Spider mite varieties
These little huas come in 2 varieties, the European red spider mite and the two-spotted spider mites. As far as I can tell they are as bad as each other, and seem to co-habitate happily together. If you have good eyes and are patient, you can see them scurrying around on the undersides of the leaves. When you move the leaf they sort of freeze and don’t start scurrying again for a while. You have to be patient and just keep staring, and eventually you will be able to see them, and even which breed they are.
Identifying spider mites
The reason it is important to learn to spot the actual beast, is because post spraying you need to know whether you have killed the buggers. If your eyes aren’t as good as they used to be, we suggest a magnifying glass. NO BULL.
The evidence they leave is a lot easier to spot; underneath, a sort of mildewy look, more in the centre of the leaf, and their tiny webs, and on the top of the leaf a paling, again mainly around the central ribs. The paling effect is due to the mites sucking the goodness out of the leaf and eventually it will turn yellow and falloff. This usually happens to more than one leaf at a time!
So if one of your roses starts looking dull and proceeds to turn a sickly shade of yellow. the chances are you have a spider mite epidemic.
Roses susceptible to spider mites
These guys are prepared to try pretty much any rose leaf, but given the choice have definite preferences. The tough, crinkly, apparently less succulent leaves, such as those belonging to the rugosas and old fashioned roses seem to be the most favoured, whilst noisettes and most hybrid teas are the least.
The next problem is that their diet extends into many annuals and perennials, not to mention most common weeds. So when spraying, all of these have to be either pulled out first, or sprayed with the roses.
Spraying for spider mites
So on with the spraying. First, find a spray which specifically kills both sorts of mite. Second, their life cycle is very quick, so at least 2 sprays at 3 -4 day intervals are necessary to subdue the population. Third, there is, at this stage, no systemic spray we know of for mites, so individual application is necessary !
As they are not hanging around the tops of leaf buds waiting to die (like aphids) but rather hiding under each and every leaf, (they start at the bottom of the plant and work their way up) complete eradication is nearly impossible. However, at low levels they are pretty inoffensive, just so long as you keep at them.
Any books you read stating they can be a problem during prolonged dry spells, scoff at and scorn. It has rained and blown nearly every day here for the last 9 weeks, (thus preventing any spraying) and whilst it has been comparatively warm, it is nearly mid-winter, and they are presently having field days in our gardens.
There are predatory mites available on the market, which you introduce at regular intervals into the garden to do the work for you without nasty insecticides. We are keen to try this approach, but have not as yet, so cannot comment on the effectiveness. The thing is, you are still going to have to spray for the funguses and aphids etc, so why not add some miticide while you’re at it ?