Q. How do I Identify and Control Red Spider Mite?
What they look like:
This little beastie is almost impossible to see with the naked eye – hiding away in a fine, silky speckled web between plant stems Look at this web with a magnifying glass and the tiny specks are actually minute red mites.
What they damage:
Initially they go for the leaves of plants - your warning sign is a pale mottled upper leaf surface and the underside may have lots of tiny yellowish green mites and old egg shells ( they only turn bright red in autumn or when resting over winter) Again, all of this activity is difficult to see with the naked eye. If undetected the infestation continues until the plant is covered with fine webbing, most of the leaves will dry up and fall off. Obviously this weakens the plant and eventually dies. It needs sorting.
Why they are clever:
Red Spider mite is very particular about where it lives, with a preference for warm, dry, cosy surroundings so its survival is not hampered by inclement weather. More often than not it will take up residence in a glasshouse, or house (where it attacks houseplants), but occasionally will appear on garden plants also.
How to sort:
- Spraying - spray if you want (your choice!) and we have suitable pesticides available. The bad news is that some strains are resistant to some pesticides. In this case it’s trial and error. Use a spray, observe its effects and if the infestation persists try another brand with a different chemical composition.
- Edible plants can be sprayed with mixes of natural plant oils, plant extracts or fatty acids. These pesticides may require frequent applications to control the mite.
- Non-chemical control - Remove severely infested plants from glasshouses in late summer to prevent the females finding warm, sheltered places where they will overwinter.
- Keep humidity up – wet the greenhouse floor ( this is called damping down and best done in early in the morning on sunny days) , spray with water every couple of days until temperatures drop in autumn.
- To minimise overwintering mites clear out plant debris, old canes, stakes and plant-ties before the spring.
- Wash down empty glass houses and clean thoroughly with a glasshouse disinfectant.
- Weeds in and around the glasshouse should be kept down as these can act as hosts for the pest.
- Plants in flower should not be sprayed due to the danger to pollinating insects.
Always check the label for details, ensure that manufacturer’s instructions are followed.
Once you’ve spotted this pest you need to take swift action to get rid of it!