Although this heat wave seems never-ending and the damage to leaves and plants from the harsh sun may look like you need to water more – check to see if the damage is not something lurking underside of the leaves.
I have a couple of plants I thought were lacking water but since I thought the soil had been relatively damp for the most part I realised the damage to the leave must be caused by something else.
Spidermites love dry warm weather (the heat increases the life-cycle so populations can soar)- which is why we may now be seeing infestations this year as opposed to other summers – the humidity is not a friend to the spidermite and can be one way to reduce the population.
When spider mites first arrive you might not think anything of it as the damage done is not noticeable – however, as the mites grow in population the leaves begin to show signs of dehydration. This is exactly what is happening – although you are watering the mites are sucking the sap and moisture straight out of the leaves.
In the photo above you can actually see a couple of mites close to the edge of the picture – orange rectagular specks along the edge of the leaf. This shows quite a bad infestation as usually they hide on the underside only.
Spider mite are almost microscopic and may not be able to be seen with the naked eye. First the topside of your leaves will look dry and ‘burnt’ in places and then if you turn over the leaf you may see a web-like covering and also if your eye is good – tiny moving specks. The spidermites live on the underside and produce a web like a spider (they are related both being arachnids) however, they do not eat insects but use the web as protection.
If you are unsure, you can rub your finger across the underside of the leaf and usually it will smear a red colour (this is spidermite bodies/blood) if that grosses you out; you could hold the leaf over a white piece of paper and shake; seeing if any specks fall onto the page. Otherwise, if you have a magnifying glass or zoom lens you can see them close up. The picture below shows the web that you can see with the naked eye if the population is high. they are also seen as dark dots all over the leaf surface.
To get rid of the mites there are a number of chemical treatments that could be used; however, many spidermites are resistant to spray and you will just end up killing the good insects instead.
Firstly, try to remove as much affected foliage as you can; this will at least reduce the number of mites and eggs that need to be treated. Then physical removal such as wiping the leaves or spraying with a strong jet of water. A spray bottle with half alcohol half water with a touch of washing up liquid can be sprayed on both surfaces of the leaves.
Predatory insects include lacewing, ladybirds, Phytoseiulus Persimilis (a type of predatory mite who attacks both red and two-spotted spidermites) Feltiella acarisuga (predatory midge) and the rove beetle. These can be used as a short-term or long-term method – helping to balance out the food chain within your garden.
Whichever method you choose, try to control spider mites when first seen because if you think it is not a big deal to have a small population they can spread and breed very quickly and damage and then kill a plant before you realise it.
Here is a video as well – showing how bad they can get; this is not the worst I have seen but I was able to capture them running around Instagram: Spidermites
Do you have spider mite problems? What solutions have you used that have been successful or unsuccessful in your garden?