Tebuconazole and Trifloxystrobin: safe for very small cacti seedlings?

[T.bridgesii]

Hello,

First time cactus seed grower here.

I have a large number (around 150) of approximately three to four week old Lophophora seedlings growing in pots in a propagator. I noticed a few instances of orangey-yellow looking fungus about a week ago (only tiny spots), and managed to stop that by applying a dusting of sulphur to the affected ones, and increasing ventilation/reducing the humidity. Most of the affected plants seem OK now.

However, today, I found one seedling that had previously had a spot of the fungus (but that I thought had recovered) totally shrivelled up into a small pile of green goo. I had another seedling spontaneously do the same thing earlier on, so I want to be proactive and stop whatever it is from spreading to others.

I’m nervous about using too much sulphur, because I know that Lophophora don’t like acidic conditions.

I’d like to spray all my pots with fungicide as a precaution. I have a systemic fungicide containing Tebuconazole and Trifloxystrobin. Would this be safe to use on very young cacti seedlings? I just don’t want to burn them or otherwise harm them.

Thanks in advance for your help!

[T.bridgesii]

If nobody knows about this specific fungicide, can you recommend one to use on seeds/seedlings that is effective and available in the UK?

What about hydrogen peroxide? Does that actually kill fungus? What’s the optimum percentage to use?

I wanted to treat the soil with a fungicide when I sowed my seeds, but I figured sulphur was out due to the acidity, and I read that a lot of other fungicides actually inhibit germination. I couldn’t find enough information to make any sense of it all. The few things people were recommending on forums are not available here as far as I can tell.

[hiawog]

I have used a product that contains Tebuconazole to control fungus in seed pots and found it quite effective. I have had very high (near 100% with good seed) germination rates when using it so I know it isn't harming that. I've sprayed it on seedlings before and not seen any downsides. I always follow concentration guidelines carefully.

I have zero experience with Trifloxystrobin.

[T.bridgesii]

I have used a product that contains Tebuconazole to control fungus in seed pots and found it quite effective.
I have zero experience with Trifloxystrobin.

Thank you so much for that!

What I have is a product with both ingredients (this stuff: https://www.amazon.co.uk/Provanto-86600 ... 787&sr=8-1), but I think I’ll probably try treating just one of the pots and then waiting a couple days to make sure all is well. The situation isn’t seriously urgent yet, but I have lost a couple of my seedlings, so I want to do something before it gets any worse.

I’ll be doing a few things differently for the next batch of seeds for sure. It’s been a good learning experience so far.

[Steve-0]

Here's what I found while looking for a specific fungicide brand name Revus.

From Hanazono: I wash Astrophytum seeds after collection with running water.
I also wash seeds with running water by myself when I bought seeds from someone.

I do not sterilize potting mix but I use a fungicide.
- Spraying fungicide over potting mix top before sowing seeds
- Spraying fungicide again over potting mix top after sown seeds
- Do not use fungicide after starting germination

I have never experience fungi problem since I started to use this process.

My various seedlings have gone through some tough times. First time growing, and I chose a challenger species of Sclerocactus.

I will use fungicide in the next batch following Hana's technique.

[greenknight]

Sulfur is only a preventative, treating seedlings with it that were already infected was useless. Some of the newer fungicides do have some ability to cure a fungus infection if it's recently started, but it's best to use any of them before infection takes place.

[T.bridgesii]

Here's what I found while looking for a specific fungicide brand name Revus.

From Hanazono: I wash Astrophytum seeds after collection with running water.
I also wash seeds with running water by myself when I bought seeds from someone.

I do not sterilize potting mix but I use a fungicide.
- Spraying fungicide over potting mix top before sowing seeds
- Spraying fungicide again over potting mix top after sown seeds
- Do not use fungicide after starting germination

I have never experience fungi problem since I started to use this process.

My various seedlings have gone through some tough times. First time growing, and I chose a challenger species of Sclerocactus.

I will use fungicide in the next batch following Hana's technique.

Great, thanks for the information! I have been rinsing my seeds in 3% hydrogen peroxide, but I don’t know if that helps or not.

If this is the right product (link below), it seems to be available on eBay UK. Bit pricy, but that probably would be a lifetime supply of the stuff for me, so I’ll give it a try!

https://www.ebay.co.uk/itm/284190775405 ... 4jEALw_wcB

[T.bridgesii]

Sulfur is only a preventative, treating seedlings with it that were already infected was useless. Some of the newer fungicides do have some ability to cure a fungus infection if it's recently started, but it's best to use any of them before infection takes place.

Oh, OK, that’s really good to know! I guess in that case the improvement was mostly down to getting more ventilation happening and letting the soil dry out more between waterings.

I’m not sure how dry I can let it get/for how long before the seedlings will suffer or die, so I am being very careful. (I know they are cacti, but my understanding is that they’re pretty vulnerable to drought at this early stage...what that means in real terms, i.e. how many hours or days they can remain dry, I have no idea.)

[greenknight]

Bottom watering helps, just a very shallow layer of water in the tray the pot's sitting in. Wicking up water from below, the mix will never get more than just damp, and the surface stays dryer than when you water from above. This also encourages deep rooting. When fighting a fungus problem, let the surface dry slightly before adding water to the tray.

[vitt13]

If this is the right product (link below), it seems to be available on eBay UK. Bit pricy, but that probably would be a lifetime supply of the stuff for me, so I’ll give it a try!

https://www.ebay.co.uk/itm/284190775405 ... 4jEALw_wcB

Probably that what you may try to use. I used Revus(tm) with mandipropamid as active ingredient to treat asterias seedlings https://www.cactiguide.com/forum/viewto ... 55#p378351
I've googled this

81YkyiU6-cL.jpg (126.33 KiB) Viewed 2607 times

[Steve-0]

On my first batch of Sclero seeds I followed steps outlined in this video.

https://www.youtube.com/watch?v=MGG2-YpGDWA&t=84s

Prep for seeds is 50/50 bleach and water soak for 20 mins then a thorough water rinse.


I thought that strong of bleach mix would kill them. Nope...it worked.

Those not pretreated did not germinate = zero percent in a month.

I did pour boiling water on my soil mix and of course let it cool before sewing seeds.

The pretreated germinated in a week or so. But I didn't have any fungicide on hand then and Scleros drop dead for any number of reasons.

Next batch get the Hanazono treatment!

[T.bridgesii]

Bottom watering helps, just a very shallow layer of water in the tray the pot's sitting in. Wicking up water from below, the mix will never get more than just damp, and the surface stays dryer than when you water from above. This also encourages deep rooting. When fighting a fungus problem, let the surface dry slightly before adding water to the tray.

Yeah, I’ll definitely do that next time. My pots are too deep really (my first mistake), so bottom watering seems like it would mean having to have quite a large volume of water in there before it reaches the roots. I am thinking that having all that soil damp throughout and a little bit of water sitting in the tray (causing very high humidity) was what originally started the fungus problem.

I will probably try it again when they get a little bigger.

Next time I plan to use shallow trays instead of pots and bottom water from the beginning. For now, I’m just adding small amounts of water near the seedlings, and avoiding getting them wet above the surface as much as possible.

[T.bridgesii]

On my first batch of Sclero seeds I followed steps outlined in this video.

https://www.youtube.com/watch?v=MGG2-YpGDWA&t=84s

Prep for seeds is 50/50 bleach and water soak for 20 mins then a thorough water rinse.


I thought that strong of bleach mix would kill them. Nope...it worked.

Those not pretreated did not germinate = zero percent in a month.

I did pour boiling water on my soil mix and of course let it cool before sewing seeds.

The pretreated germinated in a week or so. But I didn't have any fungicide on hand then and Scleros drop dead for any number of reasons.

Next batch get the Hanazono treatment!

Interesting! I did wash my seeds with peroxide and sterilised all the pots with bleach. I don’t *think* I had problems with germination. My seeds are all different varieties from a few different sources. Some varieties germinated 100%, and a couple had awful germination (only one came up out of 14 seeds for one variety). Am thinking that’s more down to those seeds themselves possibly being old or something rather than anything I did, since some others in the same environment had a 100% germination rate.

[T.bridgesii]

fungicide brand name Revus.

Well, when I looked more closely, I saw that the listing I found on eBay has a postage cost of over £25. Seems to be a “professional” product, so not at all easy to source, which is annoying. I think I’ll stick to using what I’ve got for now and hope for the best.

[Steve-0]

fungicide brand name Revus.

Well, when I looked more closely, I saw that the listing I found on eBay has a postage cost of over £25. Seems to be a “professional” product, so not at all easy to source, which is annoying. I think I’ll stick to using what I’ve got for now and hope for the best.

Same here...too spendy. I found some other stuff online...only $1025.00 USD for a gallon

I'll be getting 2 gallons just to be sure I don't run out soon.....said no one ever.

Something way more affordable and locally sourced is for me.