South: Wheat disease has potential to explode

In my last Crop Watch from November 2013, I mentioned long spells of rain followed by long spells of dry. In a way, I hope my predictions are incorrect, because if we go into as long a dry period as we’ve just had wet, we are in for trouble. These crops are only about five weeks away from taking off and the last thing they need is moisture stress in April. All we can do is hope.

One of the many differences between now and this time last year is that generally speaking, the rain has fallen onto well-structured ground. Any land high enough above the water table is draining quite freely and should travel relatively quickly when the rain eventually stops. Which it will. Low lying land will have to wait a bit longer, but even that should sort itself out when the water table finally drops.

The mild temperatures over winter have meant that the later drilled wheat crops that went in just before Christmas have grown away nicely and actually look pretty good. It also means that in earlier drilled wheats disease inocula are particularly high. Septoria tritici, brown rust and yellow rust all have the potential to explode. To that end, the first fungicide inputs (T whatever) are likely to include a very high triazole content; still the most important component of any fungicide strategy. Whatever the marketing moguls say.

Although soil nitrogen levels are likely to be very low, few crops actually look like they are suffering from lack of nitrogen. So the fact that we are unlikely to be able to get on with our first top dressings for some time should not be a problem. Another difference between this year and last. Therefore, taking advantage of the fact that nothing is likely to move in the fields for the foreseeable future, I’m off on holiday. If it’s still raining when I get back I may not be quite so upbeat.

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