What is powdery mildew?
Powdery mildew is a fungal disease that can affect a wide range crops and can be particularly problematic if left untreated in cereal crops.
There are several different strains of the mildew fungi species blumeria. Graminisf. Sp which are crop specific. Wheat, barley, rye and triticale are susceptible to powdery mildew.
Conditions favouring and promoting powdery mildew
Rising temperatures in the spring following winter, especially if conditions have been dry or there has been snow cover
Germination is promoted at moderate temperatures and during high humidity,
Powdery mildew spores germinate above 6°C
Dense crops promote the ideal micro climate for powdery mildew development
High nitrogen applications which promote rapid lush growth
Late drilled wheat crops are particularly at risk during the rapid spring growth phase,
Over use and/or under dosing with fungicides can lead to insensitive strains of powdery mildew surviving
Impact of powdery mildew
Infection on the leaves reduces the available surface area for effective photosynthesis and subsequently leads to a decline in the available energy the plant can put into growth and reproduction resulting in yield loss.
Earlier infection can produce the largest impact if it is allowed to move up the plant, especially when it infects the flag leaf. Yield loss of up to 20% is possible with high infection levels.
Mildew can be a key disease to control early on in wheat alongside septoria, especially in susceptible varieties.
Control volunteer host plants to prevent a green bridge from season to season
Planting more tolerant varieties
Avoid over applying nitrogen
Treating early infections with fungicides should be used as part of an integrated approach and particular attention on application timing, dose rate and alternating modes of action are vital to sustainable control