What would cause cucumbers to turn black?

1. Chilling Injury: Cucumbers are sensitive to low temperatures, and exposure to temperatures below 50°F (10°C) can cause chilling injury. This injury can result in the development of black spots or streaks on the cucumber's skin.

2. Anthracnose: Anthracnose is a fungal disease that affects various cucurbit crops, including cucumbers. The disease causes sunken, dark brown to black spots on the fruit. Anthracnose can spread rapidly under warm, humid conditions and can lead to severe fruit rot.

3. Blossom End Rot: Blossom end rot is a physiological disorder that occurs when the calcium supply to the developing fruit is insufficient. It causes the blossom end (opposite the stem) of the cucumber to turn black and become mushy. Blossom end rot is often associated with irregular watering practices, high humidity, or calcium deficiencies in the soil.

4. Bacterial Soft Rot: Bacterial soft rot is a common disease that affects cucumbers and other vegetables. It is caused by bacteria that enter the plant through wounds or natural openings and cause the tissue to rot. The affected areas become soft, mushy, and turn black. Bacterial soft rot spreads rapidly in warm, humid conditions.

5. Sunburn: Cucumbers can also develop black areas if exposed to excessive sunlight, particularly during hot weather. Sunburned cucumbers show sunburn on exposed areas of the fruit and may eventually turn black.

To prevent cucumbers from turning black, it is important to:

- Store cucumbers at proper temperatures (between 55-60°F/13-15°C) and avoid exposing them to chilling conditions.

- Manage watering practices to ensure consistent moisture and prevent calcium deficiencies.

- Regularly inspect the plants for signs of diseases or pests, and apply appropriate control measures if necessary.

- Avoid excessive sunlight exposure, particularly during hot weather.