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Japanese Yam Leaves Turning Yellow: Causes & How to Fix It

Are the lower leaves of your japanese yam yellowing first, or the new growth? Are the veins staying green? The pattern of yellowing points to the cause: nutrient shortage, waterlogged roots, a virus, or sap-sucking pests.

Check these first

  • Does the yellowing start at the bottom of the plant or at the tips?
  • Are the veins still green while the rest of the leaf fades? That points to a nutrient deficiency.
  • Look under the leaves for tiny insects or white specks.

Most likely causes

From the pests and diseases recorded for this plant, the ones whose symptoms match, most serious first. Symptoms alone rarely confirm a cause, so use the linked page to check the signs and treatment.

Rust

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.

General description; not specific to this plant.

How to identify and treat: Rust

Leaf Spot

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.

General description; not specific to this plant.

How to identify and treat: Leaf Spot

Root Rot

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.

General description; not specific to this plant.

How to identify and treat: Root Rot

Other possible causes

  • Root-lesion Nematode — Elongated blackish brown necrotic lesions form on the root surface and fine roots rot away…

Other symptoms on this plant

What other growers did about it

A page like this one can tell you what japanese yam leaves turning yellow is and what to try. What it cannot tell you is what actually happened to someone who had it on the same plant, at the same point in the season, and what they did next.

Gadenin is a free garden journal built around that. You photograph the plant, tag what you are seeing, and the entries line up by date for each plant you grow.

  • Tag the problem and the app tells you how many other growers have logged the same thing on the same plant.
  • Growers who make their records public can be followed, so you can read what they did and how it turned out.
  • Next season your own entries come back at the same point in the year, so you check the plant before it starts.

Free on iPhone. Recording, tagging and reading public records cost nothing.

Read next

Photograph a yellow leaf next to a healthy one and log any feeding or watering changes. Comparing week to week tells you if the fix is working.

See what other growers did about it

Log it in the free Gadenin app and tag what you are seeing. Your photos line up by date so you can tell whether it is spreading, and you can see how many other growers have logged the same problem on the same plant, follow them and read what they did next.

Free on iPhone. Android coming later.

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