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Plant Leaf Galls (Eriophyid mites)

| By | Diseases,Pests

Plant Leaf Galls (Eriophyid mites)

Overview:​​​

  • Abnormal growths triggered by various factors​
  • Appear as bumps, bladder, & spindle galls, or Erineums (dense cluster of plant hairs) as a plant’s reaction to the presence or activity of foreign substances ​
  • Appear on leaves  ​
  • Vary in size, shape, color, and texture ​
  • Caused by feeding or egg-laying Eriophyid mites which release chemicals that cause the plant cells to multiply rapidly  ​
  • Generally, not harmful, but can cause some minor issues like leaf drop or stunted growth in severe cases
  • Host plants: numerous​

Management:

  • Often, no treatment is needed (aesthetic concerns)​
  • Pruning affected areas can be an option  ​
  • Sprays can be effective if applied before gall formation​
  • Preventative treatments are available, but with a very
    small window of opportunity (leaf bud break/swell)​
  • Precise treatment timing is required (practicable?)​
  • Contact materials required (miticides)​
  • (systemics are not effective after gall formation)​
  • Horticultural dormant oils & soaps; abamectin;
    carbaryl; neem oil; acephate

Resources:

Landscape Pest Notes: Some Mid-Spring Insects/Mites – PPA

 

Maple Erinium Gall Mites on silver maple produce a reddish, beaded gall appearance. Sometimes they are mistaken as fungal leaf infections. They are another species of eriophyid mites. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Maple Bladder Gall Mites infesting silver maple leaves. Cutting & opening-up individual galls will uncover many dozens of tiny eriophyid mites. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
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