Bacterium , vine weevil and caterpillar ??

[newstart]

From what I learnt earlier on in life at my brief time in college(which is very limited compared to those with real experience I feel) we were told caterpillars generally are the hole makers in leaves and slugs the tear at the sides. Also from what I remember of bacterium they settle on a leaf until it becomes paper thin and disintegrates with a hole in the leaf. Am I right about caterpillars as I can never find them on the leaf and its certainly not bacterium always(cold be a night thing with caterpillars and certainly slugs). Also how do you stop bacterium is there a chemical?

Second I get a problem often in late summer with Sedums becoming possibly a little over watered and becoming less attached to the roots and toppling over or a vine weevil doing this. I empty the pot spread the soil out and can never find a vine weevil larva though? Is it vine weevil or gradual over watering. I don't want start thinking its vine weevil when it my negligence with watering as I would pay quite a bit of money on biological control which works very well by the way. Last time I had this toppling over and loosing roots the biological control completely cured all of them probably 15 in total and put rest on all the other plants to use up. I feared it would spread and know the Beetles lay eggs in late summer early autumn hatching to larva. It possible the tears to edges of leaf are the Beetles as well as the larva being destructive is another thought?

As you can see I am nearly there in my thought but I bet some of you would correct me with my wrong misunderstandings. I only scored 60% in my P&D exam many years ago. Enough for a pass but sadly lacking, Oh bother! I will try to look on forums and help people out eventually when I feel I know all the bits and bobs. Thanks again!

David.

[Maggi Young]

Photos of leaf damage are always useful because it is possible to tell a lot from a picture..... Can you show us some pictures of the damage?


Just because you are not finding caterpillars when you search for them on the foliage  does not mean that it is not these beasts which are causing the damage.... many are night-feeders, lurking in the soil or even underground during the day, emerging in the safety of night to munch the plants...

[iann]

Plenty of caterpillars munch at the edge of leaves.  Sawfly larvae have characteristic eating patterns but very quickly the whole leaf is gone so you don't always notice!  Slugs can certainly take chunks out of the middle or even just graze the surface, they have surprisingly sensitive mouthparts.  Also think about the various leaf cutter insects that tend to take clean shapes out of the edges of leaves.  Thrips, leaf miners, and mites make damage that is usually easy to spot.

I wish there was an obvious way to distinguish between bacterial and fungal leaf markings  Viruses too!

I'm going to guess that your Sedum parting from the roots is simple overwatering followed by root loss or stem rot.  Pests are always a possibility but hard to be sure until you see one.

[newstart]

Here are the photo's of the pests I have. I have removed most unfortunately. The difficult one which I think is the bacterium digesting the leaf till paper thin, the photo which looks like it has no damage until you look nearer the leaf tip. I have removed the rest of the damage on this unfortunately. I think caterpillars make a completely round circular hole. Thanks again everyone !

David. Alpine learner in progress!

[Maggi Young]

David, as  has already been said... there are numerous ways in which different caterpillars munch at leaves.... I'm not sure where you got this idea that they only eat neat holes?!

It looks to me as if all sorts of different pests are chewing at your plants.... and I would suggest that the damage is being doner by chewing pests, not disease, bacterial or otherwise. 

[David Pilling]

Stating the obvious, caterpillars are usually on the back of leaves, hard to see little green things, which drop off with slight disturbance. They move around, so you may have to look at several leaves with holes in, or follow the droppings (black particles) before you find them.

(I appreciate that caterpillars come in all shapes and sizes, used to be big furry ones when I was a lad)

[Maggi Young]

I appreciate that caterpillars come in all shapes and sizes, used to be big furry ones when I was a lad

Well, those are the most fun, David P, aren't they? 
 Problem is that even the miniscule ones, barely 2 or 3 mm long, seem to have appetities every bit as voracious as their larger cousins and are harder to find 

[newstart]

Don't worry Maggie its just something taught at college that the hole a caterpillar is a neat round hole normally. Education is very weak with horticultural living subjects as plants are full of surprises and experience is far more useful and accurate. I do listen very carefully to what people say.

I will look up what to do about the bacterium. Will most pest killers kill thrips and leaf miner too? Mites are normally covered with most pest killers I think?

Thanks that should do then. David.

[newstart]

Hi I found a vine weevil this morning. I turned the pot upside down gently removed the pot with the rootball in tact and still shapely. Sitting on edge or side was a vine weevil about 5mm in size. They probably find it easier to get up the sides of the pot and then burrow over to the neck of the plant where it joins the root. Some are quite small I had the same problem last year. They always seem to take a fancy to my SEDUMS not anything else. I find the best cure is the biological nematodes I never have any problems after I have used it.

David.