As well as spider mites, other microscopic mites attack ornamental crops. There are two key groups - tarsonemids (broad and cyclamen mites) and eriophyids (gall and rust mites). There are a limited number of acaricides, which should be applied preventively. Predators can be introduced to protected crops from early spring and through summer.
Host plants include amaryllis, antirrhinum, aralia, Aster novi-belgii, aubergine, begonia, chrysanthemum, cyclamen, dahlia, Fatsia, fuchsia, gerbera, Hedera, Narcissus, New Guinea impatiens, pelargonium, petunia and verbena.
Rust mites attack Alnus, chrysanthemum, Crataegus, Fraxinus, Malus, prunus, rhododendron and robinia.
Gall mites attack a range of plants including Abies, acer, Alnus, Aesculus, Betula, Carpinus, cytisus, euonymus, Fagus, Fraxinus, Juglans, Picea, Populus, prunus, Ribes, Salix, Sambucus, sorbus, syringa, Taxus, Tilia, Ulmus and Yucca.
The fuchsia gall mite (Aculops fuchsiae) is notifiable and feeding causes extensive distortion.
How to recognise them
Mites are extremely small - some smaller than 0.3mm. Elliptical or oval eggs are large compared with nymph and adult sizes. All nymph and adult stages have six legs.
- Broad mite (Polyphagotarsonemus latus) - pale brown or translucent.
- Cyclamen mite (Phytonemus pallidus) - translucent, green or yellow.
- Bulb scale mite (Stenotarsonemus laticeps) - pale brown or translucent.
- Fern mite (Hemitarsonemus tepidariorum) - can attack Polystichum but more common on Asplenium. Yellow-brown.
Strawberries are vulnerable to Phytonemus pallidus ssp. fragariae.
There are at least 12 different gall and rust mites and most originate from Acalitus, Acaricalus, Aceria, Aculops, Aculus, Artacris, Cecidophyopsis, Epitrimerus, Eriophyes, Phyllocoptes, Tegonotus and Vasates.
Mites are grub-like, pale yellow or white, and adults have just two sets of front legs. Mites can be smaller than 0.25mm - microscopes are needed to find them.
Warm, dry weather encourages these populations to increase rapidly on host plants outdoors and under protection. Pests tend to congregate in the growing tips where humidity is high. The bulb scale mite burrows into bulbs during August and September and also relies on warm conditions. Mites are spread on the wind, staff clothing, other insects and animal fur.
Tarsonemid mites cause leaves to be puckered, bronzed and distorted. Overall, affected plants can be stunted. Eriophyid mites induce leaf galls, felting, leaf rolling and leaf blistering.
Treatment: biological control
Amblyseius cucumeris, Amblyseius californicus and Amblyseius swirskii have all been found to provide supplementary control of tarsonemid and eriophyid mites.
Treatment: cultural control
Alternate acaricide sprays from different chemical groups to avoid resistance. Attack occurs more often on stressed plants so ensure appropriate irrigation, nutrition and climate are provided for the crop.
Remove and burn any badly infested material. Regularly remove and burn plant debris. Clean and disinfect between crops if possible. Keep weed populations low to avoid alternative host risks.
Treatment: chemical control
Active ingredient Abamectin
IRAC code 6
Formulations Various including Dynamec (Syngenta)
Action(s) Selective acaricide and insecticide. Do not use on adiantum ferns or Shasta daisies. Spotting may occur on carnation, kalanchoe and begonia foliage. Compatible with some biological controls.
Active ingredient Beauveria bassiana
Formulation Naturalis-L (Belchim)
Action(s) Primarily for whitefly and thrip control. Has limited effect on mites. Compatible with biological controls.
Active ingredient Chlorpyrifos
IRAC code 1B
Formulations Various including Dursban WG, Equity (Dow)
Action(s) Contact and ingested organophosphorus insecticide. Incompatible with biological controls.
Active ingredient Diflubenzuron
IRAC code 15
Formulation Dimilin Flo (Certis)
Action(s) Non-systemic growth inhibitor with contact and stomach action. Compatible with biological controls.
Active ingredient Etoxazole
IRAC code 10B
Formulation Borneo* (Interfarm), Clayton Java* (Clayton)
Action(s) Contact acaricide - moulting inhibitor on eggs, larvae and nymphs. No effect on adults. Compatible with some biological controls.
Active ingredient Fenpyroximate
IRAC code 21
Formulation Sequel* (Certis)
Action(s) Contact and ingested acaricide. Compatible with some biological controls.
Active ingredient Lambda-cyhalothrin
Formulation Various including Hallmark with Zeon Technology* (Syngenta)
IRAC code 3
Action(s) Fast-acting, persistent, contact and residual insecticide. Incompatible with biological controls.
Active ingredient Natural plant extracts
Formulation Majestik (Certis)
Action(s) Contact insecticide. Can be used as an overall spray 24 hours before introducing biological control. Do not treat ornamental crops in flower.
Active ingredient Spirodiclofen
IRAC code 23
Formulation Envidor* (Bayer)
Action(s) Non-systemic acaricide. Compatible with some biological controls.
Active ingredient Spiromesifen
IRAC code 23
Formulation Oberon* (Certis)
Action(s) Contact insecticide. Avoid applications to Cordyline. Compatible with some biological controls.
Active ingredient White petroleum oil
Formulation Spraying Oil (Certis)
Action(s) Insecticide/acaricide oil that works by physical action, blocking pest respiratory systems. On outdoor crops, apply to dormant plants with tolerance.
Active ingredient Tebufenpyrad
IRAC code 21
Formulation Masai (BASF)
Action(s) Acts on eggs and all motile stages of spider mites. Treat before infestation is established. Small-scale testing for crop sensitivity is recommended. Compatible with some biological controls.
Fully updated by Dove Associates.
Use plant protection products safely. Always read the label and product information before use.
* Extension of Authorisation for Minor Use (EAMU) required for use in ornamental plant production outdoors and/or under protection.
Dove Associates shall in no event be liable for the loss or damage to any crops or biological control agents caused by the use of products mentioned.