# Part 2. Mites that thrive in humid conditions and orchid fleck virus, a case study.



## quietaustralian (Apr 28, 2012)

*Part 2*

Wednesday 22 February 2012 

Wayne has now thrown out 150 plants and I’m up to 75. Some years ago I experienced bulb rot and I lost around 80 plants and I thought it was all doom and gloom but this Orchid Fleck Virus is worse because the False Spider mite problem won’t go away, we will have to keep spraying to keep our plants healthy. 

I have never used insecticides. The only thing I have used is ECO Oil. This mite eradication program will kill off all our beneficial bacteria and fungi and I’m not happy about that. 

Orchid Fleck Virus Symptoms 
Orchid Fleck Virus (OFV) causes necrotic or chlorotic ring spots and fleck symptoms in many orchid species and is sap transmittable (sap to sap) and by the false spider mite (Brevipalpus Californicus) the virus is transmitted by both the adult and nymph, but not the larva. 

Brevipalpus Californicus is spread throughout the world. 

Brevipalpus Californicus Taxonomy:
Class - Arachnida
Order - Acarina
Family - Tenuipalpidae
Morphology
Egg the newly laid eggs are bright orange and shiny. 
Lava the lava is bright orange and ovoid in shape 
Protonymph the protonymph has four pairs of legs and is almost colourless. 
Deutonymph the deutonymph is bigger and more slender and is also almost colourless. 
Adult the adult is similia to the deutonymph but bigger and has bright spots. The preoviposition lasts one to two days. The female lays on average 43 eggs in 20 days. 
The incubation period is 3 days. 

The mites undergo three moults which last 2-5 days between each moult. The mite reach adulthood (from egg to adult) in about 14 days and the males live for about 18 days and the females for about 21 days. 

Important 
It is important to regularly use an aracide (every 5 days) so that we can stop the life cycle and hopefully eliminate these mites. (see above recommendations on types of isecticides/aracicides and frequency) 

Brevipalpus Californicus have been known to survive for extended freezing temperatures but are supposedly susceptible to temperatures above a dry 35 degrees Celsius. I wonder if the mite we have has adapted to our Australian conditions. 

Inspect your plants every day and be aware that the infection may not show up for 24 months, although, I believe that it may be much longer. 

Saturday 25 February 2012 

Like Wayne the problem with Orchid Fleck Virus invades my thoughts quite often. I guess a couple of the questions are: How does Brevapulpus Californica – False Spider Mite migrate and where they pick up the Orchid Fleck Virus. 

The incidence of Orchid Fleck Virus is widespread throughout Western Australia, South Australia, Victoria, New South Wales and Queensland. I wonder if our changing weather is helping the spread of this mite? We used to get long periods of temperatures over 35° and into the 40’s. This is supposed to kill off these beastly critters but I wonder if like all other pests and diseases that come from overseas, they have become acclimatized to our conditions and continue to proliferate no matter what. 

Some people stated that we will be OK when the weather cools down (Wintertime), but I have read that they survive extended periods of freezing temperatures. 

Another thought: How do we know if other plants are infected because of the 24 months or more for a plant to show signs of the virus? I suppose the only way to hopefully eradicate these mites from our collections is to keep spraying with all the ‘nasties’ and be very strict on plant inspections at club meetings and shows. 

All orchid genera are susceptible to Orchid Fleck Virus. 

The False Spider Mite probably hitches a ride on the wind also by leaves from trees etc that blow in the wind and host to this mite. The mite migrates to an orchid plant with the virus then travel from leaf-to-leaf and plant-to-plant spreading the virus as they travel. 

I have heard comments from members of two different clubs as to where they think that they picked up plants with virus. I would advise people from getting on the blame game wagon because we really don’t know where or how our plants contracted the virus. The time involved between the mite infecting the plant to showing signs of the virus is at least 24 months and as I have mentioned, I think it could be a lot longer. 

These comments and the way that I am going about getting over this Orchid Fleck Virus is based on all the information I have gathered and is my own regime. I’m sure that someone who is more qualified than I am may come up with a much better solution to the problem. 

Wednesday 29 February 2012 
I have had a couple of comments on this article. One was to emphasize the introduction and use of foggers in the last 5 years. I agree that we have provided the perfect environment and habitat for the False Spider Mite therefore I will cease to use them from now on, which is a shame because they were a great way of reducing water use. The other comment was to introduce predatory mites. I spoke to Matthew Parker who breeds predatory mites (persimmilis) in Coffs Harbour - north coast New South Wales. Matthew said that persimmilis do not attack Brevipalpus Californicus. 

I also contacted Biological Services in Loxton SA and enquired if the predatory mite Californicus (Neoseiulus Californicus) would attack the False Spider Mite. James from Biological Services cannot guarantee that the predatory mite Californicus (Neoseiulus californicus) will feed on the False Spider Mite (Brevipalpus californicus) but he is quietly confident that they will.
Californicus (Neoseiulus californicus) does coexist quite well with the predatory mite Phytoseiulus persimilis.
Phytoseiulus persimilis feed on the Two Spotted (Red Spider Mite).
These two predacious mites are available from Biological Services in Loxton, South Australia. Website: http://www.biologicalservices.com.au/ 

I would like to try using both these predacious mites. I hate having to use all the nasty chemicals in the shade-house because we have a very green garden and ponds that may host the False Spider Mite. 

Please be responsible with the removal and destruction of your infected plants. One suggestion is to place the plant in a black plastic bag and leave it out in the sun for at least a week then dispose of it in the green compost bin. I have a large number of plants therefore the plastic bag method is not practical for my collection. I cut the leaves off and slice up the bulbs and place them in the green bin. 

It is important to destroy the infected plants so that no one else can pick them up at the recycle depots and attempt to grow them. 

Peter Hall


----------



## cattmad (Apr 28, 2012)

thanks for sharing this mick.

interesting to say the least, but my thoughts go out to the blokes who are dealing with this, it must be heart breaking to have to destroy a large part of your collection.

Thanks again


----------

