A tragic tale of juglone & tomato plant diseases

Tiffany Daneff / 13 May 2014

Good news all you gardeners out there, this tale should hand you a life-affirming dose of schadenfreude.



It was a lovely warm weekend, indeed a wonderfully balmy week. The central heating was off, even the towel rail in the bathroom was tightly turned to the right (Righty Tighty, Lefty Loosey – my mother-in-law’s tip for remembering which way is off and which on; and which has saved me so much angst when faced with enigmatic taps).


You can tell I’m prevaricating, can’t you?


Anyway, to cut a long story short, and for reasons that I cannot now exactly recall, I got it in my head that the precious Sungold tomatoes would do better in the sheltered south-facing corner by the compost bins where the herbs were sunning themselves and the brick felt warm under the hand. Perfect.

Rea Val Bourne's guide to growing tomatoes


So I potted them on (just a pot size up, to acclimatise them to their new home) and put them outside for some fresh air and to harden off for a few days. They loved this, responding happily by putting on a couple more inches of growth.  Ah, I thought, bigger pots, some toothsome organic matter and these babies will be ready for their final home.

Did I check the clear and helpful instructions on the Dobies seed packet?  Did I hell. No, I did what I usually do - I rushed to get all the jobs done in time. In my head a persistent voice was warning not to miss the moment. Spring! It’s spring. Got to everything planted while the sap is rising.


And I potted on the tomatoes and spent an hour clearing them a space, resting the pots on a row of old slates to give them draining and stop the grass reaching the roots.


Oh they did look smart.


The real worry was the lack of rain. We didn’t have any for several days.


On my way to work I heard warning of a possible cold front, coming in.  There might be frost in some areas. I had to pull my hood up walking the dog that evening, but that was the chill wind.  It didn’t feel like frost so I did nothing about it.  (I had a whole giant roll of horticultural fleece in the barn, ready if needed.)


Saturday morning, the sun’s shining and the husband’s back from its travels.


“Come and see the tomatoes!” I called, keen to show off my handiwork. The husband is very keen on Sungold.


How do I tell this?  The sight that met us was awful, just the worst. Nothing quite prepared me for the shock: nine of the ten sturdy, healthy specimens that I had lovingly nursed for so many weeks was shriveled, wilted, dying on their feet.


“Do you think there was a frost?” he asked with admirable composure.


“Oh no.” I assured.  “It wasn’t cold enough.”


Then what?


We got out Dr Hessayon and searched the illustrations for anything it might be. The leaves were white veined, darkened and quite unlike I had ever seen.


“Verticillium wilt.” read out the husband showing me an illustration of white-veined leaves.


“What’s that?”


“A fungus. There’s no cure. It’s soil borne.”


Panic set in.  If there was affected soil where had it come from? Was it from the old compost heap? Or was it something we had unearthed while rotavating and digging over the garden? There were too many unknowns. It was terrifying.


In the flower border a couple of young persicaria showed similar signs. And the then the hammer blow: all the marigolds had copped it. The marigolds had been sown in the same seed-sowing compost as the tomatoes, a bag that had been ripped open by the dog and scattered across the floor of the barn, and subsequently swept up and used by me.


The husband, ever hungry for a crisis, went indoors to consult Doctor Google. He came out with new news.


“It could be the black walnut.”


“What?”


“They give off this thing that is toxic to tomatoes.”


The walnut is in sight of the tomatoes and persicaria, but not the marigolds. It seemed unlikely.

To be on the safe side we bagged up all the soil from the tomatoes and dug up the marigolds and all the soil around them and bagged that up too, just in case there was some disease.  


We were devastated; to think that after all that digging and manuring and preparation we might be harbouring such a pernicious disease.   < /p>

And then I spoke to Trevor, who gardens in the next village.


“What about that hard frost on Friday night?” he asked.


Ah. So there had been a frost.  


“I never put anything out until June,” said Trevor. “We once had a frost on the 2nd June.”


“Ne’er cast a clout...” offered my friend Celestria when she very very kindly donated eight healthy, young cherry tomato plants to replace those I had lost.  


“I know.  I know...”  


What could I say in my defence?  Only this.  That until you experience something yourself you cannot fully understand it. I have read about frost, I have edited articles about protecting young plants. In short, I should have known better. But after decades of gardening in London where walls shelter you from wind and the sheer density of buildings raise the temperature I had become complacent.


NB Juglone is the chemical produced by walnut that if passed from the roots of the walnut to the roots of the tomato can produce walnut wilt.   (Ours were far too far away for that to have happened.) Find out more at www.tomatodirt.com


Verticillium is soil borne and causes die back. See the RHS website for more info.

intoGardens app logoTiffany Daneff is also the editor of the award-winning intoGardens app - the world's first magazine app for gardens. Visit the appstore to download a free sample or go to the website for more information. Gardening has never looked better or been more exciting. Visit www.into-gardens.com for more info. 

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