Spider mite season !

Hi everyone,


Just a quick note to let Lophophora and other soft skin variety growers that red mites are about in NSW. I have noticed a few plants effected over the last few days. They primarily like Lophs, Turbinicarpus and some of the Astro cultivars. They won't normally attack hard skin plants like Ariocarpus or Cereoids.

They are very small so you can't see one or two with the naked eye, but once numbers build up you will see orange patches usually in folds of the skin, growing tips or around the areoles. They are from the spider family and will also produce tiny silk like webs. They are very destructive and can kill a plant off fairly quick if not treated.

HN

What methods of treatment would you recommend?

KanJe,

They are pretty hard to deal with. Raising humidity will slow them down but does not kill them off, dusting with sulphur will also help reduce numbers and them spreading. A miticide is the best and most accurate way to send them packing.

IMLE
these are much more of a problem in winter,
when plants are kept dry.
rather than during the growing season when plants are (hopefully) actually watered.
so i am quite surprised as I thought the season just ended.

RSM absolutely HATE water.
mist spraying with plain water is fantastic.
high humidity does slow them down,
but its not as good as watering to the point of runoff.
top water all plants where appropriate.

they love Sulcorebutia, like rauschii.
also miniature Mamm. SP. especially the good ones like saboae etc.
and of course Loph. SP.
Gymnocalycium (particularly the small choice SP like ragonesei )
I think they will go for anything if it is kept dry enough,
however some plants do indeed tend to be more prone than others,
and it seems that RSM specifically seek out the slowest/choicest/rarest specimens in a collection.

The best way to get rid of them is water, and/or a miticide.
problem is you don't want to top water that prized 15yo self rooted Lophophora eh.

The worst thing you can do is apply a systemic insecticide, mites are not insects and it can actually result in increasing the mite population by killing off their natural predators.

There are thouands of mite species, some are visible to the naked eye and are predominately natural predators of the pest ones and then there are rust mites which are like RSM.

Apparently under ideal conditions a single female RSM can spawn a population of 1mil in under a month!
(which therefore means they are possibly the most effective organisms in the world at gaining pesticide resistance. doh)
so they can never be eliminated and your miticide will be eventually be rendered useless with prolonged use, thus you will have to try other chemicals or explore other means of treatment.
also the miticide kills all mites including the predacious species which naturally keep the mites in check and I'm assuming being predacious these have a comparatively much slower population turn over rate vs. RSM so will take much longer to gain pesticide-resistance also.

Oil based contact pesticides will kill them and the mites obviously cannot gain resistance to these but the use of these requires much more care such as placing the affected plant in the shade whilst it is treated and washing the oil off later.

has anyone tried any biological controls for these?

Lewis,

Yeah I used predatory mites last season, they certainly did work but were far too expensive to continue to use. They had completely eliminated the red mites in about a week, but after there is no food left they die off pretty quick.

In my climate, Syd NSW, I continually find mites are more active in spring. I remember you saying last season winter was your mite season. I NEVER (and I mean never) top water any of my miniatures so I guess this could be an issue.

Quote :

Yeah I used predatory mites last season, they certainly did work but were far too expensive to continue to use.

HN,

I heard the exact same report from a few growers here; effective but expensive.
A shame that.

I think over time they may become cheaper and more available.

Lewis I lost my beautiful [and newly bought] Gymno ragonesei too by mites!

An experienced cacti grower here says this year was their year. Everyone had infections. He also says they like wet+warm, as it is in out automn. I was surprised he told me this because I always thought they love the dry+hot, not wet+warm. This sure seems to be the case with greece's mild automn...

Nice to read your thoughts on NON-toxic chemical measures. Nicotine solutions work too is certain occasions against mites.

I really had some cacti attack this year, so I know it is an issue. Like said, they seemed to prefer Turbinicarpi, Stenocacti [thin rib curles] and Gymnocalicium ragonesei.