East: Monitor crops for flag leaf emergence

Despite the recent cold nights and dry conditions many crops are still ahead of what some might regard as a ‘normal season’. Despite high levels of disease on the lower leaves wafting around newly emerging leaves, well timed fungicides applied to final leaf 3, combined with the dry weather, has resulted in relatively clean upper crop canopies with new growth now away from the dirty lower leaves harbouring septoria.

Most crops have now reached GS31 and received their T1 fungicide, however, as crops develop and day length becomes a greater factor in crop development they have slowed with most crops showing final leaf 2. However, the importance of peeling back leaf layers to identify the emerging leaves is ever more important as we approach flag leaf emergence with the most forward crops now at GS37 and flag leaf emerging. Obviously this is earlier than the traditional ‘3rd week in May’ timing for flag leaf emerging and with this leaf contributing 40% towards growth it is crucial that we keep a close eye on crop growth stages and leaf emergence and protect the flag leaf accordingly.

Depending on the interval from T1 we will ideally wait for 50% of the flag leaf to emerge before applying the fungicide which will revolve primarily around SDHI fungicides bixafen or fluxapyroxad (plus triazole partner products) to ensure the greatest disease protection and persistency.

On the whole crops have been relatively clean for broadleaved weeds however rising soil temperatures and the recent rainfall has seen broadleaved weeds starting to germinate. Also where the soil has cracked, allowing light and moisture in, there has been a recent germination of blackgrass and wild oats along the soil cracks especially where crops are more open.

With crop growth stages very variable and earlier than previous years care should be taken regards herbicide product choice to ensure it is applied prior to its latest application growth stage on the label as different products have different growth stage cut offs.

Winter barley crops look very well and have moved from GS30 to GS37 In the blink of an eye resulting in a narrow window to apply PGR’s and herbicides. With crops potentially only at 60% of their final height some crops will receive an additional PGR at GS37 to manage crop height and reduce the risk of lodging as it is still a long way to harvest!

OSR has branched well over recent weeks and despite the frosts during early flowering is setting plenty of pods. The BASF/ADAS sclerotinia monitoring indicates sclerotia germination across all monitoring sites and the recent rainfall will again increase the risk of infection as petals fall, stick to leaves and stems and transfer infection into the plant. Due to the variation in growth within the OSR canopy most crops will receive a second sclerotinia fungicide approximately 3 weeks after the first application to ensure continued protection through flowering and petal fall.

Spring crops have established well considering the lack of moisture with slow emergence on the heavier knobbly ground causing some issues especially for sugar beet weed control.


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