There’s nothing quite like the taste of homegrown potatoes fresh from the garden. But let’s be real—if the weather doesn’t cooperate or your soil isn’t quite right, your spuds can run into some trouble. Here’s my guide on how to spot the most common potato problems and, more importantly, how to fix them.
The Colorado Potato Beetle
Originally from right here in North America, these pests can strip a potato plant bare if you aren’t careful. You’ll recognize them by the distinct black and white stripes on their backs. Their heads are orange with little markings that almost look like a tiny face.
If you spot them, your first line of defense is “hand-picking”—just grab them and get rid of them. Make sure to check the undersides of the leaves for clusters of bright yellow eggs and squish those too. One single beetle can lay up to 400 eggs! Those eggs turn into hungry reddish-brown larvae that do the most damage, so keep a sharp eye out.
Pro tip: Laying fern fronds between your rows can help deter them. You can also dust the larvae with rock flour (stone meal), which they really don’t like.
Nematodes
These tiny critters are actually roundworms, often called eelworms. They’re microscopic, but they cause big problems by sucking the nutrients out of the plant and the tubers. You’ll know you have them if your potatoes come out deformed or show signs of rot.
The best way to fight nematodes is through crop rotation—never plant your potatoes in the exact same spot two years in a row. I also highly recommend planting Marigolds (*Tagetes*) nearby; they are natural nematode fighters! Planting white mustard as a cover crop is another great way to stop their larvae from hatching.
Potato Scab
Scab is a fungus that is very picky about where it lives. If your soil is too alkaline (high lime content), you’re much more likely to see it. It looks like corky, cracked, or “scabby” patches on the potato skin. While it doesn’t ruin the whole potato, it definitely makes them spoil faster in storage.
To prevent this, make sure to check your soil’s pH level . Only add lime if your soil test specifically says you need it.
Late Blight
This is the big one. It’s a nasty fungus that attacks both potatoes and tomatoes. It usually starts on the leaves, showing up as grayish-green water-soaked spots on the tips. If you flip the leaf over, you might see a fuzzy white mold.
If the weather stays damp , the blight can destroy all the foliage in no time. When it rains, the spores wash down into the soil and infect the potatoes themselves.
To keep your garden safe, try to keep your potatoes and tomatoes as far apart as possible. Dusting the leaves with rock flour can help block spores from getting a foothold. For a more proactive approach, spray your plants with horsetail tea or strengthen them with stinging nettle tea and seaweed extracts.
Resistant Varieties to Try
- Casablanca: This variety comes from Scotland. It produces beautiful, uniform tubers and has a great natural resistance to scab.
- Frieslander: A high-yielding Dutch variety. It’s very resistant to nematodes and doesn’t get blight easily.
- Finka: A German favorite that’s perfect for mashed or boiled potatoes. It’s nematode-resistant and ready for an early harvest.
Quick Tip: Try companion planting with Marigolds and Calendula. Always water in the morning so the leaves have time to dry, and give your plants a boost with organic liquid fertilizers. Your potatoes will thank you!