Gadenin日本語Get the app
Citrullus lanatus
Growing calendar
Typical timing for central Japan (Kanto region). Shift it for your own climate, and record your actual dates.
Guides
- Planting Watermelon: Soil Warmth, Spacing and How Much Room One Plant Needs
- Training Watermelon Vines: Pruning Runners and Growing Up a Trellis
- Watermelon Pollination: Hand Pollinating and Why Fruit Drop at Golf Ball Size
- Watermelon Problems: Wilt, Anthracnose, Beetles and Split Fruit
- How to Tell When a Watermelon Is Ripe: Ground Spot, Tendril, Sound and Days
- Watermelon Growing Calendar: From Sowing to Cutting the First Fruit
Common problems
Start from what you can see on the plant.
Pests and diseases (43)
Problems recorded for this plant, most serious first.
Gummy Stem Blight
MajorDisease
Gray-brown lesions form at stem nodes and the crown, exuding brown gum and splitting lengthwise. Round to V-shaped brown lesions form on leaves, dotted with small black fruiting bodies.
Fusarium Wilt of Cucurbits
MajorDisease
Part of the vine wilts during the day and eventually the whole plant dies. The stem splits lengthwise near the soil and exudes gum, and the vascular tissue is browned when cut.
Cucurbit Leaf Beetle
CommonPest
Circular and arc-shaped feeding scars, as if drawn with a compass, line the leaves. On young seedlings the leaves can be eaten away entirely, badly setting back growth.
Watermelon Mosaic Virus
CommonDisease
Leaves show a yellow-green mosaic, crinkle and stay small. Vine extension is poor and fruit shows faint color mottling and deformity.
Cucumber Green Mottle Mosaic
CommonDisease
Dark green blotches and raised mosaic appear on the leaves. The fruit surface becomes mottled and the flesh discolors, spoiling the flavor.
Anthracnose
CommonDisease
Light brown to dark brown round lesions with sharp margins form on leaves and fruit, slightly sunken in the center. In wet weather salmon-pink slimy spore masses ooze out on the lesions.
Vine Overgrowth
CommonDisorder
Leaves grow large and dark green and the vines keep running vigorously, but no flowers or fruit set. In sweet potato the tubers fail to bulk up.
Sunscald
CommonDisorder
The sun-facing side of the fruit bleaches white to pale yellow, then dries into a sunken leathery patch. Rot organisms enter easily through the damaged tissue.
Fruit Cracking
CommonDisorder
Radial or concentric cracks open around the shoulder and calyx of the fruit. Rot organisms enter through the cracks and the fruit spoils quickly.
Blossom End Rot
OccasionalDisorder
The blossom end of the fruit turns water-soaked, then dark brown, and sinks in. It is most common on fruit in the sizing stage, and secondary rot often follows.
Zucchini Yellow Mosaic
OccasionalDisease
Strong yellow mottled mosaic appears on the leaves, which become narrow and shredded in shape. Fruit is knobbly and lumpy, twisted and bent.
Bacterial Spot
OccasionalDisease
Small water-soaked spots appear on the leaves, later turning brown with yellowing around them. Fruit develops water-soaked or scabby spots from which rot spreads.
Melon Yellow Spot Virus
OccasionalDisease
Numerous small yellow spots appear on the leaves and later turn necrotic so the leaf dies. Growth stalls and fruit fails to size up or sweeten.
Powdery Mildew
Disease
White patches appear scattered on the upper leaf surface at first, then the whole leaf is coated in a white powder. Leaves later yellow, brown and die back, and reduced photosynthesis cuts growth and yield.
Late Blight
Disease
Dark green water-soaked lesions appear on the leaves and expand quickly into brown dead tissue. White mold forms on the underside and at the lesion edge, and dark brown lesions spread to stems and fruit.
Cucumber Mosaic Virus
Disease
New leaves show a yellow-green mosaic, crinkle, and the whole plant becomes stunted. Fruit colors unevenly and grows misshapen.
Sclerotinia Rot
Disease
The crown, stem or head rots in a water-soaked way and is covered in white cottony mycelium. Black sclerotia later form inside and on the surface, and the plant wilts and dies.
Southern Blight
Disease
The stem rots at soil level and white silky mycelium spreads over the crown and the surrounding soil surface. Brown sclerotia the size of rapeseed then form and the plant wilts and dies rapidly.
Root-knot Nematode
Pest
The plant wilts in the daytime and does not recover with feeding or watering. Pull it up and the roots carry beaded chains of galls of varying size with few fine roots.
Verticillium Wilt
Disease
Only one side of the lower leaves yellows and wilts, and the symptom moves up the plant. Stem vascular tissue turns pale brown and the plant dies without ever growing well.
Leaf Spot
Disease
Small round brown to gray-white lesions appear on the lower leaves, the centers turning gray with tiny black specks. As they multiply the leaf yellows and drops early.
Downy Mildew
Disease
Pale yellow to yellow-brown angular lesions form on the upper leaf surface with a gray-purple mold in the matching spot underneath. Lesions merge, the leaves die back and the plant declines early.
