Sangeetha Pulapaka

Cucumbers (Cucumis sativus) are tender, warm-season annuals that belong to the cucurbit plant family (Cucurbitaceae), which makes them related to watermelon, squash and pumpkin. All of those crop plants have some susceptibility to damaging diseases or pests that can turn the leaves white. Catching health or insect problems early can help keep your cucumber's leaves healthy and green.

In rose plants, powdery mildew is one of the most common foliar diseases of roses. The white, powdery fungal growth can be very disfiguring, with repeated heavy infection reducing plant vigour. Cultural techniques play an important role in minimising outbreaks, and fungicides can also be used.

While it can affect any plants, there are certain species much more susceptible to heavy infection:

  • Begonia
  • California poppy
  • Dahlia
  • Delphinium
  • Hollyhock
  • Hydrangea
  • Lilacs
  • Monarda
  • Oak
  • Phlox
  • Strawberries
  • Zinnia

Peppers (Capsicum annuum) can be affected by several conditions that turn their leaves white. Causes for this include the weather, pests and diseases. 

If there is a sudden temperature drop or if the pepper plants have not been hardened off before transplant, the shock can cause the leaves to turn white. As a warm-weather vegetable, pepper plants are not frost-tolerant and require a period of adjustment to the outdoor growing environment. To harden off your pepper plants, move the seedlings outdoors gradually, exposing them to the warm, sunny days and moving them back indoors during the cooler evenings. After the pepper plants are able to tolerate spending full days outside, they have been hardened off and are ready for transplant.