How to Spot Blight in Potatoes

Potato blight has been known to endanger whole populations and can certainly cause trouble in a garden or small farm. Even if you grow potato-related plants, like tomatoes, your crop could be struck. Fortunately, you can halt this disease in its beginning stages if you can spot the signs.

Difficulty: Easy

Instructions

1. Check the recent weather. If it is, on average, above 50 degrees Fahrenheit and over 90 percent humidity over a two-day period, you have favorable conditions for growing the blight fungus, phytophthora infestans.

2. Look at the plants. Potato blight creates brown spots with yellow edges on the leaves of the plant. Advanced cases cause the rot of the plant, leaving behind a destroyed plant.

3. Examine the tuber itself. The blight begins from the skin and travels inward, consuming as it goes. In tubers, this leaves a corky, splotchy potato.

4. Check the soil. Any remnant of prior blight will infect new potato plants, even if it isn't obvious in the plants. Re-inspect the plants regularly for evidence of the fungus.

Tips & Warnings

• Water is important for the growth of blight. If a reservoir holds ground-water next to the plants, the chances of blight increase. Similarly, poor watering technique encourages the growth of blight. Be careful with water usage if you value your plants.
• Don't leave blighted potatoes in the ground. Blight goes dormant and can even survive winter. Once revived, it will spread to other plants. Remove the entire blighted plant, even parts that seem unaffected, upon detection.