Gerbera Garvinea

We are getting closer and closer to releasing our first Gerbera Garvinea. This pic is a trial planter we are preparing for retail nursery displays. No tricks, Lisa has put 9, 200mm pots in the box and taken a photo.

Garvinea is a very new Gerbera bred for outdoor growing. The emphasis is on overwintering. These plants will happily survive consistent night temperatures below zero. That's not to say they will continue to flower through winter although Kaye has grown on plants we trialled last year in her garden and she reports some flowers right through the year.

Gerberas are very drought tolerant plants, we grow our regular pot varieties under clear glass through the summer and they love it. Having grown our Garvineas outdoors through the spring and a very wet summer we have learnt that they really do need good drainage. We had a large block growing on a low bed which prevented them draining freely. Just as we thought we had them ready we started losing plants to a very ugly wilt. At first I just thought they were hungry and didn't check properly. Having had our fingers burnt we moved them to a better drained, still outdoor position and they have re-grown roots they lost very promptly. Tough as nails, just need to be kept clear of wet feet.

Garden Favourites in Summer

Happy New Year!



A couple of old favourites have bobbed up again this week. By chance Kerry proudly showed me a couple of Tomato plants I had taken home. I delivered these "spotty" plants and said I was keen to see if we could out grow the bacterial spec once the plants were in the ground. The Boss has done the rest very successfully and very simply. Cleaned off the infected foliage and top dressed around the plants with about a shovel per plant of Chook litter (litter, not raw poo). They are growing vigorously now, about 1m tall each. That's it! I'd prefer this wasn't an issue but I'm still getting questions about spots on Tomato leaves so it's nice to be able to say there is a practical solution.

The other favourite is

I was just wondering if you have any idea why I rarely ever get any female flowers on my pumpkins?  Is there a particular nutrient that produces female flowers?  I get plenty of male, but they're not that useful without the females!

Warmest regards

Sherilee

I checked with Dangerous Don who confirmed this is a common and inconsistent problem and recommended we just wait. I also checked back on my previous Newsletters and discovered I have written about it previously! Any way I had delayed answering Sherilee about a week and by the time I had suggested "pruning" the Pumpkin tentacles, 6 female flowers had appeared of their own accord. My theory is Pumpkins and other Cucurbits wait for a check to their growth before deciding it's time to reproduce. That could be the weather getting hot or someone amputating a few limbs.

Best wishes for a safe, prosperous and Happy New Year.

Soft & Downey & Deadly to Impatiens

Hello Peter, Thanks for the information on upcoming seedlings. My query is this. For a few years now I have avoided growing Impatiens due to rotting when they seemed to be doing so well. Has this problem been eliminated or will I still be taking a risk trying again. I always had such pleasure over the summer months watching my colourful friends keeping "busy"

Looking forward to seeing my garden full of Busy Lizzies again, thank you from Kay.

What a timely question. Careful Peter, timely in time of year, not that we have seen any sign of the dreaded Impatiens Downey Mildew. In fact we are growing beautiful Impatiens this year.


So beautiful in fact we are treating this tray (Summer Berries and about 30 of her friends) as not up to our standards but that's just because she's too big to offer shelf life in a retail garden centre.

I have written about Impatiens Downey Mildew previously, so you can find lots of information here. Unfortunately I can't say the Downey Mildew has gone away or that we have found a miracle cure.  We are being careful not to bring any Impatiens plants into our nursery and we grow our seedlings very 'dry' which prevents the fungi spores germinating.

There was a research program done some years back (Wow 1996) on Downey Mildew in Brassica Vegetable seedlings, a closely related but different strain.  Both diseases have similar symptoms to each other but they are very specific to the host plant, they are not interchangable. The recommendation of this research was to NOT water our plants between 9.00 & 11.00am. This is the time when the spores are most active and the addition of water just provides a perfect environment for germination. I favour 'early' watering to ensure time for evaporation through the day. Water sitting on foliage over night is just bad news as it encourages any number of fungal & bacterial diseases.

Unfortunately the other critical cultural element is to remove any diseased plant material and ensure that Impatiens are not grown in the same space again at least for a season or two. This is of course the ancient crop rotation system. Sad really, I clearly recall cousin Fred Wood lamenting that Impatiens seedlings would last so long that they had ruined the autumn flower seedling sales season... perhaps there's a conspiracy! Anyway, if Kay hasn't grown Impatiens for a few years she is a good chance to make a fresh start so long as she chooses 'clean' seedlings. This applies to potted plants as well, If you find the disease don't fight it. Remove the infected stock and clean containers thoroughly with disinfectant.

Actually, the best advice I can offer is to grow New Guinea Impatiens.  The Impatiens Downey Mildew disease is so specific that it doesn't even effect this close relative of Impatiens wallerana.

Who Powdered my Pansies?

We have the most beautiful batch of Violas in 200mm pots.  Three separate colours including white and  Deep Marina.

Oh, yes they are this beautiful.
Except for one thing.... the foliage is full of powdery mildew.  Our sales people have been driven mad with desire.  They can see these beautiful plants but the production team won't let them be touched.

Powdery Mildew is not a fungal disease that we deal with all that regularly.  We often get plenty delivered to us on hanging baskets that we are sending to the flower & Garden show.  The fungus just loves the Autumn weather; cool nights, high humidity and still days.  The other factor that has affected our Violas is they were returned from the Flower & Garden Show display and cut back to re-grow.  Under normal circumstances this wouldn't be an issue but cutting the plants back stressed them enough to allow the Powdery Mildew fungus to attack.


That's a really nasty infestation of Powdery in Zinnia.  From my experience Powdery can really destroy a plant but usually it just hangs around making the plant miserable and it is very contagious if the conditions are right.

What to do?  First and foremost prevent infestation! Remove any infected plants.  Ensure hight light levels, yes that's right if possible get your plants out from under the shade.  There are very few plants that will need or like shade cover between now and December.  The other thing we do in the green houses is turn the fans on.  Quite simple, we have fans that stir the air around to prevent that close humid environment developing that fungi like.  The other thing I have seen (but never used myself) greenhouse growers use is Sulfur Burners, sulphur is very effective in controlling the Powdery fungi. I'm sure these are available for enthusiasts from Sage Horticulture, but they are of no value out of doors.


OK so sometimes we still get infected.  Commercially there are some very specific fungicides for controlling Powdery mildew, BayletonTM  comes to mind but I'm not aware of it being available on consumer packages. A Lime Sulphur  spray should be available from most good garden centres.  I have made the mistake of spraying Powdery with a general fungicide assuming that if it was effective on Botrytis (Grey mould) it would be effective on Powdery... wrong! So don't do that. I have found two interesting organic sprays: baking soda and milk.  The baking soda idea matches one sent to me this week by Marina who suggested this basic recipe to control aphids and sooty mould.  Marina's spray didn't include baking soda and she replaced the water with dish water, I think that might just frighten the Aphids away. Thank's Marina.

Last resort?  Dilute Quarternary Ammonia, some household disinfectants contain ammonia in this (quarternary) form.  It works, but it needs care not to burn the plants and you must use the quarternary form.  If the foliage is especially dense (think our Viola crop) it is very difficult to get the ammonia solution in contact with the fungus so we might have to cut them back again.... Oh I'm getting dizzy.

A Mould for all Seasons

Thank for the news and advice!
I have a fairly large Kaffir Lime in a tub, never had a problem over many years, suddenly developed BLACK MOULD in/on/under the leaves. Also ants LOVE it and run all over it.
It looks very healthy apart from this.
What to do?
Many thanks, Lena

I love this one because I can talk about Aphid poo and snigger like a school boy.

I'm pretty sure that Lena's Lime has Sooty Mould.

That's a pretty disastrous infestation on oranges.  Click here to see the original and get some detailed information on the source of the mould, Mealy Bugs.

This mould is quite common on Citrus, Gardenias, Crepe Myrtle, Azaleas and I remember Oleander from childhood. Fortunately for me it is not a common problem with annual flower or vegetable seedlings.  The interesting thing is that the mould fungi does not actually grow on the plant but in the sugary Honeydew secreted by sap sucking insects: Aphids, Mealy Bugs, Scale, White Fly, etc.  Honeydew?  That's the polite term for bug poo, hence my juvenile merriment.

Of course it's unsightly and it is a clear sign that something will have to be done about the sap suckers.  I have written about sap suckers previously, just follow this link if you want all the details.

The short and honey sweet version is spray with Confidor if you are happy with chemicals.  Very effective and apparently safe Confidor is a 'systemic' insecticide so it gets into the plants system and is sucked up by the insect.
Not into chemicals? White oil is very effective and drowns the bugs on the plant's surface.  I have always been a fan of Clensel, a soap formulation that knocks down insects.  Keep an eye out for Neem preparations, I don't know any brand names but have a look at this link if you are interested.

Oh, and the ants that Lena noticed?  I think that's nature managing the aphid population.

Enough for now.  Di wants me to look at Powdery Mildew next week.  Timely of course.

My Broccoli has gone all fuzzy and other Autumn stories

It's raining outside.  Tumbling town.  Not a thunder storm.  Not drizzle.  Quality, soaking rain!  Oh wow!

It is a blessing of course but the humid weather leading up to this cleansing has been somewhat trying.  I'm prepared to guess that from now on we are moving towards winter.  It reminds me of one important tip for Autumn growing.  Warm days and cool, still nights are shockers for fungal diseases on the foliage of plants.

I'm particularly thinking of powdery mildew, downy mildew and a miserable spotting caused by a fungi called Alternanthera. These are all quite different diseases caused by different fungi and if you choose to treat chemically will each require a different poison.  That's three separate treatments for one plant... Pansies and Violas are certainly susceptible to all three so I would prefer to avoid the diseases altogether.
    

Downy Mildew on Broccoli                 Alternaria Spots (Geranium?)  

 
 Powdery Mildew on Pansy

This is one situation where water restrictions have been thought through effectively because the easiest way to avoid these diseases is to water early in the day to make sure the foliage is not wet over night, especially those cool clear nights that will be frosty in a few months time.  Easy!  And seriously, no watering after 10.00am (yes I know Stage 3 restrictions dictate 6am-8am but you might have tanks or use grey water).

Enjoy your long weekend.  Get into the garden the ground is still warm.

Year 8 History, Medieval Crop Rotation

I haven't had much response to last week's request for suggestions on crop rotations except for Laurie who plans to grow his Toms in 500mm pots next season because his soil is infested with either Fusarium or Verticillium.  Follow the link if you want more detail on either of these diseases but for our purposes the symptoms are very similar.  Fusarium is more noticeable in warm conditions, Verticillium when it is cool. Both of these fungi enter the plant through the roots and damage the stem of the plant choking off supply of water and nutrient to the foliage causing wilting and eventually plant death.
        
Fusarium wilt symptom and a pic showing damage to the plant stem.
Picture from Plant Pathology on line
A common solution, in fact the ancient solution is to rotate crops.  That is, avoid growing Tomatoes (or Potatoes and possibly Capsicum & Chilli as they are all related) in the same soil year after year.  Laurie has been using a 3 year rotation for his Tomatoes but has found that even this is not enough... I still remember 3 field rotation systems from year 8 history.  'Barney' Rundle made a great deal of this fact, I have no idea why.   Any way the crop rotation idea is that the fungal spores will eventually die after a few seasons if they don't find a host plant to grow and reproduce in.  But spores and seeds are fantastic plant survival agents and can survive terrible conditions for remarkable periods, just look at the wild flower shows in Central Australia (I hear the Todd river is in flood so we should see news reports of the "desert in bloom" in the next few weeks).  As we learned from Mr Rundle the three field system, one year with one crop, one year with another and the the third fallow was both inefficient and eventually unsuccessful in controlling disease.

From my reading most vegie gardening books recommend disease resistant cultivars.  This brings us back to the old question of Heirlooms vs. Hybrids.  Laurie's favourite Tomato is a classic Heirloom, Brandywine.  Half Kilo fruit if you believe him, pink skinned and solid fleshed.  Actually Laurie if you're growing fruit like that why change your system?  From my experience disease resistant varieties only offer a limited defense against heavily infested soil.

Brandywine Tomato pick from tradewindsfruit.comFollowing last week's newsletter note the cracking on the shoulder of this fruit.
Now there is one other method for protecting your garden plants from soil borne diseases: Fumigation.  Yes it is as bad as it sounds.  When we cleared out my grandfather David's garage I found a 4' tall cylinder of  Methyl Bromide.  This is filthy stuff that used to be used to kill every living thing in the soil for commercial vegetable and flower growers.  Clearly Dave had brought some home.  Well you know, he loved his flower beds.  Any way I'm sure Methyl Bromide has been banned altogether now.  Interestingly because potting mix can be "picked up" it can be steam pasteurized killing most harmful organisms but leaving the "media" inoculated with helpful bugs.  This is a bit beyond the home gardener.
So back to Laurie's original suggestion. Grow Tomatoes in big pots.  I think it's a great idea but not cheap.  If you use pots you must use good potting mix and Laurie is proposing pots twice as big as Kerry used at home this year so that's a lot of potting mix.  Of course you will remember that Kerry's 250-300mm pots just weren't big enough to supply enough nutrient or water to advanced Tomato plants.  And since we're talking about crop rotations the potting mix needs to be replaced for next year's crop or the benefit will be lost and don't forget that the big pots need to be washed out with disinfectant to ensure that all the fungal spores are gone.

That feels like a lot of reading today, see you next week I've got a great idea about attracting Lady Birds and other insect predators.
Oh and Happy Birthday to Laurie who turns 81 on Wednesday.

Black Spots on Tomato Leaves

Peter,
Could you help me out please. The tomatoes in Jack’s garden have black spots on the leaves. How do I fix?
Thanks,
Teemu

Err, that’s awkward. Black spots on Tomato leaves is a tricky problem. We were plagued by this disease for many years. Actually there are a number of diseases that can produce black spots, but let’s assume that the spots are caused by bacteria.
At Scotsburn, we almost completely eradicated the disease through good nursery hygiene and a ‘balanced’ feeding program. In the bad old days we were continually spraying copper solutions (like Bordeaux mixture) to prevent the bacterium infecting our Tomatoes but we found moving Tomato pots up onto benches much more effective. Moving to benches reduced the amount of water that was splashed around the plants – splashed water can pick up and transmit disease.
We also worked on the theory that our plants needed to be growing vigorously to prevent the disease attacking. This is a good theory but it turns out that the execution was a ‘bit out’. We were feeding our Tomatoes so much that they became lush, soft and very prone to minor physical damage which gave the bacterium access to our plants.
The solution came from Peter Wood who used to run Woodlyn Nursery and he happens to be my mum’s cousin. Peter suggested we cut back the Phosphorus (P out of the NPK ratio) in our fertilizer blend. I have previously related Phosphorus to fatty food. Great if you need it but seriously addictive. Tomatoes love it and it doesn’t take much to get your plants jumping out of their skins. So what did we do? We found a ‘balanced’ liquid fertilizer with equal quantities of Nitrogen and Potassium and almost no Phosphorus. Problem solved.
Can this be fixed at home? I think so. If you are planting in pots, use a quality potting mix. I recommend Debco’s Terra Cotta and Tub mix. If you choose to add additional fertilizer I suggest Phostrogen – Tomato Food (phew their analysis agrees with mine, takes the Potassium levels even higher). We are in the process of trialing Debco’s Organic potting mix but I don’t have any suggestions for organic fertilizers in pots yet.
I haven’t mentioned growing in soil. Soil is great, use organic fertilizer like manure. Well prepared soil protects your Tomatoes from many disease problems.
Image from University of Minnesota. Michelle Grabowski. Click on the image to see the original.