Integrated pest management (IPM) of mites

A combination of cultural, biological and conventional chemical control measures will provide the best approach for controlling mite infestations, as part of an integrated pest management programme.

Back to: The biology and control of mites in ornamentals

Cultural control

The adoption of a range of cultural control measures will help to minimise potential pest pressure on crops and reduce the need for any regular intervention.

  • Always start with clean propagating material and do not take cuttings from any infested mother plants
  • Inspect any plant deliveries in a quarantined area and reject or isolate any infested batches of plants
  • Sweep up plant debris and use a recommended biocide between crops
  • Remove weeds from both cropping and non-cropping areas, as these can act as alternative hosts for many pest species, and maintain weed control during the season. Salix and willowherb are particularly susceptible to attack from two-spotted spider mite
  • Promptly and carefully dispose of any crop debris, unmarketable plants and weeds. Place into sealed bags or covered containers, sited as far away from production areas as possible, before disposal

Monitoring

There is no substitute for regular and careful crop walking, carried out by someone who has been trained to recognise the early symptoms of mite damage, the various mite species and their biological control agents. As mites do not fly, sticky traps are ineffective for monitoring mite outbreaks. Focus on known susceptible plant species or cultivars and inspect with a hand lens (at least x10 magnification) to confirm the presence of damage symptoms, mites or eggs. A lens is also useful when introducing biological control agents, to help assess the ratio of predators to prey. Record any monitoring and note pest mite hot spots, as mites like the two-spotted spider mite, broad mite and cyclamen mite can be carried on clothing.

Biological control agents

There is a wide range of commercially available predators for use in biological control programmes that are either recommended for the control of pest mite species or will contribute to the control of pest mites when used for the control of other pests, such as thrips. Some of these predators can also occur naturally, particularly if using integrated pest management (IPM) with very limited application of plant protection products.

Choice, combinations, timings and rates of release within an IPM programme should be planned carefully. If necessary, seek advice from the supplier or a specialist IPM consultant. All biological control agents should be released as soon as possible after delivery. If storage is necessary for a short time, keep them in a cool place, out of direct sunlight and avoid any sudden temperature changes, such as refrigeration.

Table 1 lists the commercially available predators.

Control agent

Description

Pest range predated

Comments1

Predatory mites

Phytoseiulus persimilis

Pale red pear-shaped mite

Tetranychus species, spider mites only

No release restrictions. Widely used for two-spotted spider mite control

Amblyseius andersoni

 

Pale, straw-coloured mite

Spider mites

Tarsonemid mites

Eriophyid mites

Thrips larvae

Found naturally on many species of trees and shrubs.

Can be released under protection or outdoors in England and Wales. Check with supplier for other UK countries

 

Neoseiulus californicus

(formerly known as Amblyseius californicus)

Transparent mite, develops pale orange markings as a result of feeding on spider mites

Spider mites

Tarsonemid mites

Can only be released under permanent protection with full enclosure

Neoseiulus cucumeris

(formerly known as Amblyseius cucumeris)

Pale, straw-coloured mite

Thrips larvae

Tarsonemid mites

Spider mites

Tyrophagus mites

Native to UK. No release restrictions

Transeius montdorensis

(formerly known as Amblyseius montdorensis/ Typhlodromips montdorensis/Typhlodromus  montdorensis)

 

Pale, straw-coloured mite

Thrips larvae

Spider mites

Eriophyid mites

Tarsonemid mites

Can only be released under permanent protection with full enclosure

Amblyseius swirskii

Pale, straw-coloured mite

Thrips larvae

Whitefly eggs and larvae

Some mite species, including tarsonemid mites

Can be released under permanent protection with full enclosure in UK. Check with supplier about release in tunnels

Amblydromalus limonicus

(formerly known as Typhlodromalus limonicus)

Pale, straw-coloured mite

Thrips larvae

Whitefly eggs and larvae

Some mite species

Can only be released under permanent protection with full enclosure

Stratiolaelaps scimitus

(formerly known as Hypoaspis miles)

Light brown, ground-dwelling mite

Sciarid and shore flies

Thrips pupae

Tyrophagus mites

Native to UK, no release restrictions

Other predators

Feltiella acarisuga

Adult midges have red body and gnat-like appearance but are rarely seen, as nocturnal. Creamy yellow or pale orange predatory larvae. White pupal cocoons on leaf undersides

Spider mites

Native to UK. No release restrictions. Often occurs naturally when spider mite numbers are high

Stethorus punctillum

Small black ladybird, about 1.2–1.5 mm long. The larvae are also black

Spider mites

Native to UK. Not currently commercially available but can occur naturally

Chrysoperla carnea

Green lacewing larvae

Aphids

Thrips

Spider mites

Moth eggs

Native to UK and can occur naturally under protection, especially together with aphids. Also, commercially available

Orius and Anthocoris species

Predatory bugs. Adults are black with grey and brown markings

Thrips

Aphids

Moth eggs

Spider mites

Native to UK. Orius species are commercially available and have no release restrictions

1. List of licensed biocontrol agents in England can be found here: https://secure.fera.defra.gov.uk/phiw/riskRegister/plant-health/non-native-biocontrol-agents.cfm Check with your supplier regarding local release restrictions for biological control agents requiring a release licence.

Predatory mites

Several species of predatory mite are available for the control of pest mites. Choice will depend on temperature, humidity, mite pest species and whether control of other pests, such as thrips and whitefly, is also needed.

Phytoseiulus persimilis

Phytoseiulus persimilis is the most commonly used predatory mite for control of two-spotted spider mite, since it is a specialist predator which has coevolved to feed on Tetranychus species. The adult predators are slightly larger than the pest mite and are orange-red and shiny. They have longer legs than spider mites and are very active, running around the leaves searching for prey. Phytoseiulus persimilis will eat both the mobile stages and eggs of mites. Younger predators are smaller and paler than the adults. The eggs are pale pink, oval and about twice the size of those of two-spotted spider mite. These can easily be seen with a hand lens when monitoring, on leaves with spider mite damage, and are a good sign that the predators are establishing. The predators will move readily from plant to plant if they are touching. The predators are supplied in tubes with a bran or vermiculite carrier that is sprinkled on the plants. Products with larger numbers of predators in smaller amounts of carrier leave less carrier on the plants, deliver more accurate numbers of predators and allow more effective use of high doses in spider mite ‘hotspots’.

Phytoseiulus persimilis is most effective when temperatures reach 20°C for a few hours each day and can reproduce twice as fast as two-spotted spider mite between 15°C and 25°C and at over 75% relative humidity. However, as an obligate predator, P. persimilis requires reintroduction if the pest is absent. At temperatures over 30°C, P. persimilis is unable to control two-spotted spider mite. Phytoseiulus persimilis is generally reared on two-spotted spider mite and distributed without a food source in a vermiculite carrier. Therefore, it is important to release the mites as soon as they are delivered so that they can find prey. Koppert has recently developed a new product, ‘Spidex vital’ – a P. persimilis product reared on an alternative food source for quicker establishment in the crop. When first released, the P. persimilis in this product are white, but they quickly turn the characteristic orange-red colour when they start feeding on spider mites.

Month-by-month action points for the control of two-spotted spider can be found in Table 2.

Adult Phytoseiulus persimilis alongside the predator’s egg

Image © ADAS Horticulture.

Month

Action

January

Plan an IPM programme for the coming year, incorporating lessons learnt from pest problems and control strategies the previous year. Be prepared to amend this programme weekly, depending on the results of crop monitoring

February

Consider grouping susceptible plant species together on the production site as this will greatly simplify the application of control measures. Train staff to recognise mites and their damage symptoms – tiny white or yellow speckles or leaf yellowing, depending on host plant species

March

Start monitoring protected crops for eggs, mites and mite damage. Use a good hand lens (preferably x20) to check the undersides of leaves. Check areas/stock in particular that have been affected in the previous growing season. Consider using Apollo 50 SC (clofentezine) (EAMU 2082/2016) if eggs are seen on outdoor crops. Ensure a number of staff are trained in the timely introduction and management of appropriate biological control agents. Consider releasing predatory mites preventatively, which are active at low temperatures and can survive on alternative prey or other food sources, such as Amblyseius andersoni

April

Commence a preventative programme for crops under protection, involving weekly or fortnightly introductions of Phytoseiulus persimilis to susceptible crops. Monitor crops on a weekly basis

May

Continue monitoring protected crops weekly. Increase P. persimilis releases from the preventive rate to a curative rate if spider mites are detected. In general, if there are fewer than one P. persimilis for every ten two-spotted spider mites, increase the rate of release to avoid damage. However, some plants are more susceptible to damage than others. Start a preventative programme for spider mite control on outdoor crops

June/July/August

Monitor susceptible crops weekly as a routine. Rates of predator introduction are normally highest in this quarter. Maximum venting of polythene tunnels and glasshouses and use of fans can help to reduce the temperature and slow spider mite development. If needed, consider using Amblyseius andersoni or Neoseiulus californicus (the latter in glasshouses only) to supplement P. persimilis as they are less sensitive to hot, dry conditions. If localised 'hot spots' are found, consider using Feltiella acarisuga to supplement control by predatory mites. Consider using a corrective IPM-compatible plant protection product, or increasing the rate of P. persimilis if the ratio of spider mites to predators is high. Careful selection and rotation of products should be practised, in order to avoid disrupting biological control agents and developing resistance. Use IPM-compatible products and check the persistence of products that have side effects on biological controls before reintroducing them

September

Continue IPM programme until around week 38–40. Ensure spider mite numbers are as low as possible in unheated crop areas before the end of September to prevent mites going into diapause and overwintering. Consider using a plant protection product as part of the end-of-season clean-up if spider mite numbers have been high. At this stage, compatibility with biological control agents is not so critical. However, some predatory mites, such as A. andersoni, can successfully overwinter, so IPM-compatible products may be preferable if aiming to build a local population of predators

October

In heated structures, ensure spider mite numbers are as low as possible, and if need be, use a plant protection product to clean up production areas. Complete the end-of-season nursery clean-up after crops have been removed and before the next crop is stood down

November

Two-spotted spider mite can overwinter in cracks, crevices, canes, leaf litter and glasshouse or polythene tunnel structures. Ensure all surfaces are cleaned and debris is removed. Plant protection products will not be useful in unheated production areas in winter since the mites will not be active and will be protected in their overwintering locations

December

Review success of IPM programme with staff and/or your consultant

Other plant-dwelling predatory mites

Several other predatory mites are available for the control of spider mites to supplement control by P. persimilis or for control of other pest mite species.  Some predatory mites primarily used for control of other pests, such as thrips and whitefly, will also contribute to control of some mite species.

Amblyseius andersoni is native to England and Wales and can be released early in the year, before two-spotted spider mite is present, due to its cold tolerance and omnivorous diet. A. andersoni can be found naturally on many species of trees, shrubs and herbaceous plants and seems to be less susceptible to some plant protection products than some other predatory mites. Adults overwinter in cracks, crevices and leaf litter and become active in early spring. A. andersoni is a generalist predatory mite, which will feed on several mite species, including spider mites, tarsonemid mites and eriophyid mites, along with thrips larvae, pollen, fungal spores and honeydew. Adult mites are straw-coloured and pear-shaped, and, without a microscope and specialist knowledge, indistinguishable from other Amblyseius or Neoseiulus species predatory mites species.

Neoseiulus californicus is considered non-native to the UK so only has a licence for release in permanently protected structures with full enclosure. This species tolerates high temperatures and low humidities better than P. persimilis and, like A. andersoni, is also less susceptible to some plant protection products. N. californicus will feed on spider mites and tarsonemid mites and also pollen. This predator does not feed on as many spider mites as P. persimilis and does not disperse as well or control ‘hot spots’ as well as P. persimilis. Therefore, it is better released early in the season to allow a population to build up and offers useful control when P. persimilis starts to struggle in hot, dry conditions. The adult mite is oval, transparent and about 0.4 mm long. When it has fed on spider mites, N. californicus develops pale orange markings on its back.

Neoseiulus cucumeris is primarily used for thrips control on various crops, including ornamentals, but will also feed on spider mites and tarsonemid mites. This predator is routinely released into strawberry crops for preventive control of tarsonemid mites, as well as western flower thrips. Experience on protected ornamentals has shown that preventive release of N. cucumeris will give good control of broad mite. When cucumber crops used to be grown on straw bales and were attacked by Tyrophagus longior (‘French’ fly), there was some indication that N. cucumeris gave some control of these mites, when used for thrips control.

Amblyseius swirskii, Amblyseius limonicus and Transeius montdorensis are not native to the UK. All these species have a licence for release in permanently protected structures with full enclosure, but check with the supplier about restrictions for release in polythene tunnels. All three species are primarily recommended for control of thrips and whitefly, but they will also feed on pollen and some mite species. Transeius montdorensis can give good reduction of spider mites, eriophyid mites and tarsonemid mites.

Ground-dwelling predatory mites

Stratiolaelaps scimitus is a ground-dwelling predatory mite that is primarily used for control of sciarid fly in growing media but will also feed on other prey, such as thrips pupae and tyrophagus mites. The adult mites are up to 0.8 mm long, off-white, with a pale brown shield covering most of the upper surface of the body.

Amblyseius andersoni (top) alongside a two-spotted spider mite

Image © ADAS Horticulture.

Delivery systems for predatory mites

There are various different delivery mechanisms for predatory mites. They can be sprinkled onto plants each week in a bran or vermiculite carrier, either by hand or using an automatic applicator such as the ‘Airobug’ system, which saves on labour time and gives a more even distribution. Alternatively, the predators can be released every 6–8 weeks using controlled-release paper sachets that are hung onto plants, pots or baskets. The sachets generally contain a live food source, which enables the predatory mites to feed and breed within the sachets.

Supplementary food for predatory mites

Several products are available from biological control companies for boosting numbers of predatory mites for improved pest control. Cattail (Typha) pollen is available as ‘Nutrimite’ from Biobest, which has been shown to boost numbers of some species of predatory mites, including A. swirskii and T. montdorensis. Two ‘feeder mite’ products are also available, containing prey mites as supplementary food for some species of predatory mites, including all those supplied for thrips control. ‘Nutari’ is available from Koppert Biological Systems and contains Carpoglyphus lactis, and ‘Mitefood’ is available from Bioline AgroSciences and contains Thyreophagus entomophagus. So far, these products have not been used extensively in UK ornamental crops.

Other predators

The following predators can occur naturally and contribute to the control of various mite species, particularly where IPM is being used with minimal use of plant protection products. Some of them are also commercially available.

Feltiella acarisuga

The predatory midge Feltiella acarisuga is native to the UK and commercially available but can also occur naturally, especially if spider mite numbers are high. The midge is a useful supplement for spider mite control, especially for 'hot spot' treatments. The midge is supplied as pupae in cartons, which should be placed in a shady area near to the spider mite infestation. The adult midges emerge from the pupae and fly out to look for spider mite colonies in which to lay their eggs; this means they can disperse more easily than predatory mites. Adult Feltiella have a reddish body, long legs and antennae and a gnat-like appearance. The eggs are oval, slightly sickle-shaped, translucent to yellowish and are visible with a hand lens. The larvae are yellow or reddish and about 2 mm long and can consume an average of 30 adult spider mites or 80 eggs per day. When fully developed, the larvae spin small white cocoons on the undersides of the leaves, in which they pupate. Optimum conditions are 20–27°C and 80% relative humidity.

Feltiella acarisuga larva feeding on two-spotted spider mite

Feltiella larva with two-spotted spider mite. Image © Nigel Cattlin

Image © Nigel Cattlin.

Stethorus punctillum

Stethorus punctillum is a small black ladybird that feeds on spider mites. It is no longer commercially available in the UK but can occur naturally where IPM is being used. Adults are attracted to colonies of spider mites to lay their eggs. Adults and larvae are active predators on all spider mite stages.

Anthocorid bugs

There are several species of anthocorid bugs native to the UK, including commercially available Orius species like Orius laevigatus, which can also occur naturally, and naturally occurring Anthocoris species, such as Anthocoris nemorum. Adults and nymphs are voracious predators of various small prey, including thrips, spider mites, moth eggs and aphids, and they also feed on pollen. The flying adults can disperse easily and are about 3–4 mm long, black with grey and brown chequerboard markings on their backs. Orius laevigatus is primarily used for thrips control and needs temperatures of at least 15°C for egg laying and temperatures of at least 20ºC for good establishment.

Black-kneed capsid bug

The black-kneed capsid bug (Blepharidopterus angulatus) is a common and widespread naturally occurring green bug with a slim, parallel-sided body and black ‘knees’. Adults and nymphs feed on mites, aphids, thrips and other small prey.

Lacewings

The green lacewing Chrysoperla carnea is native to the UK and sometimes occurs naturally in protected crops where IPM is being used, usually together with aphids, which are its preferred prey. The predator is available as eggs or larvae for the control of aphids, but the larvae will feed on other prey, including spider mites and thrips. The adults are not predatory and the predator will not establish in glasshouses, therefore repeated releases of larvae are needed.

Typhlodromus pyri

Typhlodromus pyri is a very common species of predatory mite, found in fruit trees, among a variety of habitats. The mites feed on pollen, fungal spores and mite pest species, particularly the fruit tree red spider mite.

Entomopathogenic fungi

Entomopathogenic fungi are microbiological bioprotectants and therefore need to be approved for use in the UK (unlike predators, parasitoids and nematode biological control agents). Two species of fungal products are approved for use on protected ornamentals in the UK for control of whitefly and they may also give some control of mites: Beauveria bassiana (Botanigard WP and Naturalis-L) and Lecanicillium muscarium (Mycotal).

Plant protection products

When using an integrated pest management programme, there may be a requirement to use a plant protection product if the mite population grows too rapidly for the predator(s) to control, or if there is a sudden outbreak of the pest mite and an infestation 'hot spot' occurs. Products may also be needed at the end of the season as a clean-up measure to reduce the population of spider mites carrying over to next season.

Plant protection products should be selected and their application timed carefully, using the least harmful and persistent products where possible. Applications should be planned according to product-label recommendations, life stages of the pest mite controlled, permitted frequency and number of applications and resistance management guidelines.

Table 3 lists both bioprotectant and conventional plant protection products that are currently approved on protected ornamentals that should give some control of mite pests.

Handheld applicator (‘Mini-Airbug’) for biological control agents

Image © AHDB.

Example product(s)

Active ingredient

Chemical group (IRAC group)

Approval outdoors

Approval under protection

IPM compatibility

Comments

Bioprotectants

Botanigard WP

Naturalis-L

Beauveria bassiana

 

Entomopathogenic fungus (microbial bioprotectant)

Botanigard WP EAMU 0791/2020 -outdoor/outdoor with temporary rain covers for control of two-spotted spider mite, fruit tree red spider mite, plum leaf gall mite and plum rust mite on apricot, cherry, peach, nectarine and plum

On-label for ornamental plant production

Botanigard WP (permanent protection with full enclosure, recommended for whitefly control)

Naturalis-L (protected, recommended for whitefly control, with some reduction of thrips and potential against other pests including spider mites)

Safe to most biological control agents

Contact action

Botanigard WP needs 20–30°C and over 70% relative humidity for optimum control

Naturalis-L needs 20–30°C and over 60% relative humidity for optimum control

Both products may give some control of spider mites

 

Eradicoat

Eradicoat Max

Majestik

 

Maltodextrin

Botanical bioprotectant

On-label approval for all non-edible crops

Eradicoat Max (permanent protection only)

Label recommendations for spider mite and whitefly control

Safe to biocontrols once spray deposit dry

Contact action

Eggs not controlled

Eradicoat Max has been shown to affect tomato russet mite as well as two-spotted spider mite

Best applied in hot, dry conditions

Flipper

Fatty acids

Botanical bioprotectant

EAMU 1415/2020 – protected (temporary protection) and outdoor ornamental plant production

EAMU 2842/2018 and 3171/2019 – permanent protection with full enclosure, ornamentals

Safe/slightly harmful depending on species

Safe once deposits dry

Contact action

Use soft water or rainwater or add X-Fusion conditioner

Mycotal

Lecanicillium muscarium

Entomopathogenic fungus (microbial bioprotectant)

N/A

On-label for ornamental plant production (protected, for whitefly control)

 

Safe to most biological control agents

Contact action

Use with adjuvant Addit

Needs 18–30°C and 70% relative humidity for several days after application

May give some control of spider mites

 

 

Physically acting products (exempt from plant protection product regulations)

Agri-50E

Propylene glycol alginate

Physically acting

Exempt

Label claims compatibility with natural enemies used in IPM

Contact action

Phytotoxicity recorded on poinsettia

Use on ornamentals is not recommended without performing a crop safety check

Protac SF

Mixture of polymers, mainly silicone polymers, siloxanes and organic antioxidants

Physically acting

Exempt

Likely to be harmful to soft-bodied biological control agents hit by the spray, but safe once spray residues dry

Contact action

Spray during day in low humidities to allow product to dry quickly and avoid plant scorch

Do not spray to flowering crops due to high risk of damage

Only mobile life stages are affected

SB Plant Invigorator

Diamide of carbonic acid

Physically acting

Exempt

Can be harmful to predators

Contact action

Chemical plant protection products

Apollo 50 SC

Clofentezine

Tetrazine

(Group 10A)

EAMU 2082/2016

 

N/A

Safe to biological control agents, except slightly harmful to Amblyseius andersoni

Needs careful timing in early spring to coincide with egg-laying period

Magenta product colour leaves a deposit on treated leaves

Contact action

Only controls eggs and young mobile stages of spider mites

Will give some control of rust mites (eriophyids)

Batavia

Spirotetramat

Ketoenol

(Group 23)

EAMU 1058/2019 – outdoor ornamental plant production

 

EAMU 2597/2019 – protected and permanent protection with full enclosure, ornamental plant production for control of thrips, aphid and whitefly

 

Harmful to Phytoseiulus persimilis for up to six weeks

Harmful to Neoseiulus californicus for less than one week

Moderately harmful to Neoseiulus cucumeris

 

Incidental control of tarsonemid mites

Check EAMU for ornamentals not to treat due to risk of plant damage

Borneo

Clayton Java

Etoxazole

 

Diphenyl Oxazoline

(Group 10B)

N/A

Borneo EAMU 3043/2019 – protected ornamental plant production

Clayton Java EAMU 1544/2011 – protected ornamental plant production

Harmful to Phytoseiulus persimilis eggs for two weeks

Moderately harmful to Amblyseius swirskii, Neoseiulus californicus and Transeius montdorensis

Inhibits development of two-spotted spider eggs and larvae

Contact action and residual action for 45–60 days

Best used at first appearance of mobile spider mites

 

Clayton Abba

Dynamec

Abamectin

 

Avermectin

(Group 6)

N/A

On-label approval for ornamentals (permanent protection with full enclosure). Recommended for control of two-spotted spider mite

Harmful to most biological control agents for 1–3 weeks depending on species (up to six weeks for Orius)

 

Contact-acting and translaminar

Nymph and adult two-spotted spider mite life stages controlled

Should have some effect on tarsonemid mites

 

Envidor

Spirodiclofen

Ketoenol

(Group 23)

EAMU 0997/2016 –  outdoor use only in ornamental plant production for control of two-spotted spider mite

 

N/A

Very harmful to Phytoseiulus persimilis for up to four weeks

Very harmful to Feltiella acarisuga and Orius species

Moderately harmful to Neoseilus californicus, N. cucumeris and Stratiolaelaps species

Non-toxic to N. californicus eggs

 

Not thought to be safe on Cordyline as Movento (same active ingredient) has previously caused damage on this crop

Floramite 240 SC

Bifenazate

Mitochondrial complex III electron transport inhibitors (METI) (Group 20D)

N/A

EAMU 1911/2020 and 2717/2020 – permanent protection with full enclosure ornamental plant production, container-grown crops

Safe/slightly harmful to most biological control agents

Conflicting information on Feltiella acarisuga – potentially harmful

 

Contact and residual action

Kills all mobile stages of two-spotted spider mite and also some eggs

 

 

 

 

 

Nealta

Cyflumetofen

Beta-ketonitrile derivatives

(Group 25A)

Label recommendation for spider mite control on apple, pear, quince and medlar

On-label approval - permanent protection with full enclosure, for spider mite control on roses. Minimum of two years between applications

Safe to most biological control agents, but populations of Amblyseius andersoni and Orius laevigatus may be slightly affected

Kills mobile stages of two-spotted spider mite and fruit tree red spider mite and may reduce numbers of eggs

Spruzit

Pyrethrins

Pyrethrins

(Group 3A)

N/A

On-label approval - ornamental plant production (permanent protection with full enclosure), for control of various pests including two-spotted spider mite

Harmful to some biological control agents for up to one week

Contact action

The information in this table has been collated using information from the Health and Safety Executive (HSE) website (www.pesticides.gov.uk) and from suppliers’ labels and product technical information. Important – regular changes occur in the approval status of plant protection products, arising from changes in legislation or for other reasons. For the most up-to-date information, please check the HSE website or with a professional supplier or BASIS-qualified consultant, as information could have changed since this factsheet was produced.

EAMU – Extension of authorisation for minor use.

Growers must hold a paper or electronic copy of an EAMU before using any product under the EAMU arrangements. Any use of a plant protection product with an EAMU is at grower’s own risk.

Always follow approved label or EAMU recommendations, including rate of use, maximum number of applications per crop or year. Where crop safety information is not available, test the product on a small number of plants to determine crop safety prior to widespread commercial use.

* Further details of compatibility of plant protection products with biological control agents are available from suppliers of biological control agents or plant protection products or consultants. See the following websites: https://www.biobestgroup.com/en/side-effect-manual and https://sideeffects.koppert.com/side-effects/

 ‘Safe’: kills <25% of the biological control agents; ‘slightly harmful’: kills 25–50%; ‘moderately harmful’: kills 50–75%; ‘harmful’: kills >75%.

Resistance management

As mites can complete many generations each year, there is always the potential of selecting for resistance if the same plant protection product is used too frequently. Two-spotted spider mite is considered to be one of the most resistant pests in the world due to the total number of plant protection products which populations have developed resistance to. In order to reduce the risk of resistance development, it is very important to rotate between different Insecticide Resistance Action Committee (IRAC) groups and to always follow the resistance management strategy outlined on the product label or Extension of Authorisation for Minor Use (EAMU). This will specify the recommended rate and the maximum number of treatments in a year. Integrated pest management also provides a solution to resistance, as using biological control agents will reduce the selection pressure for resistance to plant protection products. Mites are unlikely to develop resistance to physically acting products which work by coating the mites and suffocating or immobilising them.

Useful links

For further details of compatibility of plant protection products with biological control agents, see the Biobest website and the Koppert Biological Systems website

For more information about resistance management, visit the IRAC website.

Authors

Authors – Elysia Bartel and Jude Bennison, ADAS Horticulture.

Original author (08/05 ‘The biology and control of two-spotted spider mite in nursery stock’ and 12/09 ‘The biology and control of mites in pot and bedding plants’) – John Buxton, ADAS.

Got a question? Ask a member of the team:

Web page content correct as of June 2021.

×