What Does It Mean When Your Cantaloupe's Leaves Are Yellow?

Squash Bug

• If your plant's leaves are covered with small yellow specks that turn brown, you might have a problem with squash bugs. These brownish-black insects feed on plants by sucking sap from the stems. Repeated feedings cause the plant's vines to wilt. If left untreated, the entire plant may die. To treat, look for squash bug eggs underneath the leaves. Pick off and destroy the eggs before they hatch. Remove all debris surrounding your plants so squash bugs can't hide there. In the spring, lay down plastic or wooden boards at night. The insects will congregate beneath the boards. Collect and kill them in the morning.

Whiteflies

• Like squash bugs, whiteflies harm cantaloupe plants by sucking out sap through the stems. They also excrete honeydew, a substance that can cause black sooty mold to develop on the leaves. If you see ants on your plants, they may have traveled there to harvest the honeydew. An easy way to test for whiteflies is to shake the plant. When you do this, the tiny white insects will fly away from it. Small numbers of whiteflies won't cause a significant problem, but large infestations can kill your cantaloupes. If just a few leaves are covered, remove and destroy them. Sticky traps help catch the flying adults. If a plant has a large infestation, you may need to destroy it.

Downy Mildew

• If your cantaloupe plant has downy mildew, you'll first notice angular yellow spots on the tops of leaves. The spots will grow larger until the entire leaf turns brown. You may also see fuzzy gray growth on the bottoms of leaves during wet weather. This disease requires a wet leaf surface to develop. Do not use overhead sprinklers to water your plants, and instead, water at the soil level. Crowded plants are also more likely to develop the disease. A copper fungicide may help treat plants if you discover the disease before it spreads. If the entire plant is infected, you probably can't save it.

Other Issues

• If only the older leaves on your cantaloupe plants are turning yellow, this is normal. When older leaves start to lose water, the edges turn bright yellow and curl up. This is caused by excess salt buildup, also called salt burn. You can remove the leaves if you like, but leaving them will not harm the plant.

  Nutrient deficiency and toxicity also cause leaf yellowing. For example, your plant might be getting too much manganese. If you think this is the problem, check your soil's nutrient levels with a soil-testing kit. You can also send a soil sample to your local cooperative extension for testing. Typically, you should fertilize once with nitrogen fertilizer, such as 12-0-0, after the vines put out runners. Use 1 to 2 tablespoons of fertilizer per plant.