[Dan78]

I know there is a similar thread about talking about brown spots on potatos but didnt want to clutter it up with my pics!

Noticed the plot next to mine had some brown marks starting on his potatos a week or so ago but it seems a lot worse today! And now a couple of my potatos (nearest to his plot) are also showing this on a few leaves   These potatos are ones my mum is growing on the plot and she hasnt used any fertiliser or feed etc.. also no watering. Mine are treated the same but have been fed with growmore when planting. All mine look ok so far but they are further away from the next plot!

Anyway here are some pics of the potatos next door. I also notice the next plot along from his are also showing a few signs of the same..

please someone reassure me its not blight.... especially when no other cases have been reported yet this year!  

[Dan78]

there is also a lot of bindweed growing with his potatos.. Not sure if this may have anything to do with it ? I have been digging it out of my potatos as much as possible but my mum has just left it with hers...

[BabbyAnn]

at a guess, I'd say it could be frost damage as it appears to be on older leaves above the green ones.

[m1ckz]

ditto

[lucywil]

i agree, looks like frost damage to me too

[viettaclark]

New growth is healthy so I agree.

[Dan78]

Ah brilliant thanks guys Didnt think it had been that cold in the last week though!

Happy to hear it is not blight.. thought it was a little early!!

[Aunt Sally]

Well I've enlarged a bit of one of the pictures and the thing in the red circle looks like a spider and the portion of leaf in the blue circle looks like target spot (early blight)

Infected leaves should be removed and disposed of (not composted).  It won't affect the tubers.

If not target spot it could be magnesium deficiency (better close up needed) so give them some food and water.

[Salmo]

It could be frost but the leaves in photo 2 show typical magnesium defficiency with yellowing between the veins and the veins still green.

Epsom salts (2 tablespoons to a can of water) will stop this affecting more leaves. It will do no harm anyway.

[Aunt Sally]

Definitly not frost in my opinion.

[Growem]

This is similar to the damage I have suffered for the last three years. I believe it is caused by herbicide drift. It occurs about 4 to 5 days after a nearby field is sprayed with herbicide. It is most noticeable on the plants nearest the field in question. The chlorosis becomes more noticeable until the leaves turn brown and die.

Do you think it looks the same?

[Salmo]

Growem - Most herbicides would curl or distort the leaves. The photo looks like magnesium defficiency.

If you really think that the farmer is allowing herbicide to drift over your veg plot then you should politely tell him about it. Do not expect him to admit liability but I am sure he will be more careful in future.

[Growem]

Hi Salmo

The symptoms of herbicide damage can be pretty much indistinguishable from nutrient deficiency. I believe this is due to the way some herbicides work, preventing the uptake or use of nutrients.

I was fairly convinced last year about the cause of the problem. I know there is drift as it irritates my eyes. This year after the field was sprayed, I washed all the plants but left some strategically, unwashed. Only the unwashed plants were damaged this year. So I am fairly sure and of course, now I know how to prevent the problem, so that's even better.

If you look at the picture below which has part of Dan's photo to the left and mine to the right. I apologise for the poor quality of mine, it was taken with a very old camera which struggles in certain light conditions. The features I recognised particularly were the small brown dots, the yellowing and later browning of the edges of the leaves, the gradual chlorosis of the leaf as a whole and a small amount of leaf curl. Also the leaves with damage are those exposed rather than the older leaves below which I tend to associate with nutrient deficiencies.

My problem can also be seen more severely on tomatoes with severe leaf curl and to a smaller extent on peppers and beans which is consistent with my research into the subject.

With swift action I was able to save the damaged plants last year, albeit with reduced yield. Those plants left alone deteriorated quite quickly and died with almost no yield at all. Hence my reason for posting.

I cannot say with any certainty whether the two problems are the same in effect, hence my question, and certainly not in cause.

I recently came across an article which suggested that some herbicides including glyphosate can get into the air and distribute over about a hundred metres on a calm, warm day. I think the word used was volatise ... or maybe more likely with a 'z'. 

I could go on and on about this subject, it's been a bit of a hobby horse for the last two years and I've found tons of info, but best not.

[Growem]

Oooops, forgot the picture.

[TheSpartacat]

Hi Salmo

The symptoms of herbicide damage can be pretty much indistinguishable from nutrient deficiency. I believe this is due to the way some herbicides work, preventing the uptake or use of nutrients.

Hi Growem,

Yup, I'm pretty certain you're right- was reading a while back on how it actually works on the plant. It's a process called 'chelation' - glyphosate inhibits the plant's ability to take up nutrients, such as Magnesium, so it becomes weakened and is actually killed by disease/pathogens, rather than killed by the glyphosate itself.