Post by murrayc on Aug 7, 2019 14:39:41 GMT
Six weeks after uplifting all my onions, garlic and shallots and drying them on racks at home and my worst fears are realised. Between a third and a half of these are all infected with rot and will not keep. I suspected it last year in an adjacent patch of soil but this year is by far the worst.
If you haven't got it let me save you the research: its a serious fungal disease that shows itself first as a white, soft mould on the bottoms of the onions, which then go soft and rot away. It stays in the soil for many years and is highly resistant to any chemical treatment. Most authorities advise destroying, not composting, any onions affected and even caution against treading the affected soil onto another part of the plot or a neighbouring plot.
I've been looking at different forums and this advice from the Allotment Growers UK Facebook group looks the most promising, as well as being very authoritative:
"It's gutting, but not the end of the world. I have it, to a greater or lesser extent, on all three of my plots and I'm still growing onions, garlic, leeks and shallots.
First you want to interrupt the cycle of the disease by stopping the next generation producing sclerotina, the spore-like bodies that will infect future generations of allium. Give each onion a little wiggle. If it is firmly set in the ground, leave it. If it wobbles, the onion rot fungus has already killed its roots and the plant has to be removed. Hauling it out of the ground by force will scatter any sclerotina it has already formed on the surface of the soil, which makes it more likely it will infect more plants in years to come, or travel or your boots to another part of your plot. To minimise the spread therefore, ease loose plants out of the ground gently with a trowel, taking the soil immediately around the roots up with the plant and popping it all into a plastic bag. Burn the waste, bin it or bury it 12" deep.
The sclerotina look like small, black poppy seeds. Their hard case makes them very long lived for any fungal spore, up to 25 years. They sit in the soil until they detect the root exudates of allium crops; this activates them into sending out a hyphae (root-like feeding thread) but this can only reach a few millimetres before it becomes exhausted. You can therefore beat the onion white rot by watering the soil with a solution of water and allium root exudates or even garlic powder. Pour this summer over the beds you want to grow alliums on next year. This allium juice activates the sclerotina, but there are no alliums planted to feed on and they die, much reducing the impact of disease for the next allium crop. The beds don't have to be bare when you treat them, though obviously this makes it easier. I cut the roots of all my alliums as I crop them and they go into a bucket to soak. Otherwise I'll use 1 bulb cut up very fine or mashed up in a food mixer, diluted in 20 litres of water and watered onto the soil through a fine rose on a watering can. No dig beds and raised beds also resist infection by raising the plants roots fat out of reach of the scelortina hyphae”
First you want to interrupt the cycle of the disease by stopping the next generation producing sclerotina, the spore-like bodies that will infect future generations of allium. Give each onion a little wiggle. If it is firmly set in the ground, leave it. If it wobbles, the onion rot fungus has already killed its roots and the plant has to be removed. Hauling it out of the ground by force will scatter any sclerotina it has already formed on the surface of the soil, which makes it more likely it will infect more plants in years to come, or travel or your boots to another part of your plot. To minimise the spread therefore, ease loose plants out of the ground gently with a trowel, taking the soil immediately around the roots up with the plant and popping it all into a plastic bag. Burn the waste, bin it or bury it 12" deep.
The sclerotina look like small, black poppy seeds. Their hard case makes them very long lived for any fungal spore, up to 25 years. They sit in the soil until they detect the root exudates of allium crops; this activates them into sending out a hyphae (root-like feeding thread) but this can only reach a few millimetres before it becomes exhausted. You can therefore beat the onion white rot by watering the soil with a solution of water and allium root exudates or even garlic powder. Pour this summer over the beds you want to grow alliums on next year. This allium juice activates the sclerotina, but there are no alliums planted to feed on and they die, much reducing the impact of disease for the next allium crop. The beds don't have to be bare when you treat them, though obviously this makes it easier. I cut the roots of all my alliums as I crop them and they go into a bucket to soak. Otherwise I'll use 1 bulb cut up very fine or mashed up in a food mixer, diluted in 20 litres of water and watered onto the soil through a fine rose on a watering can. No dig beds and raised beds also resist infection by raising the plants roots fat out of reach of the scelortina hyphae”
Does anyone else have experience of this any any personal recommendations?