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Broad mites (Acari) on impatiens (Impatiens) |
Cyclamen and broad mites are microscopic mites (less than 0.02mm in length) that deform and distort the growing tips of plants that can result in stunted tips, curled leaves and lack of flowering. Cyclamen mites can be a pest of garden strawberry plants and both can be serious pests of a wide range of plants including: African violet, cyclamen, begonia, snapdragon, impatien, gerbera, ivy, and many indoor tropical plants.
Symptoms and Diagnosis
The mites are generally not detected until after they have caused significant damage and then only with the aid of a dissecting microscope. Hand lenses are usually not powerful enough to see these small mites. Mites are closely related to spiders and likewise adults have 4 pairs of legs. Larvae, however, have only 3 pairs.
Cyclamen mites are usually greenish and transparent and less than 1 mm in size. Their eggs are smooth and more apt to be found hidden in folds of plant tissue. They like to hide in buds or tips of new growth. They avoid light and prefer high humidity and cool (60 degrees F.) temperatures. Their feeding results in stunted growth with leaves generally curling upward. Leaves become stiffened and brittle (black in the case of delphiniums) and flowers are deformed or reduced.
Broad mites are smaller than cyclamen mites, broader, and are faster moving. Adult females are straw colored. Broad mites have a white stripe down their back, but the easiest way to differentiate the two may be by their eggs. Broad mites eggs have many small white bumps on them and are usually observed in more open locations. Typically adults cause deformed shoots and leaves, which usually curl downward, and reduced flowering. Bronzing or purpling of the leaves commonly occurs on the underside of leaves where the mites feed. Broad mites reproduce most prolifically at temperatures between 70 and 80 degrees F.
Lifecycle
Cyclamen mites can complete their lifecycle in only 1 to 3 weeks depending upon conditions. Adults can overwinter out of doors as far north as Canada in protected locations and complete many generations a year.
Broad mites can complete their lifecycle in only one week and also have a resting, pupal stage. They can overwinter in greenhouses or on indoor plants but is doubtful they can overwinter out or doors in Missouri. Meaning that each year new infestations out of doors develop from plants that have been overwintered indoors or from infested plants obtained from a nursery or garden center.
Integrated Pest Management
1. Dispose of infested plants. Since these mites can be difficult to control and reproduce rapidly, disposing of infested plants is often wise.
2. Sanitation. Examine newly purchases plant in the spring and reject them if they have curled or deformed tips and shoots that may be signs of mites.
3. Heat treatment. Cyclamen and broad mites are heat sensitive and can be killed if immersed in 110 degree F water for 30 minutes. These temperatures are generally low enough to cause little damage to most plants but water temperature must be maintained properly and the whole plant, pot and all, needs to be immersed. Removing heavily infested shoots first may make this process easier.
4. Treat with miticidal/ insecticidal soap or horticultural oil. To be effective the spray must completely cover the insects so apply liberally and make sure the spray reaches under leaves and into shoot tips where the mites hide.
5. Use chemical sprays. Dicofol (Kelthane) a broad-spectrum miticide can give good control. Follow label instructions.
Organic Strategies
Strategies 1, 2, and 3 are strictly organic approaches. For an organic approach to Strategy 4, consult the Organic Materials Review Institute (OMRI™) for appropriate insecticidal soap products.
More images:
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| African violet (Saintpaulia) with stunted, twisted growth typical of damage by cyclamen mites (Acari) |
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| Close-up of cyclamen mite (Acari) damage on African violet (Saintpaulia) |
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| Cyclamen mites (Acari) can only be seen with a microscope; this one is on African violet (Saintpaulia) |
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| Impatiens (Impatiens) damaged by broad mites (Acari) |
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| Impatiens (Impatiens) damaged by broad mites (Acari) |
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| Impatiens (Impatiens) damaged by broad mites (Acari) |
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| Impatiens (Impatiens) damaged by broad mites (Acari) |
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| Microscopic view of broad mite (Acari) and russetting caused by broad mite feeding on impatiens (Impatiens) |
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| Microscopic close-up of broad mites (Acari) on impatiens (Impatiens) |
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| Microscopic close-up of broad mites (Acari) on impatiens (Impatiens) |
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| Microscopic close-up of broad mites (Acari) on impatiens (Impatiens) |
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| Stunted, distorted leaves on African violet (Saintpaulia) caused by cyclamen mite (Acari); brown lesions were caused by sunburn |
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| Broad mite (Acari) damage on cyclamen (Cyclamen) |
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| Broad mite (Acari) feeding can sometimes cause the leaves to curl under as on this cyclamen (Cyclamen) |
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| Broad mites (Acari) on impatiens (Impatiens) |
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| Broad mites (Acari) on impatiens (Impatiens) |
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