Royal flush: T2s need to be fit for a king

What lovely weather May has brought us, almost good enough for a royal wedding. Definitely good enough for me to go crop walking in Northamptonshire yesterday!

Crops are romping through the growth stages and T2 applications are pending on most winter wheats, especially on the most forward varieties. If these can be applied during this lovely spell of weather, then the flag leaf will be protected from any disease that rain events may splash up the crop (provided the flag leaf is fully unfolded). It won’t be long before ears start to emerge:

The warm weather is also providing ideal conditions for brown rust in wheat, causing many growers to consider using a product with good activity on this disease at T2, especially in the most susceptible varieties.

The lush and rapid growth has also caused mildew to be more of a problem than usual, and is prevalent on the leaves and stems of winter wheat and barley.

Now is the time when mis-identification of ramularia starts becoming a problem in winter barley. Ramularia doesn’t usually express its symptoms until after flowering and symptoms will follow the ‘five Rs’: Right through the leaf, Rectangular lesions, Ring of chlorosis, Restricted by the veins, and Reddish-brown. More information on ramularia identification can be found here.

For example, we saw this on the newer emerged leaves in one patch of a crop of winter barley, when the rest of the field appeared clean apart from mildew. While it is easy to assume it is ramularia, it is likely to be the necrotic stage of mildew or physiological spotting as a result of stress.

Most OSR crops in Northamptonshire have lost all their petals, meaning the risk of sclerotinia infection has passed. We saw one crop, however, that was clinging on to its petals and a decision needed to be made whether or not to recommend a second spray for sclerotinia. Since the soils were dry and there were no weather-based alerts to suggest conditions were conducive to sclerotinia infection, the decision was made not to spray.

Catherine Garman

Catherine Garman

Catherine is Crop Health & Protection Scientist (Diseases) at AHDB

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