August is often the make or break month for potatoes. No doubt, if you’ve planted a few rows (or a lot) of potatoes, you’ve already dug a few plants for new potatoes which are usually ready two weeks or so after the plants blossom. But if you’re waiting until the first frost so you’ll have big tasty tubers for winter storage, now’s the time to be on alert. Warms days with high consistent humidity encourage blight, as does wet weather. The problem with potato blight is that once it starts, it’s nearly impossible to make it disappear completely. Still there are things you can do to prevent and impede potato disease. The ultimate goal is to keep them from the tubers.
If you notice dark blemishes on mature leaves, often with target-like rings, your potatoes are probably suffering from one of the most common diseases, early blight. If left untreated, this fungus will result in collar rot, essentially strangling the plant at the soil line. Luckily, there is a treatment that will slow or even stop the fungus that causes potato blight, if applied early enough. A good copper-based fungicide applied every week or so should give your spuds time to develop. (more…)