Possible fungus?

[AaronJ]

I have what I think might be some type of fungus (or something else) on some of my Nep leaves.

It ONLY effects the oldest leaves on the plant that have no pitcher anymore. It is also ONLY on a few plants and does not appear to be impacting on new growth.

At first I passed it off as simply the leaves dying but it seems a bit different to when they usually brown off.

Even if it is harmless it is unsightly so any thoughts as to what it might be and if there is anything to combat it?

N. truncata x ventricosa (top and bottom of leaf) - worst effected)

N. (tobaica x ovata) x (bellii x veitchii)

N. merilliana

N. sanguinea

Aaron.

 

[Seandew]

Looks reminiscent of a virus. Let's hope for your sake it isn't. I'm probably completely wrong as my experience with Neps is pretty much non-existent.

 

[Joachim Danz]

Hi Aaron,

it looks like something has bitten into the leafes and fungus has entered through these wounds. Have you tried a systematic fungizide?

Good luck!

Joachim

 

[rlhirst]

Yeah, I have similar spots on some of my plants. I would really like to know what it is too. I have heard that it is due to cold temps, but I'm not sure about that. I'll look into system fungicides as well.

 

[AaronJ]

@ Joachim,
I've tried no treatments as yet as up until the last few days I had taken it to simply be part of the process when a leaf is dying off.

As for the bitting, I have no idea what would have  I've not see ANY bug or pest in the glasshouse other than the odd slug or snail and my resident colonies of ants.  99% sure none of them are the culprit.  Certainly no small bugs like mites, thrips, aphids, scale, etc, etc.

I also have some plants that have sustained small amounts of leaf damage through transportation and it seems not to have appeared at those sites.

A while back Hamish mentioned a few locally available systemic fungicides, so I might give one of those a try unless someone here is able to give a more accurate idea of what this might be.

@ rlhirst,
I've actually seen it on plants in quite a few people collections.  I'm sure it's nothing overly sinister and am hoping it's just some type of fungus that has that inpact on older/weaker leaves.

I would say that cold temps are an issue for me so that could be rulled out. Minimum night temp is about 13C with the average being closer to 15C.

Anyone else got an idea?

Aaron.

 

[BobZ]

It does look like a leaf spot fungus or virus. It appears that it is affecting only the older leaves.

Here is what I found on a cached version of
www.malesiana.tropicals.com.my/cultiv-nep.html

Quote[/b] ]Leaf-spot fungus, which is a common problem in some species especially when grown in bright sunlight, can be effectively treated with thiophanate-methyl.

 

[Tony Paroubek]

Well if the spots continue to get larger then it would be some sort of pathogen. Also the reddish area surrounding the necrotic area speaks pathogen. My guess would be fungus. Bacterial pathogens usually move very fast and cause a clear liquidy look and often ooze.

I would not say it's just affecting the older leaves. The N. merrilliana and N. truncata x ventricosa are showing it on all but the newest leaf. It's not as bad on them because it is a slow progressing pathogen, but they are already infected.

Tony

 

[AaronJ]

@BobZ,
Thanks for that link.  Certainly my setup does recieve hight light.

@Tony,
In your experience, have you actually seen this before or have any suggestions? My hope was that this was something not overly unusualy that other may have experienced.

Aaron.

 

[SydneyNeps]

Aaron, I also believe it is a fungus. As I've said before, labs tests I've had done on my collection by the Botanic Gardens have found colletotrichum, cercospora and mycosphaerella fungus as common Nepenthes pathogens. There are a couple of other types that have been identified in lab work on other collections.

I think I've also mentioned that thiophanata methyl is the best treatment for leaf fungal attacks. But there are several things to note. It's not a "one-treatment" fix - there needs to be three or four treatments at set intervals, as most fungicides kill only the fungus and not the spores, so after one treatment, the existing spores start to grow.

With thiophanata methyl, it is in a class of fungicides which has shown resistance patterns in field tests. If you use it continuously, you will end up with resistant strains. You need to alternate it with a different family of fungicide, or use a mixed fungicide (where several families are in one mixture). Zyban is one I know of. It is not cheap though.

The other thing with fungicides is there will be side effects. You'll get a bit of deformed new growth for a couple of leaves, or thickened growth. Nothing serious. However, some species can be touchy with some fungicides. I had a nasty experience with Bayleton on highland truncata.

Hamish

 

[AaronJ]

Thanks Hamish,

I just went through my old email to look for the ones where you made the above suggestions, so thanks again.

Having some trouble locating a source for Zyban. Do you know of one?

Aaron.

 

[Tony Paroubek]

Hamish pretty much as it all spelled out. Your probably going to need to find a place that deals in products for commercial growers. The ones Hamish listed are not garden center products. Maybe contact one of the commercial nurseries too and see if they can help.

T

 

[AaronJ]

Thanks Tony and Hamish.

Wheels are already in motion to get some Zyban.

Aaron.

 

[Borneo]

Aaron,

Egad! How do the undersides of the leaves look, especially on the N. merrilliana? Are there any brown blisters, sort of like raised to the touch, or do the undersides show similar damage characteristics to the upper surface?

Do be careful not to touch these plants and then touch any others in your collection without washing your hands. Also suggest you make sure that if you water from above that water doesn't splash from one plant to another.

 

[AaronJ]

Rob,

I feel like I must be missing something but what's "Egad!"?

The first two photos on page 1 show the upper and under side of the N. truncata x ventricosa. Is that the blistering you are referring to and does it mean something to you? I'll have to check under the Merrilliana tonight. I've admittedly not looked in my attempts to not ouch these plants!

It 'looks' like the upper surface is slightly concave while the under does look somewhat blister-like or raised.

No worries on the watering as I only top water using a watering can and not on the leaves (direct on to the soil/moss surface only). Plus I am only watering about 1x per week right now as it's not too warm yet.

I'll be careful with the hands too.

Aaron.

 

[AaronJ]

Just adding a thought….

Chicken or the egg?

Upon thinking about this pathogen some more, these effected plants are plants that have not gown as vigorously as I would have expected given their parentage or compared to other samples of the same plant.  The N. merrilliana maybe as it’s a new plant and I’m not catering to pure lowland conditions, but the others definitely.

So, could this be a case that, for some reason, these plants are stressed to a degree that has allowed an already present pathogen to gain a foothold?

Or, could it be that this pathogen already had a foothold and subsequently effected the vigour and health of these plants?

My gut feeling would be that the latter is more likely to be the case given that most of these plants SHOULD have been pretty well set in my intermediate conditions.

Aaron.

 

[rlhirst]

Thanks for all your answers guys. Aaron thanks for posting the pics for proper identification. I have overlooked this as regular aging of some leaves..

 That explaines a few things..I have some Zyban on the way too

 

[Borneo]

Aaron, Ha! Sorry, "Egad" is an ancient English expression of amazement or dismay. We sometimes use it around the office for some reason and forget that it probably dropped out of common useage centuries ago!

Was wondering about the N. merrilliana as some of the pathogens mentioned earlier by hamish produce smaller red spots than this and pronounced raised blisters under the leaves on leathery leaved species such as N. merrilliana, N. sibuyanensis etc.

Have to say, I've not seen fungal damage quite like that before. My first thought was chemical damage but unless you've used any chemicals on the plants recently that can't be so. Guess the Zyban will help.

 

[Tony Paroubek]

I still say Egad

  Rob and I can retire to the old fuddy duddy farm together..

Could be a combination of things.  Looks like some pathogen on some.  The sunken irregular look to some of the blotches is odd and could be caused by other factors such as cold water spotting or sunburn from water on the leaf.  The water acts as a magnifying glass and you get funny burns that look odd compared to burning when a leaf is dry.  But they could also be caused by a pathogen too.  Which is why I asked if they continued to get larger.  Burning or some sort of mechanical damage would not progress beyond what was damaged initially.

Tony

 

[AaronJ]

Rob,

Thanks for the English lesson

I’ll have a look at the underside of the N. merrilliana tonight.

My very first thought was that is looked like chemical burning, but I use no chemicals what so ever in the glasshouse and I can't think of anything that could have got in inadvertently.  We have been using White Oil and Pyrethrum based sprays on plants (roses and fruit trees) outside the glasshouse though this spring, but I always make sure all vents are closed first so I can’t see how this could be a source.

Not much I can do I suspect until I get hold of this fungicide and see how that goes.

I know the brand names vary internationally, but I have also been recommended a cheaper alternative to Zyban called Fongarid.  Anyone know of this?

Quote[/b] ] Garden King Fongarid Systemic Fungicide

Fongarid controls damping off, and root rots caused by soil-borne fungal diseases. It is only registered for ornamental plants, and so should not be used on fruit and vegetable crops. Fongarid can give approximately 6 to 10 weeks protection from soil-borne disease attack, depending on rate applied, soil type and cultural practice.

Pack Size: 10g ( 5 x 2g sachets)

Active Constituent: 250g/kg Furalaxyl

How To Apply: Mix 2g of powder with 2 litres of water, and apply to soil or potting mix at the rate recommended on the label. It is important to water in thoroughly. Consult the pack for full details.

Thanks for everyone's input thus far.

Aaron.

 

[Tony Paroubek]

Furalaxyl is in the same class of fungicides as Subdue 2e (metalaxyl). These fungicides are specific for damp off and pythium and phytophthora root rots. Unless the person recommending it has personal experience with it controlling leaf spot and other leaf/stem pathogens, particularly the ones Hamish listed, I would not recommend it.

Tony