Cucumber diseases are usually found on the leaves first, and farmers can learn to distinguish them by observing the leaves in cucumber planting, so as to prevent them in advance and achieve the goal of increasing cucumber production and income.

(1) cucumber downy mildew

cucumber downy mildew

Green, yellow and irregular spots appear in cotyledons of cucumber downy mildew at seedling stage, and there is a gray-black mold layer on the back of leaves when humidity is high. The mature stage of cucumber generally starts from the middle leaf and spreads upward and downward. Light green water spots appeared on cucumber leaves. After expansion, the spots are polygonal and yellow-green. Then it turns light brown, and the diseased spots of cucumber turn into patches in the later stage, and the whole leaves of cucumber shrink. When the humidity is high, a gray-black mold layer will also appear on the back of cucumber leaves.

(2) Fusarium wilt of cucumber

Fusarium wilt of cucumber

Cucumber Fusarium wilt in seedling stage, the stem base turns yellow-brown or the whole plant withers, mostly in the form of sudden collapse. In the adult stage of cucumber, at the beginning of cucumber Fusarium wilt, cucumber leaves wilted gradually from bottom to top, which seemed to be short of water, especially at noon, and returned to normal sooner or later. In the later stage, the whole cucumber leaves withered and drooped, and never returned to normal.

(3) Fusarium wilt of cucumber

Fusarium wilt of cucumber

Cucumber seedlings were tender and dark green, like soft rot in water, and finally the whole cucumber died. During the adult stage of cucumber, the diseased leaves produced dark green waterlogged spots, which later expanded into nearly round diseased spots. When the humidity is high, the whole leaf will rot quickly.

(4) Cucumber powdery mildew

Cucumber powdery mildew

At the early stage of cucumber disease, small white powder spots are produced on the front or back of cucumber leaves, which gradually expand into contiguous white powder with obvious edges and finally become grayish white or reddish brown. Cucumber leaves will turn yellow and brittle, and generally will not fall off.

(5) cucumber anthracnose

Cucumber anthracnose

At seedling stage, semi-circular brown spots appeared on the edge of cucumber cotyledons, which were slightly concave. At the adult stage of cucumber, the diseased spots on the leaves are nearly round and have different sizes. At first, they were soaked in water and soon dried to reddish brown, with yellow halo on the edge and concentric black spots on the lesion. When wet, the pink sticky substance overflows, and when dry, the diseased spot is cracked and perforated.

(6) Bacterial angular leaf spot of cucumber

Bacterial angular leaf spot of cucumber

In cucumber seedling stage, round or nearly round water-soaked pits appeared on cotyledons, which gradually turned brown and dry. At the adult stage, the lesion on the front of cucumber leaves was light brown, and the lesion on the back was polygonal due to the restriction of vein. At first, it was flooded. In the later stage, the lesion on the back of cucumber leaves is milky white pus, which is brittle and easy to puncture, leading to the fall of cucumber leaves.

(7) Cucumber virus disease

bpyv，cgmmv，cmv，wmv 2，zymv

At the seedling stage of cucumber, cotyledons turned yellow and withered, and young leaves of cucumber were uneven and mottled with dark green and light green, and gradually developed into dark green and light green mosaic. The diseased leaves are small, shriveled and tend to roll down, cucumber leaves become hard and brittle, and cucumber plants are short. In the later stage, the lower leaves of cucumber gradually turned yellow and died.

(8) Cucumber leaf blight

Cucumber leaf blight

At the beginning of cucumber injury, it was small round spots with water stains. After expansion, there are concentric wheel marks at the front of the diseased spots, and several diseased spots often merge into large spots, which makes cucumber leaves curl or the whole plant fall off a large number of leaves.

(9) Cucumber scab

Gourd scab

After cucumber leaves were damaged, wet spots appeared, which gradually turned into light brown spots and finally fell off to form perforations.

(10) cucumber brown spot disease

Cucumber brown spot

Chlorotic spots appeared in cucumber leaves at the initial stage of injury, and then gradually developed into polygonal to irregular necrotic spots, grayish white to yellowish brown, with obvious edges or halo. In the later stage, the diseased spots are sunken, and when the humidity is high, grayish brown to light black mold is produced on the surface, and multiple diseased spots are connected, resulting in premature aging and death of leaves.

The above are the manifestations of ten common cucumber diseases on cucumber leaves of farmers who grow cucumbers, but remind farmers to be careful when distinguishing cucumber diseases, otherwise several diseases are easy to make mistakes.

Sometimes in a cucumber field, even on the same cucumber leaf, several diseases will occur at the same time, that is, we often say that cucumber diseases are mixed, so farmers must be careful when distinguishing cucumber diseases.