My friend Lieven reports potato and tomato blight in his area of Belgium. If you live in Northern Europe and are growing either of these, keep an eye on your plants!
In particular, blight likes cool nights, warm days and wet weather.
On potatoes, blight shows up as gray spots on the leaves that spread. On tomatoes, it usually shows up as black or grey spots or rings on the stems and foliage and blemishes on the fruit.
For tomatoes it’s almost always very quickly fatal. Usually if you try to quickly harvest tomatoes on the plant for indoor ripening, they will already be infected and will rot within a few days. Because the plants are very contagious, and the spores of blight last a long time in the ground, usually the only prudent course of action is to destroy infected plants as quickly as possible. Don’t compost infected plants! Burn them or dispose of them in the trash.
My understanding is for potatoes there are some alternates to destroying your plants, and early harvest or removing the plant’s foliage are sometimes options. I’m not experienced enough of a potato grower to offer advice on this, so perhaps some other people will post some suggestions.
If you come in contact with infected plants, be sure to shower and change your clothes before handling plants that aren’t yet infected.
There are no chemical or organic treatments available to home gardeners that are effective once your plants become infected.
Haven’t had a bad bout of blight (how’s that for alliteration) for several years but when it did strike I cut down all foliage (even the unaffected plants)and continued harvesting. The spuds were unaffected, I probably caught it early and also I didn’t store any so I can’t tell if they would have kept over the winter.
I’m hoping we’ll escape this year as I have a lot of tomatoes in the ground and also aubergine, same family so I guess similarily affected.
I had tomato blight last year; it was very wet. I did some research and while it can’t be cured I’m hoping to prevent it this year, or at least delay it until I can harvest some tomatoes. We really like our marinara and salsa here!
I’m spraying very occasionally with Neem Oil (organic) in the evenings. I have also trimmed the lower branches and leaves so they don’t come near the ground and hopefully they are up high enough to avoid getting dirt splashed on them when it rains… IF it ever rains.
I don’t know if this will work but thought I’d pass it on. It certainly won’t hurt.
The blight has arrived in my garden. So far I’m only finding it on potatoes, but I’m worried that if it afflicts the tomatoes this early in the season I will get no fruits at all. They’re only just starting to produce flower buds.
In some ways it’s not surprising, because the weather has been diabolical … constantly warm and soaking wet for the last eight weeks or so, which makes it a paradise for blight. Just about everything in the garden is afflicted with some kind of bacterial or fungal disease, or mould or mildew. It’s really quite depressing to see the state of the garden at the moment.
That’s really too bad you got blight so early. I hope you end up with some potatoes and tomatoes. If your potatoes have it now, I suspect your tomatoes will have it within a few days.
So far my plants are okay, but like you said with this horrible weather it could only be a matter of days before I have it too.
Some growing years are better than others…
Yes, potato blight is a big worry – especially when we work hard and plant lots of sets.
As mentioned by others above, I cut down the infected foliage and removed it last year, even though the plants were not fully mature due to unavoidably planting late.
The ‘resistent’ varieties: Sarpo mira and axona and Lady Balfour stood longer and more robustly but even they eventually showed infection and were treated in the same way.
I didn’t disturb the ground by harvesting the crop for at least two or three weeks. I had some good spuds, which were hardly damaged. I washed and dried most of them (very time-consuming) and they stored well with regular checks. They were ok up until they were used up in February this year.
As an amateur gardener, I’m not sure that spraying with a copper-based mixture has been useful in the past. I didn’t spray the potatoes last year.
Further to my earlier comments about potato blight: My potato plants have now been attacked by the early strain of Phytopthera infestans; brought on by the unusually heavy and prolonged rainfall and humid conditions in this region of the central West Midlands UK, recently.
I have sprayed with a copper fungicide this year but I feel this has had little effect due to the speed of the infection. However, there may be some later benefits on contact with the soil – perhaps.
The strongest varieties on my plots, were Ambo, Arran Victory, Bonnie, Cara, Cosmos, Fambo, International Kidney, Maris Piper, Mayan Gold (a genera/species cross), Orla, Kuroda and Saxon. The varieties: Lady Balfour, Sarpo Axona and S. Mira are looking strong and clean, and doing as well as can be expected in these conditions. I expect them to resist the infection for just a few more weeks yet, thus allowing a little more growing and tuber development time.
The, weaker blight resisters sadly included: British Queen, Edzell Blue, Fortyfold, Home Guard, Karlina, Kestrel, King Edward, Markies, Milva, Mr Little’s Yetholme Gypsy, Record, Robinta, Red Duke of York, Swift, The Bishop and Valor. Some of these poorer blight attack resisters were not unexpected failures in these conditions, whilst others, such as: Markies, Record, Robinta and Valor were expected to do better. However. in other circumstances, all of these potatoes often perform well, and they could well provide a reasonable crop.
The badly affected plants are now being cut back carefully; the foliage disposed of, and the partly developed tubers will be left in the ground for at least two weeks to toughen the skin and to avoid contact with fresh blight spores above ground. The yield will now be poor due to this early damage.
Hi Dave —
Thanks for the comments! You have a very interesting collection of potatoes. It’s too bad this has been a bad year for blight and wet weather problems.
While this post was intended to be on late blight, I too ended up with early blight this year. I have both potatoes and tomatoes on my roof in pots, and while several plants have been infected, so far I have been able to control it by removing the infected foliage. In one case, I completely removed the foliage on a potato plant. In my case it’s spreading slowly.
Hi, Patrick and other gardening posters.
Thanks for your notes, and other remarks on potato blight.
Regarding my potato collection. Its no big deal, really: In most cases I have just one or two rows of each variety – and a few more of my family’s favourites, such as ‘Colleen’ (Irish, of course) and ‘Ambo’. These are grown on an inner-city allotment plot, which I cannot cultivate as well as I would like to due to being busy with my job, although I do spend some time preparing the ground well before planting. Weeds are a problem to keep down but being a mainly ‘organic’ grower I believe there are some benefits too in having a few around.
A variety of potato called ‘Verity’, which I planted in a different plot, a few miles away, did quite well but the partially resistant plants were blighted eventually.
Now, following your remarks, Patrick, and without trying to labour the point too much, I feel that I must emphasise the words in my previous post that due to the bad weather most of my plants have shown typical symptoms of a very early attack of Phytophthora infestans, which in fact usually occurs in this region (West Midlands UK) during late summer/early autumn. As I understand it this should not be confused with the rarer, less damaging infection known as ‘early blight’ or ‘target spot’ and technically known as Alternaria solani, which occurs during hot,dry summers (see, for example, Alan Romans: ‘The Potato Book’, Frances Lincoln, 2005,p.p.26-7, 35).
As Rebsie F. wrote earlier: this is all very depressing. What I believe does help in extending the growth, vigour and blight resistance of potatoes is the use of a spray mixture of seaweed liquid feed and organic plant oils (ironically blight evolved from seaweed). This year, I did add a copper preparation to the mixture. where necessary, at planting time I also incorporated some sulphur chips into and over the planting trenches to acidify alkaline soil.
I might look up some Neem tree oil as mentioned by Leslie in a previous post. However, I think I may have to revise my cultivation plans and grow more of other vegetables and less of the vulnerable varieties of potatoes if these warmer, wetter spells continue. This is a shame because my own family and friends have enjoyed lots of fresh, tasty organic spuds in recent years.
I would welcome any further advice and points of interest regarding this topic and other related matters.
Thanks for your time: Patrick, John, Leslie and Rebsie, and others. Good luck, etc.
I have been planting my potatoes in early February for the last few years, I haven’t bothered with chitting. I use no dig potato growing method. I pop the tubers just into the soil and cover with the soil, then I put a layer of newspaper over the bed, if I have straw or hay I cover with that as well then pop some fleece over. I earth up with grass mowings once the foliage pops through, keep fleece on until risk of frost has passed, water pipe cloche is useful to lift the fleece away from the crop. I find my spuds are then ready by early July to harvest,and even if blight strikes, the tubers are a decent size, the earlies are usually lifted and eaten before then. I store the harvested tubers in boxes of damp compost and put in a cool dark place away from rodents, we ate our last potatoes at the end of March this year.
Hi Lyn,
Thanks for stopping by and leaving a comment. It sounds like you use the Irish ‘lazy bed’ method for your potatoes, and I’ve heard it works very well. Good luck, and I hope you have a great harvest this year.