So my beautiful potatoes were growing so well! Beautiful flowers, strong green leaves, huge tall stalks. Until they weren’t. In my last post about the potatoes What’s wrong with my potatoes? I discussed the treatment I was attempting.
The leaves of my potatoes had started turning yellow with stupid purpley-brown spots. And the leaves went from spotted yellow to brown and fucking dead. My research told me that yellowing leaves, the oldest ones first, could be a nutrient uptake issue. And I hadn’t treated the soil with any fertilizer at all this season (I’m still learning about fertilizer).
So to try and fix the yellowing leaves, or at least stop the spread, I applied a standard Miracle-Gro garden fertilizer, and a magnesium (Mg) treatment. The Mg helps the plant to take in the proper nutrients from the soil. A deficiency of Mg means that even if the soil is rich and nutritious, the plant won’t be able to take in the treasure. It was a highly effective treatment for the Mg deficiency I experienced earlier in the season with my zucchini. See Something’s going on with the Zucchini.
More than two weeks later, there’s no discernable improvement, and in fact, the plants are very clearly dying.
When potatoes mature to the point of harvest, the stalks and leaves yellow and die back, so I’ve been trying to kid myself that it’s near harvest time. But NO. Die back should not be happening in July.
Shortly after the potato plant flowers, you’re supposed to be able to harvest some new potatoes from the potato sack. Because of this yellowing issue, I chose not to disturb the soil, and instead just checked for moisture problems. I was worried about overwatering because, to prep for an out of town trip, I had attached drip lines to water while we were gone. It’s handy to not have to hand water with the hose, so upon return, I left the drip lines in place.
All of my research is very clear about potatoes. Do not over or under water them. No shit.
It’s super fucking dry in Colorado, and the stupid-ass wildfires and global warming are not helping. To keep any plants alive in my garden, they must be watered AT MINIMUM once a day; to thrive, they need more than that. After seven years of messing with drip schedules, we’ve settled on a schedule that uses the least amount of water (we’re in perpetual draught here in the Front Range), and gives the most benefit. We water twice: three minutes at 6 AM, and another three minutes at 2 PM.
Point is, the potatoes are not UNDER watered.
So I had to check for overwatering. But how to know? I opened all of the sacks and found rich moist soil, but there was some white powdery stuff on th outside of the felt sacks (could be minerals from the water or could be a mold/mildew), and one of the sacks did seem too moist. But I don’t know for sure.
Needing to start somewhere, I chose a working hypothesis that the drip lines allowed me to overwater. But how? These plants are huge, they should be sucking up every last drop. But they don’t. Because they’re fucking dying.
Now that I have a hypothesis to test, I needed to do some testing. First, I looked inside the bags to observe the soil moisture and root systems. Here’s what I found when I dug around:
To my shock, I found several lovely firm beautiful potatoes! They’re drying on my counter, and I haven’t eaten or cut into them yet, so I don’t know what they look like inside.
I felt around for more and smaller tubers in the bags, and didn’t feel much of anything except roots. I went ahead and pulled the potatoes I did find, because I am not optimistic that there’s more coming, and I don’t want the ones I have to rot in the bag.
But back to what’s wrong with the little fuckers.
Having investigated the soil in all the bags, I replaced everything back to their positions minus my little treasures, and waited 24 hours to dry out the soil. The bags dried out quickly, and I’m back to hand watering – just a little bit, so I can make sure not to make them too moist.
But folks, that’s not the problem. I still have one nice green potato plant, it’s the purple variety of seed potatoes that I picked up on a whim from Lowe’s in the spring. The other four bags are the Yukon seed potatoes I ordered from Gurney’s back in February.
Here’s the thing. It’s best to use seed potatoes because the seed companies make sure the seed potatoes are blight and fungus free. Well, they try to. And because all of my seed potatoes are from reputable seed places, I haven’t considered blight or fungus as a real threat. But after my initial investigation, and with further research, I sadly have come to believe that the Yukons (four of my five potato bags) are plagued with Shit Spot. Oh, I mean Brown Leaf Spot.
I did a whole bunch of research, and this article has me close to convinced, because of the picture of the leaves. These leaves look just like mine (the brown spots were all purpley just a week or so ago):
To be honest, I don’t actually know what’s wrong with these potatoes, I’m just using the science techniques of literature review, testing hypotheses, and data collection. There’s a real possibility that the problem could be Verticillium Wilt or Fusarium Wilt, both of which are common fungal issues, and of which, my potatoes have several of the same symptoms.
I’m not a botanist or master gardener, so I’m having a hell of a time diagnosing the problem with any certainty. One of the reasons I can doubt the Brown Leaf Spot diagnosis is because my research says that it will cause reduced crop, like around 10%. But what I’m seeing from my actual plants is something far more devastating, which leans me towards the fungi or a bacterial wilt. For a few minutes, I was actually sure it was bacterial wilt.
Well, sonofabitch. If the problem is Brown Leaf Spot, then my research says it can be managed with a couple fungicides for the rest of the season, but my research results have yielded information primarily for farmers, not for the home garden, and not for potatoes in containers. And, at this stage of progression, even if I can keep the plants alive, there’s not enough time in the season for growth of a real crop of potatoes.
The other possibilities of wilts and bacteria will simply be the end, and will require me to destroy the plants and fallow the soil for years. Fuck a duck.
So, what am I left with? A handful of yummy new potatoes, and 4 containers full of tainted-ass potato plants, and no real solutions.
My plan: The one remaining healthy-looking bag will remain, and I’ll keep my fingers crossed for some yummy purple tubers in the fall. For the other four bags, I’m going to keep hand watering as necessary, until they finish dying. Just in case there’s another edible potato or two to come. At the end of the season I’m going to dump the bags and the soil entirely, maybe even burn them all (burning everything is one of the requirements for farmers who have blight), and start all over again next year with new bags, new soil, and new seed potatoes. Grrr, fucking pesticles!!! I’m really bummed out about this. Potatoes have been so easy to grow in the past, and so very very yummy!
The Pottymouth Gardener 