Juicy, delectable cantaloupe slices fresh from the garden are a summer treat for kids and grownups alike. But numerous problems can cause their profusion of large green leaves to yellow on the vine. Everything from air pollution to insect pests can cause the leaves to turn yellow, and it may take some detective work to find the culprit.
Too Much or Too Little Water
Cantaloupe plants need plenty of water to produce juicy fruit. The soil should be kept moist to prevent leaves from wilting and yellowing due to lack of water. Try not to get water on the the leaves, however, as moisture can lead to fungus. At the same time, overwatering can also cause leaves to turn yellow. Plants should receive about 1 to 2 inches of water a week.
Tiny spider mites can turn the surface of cantaloupe leaves yellow or brown, while the leaf undersides may be a silvery-gray spotted with yellow, orange or red. Mites can be controlled by spraying the cantaloupe's leaves with insecticidal soap or horticultural oil.
If swarms of tiny white insects fly up while you're weeding or when the cantaloupe plant is disturbed and the leaves are yellow, whiteflies are probably to blame. Whitefly problems often occur in tandem with sooty mold. Plants that are infested need to be removed from the garden
If the leaves are speckled with tiny flecks of yellow, squash bugs may be on the attack. Leaves will eventually turn all brown. These little brown bugs can be hand-picked off plants if there is a small infestation. Mulch provides protective cover for squash bugs, so it should be removed. Diatomaceous earth and pyrethrins can be sprayed around the base of the plant to control the pests.
Downy mildew causes yellow spots on leaf surfaces, while the undersides appear gray and fuzzy. To control downy mildew, remove old plant debris from the garden.
Air pollution can cause yellowing of cantaloupe leaves, particularly ones that are older and at the crown of the plant. Despite the discoloration of the leaves, the cantaloupes will develop and grow.
Too Much Manganese
Leaves can also turn yellow due to too much manganese in the soil. If soil pH drops below 5.4, plants take up too much of this micronutrient. Manganese is often found in fertilizers. If you suspect manganese toxicity, stop using fertilizer and test the soil's pH. If it is too low, apply lime or dolomite to the soil.