severe diseases in winter barley. Many combina- tions of fungicides using triazoles and strobilurins provide similar control and yield responses. In most seasons one treatment at GS 37-39 will provide sufficient control using approximately 33-50% rates. In case of early and severe attacks of net blotch, scald and brown rust and late attack of Ramularia two treatments might be profitable.
In 2017 3 trials in winter barley were carried out testing different combinations of fungicide solutions against specific diseases. Treatments were applied at GS 37-39 using half rates, which have typically been seen as economically optimal solutions. Results from the trials are shown in Table 25. The trials in 2017 were dominated by brown rust (Puccinia hordei) and late attack of ramularia leaf spot (Ramularia collo-cygni). As shown in Table 25 and Figure 18 most of the tested solutions provided very similar and good control of all assessed diseases. With the exception of Propulse SE 250 all treatments gave good control of brown rust. The attack of net blotch was slight to moderate, and no clear differences were seen from the various treatments. The level of Ramularia control was quite moderate, partly due to the early timing relative to the late development. Yield increases varied between 10 and 15 hkg/ha. Due to the domin- ance of brown rust, Propulse SE 250 was inferior on yields, but mixed with Comet 200 both % control and yield were improved.
Table 26 summarises results from different years, which indicate very similar results from different