Fungicide strategy in wheat for 2015
The progress of disease in 2014 in winter grains was a challenge for many farmers. The focus was certainly on yellow rust. The unusually early and sustained pressure from pathogens led to an early spraying start in many places.
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- Strong yellow rust infection can lead to yield losses of up to 40 percent in susceptible species.
However, other pathogens also profited from the unusually mild winter in 2013/14. For example, eyespot and Septoria tritici was found regionally in increased occurrences. Product selection and application date of the first fungicide measure were critical for the success of the overall strategy in many cases.
In view of these experiences, the plan for the start of spraying in 2015 must be considered carefully. To this end, the first step has to be a realistic assessment of the specific risk factors. There is a generally increased potential for infection for the current culture, for example, if:
- The previous crop was already susceptible to the relevant pathogens,
- The proportion of winter grains in the overall crop rotation is high,
- Earlier sowing dates are selected,
- The ground preparation is as mulch drilling,
- The cultivated species is more susceptible.
Important: risk assessment
Together with a look at the winter weather, a reasonable risk assessment can be performed with these factors for the eyespot pathogen. Mild winters with long, wet and cold phases are ideal for this pathogen. This description is certainly true for large parts of the winter 2014/2015. If an earlier sowing date is considered within the framework of the specific consideration as well as a susceptible previous crop, an anti-eyespot fungicide measure should be scheduled for the shooting date. Products with boscalid, prothioconazole, cyprodinil or xemium perform best. A risk analysis is particularly important for this pathogen because the extent of the damage only becomes visible late in the season, while effective treatment is only possible until the middle of shooting.
Apart from maintaining the health of the stem base, a targeted fungicide measure at the start of the longitudinal growty should keep the leaves healthy and clear possible initial attack. During this phase, mildew, yellow rust and S. tritici play the main role. A regular check of the stocks in spring can help prevent bad surprises. Knowledge of the specific risk factors also helps.
Different susceptibility to yellow rust
There are, for example, considerable differences with regard to suscpetibility to yellow rust. Wheat species such as JB Asano, Akteur or Primus are highly susceptible since last year at the latest. If early sowing is involved, it is recommended that you look more closely. A broad range of products is available for fighting yellow rust. Fungicides with epoxiconazole or tebuconazols are particularly effective. Depending on the weather in the spring, a treatment can be applied against pathogens such as yellow rust of mildew before shooting starts. In this case, however, special fungicides should be used.
The use of broadly effective combinations such as AGRAVIS Flexion Viva, Aviator Xpro + Talius oder Capalo should not be used until EC 31, as the effect of the products otherwise is not fuly exploited. The most important disease when plating wheat, however, is S. tritici. On average, it leads to the maximum yield losses.
Curative or protective performance?
Because of the comparably slow development of the pathogen, strong damage can primarily be expected if there is considerble initial infection and good infection conditions at the start of shooting (rain with wet leaf phases over 35 hours). If a new infection is successfully avoided at this time, the potential damage is greatly reduced.
When selecting the product, a distinction has to be made between curative and protective performance. A good preventative effect can be achieved, for example, by all above combinations. The product "Bravo" can also be used effectively under these conditions. This contact fungicide is also a decisive tool for an effective resistance management in Septoria control. If, on the other hand, maximum curative performance is needed – strong initial infection, intensive rain fall, more than four days restricted accessibility – prothioconazole or xemium fungicides have to be used.
More information and tips are available from AGRAVIS crop farming advice or directly from Eiko Tjaden, Tel. 0521 . 682-2574, firstname.lastname@example.org.