Problems of Cucumbers

How To Use This Problems Section
The chart is organized to give you a quick and dirty summary of the possible symptoms that you may encounter. Those problem causes for which we have full files will be linked to those files. Those causes with no link will have a paragraph below the chart helping you deal with that particular problem.

Problems of Cucumbers
SymptomsProbable Causes
Cucumbers Taste BitterVarious Plant Stresses
Leaves Pale; Turning YellowNitrogen Deficiency
Foliage Curls; Puckers; Turns YellowAphids
Holes in Leaves; Stalks; and StemsCucumber Beetles
Large Ragged Holes in LeavesSlugs
Wilted; Dried-up LeavesSquash Bugs
Sudden Wilting of PlantsSquash Vine Borers
Flowers and New Fruits DamagedPickleworms
Water-soaked Spots on LeavesAngular Leaf Spots
Leaves Turn BlackAnthracnose a fungal disease
Plants Wilt QuicklyBacterial Wilt
Downy Purple Spots on LeavesDowny Mildew a fungal disease
Yellow-Green Mottling of LeavesYellow Mosaic Virus
White Spots on Undersides of LeavesPowdery Mildew a fungal disease
Sunken Green Spots on CucumbersScab

Cucumbers Taste Bitter Because Of Various Plant Stresses

Stress factors such as inconsistent watering, low soil fertility, diseased foliage, and hot temperatures can cause some cucumber varieties to produce excessive amounts of a natural chemical that makes the fruit taste very bitter. The solution is to try to avoid stressful conditions for your plants or use varieties advertised to be mild tasting (and there are many). Consistent watering is probably the most important corrective.

Once a plant starts producing bitter fruit, pull it out--the rest of the fruits will be bitter, too. However, sometimes the worst part of a bitter cuke is in the 2 inches of fruit nearest the stem. Discard that part and the rest of the cucumber may taste just fine. Or, peel the entire cucumber before eating it; most of the bitterness lies just beneath the skin.

Leaves Pale, Turning Yellow Because of Nitrogen Deficiency.

If the leaves on your cucumber plants are pale and turning yellow, especially the lower leaves, the soil may be lacking in nitrogen. Also check for stunted growth and undersized leaves. Fruits may be pointed at the blossom end. To quickly solve this problem, spray your plants with dilute fish emulsion or another liquid fertilizer.

Water-soaked Spots on Leaves Caused By Angular Leaf Spot

Cucumbers infected with angular leaf spot disease develop water-soaked spots that turn tan and gray, and then drop out, leaving ragged holes. Rounded spots form on the leaves and may exude thick ooze. Fruit may be covered with cracked white spots. The infection will spread into the seed cavity, making the fruit inedible. There is nothing you can do except immediately remove and destroy infected and surrounding plants. Resistant cucumber varieties include Bounty, Carolina, Liberty Hybrid, Score, Stokes Early Hybrid, Sweet Slice Hybrid, and many others.

Yellow-Green Mottling of Leaves Caused By Yellow Mosaic Virus

This virus disease is spreading throughout the U.S. Symptoms of mosaic in cucumbers include a yellow-green mottling of the leaves near the growing terminals, a similar mottling of the fruit, misshapen fruit and stunted plants. (The fruits can be eaten with no ill effects.) Mosaic cannot be cured. Remove and destroy infected and surrounding plants. Control aphids and cucumber beetles, because they spread mosaic. The following weeds also carry mosaic: bittersweet, chickweed, ground cherry, horse nettle, jimson weed, mints, nightshade, pokeweed, ragweed, and wild cucurbits. Resistant cuke varieties include Burpee Hybrid, Burpee Pickler, Bush Champion, Challenger, China, Comanche, Dublin, Early Set, Gemini Hybrid, High Mark II, Marketmore 70, Pacer, Pot Luck, Saladin, Salty, Slicemaster, SMR, Spacemaster, Spartan Dawn, Tablegreen 65, and Victory.

Sunken Green Spots on Cucumbers Caused By Scab

Cucumbers infected with scab develop water-soaked spots on leaves, which may cause them to wilt. Stems may develop small cankers. Young cucumbers develop slightly sunken gray spots. As the plant matures, these spots darken and deepen, and develop a greenish velvety mold. Scab cannot be controlled, so remove and destroy infected plants.
Resistant Varieties. - Bounty, Calypso, Carolina, County Fair, Early Triumph, Gemini Hybrid, Highmoor, Lucky Strike, Maine No. 2, Burpee's M & M Hybrid, Marketmore 80, Northern Pickling, Pacer, Salty, Salvo Hybrid, Slicemaster, Spacemaster, Victory Hybrid, Wisconsin SR 6, and Wisconsin SR 10.