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Cimi

Seedlings getting eaten :(

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Do any of you guys ever have problems with seedlings getting nibbled by large bugs and then shrivelling up and dying? I have some seedlings sitting inside near a window which are about 3-4 months old, just starting to toughen up a little (uncovered, weekly bottom-waterings). (no fungus gnats or mold; soil completely dries out every week. There is noticeable salt buildup however, which I mist down about once a week)

I had 7 germinate, lost 4 very young, and then had 4 live until about 3 months. Since then, I noticed chew-marks in 3 seedlings on 3 separate occasions. A little cockroach-like thing had been hanging around. I thought I was keeping him out with a cake-cover put over the seedling tray but alas today my best seedling has had his round top chewed right off :( I hope he lives. It's possible as he is pretty big but all the others have perished after being nibbled. They just dry up and shrivel dead once their skin has been broken.

I just watered them so hopefully he will get some moisture and live through this! If he dies, this leaves only one seedling alive in the tray!

I gave up and got out the surface spray to keep roachy away. Sprayed a square around where the tray sits (none on the seedlings!)

I would like to know how you guys protect your seedlings from bugs while they are uncovered and hardening off but still quite young? Maybe I should use the plastic bag method and let them stay wetter for longer. But they have to come out into the air some time. So tell me cactus lovers, how do you prevent death by nibbling?

post-9438-0-72292300-1301966713_thumb.jp 3 musketeers (middle one has just been chewed and is starting to curl up)

post-9438-0-04799300-1301966832_thumb.jp This is the middle guy. You can see where he has been chewed down the centre.

post-9438-0-36206400-1301966975_thumb.jp Slowly shrivelling away

post-9438-0-31108800-1301967015_thumb.jp And this is how the left-most one looks today! round head completely eaten away :( He probably won't survive this

post-9438-0-89326500-1301967090_thumb.jp Finally the last uneaten one left (right-hand seedling in the first photo). This one is recovering from some earlier sun damage.

post-9438-0-72292300-1301966713_thumb.jpg

post-9438-0-04799300-1301966832_thumb.jpg

post-9438-0-36206400-1301966975_thumb.jpg

post-9438-0-31108800-1301967015_thumb.jpg

post-9438-0-89326500-1301967090_thumb.jpg

post-9438-0-72292300-1301966713_thumb.jpg

post-9438-0-04799300-1301966832_thumb.jpg

post-9438-0-36206400-1301966975_thumb.jpg

post-9438-0-31108800-1301967015_thumb.jpg

post-9438-0-89326500-1301967090_thumb.jpg

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I had a cricket do the same to mine bit a chunk out of a tiny achuma seedling and it died, the main bug problem i have with cacti seeds especially in humidity dome is gnats & I get em with pyretheum spray, but they always reappear, so i diligently spray weekly...

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What are/were the seedlings ? I think i can see a bit of fungus on the very tip of the seedling of image number 2 ?

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Etoliated Lophs I reckon. I don't think that's fungus, but rather the wool/spines that baby Lophs have.

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Good to know. I didnt think that wool/spines would be present at such an early stage.

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Late last year I lost about 500-600 seedlings to slugsmad.gif pretty much wiped out a couple of big trays worth, I'm just glad I sowed a couple of thousand seeds this season, power in numbers.

Might be worth building a little greenhouse to slow the little critters up a bit or like you mentioned leave them in a plastic bag as long as you can, I've heard of growers leaving them for well over a year in plastic though I've not tried it myself they swear by it.

peace

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yep i keep my seedlings in sealed takeaway containers for a year roughly, by then they tend to have a higher chance of surviving. Which also leaves fuckloads of work transplanting them.

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.

Edited by spacemonk

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Thanks. Hopefully the surface spray will work for now. I will also try to give them a little more light as new seedlings in the future to minimise etoliation. One day I will have a greenhouse, that will be the best. Cheers guys.

Edit: sealed takeaway containers might be the go as well.

Edited by Cimi

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By the look of that first pic I would say rodents/mice/rats etc. Set up a trap and wait.

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Cockroach thing you say, may be roly-poly bugs or woodlice

They usually eat decomposing plants & mulch but they will eat young seedlings, you could try putting seedlings in the middle of a tray with a few cm of water in it (a type of moat) or some sticky paper like they use for roaches

woodlouse.jpg

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I've actually caught out a cockroach munching on one of my cacti before. I think it was a Loph, can't quit remember. It was a while ago.

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There is noticeable salt buildup however

what is curious is why they are being eaten, and why they are not recovering

I would suggest trying a sealed container, baggies are nice because thin plastic can still be penetrated by gasses so you have some passive air exchange

how large are these seedlings after 3 months?

How thick are they getting in the same amount of time?

The ones in the photographs seem to be getting less light than they should

you mentioned sun damage, what light intensity is there?

What are you calling damage? is it pigment?

pigment is not damage and healthy seedlings can show stress pigment and still grow very well

true damage results in scars and dead tissue

goodluck! skill is the result of refinement of technique over time, this can only happen to those who make and correct mistakes

this is certainly a learning experience that has the capacity to help you be an excellent cactus care giver

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I think the real issue here, is that your kitchen has no scraps of food to feed the cockroaches. So, get to work. Old pizza boxes, expired food. It's all good - leave it everywhere, and I guarantee that your seedlings will get the reprieve they need.

But seriously. I use a humidity container, with the slots opened to allow airflow. This gives protection from the bugs (of which, there are many). Also, <unsupported_opinion> I think that the type of fertilizer, or the soil pH has an effect on the palatability. I've only got one plant so far to base this on (soil would've been quite high pH, blood and bone and 4:8:6 potato fertilizer were the main ferts), but the eating was marked. Once I have enough plants to sacrifice - I'll try some more variations. </unsupported_opinion>

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Yeah mac, the roach thing looked more like that - not as flat as the cockroaches I see in google images for "cockroach". That segmented look. Water moats and sticky paper are great ideas!

By the way - somehow the latest one to be eaten is still alive. Hasn't shrivelled like the others. He was the biggest so maybe a bit tougher.

Thanks tripsis - I guess that means they do like lophs! Archaea - they are like 1.5 cm tall and very thin. The stems are about 1-2 mm thick. The sun damage was actually just pigment which was pale green-white, then orange, red, then purple now fading back to blue-green. It started at about 2 months in. Initially, I had them germinate in a propogation tray with a clear plastic lid beside a frosted window. I placed a tea towel over the plastic lid to reduce the chance of sunburn. I began removing it for short periods to ease the seedlings gradually into light after 1.5 months. That was when the sunburn happened so I guess the others got deprived of light because I was giving the whole tray the same dim conditions when different seedlings had different needs. I did lose a few seedlings to sunburn in those days. Maybe they were more sensitive to it because they were covered up too much initially. There was a fine line between too much and not enough light. I've had 1-2 month old lophs die early from sunburn in just indirect light through frosted glass windows on overcast days.

As for light now, they are on a pretty bright windowsill (still frosted glass, but uncovered). Should I give them sun outside yet or not?

Another factor which I now know is that the mix in the propogation tray was way too coarse - big bits of bark from the potting mix (I didn't sift it). I used 1/3 perlite, 1/3 propogation sand from Bunnings, and 1.3 commercial cacti potting mix (Debco from Bunnings). http://www.gardenexpress.com.au/debco-cacti-succulent-mix/ I will sift in future!

Hmm interesting topic - are alkaline cacti more tasty to the bugs? Greedy buggers...

Thanks for your encouragement. Hopefully the left one will live and we will have 2 alive in the tray long term He isn't giving up as easily as the others.

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I would hold off on giving them direct sun

I've had 1-2 month old lophs die early from sunburn in just indirect light through frosted glass windows on overcast days.

How hot was it?

I've seen lophs germinate and grow in part sun (5-6 hours direct sun per day) and grow fine, but i have seen plants started in darker conditions burn when given just a couple hours of sun... tricky.

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I would hold off on giving them direct sun

How hot was it?

I've seen lophs germinate and grow in part sun (5-6 hours direct sun per day) and grow fine, but i have seen plants started in darker conditions burn when given just a couple hours of sun... tricky.

 

Yeah? Well I guess that proves that you can sensitise seedlings to sun stress by starting them too dark. Cheers for that. This means I will just need to keep up the gradual exposure to light for these two but I might give future batches more light from the start.

There must be some kind of mechanism which determines their light sensitivity really early on, like upon germination. I'll see what happens with my next batch.

Edit: It's possible I left them on the heat mat too long trying to induce the rest to germinate, so it may have been a heat problem. Can heat cause greater light sensitivity, or even 'sunburn' in itself?

Edited by Cimi

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in my experience the heat can be a killer, it can make moisture evaporate faster than the plant can take it up

this is less of a problem with plants in a humid environment, but is still an issue with young plants, which can be sensitive

often seedlings in nature grow in the shelter and shade of another plant, typically called a nurse plant

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extreme heat, free draining soil and clay pot in combo can be a disaster IMO. Even mature plants will suffer [lopho and other slowgrowers] even though they will not die, and I am talking about mature flowering plants now, if the heat and sun is hot enough, so go figure about seedlings which generally like it wetter.

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