SPRAY TIMING TIPS
- Keep intervals tight (3-4 weeks max)
- Prioritise susceptible varieties
- Apply T2 once flag leaf is at least 75% to fully emerged
- Include multisite and triazole with SDHIs
- Consider intermediary T1.5 spray to protect leaf 2 if gap to T2 is stretched
Kent-based agronomist David Shepard says that most crops will have had a T0 and PGR application which will have provided early canopy management and insurance against a possibly delayed T1.
“Mild, dry conditions last autumn allowed crops to establish well and the majority in this area now have big, lush canopies which are at greater disease risk,” he says.
“As always, Septoria is also present on lower leaves, so we can’t be complacent. Cooler conditions in mid-April, means we could be in latent period for infection, so even the leaves that look clean now could be infected, and it’s not worth taking the risk.”
With that in mind, Mr Shepard says to build on the foundation of the earlier sprays. If crops remain very lush and disease pressure is high, he believes there is a strong case for using SDHI chemistry at both timings and he supports mixing with a triazole and multisite for resistance management.
“We no longer have the level of curative activity from our chemistry we once had, so we need to try and stay in a protectant situation. It’s far better to mop up any disease early in the programme, with the flexibility to reduce rates later in the season if disease pressure drops and crops are at less risk.”
“Where the T1 timing has been early and intervals stretched I would suggest going on with a holding spray at T1.5 to ensure that crops remain protected in the run-up to flag leaf emergence.”
Product choice depends on the individual situation, variety and disease pressure, but generally Septoria and yellow rust are the biggest threats in his area, so an active with good rust activity such as epoxiconazole is essential.
“Although crops are generally quite well advanced in Kent, there can be up to two weeks difference across the county. You can soon come unstuck making general recommendations, so it’s vital to inspect crops in the field and judge the best course of action accordingly.”