Accuratelyidentifying wheat growth stages can be tricky to get right, but crucial forensuring successful disease protection according to BASFs Ben Freer.
To help growersget their eye in in time for their main fungicide sprays, Mr Freer hasproduced a short growth stage guidance video.
In the sixminute film he explains that getting the early spray timings spot on will setyou well up for the rest of the season.
If you seeSeptoria infections on the tip of leaf three at GS 39, then you didnt get thespray timings quite right. Either you have either gone too early with your T0spray, or too late with your T1 spray leaving too long a gap between the applications.If your leaf three is clean, youve got your timings bang on.
His how toadvice for accurate growth stage identification is to select the main tiller,slice through the stem to see where the nodes are and what stage each leafemergence has reached. His practical rules of thumb are as follows:
Less than 1cm from base node tofirst node = GS 30, the leaf emerging is leaf four and rolled in the leaf sheath; this is too early for T0 sprays.
More than 1cm from base node tofirst node, the gap from first node to second node is less than 2cm, and leaf fouris well or fully emerged = GS 31, the time to apply T0 spray.
The gap from first to second node isnow 2cm or more, leaf three fully emerged = GS32, the time to apply a T1 spray.Treat any crops that havent had a T0.
Flag leaf (leaf one) fully emerged= GS39, time to apply the T2 spray.
Hisrecommendations for T1 is 1.0-1.25l/ha of Tracker + 1.0l/ha chlorothalonil andat T2, 1.0-1.25l/ha of Adexar + 1.0l/ha chlorothalonil.
Its easier toslice the stem with a knife and measure the distance than try to unpick theleaves as you can inadvertently miss the tiny flag leaf at GS 31-32 which canmake you think its final leaf three emerging when in fact its final leaf 4.Only in exceptional circumstances is it not final leaf three emerged at GS 32 unlikely in mid-September to mid-October sown crops.
Tracker is agood, cost-effective all-rounder at T1 giving you good Septoria control, plusthe boscalid in Tracker will give you very good protection against eyespot andepoxiconazole will deliver very good yellow rust control, he says.
For T1 sprays,BASFs Agronomy Manager, Jared Bonner adds some reminders about eyespot: The diseasecan cause around 1t/ha yield loss. The main driver for infection is theinoculum from previous crop, so second wheats or wheat in very short rotations aremost at risk.
Early drilling is also a factor but the influence is relatively small,whilst a mild wet spring is also an influencing factor, as the lower leavescling around the stem making infection more likely to penetrate.
Minimum tillage slightly reduces the risk so ploughed crops have aninherent higher risk. Soil type is a factor too, with heavy soils that retainmoisture increasing the humidity at the stem base creating more risk. Yourprevious experience of the disease is also very important if you see itregularly then you should be concerned about it this year.
The growth stageguidance video can be viewed at: http://www.agricentre.basf.co.uk/agroportal/uk/en/newsdesk/crop_news/cereals_3/cereals.html?news=44672