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Seedlings in danger

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Seedlings in danger

Post by Meryl on 1st January 2011, 17:05

At present, I have four seedlings between about 5 and 9 cms tall, three from Purple Simplicity and one sole survivor from a batch from Rhapsody in Blue (yes, I'm another tragic for purple). They are each in seedling pots. The 3 PSs all have minuscule long thin buds, so I guess they are probably singles and repeaters. The RinB is a bit smaller and yet to bud. For the life of me, I cannot find a place around my suburban house, with a river in front and a cliff behind, which sunny enough for the seedlings yet protected from wind. As a result, they are being damaged at the base of the stem and I fear I will lose them.

If I tuck straw around them, I'm afraid they will be attacked by fungal disease (it is extremely humid here at present). Should I try to tie these tiny things to a minuscule stake? Or what? Advice would be very welcome.

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Re: Seedlings in danger

Post by Guest on 1st January 2011, 19:35

Howdy meryl

All my young seedlings are staked at this stage with sate sticks ( the ones you buy in coles around 1 ft long and in plastic packets) and tied with kitchen string. I did this to 450 seedlings in an area with pretty strong wind in spring and find this does the job. Also I found mulching with straw is quite benificial , as it keeps the soil cool which they like, but do not place up against the young stems as the bark is quite tender and you may get stem rot, keep it out to about 3 " and every thing will be honky dory,

Also give them a weekly feed of Aquasol , but do follow the intructions on the packet , you will see them power away


cheers warren

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Re: Seedlings in danger

Post by Meryl on 2nd January 2011, 12:06

Having now staked 4, and been all thumbs, I am gobsmacked thinking what the task must have been to do 450. I hope I have been in time with mine. Can't mulch as they are still in 6 cm (?) pots but I have been giving them Aquasol at intervals. Thank you very much indeed, Warren.

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Re: Seedlings in danger

Post by The Lazy Rosarian on 2nd January 2011, 13:38

Meryl, Meryl, what can I say, you can't mulch. I assume you might have slugs or snails, if so why not snail bait. shredded paper will help also, Happy new year to you both.
Old age thinks of things after posting, could you place small amount of sawdust at the edge of pot.
Another old age thing, is the damage from bugs or wind.
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Re: Seedlings in danger

Post by Admin on 2nd January 2011, 15:15

The skewer thing is what I use as well and when they form a bud I snip it off to encourage branching. People have also found that a little wind movement is good for the plant and encourages it to form stronger stems (more lignfied) and roots.


Last edited by Simon on 27th August 2011, 16:39; edited 1 time in total

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Re: Seedlings in danger

Post by IanM on 27th August 2011, 15:42

Spray with Yates Rose Shield, and do so often. I drown my seedlings in it every couple of weeks. Only way to be sure to ward off the pesky fungus and insect diseases that are always present and always "out to get" your vulnerable seedlings. Just because I'm paranoid does not mean they're not still out to get to me! Very Happy
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Re: Seedlings in danger

Post by Admin on 27th August 2011, 17:13

Bringing up this old thread is timely as seedlings are again starting to germinate everywhere. The number one priority, and the ultimate goal of growing rose seedlings, should be to make roses that are healthy as healthy roses don't require spraying against fungal diseases. Ones that get fungal diseases in your climate should be culled early and only the clean ones kept. If they get fungus in your area it is a clear indication that there are probably better, more appropriate, roses for you to grow in your area. You can do a few things to minimise the effects of fungus on your seeds:

1. A trick learnt from Paul Barden, who learnt it from Mr Moore, was to cover your seeds with perlite on sowing them. They found, and I can verify this as I have used it for years now and have not sprayed my seedlings against damping off in years, that it seems to prevent damping off. They have no trouble pushing their way up through the perllite and can grow quite nicely without the need for prophylactic spraying against damping off. The perlite also acts as a mulch and helps to prevent drying out.

2. Water your seedlings in the morning thoroughly. Mildew hates this. Mildew is an issue during dry times when the nights are cool and the days are warm. Disrupt this and you disrupt the mildew. You can effectively control mildew this way to allow your seedlings to build up their own resistances against it. Mildew can also be a symptom of water stress so ensuring your seedlings don't fully dry out will assist in its control. Some seedlings grow out of mildew issues and make fine garden plants but ones that start out clean usually stay clean and pass on this trait to their offspring. Breeders have found that mildew resistance is probably a dominant trait so it's worth selecting for. Cull, cull, cull.

3. If they get blackspot as seedlings this won't change as they age. Cull, cull, cull.

4. Downy mildew is a real problem! It occurs when the temperatures are mild and conditions are humid... cool rainy weather can bring it on in a flash and very few roses have any natural resistance against it. It looks like scorch marks on the leaves and can suddenly appear and kill a plant in a very short space of time. Downy mildew hates high temperatures. One way to combat it is to place the seedlings into a small glasshouse where the temperatures are too high for it to thrive. This is the only fungal issue that I wil spray my seedlings for and my weapon of choice is Fongarid. I don't protect my breeding plants against it. It works wonderfully on roses to bring downy mildew under control. I'm changng my thinking about this as time goes on too as some of my roses were unaffected by downy last season (a record bad year for downy for me) and some of these are also resistant aganst blackspot, mildew and rust. Seems you can have resistance to downy mildew and so letting nature take its course on this front may also result in more resistant roses in the future.

It doesn't matter where we live... the goal should be the same... cull, cull, cull.

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Re: Seedlings in danger

Post by IanM on 27th August 2011, 22:43

Okay, so if I have 1 or a few germinants does this mean I should cull them rather than spray them?
I believe it is a myth that pests and diseases only attack the weakest plants. In my long experience with gardening, it is often the healthiest plants that are attacked first and this usually happens very fast (like overnight). A plant can be flourishing one day. Go out and look at it the next morning and it is covered in aphids. Many diseases in humans also attack the healthiest and fittest, not the weakest. Others don't appear to discriminate. Of course anything in a weakened state can be vulnerable to less discriminating pests and diseases. I would rather spray if I have only a few of something rather than risk losing them. Adult roses are able to withstand attack by fungus diseases, but seedlings are extremely vulnerable to those same diseases. Makes sense. They are smaller, closer to the ground, and have much softer tissues.
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Re: Seedlings in danger

Post by Admin on 28th August 2011, 00:03

Okay, so if I have 1 or a few germinants does this mean I should cull them rather than spray them?

Yes, that's exactly what I'm saying. I do it all the time. In my long experience in roses... I have grown many tens-of-thousands of rose seedlings... and the ones that start out clean without my help are very often the ones that stay clean for longer (because horizontal and vertical resistance can break down over time... it's an arms race), and pass these features on to future generations. It is also very clear that those that are clean for me may not be for someone somewhere else. I can assure you that the ones that are really clean number in the very low 10s and the ones that actually stay clean for extended periods of time is even smaller.

I am not talking about insect pests that don't discriminate...well I guess it could be argued that they do discriminate because they are looking for the choicest food too. I am talking about fungal infections which do discriminate against those plants that may not be weak, as such, but are not possesseed of the means to resist their attack. In certain environments where the fungal pressure is low they might be terrific. Rosa foetida is a classic example. In the right place it is a fantastic garden plant. Tasmania is not one of them. I know they do discriminate against individuals because in a batch of seedlings you can have 95% develop mildew and in the same tray from the same cross you might have 5% that don't when given the same treatment. I also know that when these 5% are used in breeding the percentages increase in favour of resistant individuals. Sure, some develop resistance as they mature but some have it right from the start too.

Kordes has been doing this for years and you can do a lot worse, today, than grow some of the modern Kordes roses because they switched to a survival of the fittest regime in selecting their breeding stock a long time ago. Ping Lim, an acquaintance of mine and breeder for Baileys in the U.S., would actively seek out different strains of blackspot and deliberately infect his seedlings to weed out the less resistant ones to try and develop varieties with 'broad spectrum' resistance. In the end, however, all we can hope for is a rose that is healthy where we live at this point in time.

The actual means of resistance is not fully understood and is believed to be a combination of both structural adaptations and genetic resistance. Dr David Zlesak once told me he believed black spot resistance, for instance, was a qualitative dominant trait and so could be inherited. It has also been said that the waxy cuticle plays a part in warding off fungal infections. Others have also mentioned that they believed mildew resistance is a qualitative dominant trait. Given that this adivce comes from people who are far more experienced and knowledgeable than I am, yes, I am willing to cull even small numbers of seedlings that show incidence of disease at any stage of development when right next to it I might have some that don't. I am of the opinion that it is more multigenic than this, but the principles are essentially the same. Individuals are only as valuable as the worth they have in the breeding program. If they will impart susceptibility to future generations then yes, they should be culled regardless of the importance we place on them.

All I am saying is that there are other ways to give your seedlings a fighting chance against fungal issues to which you rightly state they are more susceptible to as babies. For me, it is also an ethical decision not to use chemicals. I don't believe there are many situations in which their use is justified and it comes back to what I value. You can make your own mind up where you sit with your own values. I have a degree in chemistry (inorganic and biochem) and love it... I believe it has its time and place. However, I also believe it has a negative impact on ecosystems, of which we are part, and I cannot be party to that for the sole purpose of having something aesthetically appealling in my garden, especially when I have a perfectly good model that mother nature has been using for eons right here at my disposal.

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Re: Seedlings in danger

Post by IanM on 28th August 2011, 11:26

Point taken. I spray for four reasons mainly:

1) After going to all the trouble of importing a dozen seeds and getting them through Quarantine, I am not going to cull a seedling just because I think it might "look weak". Some species naturally are "weak-looking".

2) In my experience damping off does not discriminate between healthy and weak. Once it starts in a tray it will keep spreading and take everything. This has nothing to do with seed health. It has more to do with soil hygiene and often just bad luck (e.g. wind blowing in some fungi spores). By using fungicides at time of sowing and at intervals after this you can at least help ensure seedlings remain in top health from the outset.

3) Quarantine is as much our responsibility as the Governments and we should not expect AQIS to "get it right" all of the time. Imported seed should always be treated as suspect. AQIS may have passed it, but that means nothing. They are only human and are bound to make mistakes every so often. Spraying with insecticides and fungicides during the sowing, germination, and seedling stages will help ensure that no microscopic nasties have "hitched a ride". I once discovered some rose wasp larvae developing inside some seed from the US. A couple had even hatched and I found the little blighters flying about on the ceiling. The seed had just been passed by AQIS! So I sprayed the live wasps, inspected the seed thoroughly, burnt any suspect ones, then soaked the remaining seed in a strong insecticide to make sure they were safe before sowing.

4) I rarely spray adult plants and if I do I try to use something organic. I am more vigilant with new plants though and these all go through my personal quarantine process before being placed with the general population. The first thing new plants get is a good dose of fungicide and insecticide. It also depends on where I obtain plants from. If I know a nursery is clean in their habits, I am not so concerned.

Well we could make this 5 reasons.

5) I am not a rose breeder, just a general hobbyist who likes to raise a few interesting things for the garden and to potentially share with others.

Generally I take a precautionary approach when raising seeds, rather than just leaving it to cruel old Mother Nature to sort out. It is what works best for me.
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