Beware of blueberry leaf rust
July 28, 2010 By Annemiek Schilder Plant Pathology
July 26, 2010 – Be on the look-out for blueberry leaf rust,
particularly in fields that have had a problem in previous years, it can be severe in fields
that are affected.
|Photo 1: Yellow spots appear on
leaves by mid-season and eventually
|Photo 2: yellow to orange spore
pustules (uredia) present, may turn
rusty red with age.
July 26, 2010 – Be on the look-out for blueberry leaf rust, particularly in fields that have had a problem in previous years. While this disease is relatively rare in Michigan, it can be severe in fields that are affected.
Rainy periods in the middle of the growing season are conducive to disease development. It also occasionally pops up on blueberry plants in greenhouses. Leaf rust is caused by the fungus Pucciniastrum vaccinii.
Yellow spots appear on leaves by mid-season and eventually turn reddish-brown (Photo 1).
On the lower leaf surface, yellow to orange spore pustules (uredia) are present, which may turn rusty red with age (Photo 2).
You have to turn the leaf over to see the orange pustules. The disease is not systemic in blueberries. Leaf rust can rapidly increase towards the end of the season.
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