T0. Disease Control Starting Point.

T0 is the right time for some crops to set up season-long control of key diseases in wheat and barley.

Growers this season are again facing different crop situations this spring, with variability in crops due to later autumn drilling and wet field conditions coming out of the winter, so not all crops are in peak condition going into the spring especially on heavier land. Where yield potential is limited, growers should consider using cost-effective fungicide product options for early spray timings in many situations this spring. Added to this, Clayton trials in 2024 looking at fungicide responses around T1 showed that higher input spend on newer chemistry at these earlier timings did not result in a significant yield advantage benefit. So overall margin over input costs can very easily become negative unless growers consider more cost-effective generic chemistry at this timing. T0 is therefore the ideal timing to start looking for cost savings whilst still adequately dealing with early disease management, notably rust, and crop variability.

• Protecting yield potential all starts at T0 even with later sown or stressed crops where the risk of Septoria maybe lower but where Yellow rust could be more problematic.
• An early rust fungicide at T0 has proven often well worthwhile even in seasons with changeable weather.
• Yellow rust should be a consideration for low resistance scoring varieties; a number of major varieties on the RL score 5 or below.
• Assessing each crop in terms of its over-wintered condition and yield potential should be a priority, to tailor T0 sprays accordingly.
• Consider cost-effective upgrades at T0 from straight triazoles to higher performance co-formulations e.g. tebuconazole + prothioconazole or spiroxamine + prothioconazole for added benefits at little extra cost.
• Use T0 as a ‘cost-effective’ start to control of key diseases along with other integrated disease control strategies.

Rust – the main T0 disease focus:

With reasonably high carryover inoculum levels possible in some areas after yellow rust and brown rust was present quite early in the season last year, there may be disease pressure building in some crops now, especially with the recent slight rise in temperatures. All of these factors can affect disease cycles in terms of re-infecting crops more rapidly, so the possibility of early epidemics are as likely this spring as in previous seasons. Several key varieties on the 2025/26 RL score 5 or less for Yellow rust resistance, notably the milling wheats KWS Zyatt and Skyfall (both score 3 for Yellow rust) and group 4’s SY Insitor (3), Gleam (5) and RGT Wolverine (5). Starting a proactive programme at T0 can be key to controlling the disease through to harvest cost-effectively. An effective, preventative triazole-based T0 fungicide treatment is key to season-long Yellow rust control in wheat and Brown rust control in barley (especially hybrids).

Septoria – a useful secondary disease focus at T0:

Even if overall disease pressure is on the lower side, it will be important to keep Septoria in check in certain crops, relieving pressure and allowing flexibility for growers with later T1 sprays. This is especially the case in earlier sown crops, more susceptible varieties or areas where disease risk is higher. Folpet offers strong protection against Septoria and is a useful, cost-effective option to consider.

T0 timing flexibility:

T0 sprays should be tailored to disease requirements in each crop. With rust normally the main focus, T0 applications can also reduce Septoria pressure too. The traditional ‘target timing’ for T0 is GS 30 although there is scope for flexibility (especially given variability in crops this spring) around this timing for growers, with a wider window of GS25-30 possible depending on each individual situation and in fields where disease pressure is higher. Tebuconazole and prothioconazole options are ideal for T0 alongside azoxystrobin, possibly together with a multi-site like folpet to provide extra protection for Septoria. All of these options can be applied very cost-effectively.

Key T0 options for Clayton fungicides:

Clayton Tebucon 250EW

Active: 250g tebuconazole

Suggested rates: 0.5L

Disease strengths: Cost-effective rust activity

Clayton Tuskar

Active: 250g prothioconazole

Suggested rates:0.55L

Disease strengths: Strongest active for stem-based diseases (e.g. Eyespot & stem-based Fusarium), Septoria: protectant and eradicant activity*

*prothioconazole has good activity on Brown rust in barley, moderate Yellow rust activity in wheat and good protectant activity against mildew.

Clayton Navaro

Active: 125g tebuconazole + 125g prothioconazole

Suggested rates: 0.6 – 0.7L

Disease strengths:Strong all-round activity.

Clayton Tendril

Active: 300g spiroxamine + 160g prothioconazole

Suggested rates:0.625 – 1.25L

Disease strengths: High performance disease control

Additional T0 options for Clayton fungicides:

Clayton Ozark

Active: 250g azoxystrobin

Suggested rates: 0.4L (Rust)

Disease strengths: Rust and Take-all.

Clayton Canyon SC

Active: 500g folpet

Suggested rates: 1.0L

Disease strengths: Strong protection against Septoria.

Explore all options in our latest bulletin and ensure you’re prepared for whatever the season brings.

Need help selecting your T0 strategy?

For further information on products in this update and our full product range, Get in touch with our Technical Team:

Will Ridgwell – Commercial Manager – will@claytonpp.com
Martyn Rogers – Product Development Manager – martyn@claytonpp.com

Information in this update does not constitute a recommendation; it is for guidance only. Detailed information about our products can be found on our website. Brand names used in this update are trademarks of Clayton Plant Protection. Use plant protection products safely. Always read the label and product information before use.