Tiny spherical "greenfly?" on violas and other plants.

Many of my violas are covered with what look like tiny spherical greenfly, and the worst affected of them have already just shrivelled and died. One viola that died was in a pot with some lemon thyme that was doing just fine before, starting to grow again after the winter, and last summer it filled the pot. Now that lemon thyme is also covered with these things and shrivelling and dying like the violas.

Does anyone have any idea what they are? Are they ordinary greenfly?

 

I think we need a picture.

 

They are very tiny, about half the size of a pinhead. I will try to take a photograph tomorrow when there is more light.

 

There is a beasty called the violet aphid (Myzus ornatus) described as (Pests, Disease and Disorders of Garden Plants by Buczacki and Harris) "small green or yellow aphids with paired dark markings on the thoracic and abdominal segments. Infest violets, violas and some other plants". Treatment as for any other aphid.

 

My Pansies & Violas are often infested with "millions" of itsy bitsy tiny white aphids which kill the plants in a few weeks. I had stopped growing Pansies because of these & last year only grew Violas. Late in the spring they also suffered & this year the same has happened with my Violas once again. I've seen less of these this year.

But there is also another problem - the apparently heathy plants start to look as if they were very dry, wilting & collapsing. When I remove them from the pots I can't see anything wrong with them. They haven't rotted from overwatering nor have they dried up from underwatering. The roots seem to be fine & I've opened up the rootballs on a few but found nothing eating the roots or any other kind of pest.

I've noticed the same phenomenon on Pansies planted out in flowerbeds by the local town council gardeners.

Has anybody any idea of what may be happening? Is there some kind of Virus going around during these last few years?

 

There is a problem known as Pansy sickness, I think it might be a soil borne condition, but not sure.

 

I will try to get better photographs later.

 

They do look like aphids,but there could be something else there feeding on them.

 

I just tried spraying them with some water that I had soaked and squeezed some Erigeron karvinskianus in for a couple of minutes (I will try again later when the Erigeron has had chance to percolate into the water). Loads of tiny gritty little things came into my hand. They don't seem like the greenfly I am used to seeing on roses etc.

(I just noticed that Erigeron karvinskianus, otherwise known as Fleabane, never gets attacked by greenfly or anything else, so wondered if it has a substance in in that repels them. Worth a try, as I have to trim the Erigeron karvinskianus anyway, and I have to water plants, so just trying watering and spraying them with hopefully some substance from the Erigeron).

 

I am only in the experimental stage, but I found that by soaking the trimmings of my Erigeron karvinskianus, Mexican daisies, in a bucket of water for a couple of days, giving it a stir to extract into the water whatever is in the Erigeron karvinskianus, then straining by pouring the water through a sieve into another bucket, and using that to drench my plants seems to work quite well for greenfly and aphids.

A few weeks ago I lost some Viola plants to weird greenfly like aphids, and then used this water on the remaining Viola plants. Those that hadn't yet been affected or only slightly affected remained clear and are still healthy, and one Viola plant that was just about still holding on that I treated with this water now seems to be recovering. It was badly affected and covered with these little aphids, and now it doesn't have any and it is recovering, growing fresh leaves. This Viola plant I poured the water all over its leaves and also its soil, a proper drenching.

I am no expert, I just noticed that my Erigeron karvinskianus never gets aphids and I wondered if it had any substance in it that repells or kills them. As it is also known as Fleabane, maybe whoever named it knew something. (The German for aphids literally translates as leaf lice). I don't know if it is having this Erigeron water poured over the affected leaves or into the soil that has the effect. I was so desperate to get rid of the aphids I did both, and the plants recovered and weren't harmed.

I will try to post a photograph of the recovering Viola plant later. I couldn't believe my luck that something actually seemed to be working, after the way the greenfly just seemed to take over my plants and actually kill some of my Violas.

Next issue is to find something to deal with mildew, which I noticed in one Viola plant, and had in some Viola plants last year but not others, it seems to be the place they are growing in, maybe, or it could be that variety which is especially susceptible. I love Violas and will try to think how to deal with the mildew they seem to be susceptible to.

Another thing I learnt is that it is easier to squish aphids without unduly disturbing the plant if your hands are wet. I found that out by having my hands in the Erigeron water before squishing aphids. Otherwise aphids are quite difficult to grab hold of as they seem to adhere to the plant.

 

Need to do a control experiment. So split affected plants into two groups one set gets the mixture; the other gets an equivalent drench of tap water.Use separate watering cans

 

I was using a jug to pour the Erigeron water from the bucket over all the leaves and soil of the Violas, and also (with not so much vehemence) on other plants affected by greenfly, such as roses and Feverfew. I wasn't using any kind of spray, as I haven't had much luck using those. So the water wasn't physically removing the greenfly (although the gritty things with them were coming off in my hands) They just seemed to be killed by it and disappeared, cleared up completely, in a way that water alone wouldn't have done. If you pour plain water over the leaves of a plant affected by greenfly, it won't remove them or affect them. I suspect the Erigeron water was somehow taken into the plant, either through the leaves or through the soil. It might have worked just to pour it into the soil surrounding their roots, but the situation was that the Violas were dying fast.

The Violas that were only slightly affected lost their greenfly and are now very healthy, the one white Viola that was almost gone has recovered, has no greenfly, and is growing back new leaves. I used it on all the Violas in that area (I didn't use it on the one Viola in another part of the garden which is now showing mildew, I must try it, maybe it will work for mildew too...)

I take your point about controlled experiments, and if I get a straightforward apples to apples situation I might sacrifice one plant to be the control.