Cucumber Mosaic causes mottled dark and light green, crinkled leaves. The disease is more noticeable on young leaves. Old leaves have V shaped dead areas extending from the leaf margins to the middle vein. The cucumbers are mottled, warty and misshapen.
Cucumber Mosaic is favored by poor weed control, as many weeds act as a host to the virus. The disease is also spread by aphids and cucumber beetles. There is no chemical control.
As is the case with other cucumber diseases such as Bacterial wilt, Beetles and other pests can be prevented from feeding on them by enclosing the cucumber vines in fine mesh wire enclosure or cheese cloth tents supported by a framework as soon as they emerge in the spring.
Bioneem, Insecticidal soap or Pyrethin based products are registered to manage cucumber beetles. The Cheesecloth method won't help much with aphids as they are too small but insecticidal soap and other methods will.
Leaves turn dull green, the vines and finally the whole cucumber vine wilts and dies. When the stem is cut and squeezed a sticky, stringy ooze comes out.
Bacterial Wilt is spread by cucumber beetles and some varieties of Flea Beetles. Cucumber beetle migration and feeding is favored by dry weather. The disease is favored by temperatures between 50 and 70 degrees and frequent dews. Prevent its occurrence by controlling the beetles.
Beetles and other pests can be prevented from feeding on cucumbers and foliage by enclosing them in a fine mesh wire enclosure or cheesecloth tents supported by a framework as soon as they emerge in the spring.
The cheesecloth is stretched over the frame and its lower edges weighted with stones or soil to prevent beetles from crawling underneath. The cheescloth tent should be removed as soon as the vines becomes well established.
Bioneem, Insecticidal soap or Pyrethin based products are registered to manage cucumber beetles.
A fungal disease which infects a wide array of plants, Cucumbers being no exception. There are several species of the fungus Botrytis which can cause blights; the most common is Botrytis cinerea. Botrytis infections are prominent following, wet spring and summer weather . Gray mold (A common name for Botrytis blight ) can be particularly damaging when rainy, drizzly weather continues over several days.
Botrytis blight can affect leaves, stems, crowns, flowers, flower buds, seeds, seedlings, bulbs, and just about any other part of a plant with the exception of the roots.
Control: Avoid overcrowding the plants and refrain overhead watering, where wet soil splashes onto the foliage. Drip systems are preferable. Prune away and discard diseased tissue. Maintain healthy plants by locating them properly, fertilize at the right time of year with the proper nutrients, and keep a 2-3-inch layer of mulch around the base of the plants. Fungicides are available, Bonide Remedy Fungicide has proven effective against against Botrytis Fruit rot.
Any fungicides registered for grey mold control must be applied before infection takes place, they won't cure an existing infestation. If you've had problems with gray mold in the past apply fungicide before the infestation gets to the plant.
Powdery Mildew causes a white powdery growth on leaves and stems. Infected parts turn yellow, shrivel and vines are defoliated prematurely. [Image 3] Yield is greatly reduced and cucumber quality is poor. The disease is prevalent in humid weather with frequent dew and temperatures between 70 and 90 degree
There are a number of products which can be utilized to control and or eradicate Powdery Mildew
Fungicides for the Treatment of Powdery Mildew.
Angular Leaf Spot
During warm, wet weather, bacterial angular leafspot can cause serious yield and quality loss to cucumbers. The bacterium, also infects zucchini, squash, and many varieties of Melon.
Resistant varieties are available. The code on the seed Packet that represents Angular Leaf Spot is ALS.
Try to limit the use of overhead irrigation, drip systems are better. Pick the cucumbers when the vines are dry to prevent further spreading. Copper Containing Bactericides are used to treat Angular Leaf Spot.
It maintains a "protective" coat on the foliage and fruit. Few strains of the pathogens are resistant.
Not really a disease, but it can render a cucumber crop unpalatable The bitterness that is sometimes noticed in cucumbers is because of a substance known as cucurbitacin. Cucurbitacin is a toxin that is believed to play a role in cucumber disease resistance. The higher the concentration of this substance, the more intense the bitter taste. A very high concentration of cucurbitacin can cause a painful stomachache. Bitter Cuke Syndrome (I made that up ) is usually triggered by some environmental stress or Nutrient Disorders ,and there is no real treatment. It is generally not recurring if proper gardening practices are adhered to.
Blossom End Rot
Blossom end rot is caused by a calcium deficiency. Calcium Deficiency can also can cause yellowing, pale and curling leaves, and stunted growth.
Generally the first visible sign sign of blossom end rot is a depressed rot spot on The end of the cucumber. Once the fruit shows signs of end rot, it's advisable to get rid of it. You can also cut off the end of the fruit to try and salvage the rest, just be certain there are no secondary opportunistic fungus or mold present. To salvage the developing cukes You should start applying blossom end rot spray to help protect future fruits.
Cucumbers Turning White
If you planted standard green cucumbers and they turn white instead you have a problem. See -Why Cucumbers Turn White