WSU Extension

Hortsense

Azalea
 
Disease
Botrytis petal blight 
Cylindrocladium blight & root rot 
Leaf and flower gall 
Leaf spot 
Lime-induced chlorosis 
Marginal leaf necrosis 
Nematode (stunt) 
Ovulinia petal blight 
Powdery mildew 
Root rot (Phytophthora) 
Insect
Azalea bark scale 
Azalea lace bug 
Azalea leafminer 
Obliquebanded leafroller 
Root weevils 
Spider mites 



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Caption: Lime-induced chlorosis
Photo by: R.S. Byther
  
Azalea : Lime-induced chlorosis
(revision date: 4/23/2014)


Biology
Lime-induced chlorosis, or leaf yellowing, is caused by alkaline soil conditions. High alkalinity of soils can make iron or manganese unavailable to plants, causing leaf chlorosis. Pale to bright yellow leaves, particularly on the new growth, are common symptoms. Typically the chlorosis begins at the edges and progresses into the leaf, with only the veins remaining green in severe cases. Plants near new concrete may also suffer from lime-induced chlorosis.
Management Options


Non-Chemical Management
  • Adjust soil pH to 4.5-6.0. Addition of sulfur or organic matter, especially conifer needle mulch, which is highly acidic, may be beneficial. Work soil under plant carefully to avoid damage to the shallow root system.
  • Use iron chelate, either as a soil treatment or by foliar feeding to quickly help chlorotic plants. Read and follow all label instructions.
  • Check plant's proximity to newly poured concrete. New concrete leaches lime into the surrounding soil, raising the pH.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Lime-induced chlorosis
Photo by: R.S. Byther