North: Optimum timing wheat fungicides proving tricky

In early May over 50mm of much needed rain finally arrived and since then crops have dramatically improved. Strong winds and showers have caused some spraying backlogs, but most have now been able to get caught up.

In winter wheat, many T1 fungicides were delayed to the point where leaf two was well emerged by the time the T1 was applied. In contrast, where the T1 was well timed on early sown crops the gap to T2 is proving to be wider than ideal due to slow leaf emergence from the continued cool weather.

T2 fungicides are currently being applied and although some tweaking of rates is possible at this timing, anything more severe will prove false economy. This is because the top two leaves produce around 60-70% of yield, so a small fungicide saving can prove to be costly if rates are cut too far.

Septoria tritici is now very evident on the older leaves and the recent rains will have splashed spores higher up the canopy, causing infection that cannot yet be seen. Mildew is also easy to find on late sown crops, which have grown very rapidly and have a lot of soft growth.

Spring barley crops range from good thick crops to those that are desperately thin. Unfortunately there are too many spring barley crops which appear on the thin side, with yield potential significantly reduced.

The cold dry spring has caused slow crop emergence followed by low tiller number development and it is the later sown crops that have suffered the most. T1 fungicides are being applied to the earlier sown crops, with any remaining weeds being controlled at the same time.

Winter beans are now in full flower and a fungicide has been applied to protect mainly against chocolate spot. Most spring bean crops have required post-emergence herbicide bentazone to try and clean up some of the key weeds which came through the pre-emergence treatments due to seed-beds being so dry.

In oilseed rape, sclerotinia fungicides have now been applied and in many instances they were delayed by the weather. This could mean a single fungicide will be sufficient, unless flowering is prolonged or the risk of sclerotinia is high.

Many growers are rightly looking at alternative cropping options for next year, with the question often being “What other break crop should I grow rather than oilseed rape?”. Low commodity prices are going to cause noticeable cropping changes, with early indications showing a lower oilseed rape area and more spring cropping.

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