Last autumn presented some real challenges getting winter wheat sown on time and as such there is a bigger range in plant development this spring than usual.

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Today we've dissected out crops of Grafton and Humber sown in mid September and crops of Oakley and JB Diego sown in the first week of October. All crops are first wheat after oilseed rape. We've used a standard stereo dissection scope with a magnification of 30 to determine which is the final leaf emerging.

The mid-September sown Humber is the most forward crop we looked at and on the majority of main stems this had three quarters of final leaf 3 emerged. So this leaf was already unfurling and beginning to expand but the auricles were not yet visible. However, on a few tillers the final leaf two was visible “in the spear”, in other words still tightly furled but poking through the top of the canopy. Crops of Grafton sown at the same time were at a similar stage although none of the forward main tillers had final leaf two visible.

Crops of JB Diego sown in early October had final leaf five as the most recently unfurled leaf with final leaf four at 50% emergence. Crops of Oakley sown at the same time were slightly in advance of this. Crops of Relay sown in mid-October had final leaf six as the most recently unfurled leaf.

In terms of fungicide timings the mid-September sown crops would be ready for T1 fungicides early next week. The early October sown crops will need another 7 – 10 days before the final leaf three has emerged and therefore ready for T1 fungicides. That assumes typical temperatures for late April to early May. The forecast for a cold snap at the end of this week could delay leaf emergence beyond these timings.