Gardening with Wilson

Even though it has been documented in books, spider mites are pests that rarely visit bromeliads. I told my friends who grow bromeliads about it and they were quite astonished to know. In fact, this misfortune have become quite a ‘laughable’ matter to them. They were wondering how on earth did my bromeliads get infested?

As far as I can trace, I suspect it was a costus cutting that I brought back home from the garden to nurse under my light garden that is located in my bedroom. It was seemingly clean but as we all know, spider mites and their eggs are not easily visible to the human eye and I won’t be surprised that some were hiding somewhere. Prior to that, my bromeliads have been growing happily indoors under the fluorescent light lit garden for more than a year.

Lesson learnt – please quarantine your plants. Pests and disease can be introduced into a healthy collection of plants very easily.

It all started with me having noticed that my bromeliads showed wierd spots of discoloration on their leaves. These weren’t too visible when the leaves were dry. Because I either periodically mist the leaves of my plants or bring them under the shower to wash the dust off and to flush their tanks, those ugly spots became obvious when the leaves became wet.

At that time, I couldn’t quite figure out what happened. Nothing could be seen because the plants then had just been washed relatively clean. It wasn’t long when I saw web-like substances appearing on my bromeliads. Those fine silks straight-away raised an alarm – spider mites. I examined those threads and I saw small little cream-coloured creatures crawling on them!

Upon closer inspection of all my plants, I noticed colonies of mites having a good time on the undersides of my plants’ leaves.  I also later realised that the spot where these idiotic pests gathered, the colouration of the leaves at that particular location will be permanently destroyed.

Some plants were so badly affected that almost all their leaves became damaged as shown in the photograph below. There is no way to salvage those damaged leaves. I just had to wait for the new ones to appear to replace those that have been damaged and if the entire crown dies, the only next best thing to do is to wait patiently for a new pup to appear.

As I have mentioned earlier, washing away with water did not work too well for this bout of spider mite attack. The eggs that were laid earlier probably did not get washed away and were allowed to hatch.

Next, I tried something that was not that toxic to start with. I used a very diluted summer oil spray to treat my plants on every alternate day. Bromeliads have been reported to be somewhat sensitive to oil-based sprays. That failed to work. The mites came back.

I then frantically went through my chest of garden chemicals and found something that I have bought quite long ago but never used it. The bottle read “Abamectin”. I checked with my fellow gardening friend who grows African violets. He told me that abamectin is very effective against mites but it is very smelly to apply.

Yes – the odour from the spray was quite difficult to bear. Had to hold my breath when I sprayed my plants, leaf undersides and all. Wore gloves as a safety precaution too. I did not bring my plants back into the room for several days. I washed them with water before bringing them back to the light garden – just to play safe.

Abamectin in miticide preparations consist of a mixture of  avermectin B1a and less  avermectin B1b . These two components are derived from the soil bacterium Streptomyces avermitilis and have some systemic activity. It also has a long residue life – up to 30 days but is highly toxic to aquatic life.

So far, abamectin has kept the mites away from my bromeliads for about a week already. Will continue to monitor. Hope the mites will never come back again.

P/S – At present, I am still not very comfortable of using abamectin on edible plants until I am really sure of its safety.