Bacterial spot/speck? That's what my tomatoes had earlier in the summer and it looks exactly the same as what's attacked your potatoes.

Do the really infected leaves seem to simply fall off the plant?

Ants love potato plants for some reason, I discovered that when harvesting my new potatoes.

From the photos it looks as if it may be blight, I am no expert but google potato blight and compare photos.

When did you plant? Potato vines wither naturally about 3 months after they come up, less time in hot dry conditions and a longer time in a cool moist climate.

I would also ask when did you plant? The bug problem isn't serious. Maybe try another fungicide, and remove the affected leaves. The yellow spotted leaves aren't coming back. How wet is the soil? Potatoes don't like wet feet.

Looks to me like it could be normal dying back, as others have mentioned. Did they flower yet? If so, you can start eating anytime, or wait until all the leaves die back if you want them to grow as big as potatoly possible.

And I certainly agree with ed, that little bit of bug snacking won't affect your yield.

I read recently that potatoes can tolerate about 30% defoliation during the early growth stage, but only about 10% during the fruiting stage, before suffering yield reduction. My CPB infestations sometimes run over 50% defoliation and consequent near-zero yields. That is the case this year. The field mice will have to look elsewhere for winter food this year, I'm not sharing.

If they have been 3 months ago or before, then it is not worth the efforts trying to save them. I would harvest whatever there is. Probably will be mostly tiny potatoes.

Why mostly tiny potatoes if they've been in the ground 90 days or more? In my experience that's the right amount of time for potatoes to form and the tops to begin to die back. Leaving them in is mostly for the skins to harden for storage. Some early season types only require 60 days (like yukon red gold). So . . . the type of potato, whether it's early season, mid or late season variety, and when they were planted would be good info to have.

Pat -- that's a shame about your potatoes this year. I LOVE killing CPBs, one of my most favoritest garden activities is getting every single one of them, and their eggs, and their babies, every day (I grow about 200 linear feet -- you might be growing lots more?) Are there nearby kids who might also enjoy CPB assassination? Sad to go through all the work of planting, and maybe even hilling, without the harvest!

If you are in New York State, you've had a VERY WET past 8 weeks. The yellowing may just be stress from being too wet. My potatoes have been stunted in their growth, but for some reason haven't turned yellow yet. I'm growing Red Norland and Kennebec.

Thanks all. I planted the potatoes on 4/18, so it's been 76 days. They have not flowered yet, and like the last post said, I'm in Western NY, we've had a lot of rain. They're in a canvas container that has drainage, but they are still probably quite wet (all my zucchini are rotting at about 2 inches long). I'll try removing the leaves and see how things go.

Some of mine look like that, and we've had the wettest Jan - June on record here. I notice that the worst-looking plants are in the lowest corner of the bed.

The ones that are flowering are doing that now, and the early baby potatoes are just pea-sized. So I'll just leave them in the bed and keep up my regular spraying, see what I get.

Elisa, I probably have about 300 feet going. The main issue is that garden is two miles away so when I get there I always find something more pressing to do. I hit them a while back with DE which helped for a while, and did some picking - or brushing into a bucket. I'm fairly confident in being able to get a cwt or two from someone I help out - that field is not too badly infested as of today so I think I will not have to buy potatoes.

pn - how do you store that quantity of potatoes?

I store them in an outdoor pit. This year I'm going to dig them earlier than usual (september instead of november) to try and avoid sprouting and mouse damage.

They have not flowered yet,

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If they have not flowered in 80 days, they won't. Not all potatoes flower. That's OK. Mine haven't either.

Hey vacant -- if all your zukes are rotting at 2 inches long you may want to try hand pollination, as lack of pollination could cause that too. Just an idea.

Pat -- Oh -- 2 miles away. I might lose my Minister of Death mojo if I had to drive that far to kill CPB :) Hope you won't have to buy potatoes this year. We had to buy them last year and that felt crummy (a zillion inches of rain right after tilling which created hard pan.)

Now I'm sadder. The yellowing and spotting has moved on to my tomatoes. So does that mean it was definitely a disease/blight? I cut off all the affected leaves from the tomatoes.

Sara

Both tomato and potato are very prone to die-off of the lower leaves. They are very heavy feeders and when they draw down available nutrients they start to catabolize the lower leaves. As well early blight starts at the bottom and works up.

What can I do if it's blight? I feel like I know nothing even though this is my 5th year with a garden that keeps getting bigger every year. But I usually just let things take their course and don't interfere too much. The tomatoes look bad, big black spots :(

Sara

If it's late blight you'll know it. The fact that the spotting and yellowing is happening relatively slowly gives you at least a fighting chance. I'd be removing the bad foliage and spraying a fungicide like crazy. We've had almost a foot of rain here in the past 5 weeks and I've already sprayed twice. Will be spraying again tomorrow with a fungicide and insecticide.

So these are definitely dead, or nearly dead now. I'm guessing I should stop watering them now and let them sit until i harvest (and hope i have something!)?

Sara

Since the potato plants completely died and shriveled up and disappeared I decided to dig in today and see if anything had survived. OMG I'm so excited. I got about 7 lbs, which isn't that much I guess, but considering it didn't seem to go so well, I'm happy.

{{gwi:88469}}

Thank you for the update! My potato plant has just gone yellow. So I am worried I won't have any potatoes. Your post gives me hope.