Pest & Disease Management - Tarsonemid and eriophyid mites

These two key groups can cause damage across a variety of ornamental crops.

Gall mite damage: a risk for ornamentals - image: Dove Associates
Gall mite damage: a risk for ornamentals - image: Dove Associates

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.

Tarsonemid mites

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.

Eriophyid mites

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

Tarsonemid mites

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.

Eriophyid mites

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.

Biology

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.

Symptoms

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.


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