Japanese Yam Growing Guide: Planting, Care & Harvest

Dioscorea japonica

Growing calendar

Typical timing for central Japan (Kanto region). Shift it for your own climate, and record your actual dates.

JanFebMarAprMayJunJulAugSepOctNovDec

Sow / plantGrowingHarvest

Guides

Common problems

Start from what you can see on the plant.

Wilting Yellow leaves Leaves dying Leaf spots Fruit problems

Pests and diseases (29)

Problems recorded for this plant, most serious first.

Brown Leaf Spot

Disease

Small light brown to gray-brown spots form on the leaves and enlarge into irregular lesions. When they merge the whole leaf dies and plant vigor drops sharply.

Rust

Disease

Small raised orange-yellow to red-brown pustules form on both leaf surfaces, then rupture and release powdery spores. Heavy infection yellows the leaves and kills them early.

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.

Anthracnose

Disease

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.

Bacterial Soft Rot

Disease

The crown or the head becomes water-soaked and soft, then collapses into a slimy mush. The rotting tissue gives off a distinctive foul odor.

Root-lesion Nematode

Pest

Elongated blackish brown necrotic lesions form on the root surface and fine roots rot away. Above ground the stand is uneven and plants stay small with pale foliage.

Root Rot

Disease

Fine roots rot brown to blackish brown, growth stops and the lower leaves yellow. The plant wilts easily in the daytime and eventually dies outright.

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.

Gray Mold

Disease

Water-soaked brown lesions form on flowers, fruit and leaves, densely covered by a fuzzy gray mold. Fruit rots and drops, and decay continues in storage after harvest.

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.

Necrotic MosaicNorthern Corn Leaf BlightScabStubby-root NematodePythium RotMosaic DiseaseTyphula Snow BlightPlant-parasitic NematodesZonate Leaf BlightPink RootBacterial RotLeaf BlightFoliar NematodeLeaf Blemish DiseaseUnderside Sooty SpotBrown Spot Root RotBrown RotBlue MoldBlackening Disorder

Written byYasuGrowing vegetables and fruit in Chiba, Japan, and building Gadenin. Corrections are welcome. 15 years of growing.