According to head of integrated crop management at Hutchinsons, David Howard, the lack of rainfall can stress plants and lead to nutrient deficiencies, potentially increasing the risk of some diseases.
“Crops remain variable across the UK, largely based on the state of soils at drilling, and the weather received over winter,” he says. “Prolonged cool nights and dry weather have extended early growth stages, but with daytime temperatures spiking into the high teens, some barley crops are now moving rapidly towards T1.”
He warns that plant defences may be weakened by the ongoing dry spell, so disease pressure must be judged on a field-by-field basis before selecting fungicides.
Mixed disease outlook
Reports from the southwest suggest ramularia could appear earlier this year, especially in crops on light soils or those under stress from pests or poor nutrition.
Mildew is widespread too, particularly in crops affected by high nitrogen, dry weather, or other stress factors.
On the upside, net blotch and rhynchosporium levels are lower than in previous wet springs. Brown rust has also been kept in check by cooler temperatures, though some early signs are appearing in susceptible hybrids.
Key timing for disease control
Growth stages 30-31 are critical for yield and disease control in barley, Howard explains: “Barley grows rapidly during this time, adding biomass quickly and relying heavily on lower leaves, which contribute significantly to green area index,” he says. “Barley’s lower leaves are larger and play a more prominent role in photosynthesis alongside stems and ears, unlike wheat, where upper leaves dominate yield contribution.
“Retention of tillers is also essential in barley to maintain yield potential, therefore getting disease control right and reducing plant stress at this early timing is key.”
Howard recommends SDHI and azole combinations for broad-spectrum disease control but stresses the importance of alternating actives and mixing modes of action to delay resistance.
Resistant net blotch strains are becoming more common, he notes. Among strobilurins, pyraclostrobin currently holds up better than others.
For ramularia, pydiflumetofen is the most effective option and should be used where symptoms are confirmed.
Otherwise, it’s best held back for T2.
Mefentrifluconazole is another option in high-pressure situations, and folpet or biostimulants like Scyon can offer added protection.
Where mildew is an issue cyflufenamid is effective, but avoid using it in back-to-back sprays to reduce resistance risks. For moderate mildew, prothioconazole-based products are suitable.
Brown rust can be tackled with benzovindiflupyr, tebuconazole, or pyraclostrobin, depending on whether curative action or longer protection is needed.
