Control of tarsonemid mite on strawberry: chemical

Biological control is considered the best course of action in combating the tarsonemid mite. However chemical controls can work alongside, or sometimes instead of, biological measures.

This information was last updated in 2018.

The importance of good spray cover

Tarsonemid mites are susceptible to most acaricides when directly intercepted by sprays.

However, the majority of the mites and eggs reside between the blades of folded leaves and are relatively inaccessible to sprays.

Most currently used acaricides are contact acting and the spray penetration can be the chief factor limiting efficacy.

In addition, strawberry leaves are waxy and hairy and spray droplets can be prevented from reaching the inner leaflets.

Penetrate crowns

To achieve maximum penetration, sprays should be applied in high water volumes (at least 1,000 l/ha) using efficient application equipment to ensure the crowns of the plants are thoroughly penetrated.

Spray operators should use water sensitive papers or other spray deposit technology to ensure the crown of the plant has been reached with good coverage.

Figure 1.Efficient spray application is required to achieve maximum penetration of acaricides into the plant crown.

Crops for fruit production

In crops for fruit production, where it is especially important to minimise pesticide residues, biological control with the predatory mites is the preferred option for control of tarsonemid mite.

Chemical control should only be used as a last resort, where extensive infestation and damage is present. Biocidal and plant protection products must only be used in accordance with the authorised conditions of use. Regular changes occur in the authorisation status of biocides and plant protection products. For the most up to date information, please check with your professional supplier, BASIS registered adviser or the Chemical Regulation Division (CRD) of HSE (https://www.hse.gov.uk/crd/) before use.

Early AHDB trials in the 1990s indicated that abamectin (Dynamec) and tebufenpyrad (Masai) are both effective for control of the pest.

Floramite (bifenazate) is currently approved for use on protected strawberry for two-spotted spider mite control, but is not considered effective for tarsonemid control.

Ineffective insecticides 

All the synthetic pyrethroid insecticides tested in the AHDB trials have been ineffective against tarsonemid mite.

Control can be improved by using a silicone wetter mixed with the effective acaricide. AHDB Project SF 79 in 2006 demonstrated that the activity of Dynamec, Masai and Borneo could be improved with the addition of a silicone wetter.

Note that Envidor was not approved for use on strawberry at the time of testing.

The adjuvant label should be carefully checked before application as there is often a requirement to reduce the acaricide concentration by 50% when applied in combination.

Choice of product

Table 2. Products approved for use on strawberry for which control tarsonemid mite or which offer incidental control when used against other mite species. This information was last updated 2018.

*IRAC code – Further details about IRAC (Insecticide Resistance Action Committee) and the full IRAC code list, can be found at http://www.irac-online.org/modes -of-action/. Products with the same Mode of Action should not be applied consecutively.

**Data on side effects is from the Koppert and Biobest ‘side-effects’ website (https://www.koppert.com/side-effects and http://www.biobestgroup.com/en/side-effect-manual).

Growers should seek advice from a BASIS qualified consultant before choosing to apply a crop protection product.

Important considerations are:

• Both Dynamec/Clayton Abba and Masai have translaminar activity and can reach mites in the folded leaflets to some extent.
• The residue of Masai on foliage is likely to be more persistent, preventing the migration of tarsonemid mites to new growing points over a longer period.
• Masai is active against eggs, larvae and adults. Dynamec/Clayton Abba is active against adults and larvae only.
• Dynamec/Clayton Abba remains harmful to predatory mites for approximately two weeks. It degrades somewhat more rapidly in high light conditions, which may allow a slightly shorter interval between spraying and introducing the predators.
• Masai is considered to be comparatively safe to predators.
• Envidor and Borneo/Clayton Java are moderately harmful to predatory mites and the latter can persist in the crop for two weeks.

Crops in propagation

Like fruiting crops, biological control is the preferred option for tarsonemid mite as it is more effective at gaining access to mites which are inaccessible to sprays.

Should high populations require to be reduced quickly, recourse to acaricides may be necessary, in which case propagators should choose from the products in the table.

The EAMU approvals for Dynamec and Clayton Abba permit their use on outdoor strawberry in propagation, but if used for this purpose, they should be applied before the end of October.

Author/s

The content for these web pages was authored for AHDB by Michelle Fountain and Jerry Cross (NIAB).

Please note this information was last updated in 2018. Biocidal and plant protection products must only be used in accordance with the authorised conditions of use. Regular changes occur in the authorisation status of biocides and plant protection products. For the most up to date information, please check with your professional supplier, BASIS registered adviser or the Chemical Regulation Division (CRD) of HSE (https://www.hse.gov.uk/crd/) before use.

While the Agriculture and Horticulture Development Board seeks to ensure that the information outlined on this page is accurate at the time of publishing, no warranty is given in respect thereof and, to the maximum extent permitted by law the Agriculture and Horticulture Development Board accepts no liability for loss, damage or injury howsoever caused (including that caused by negligence) or suffered directly or indirectly in relation to information and opinions contained in or omitted from this information.