Is It Blight?

[snohare]

Aha, thank you for that, Sarah. That does simplify matters for me knowing that the warnings are for Phytopthora infestans, rather than Alternaria solani. I couldn't remember whether there was some kind of limiting factor for when late blight pops up - I thought decreasing daylength might be a factor besides the heat and humidity, and I had just forgotten that. We lost almost all the tattie plants on our site in August last year, I was hoping to forestall that this year by planting only earlies.
This is a situation where I would be tempted to spray - but it is very evident to me from my experiences of eating non-organic potatoes, which sometimes I get away with and sometimes don't, that there is something that tatties sometimes have in them that makes me ill. I am inclined to think that it is the carbamyls like Dithane (I know I am sensitive to other pesticide residues, they don't go well with a damaged gut) and I don't consider Bordeaux mixture to be much less nasty, so I suppose I will just have a really good excuse to be down at the plot every day !
I think I will try the milk/water antifungal feed I read about, and hope that my dairy allergies don't kick in...

[snohare]

Cheers Tattieman, I can see exactly why commercial growers are reluctant to swap to organic growing. Talk about a leap of faith ! Personally I think long term, blight is going to be an enormous problem for tattie growers, and might even force organic growers out of business.
Since all sorts of chemicals make me so ill, maybe I should just get on my knees and pray for a change in the weather...

[tattieman]

There are ten organic growers go out of organic farming everyday as the cost is far too high for the losses you have due to all sorts of disease which can mutate and become stronger and cause more problems. The problem for peolpe like us is that crops grown large scale with no spraying can become disease hot beds that spread to our crops and create problems for us.

[snohare]

crops grown large scale with no spraying can become disease hot beds that spread to our crops and create problems for us.

Yep, that's a real thorn in the flesh for you guys ! I take it that this is why so many of the organic potatoes I eat are from Israel.
For organically grown potatoes, should blight become more common as is forecast, it might be that the writing is on the wall - private allotments and gardens only, where they can be babied along as a luxury crop. Short of some really intensive large scale breeding experiments - say, if nothing but TPS was used for a few years, and crop losses were subsidised - I can't see what would get us out of the genetic bottleneck. Of course as long as the sprays work, commercial growers won't care, but what happens if long periods of heavy rain coincide with blight like it did last year in Aberdeen ? You can't spray in the rain can you ?
Or perhaps that gene I have heard of for universal blight resistance obtained from solanum bulbocastum will charge in and save the day. But like the bacterium that prevents tooth decay, that's a product of genetic modification...
And some folk think farming is just ploughing fields and sticking some seeds in.

[annacruachan]

I have removed two stems this morning from my Desirees; they were blackened and the foliage yellow. From what you are all saying it sounds like blight. Should I furtle out the spuds that were on these stems in case they are infected? The stem was black where it entered the soil.

[snohare]

The stem was black where it entered the soil.

Yes ! You are catching them at the last minute, Anna. Not surprising since it can develop to that stage in hours. Their resistance to tuber blight is slightly higher than to foliar blight, but particularly if it rains, you are scuppered, the spores will get down into the soil.
I did this last year with Desiree plants that were very clearly dead on their feet, every leaf brown and withered, stems shrivelled down to the soil - the crop was still usable though. (Given away rapidly to prevent an almighty smell from the occasional tattie going off with blight in storage - you smell 'em before you see 'em. They tasted absolutely fine though.)
Tattieman may have better knowledge concerning Desirees, but if it wasn't infected right down to the ground, I'd cut the haulms off at soil level, remove every scrap of foliage or ground debris that might shelter moisture for spores, and wait three weeks before harvesting - that gives the tubers time to bulk up. I don't know what to advise on the uninfected plants except to keep an eagle eye on them, check them several times a day.
Don't forget to dispose of the haulms in a way that does not produce overwintering spores - send them to landfill or burn them, don't compost them.

[tattieman]

annacruachan have a look on google for a disease called blackleg and see if that is what your desiree has. Desiree are bad for blackleg in hot years so that is another possibility Might not be blight?

[JenFeet]

Blight?

Hi everybody.

I'm new to veg growing - loving it so far - finding it frustrating yet fabulous and getting such a buzz everytime my family eat something from the veg plot.

I stay in Caithness - far north of scotland - and Blightwatch has reported 10/14 days in my postcode and 8 Full Smith periods recorded - it's been scorching hot yet raining buckets. The air has been thick but not knowing much about it I didn't worry and I didn't spray anything like I've now been reading about.

Yesterday one of my beds growing tatties looked unwell - brown curled leaves and wilting plants. I've attached a photo (hope it works) - and today it's worse. I've felt around for tatties and they're tiny wee marble sized. I'm sorry but I don't know what tatties they are - but I've harvested a different type from a different bed which have been fine (lovely actually!) - they were seed tatties from B&Q.

I'd appreciate any advice or suggestions please? I've left them in place but have a horrible feeling they'll need to come up tomorrow? I have these types in another bed but they're not (yet) looking affected - who knows what tomorrow will bring?

Thanks ever so much for the forum - I haven't posted until today but have been a fervent reader of the posts.

Jen x

[SarzWix]

Welcome to the Vine Jen
I'm sorry it's not a more auspicious welcome, but, those plants do look decidedly iffy
I'd be cutting off every piece of affected foliage you can see - you might not get much crop from those particular plants, but you may be able to keep the others healthy until they get a bit bigger?! I guess it has to be worth a go at saving the others and spraying them, if they aren't showing any signs...
It's very disheartening when it happens, but don't let it put you off - maybe try some blight resistant types next year, or plant salad types a bit earlier so as to harvest before the main blight hits?

[JenFeet]

Oh no... Not good - but thank you for your reply. I'll do what you say in the morning and keep my fingers crossed. I live in the middle of nowhere (literally) so how are the beasties finding my vegetables? I've lost one full bed of cauli, broccoli, sprouts to cabbage fly maggot and now this!! Aaaghhh.... Oh well. What joy it is bringing too!

Thanks again
Jen x

[SarzWix]

You could try only cutting off the bits of foliage that have the splotches on them, in an attempt to get the tubers a bit bigger, but you'd have to watch like a hawk for any new ones appearing.

[dinah gale]

Thanks to all of you who've given such good advice. This is is such a useful thread - the photos are particularly useful because potatoes leaves get so many peculiar spots and discolouration on them that are hard for the average gardener to identify.

I try to grow without any chemicals but MIGHT be tempted to get some bordeaux in just in case. I can't remember whether it has been said that it works equally well on tomatoes. In past blight years I've managed to get a crop of spuds by cutting the foliage right down at the first sign but have lost all the tomatoes on my allotment for the past two years. Call me a sucker but I've planted lots again this year in hopes.

The photos have certainly shown me that the soil if magnesium deficient is. Other crops, rhubarb particularly, has shown yellowing between the veins so something else to be added to the shopping list.

[Beetroot Bob]

Help please.

I've looked at loads of pics and read loads of posts. Sorry the only way for me to be sure is to post some pics !!

It's my 1st year growing and until now I've been really proud of my nice new greenhouse full of toms and cucs.

Went to the plot tonight to water and check up and found one of my toms had yellow leafs with brown/black batches. They were mid way up the plant not low down as I had when I was over watering .

Is it blight and what is my best course of action to save what I can ??

Poorly toms

Poorly toms 2

[SarzWix]

Hmmmm... Tis a bit hard to tell, inconclusive I'd say. Possible it may be botrytis. Is the plant near the door?
For now, snip off any affected leaves and burn them or bin them, and see what else happens. If it's botrytis, it could have been caused by condensation dripping from the roof onto the plant, so try and keep the atmosphere a bit dryer if you can - that will also help if it is blight.
Good luck Bob.

[Beetroot Bob]

Thank StarWix. No it's not next to the door. It's in the corner but next to the louver (with auto opener). It does seem quite damp in there I'll try to keep the door open a bit to try and keep the air flowing.

Fingers crossed