East of Scotland Begonia Society

Tarsonemid  Mite 

July 2004

            This pest seems to have increased in the last few years as has been shown by the reports from around the country. I can now officially say that it has reached the East of Scotland Begonia Society because another member and I have had this scourge for the past season. How it was introduced to the greenhouse is not certain, but I suspect it was brought in by three plants I received in the spring that were late cuttings taken the previous year and over wintered green. When I first saw the plants they certainly did not look healthy but thought with a bit of TLC they  would be OK. How wrong I was !!    

                                                      Mite on Flower and Stem

The mite soon spread to many of my other begonias. and in fact all the plants on one side of my house were affected. At this point I was given some "Dynamec" to spray them but it was a case of too little too late and I was forced to take all the begonias on one side of my greenhouse outside to the farthest point in the garden and cut off the tops
Plants on the other side appeared to be OK so were sprayed a second time with Dynamec and they all looked fine. I was away on holiday for a week and when I returned it was obvious that the little blighters were now feeding on these plants as well. They were sprayed again with the aricide but as before many of the plants had to have the tops removed as it was clear that they were not going to produce a worthwhile flower. Eventually I was left with only a dozen flowers from a total of nearly ninety plants. Of course I was unable to show any of them because of the risk of spreading this serious pest. .
When I was away in June I visited Blackmore & Langdon and John, the foreman, told me that they use a product called "Dycofol" as a preventative. This chemical  is not available to amateur growers. However John also told me that the tubers would be OK next year

                                                                      Mite damage on Leaf

Now the difficulty is trying to eradicate the last of the mites so that there is no infection carried forward to the new season. To this end the houses will be smoked with both sulphur and "Fumite", pressure washed then washed again with Jeyes Fluid. Hopefully this will be sufficient to eliminate the pest, but as an added precaution the compost the plants were grown in will be dumped and not as usual spread in the garden The tubers will be given the bleach treatment as a further safeguard.
I will add a Post Mortem to this page next year 
   Post Mortem Update
Points to watch out for;-
Look for any buds that appear rounded and closed up with brown/black markings on the petal edges. The top leaves can sometimes curl so watch carefully. These mites are too small to see with the naked eye so the first thing you see is the damage.   
.Never introduce growing plants into your greenhouse except after being quarantined for an extended period.
Spray early if you can.
Take affected plants and those around them out of your greenhouse as soon as you suspect.
Dynamec and other aricides control, but seem unable to eliminate, ;- You never get the last one and they do seem to breed at an alarming rate.
My experience leads me to believe that if your greenhouse becomes infected then you lose a complete year
You have been warned
I would love to hear from anyone who has experienced the ravages of the Tarsonemid mite, how they coped, and how they got rid of it.

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