Tillage: Bypassing fungicides in fine weather is a risky strategy
Published 08/06/2016 | 02:30
As the country basks in the glorious weather luxuriant crops are the norm as they lap up the sunny weather and utilise the moisture that had plenty of opportunity to build up in the winter and spring.
As winter barley heads towards grain fill, this weather may well have some long-term benefits in terms of enhanced yield. Even some of the early oats and oilseed rape crops may benefit from the current good weather. Yet it has to be said that cereal crops prefer cooler bright weather for maximum grain fill conditions, rather than the hot bright weather experienced.
For winter wheat and spring sown crops however, it's the weather in late June to mid July that will have a bigger bearing on yield formation than the current weather patterns. However, that is not to suggest that good weather at this time of the year does not have a significant benefit on these crops.
The biggest advantage of warm dry weather comes in terms of disease amelioration as wet weather diseases are the most yield debilitating diseases in cereal production. Whether this lack of disease development can be monetised by reducing fungicide spend on these crops is not a decision to take lightly.
While it is true that if there is no disease present, there is no requirement for curative action from a fungicide, most applications are made on the basis of disease prevention and are applied to prevent disease that may occur three to four weeks after application and indeed for the final application, up to six weeks after application.
So there is a significant gamble when deciding not to spray today as you then must predict what the weather will be in a month or six weeks' time. It could well turn out that leaving out a fungicide spray works for three weeks, but just as the crop begins to mature, the weather breaks and disease runs riot through a crop. At this point in the season, it's too late to take action so the disease has a seriously negative effect on yield.
A more prudent approach may be to maintain planned timings for fungicide applications, but there may well be an opportunity to modify the product mix and savings may be available here, for example use of older chemistry or using less comprehensive product mixes.
However, it is important to maintain cognisance of the risk of development of septoria resistance. The risk of resistance development with this disease is such that each application should have a number of modes of action or fungicide groupings included, but the product may not need to be the latest and greatest combinations.