1. Downy Mildew
Light green or yellow spots on the leaves that appear angular.

Downy mildew causes light green to yellow, angular spots on the leaves. Also find fuzzy, dark gray spots with a purplish tint (spores) on the underside of the leaves—a tell-tale sign of downy mildew. As the disease progresses, leaves will dry out, become brown, and fall off. However, visible symptoms are not always consistent.

- Recommended drip irrigation to control the humidity and reduce risk of disease occurs.
- Spray metalaxyl fungicide to protect and defeat the disease (avoid spraying during the flowering stage)
- Remove infected plant parts and dispose of carefully in order to limit the spread of disease.

2. Bacterial Wilt
Yellow, wilting leaves that appear to be drying out.

Initially, a few yellowing, drying, and wilting leaves. Within a few days, the stems and vines will also wilt, turning yellow and brown. Cutting a section of the affected stem and place it in a glass of water. The presence of a milky sap oozing from the cut signifies bacterial wilt.

- Crop rotation to reduce the disease severe in soil by growing different crop family such as growing corn or bean after cucumber.
- Selecting high disease tolerance varieties.

3. Begomovirus
The infection may include upward curling of leaf margins, foliar stunting, chlorosis, interveinal mottling, vein clearing and thick, distorted veins.

- Get rid of weed, which is the host of the whitefly and thrips.
- Spraying imidacloprid insecticide to eliminate insects.
- Recommended install yellow and blue sticky trap around plot to reduce insects population.

4. Tospovirus
mainly stunting and yellowing of the whole plant. Leaves may show chlorotic line patterns or mosaic with necrotic spots. Necrotic streaks appear on stems extending to the terminal shoots. On ripe fruits, yellow spots with concentric rings or necrotic streaks have been observed.

- Preventing thrips by pruning or pulling weeds, remove the plant debris immediately.
- To keep thrips population under control, try using yellow or blue sticky traps.
- Spraying imidacloprid insecticide to eliminate thrips.