Why are the leaves on my vine turning yellow with black spots?

What's likely going on

From the photo, the plant has:

• Many leaves turning yellow
• Dark, fairly round spots scattered across the yellowing leaves
• A vining or scrambling growth on a trellis

That combination strongly suggests a fungal leaf-spot disease (such as black spot or Cercospora leaf spot). These fungi thrive when:

• Leaves stay wet for long periods (overhead watering, frequent rain, poor air flow)
• The plant is crowded or growing in still, humid air

The yellowing itself is usually the leaf reacting to the infection; once a leaf is speckled and yellow, it won’t recover.

Nutrient problems or normal aging usually cause more even yellowing without so many dark spots, so they’re less likely here.

What to do

1. Remove affected leaves
   Using clean scissors, cut off the worst spotted/yellow leaves and any dead bits. Bag and bin them; don’t compost, as that can spread the fungus.

2. Improve air flow
   Gently thin out crowded stems so air can move through the plant. Make sure nearby plants aren’t pressed tightly against it.

3. Change watering habits
   Water at the base of the plant, not over the top. Water early in the day so any splashes can dry quickly.

4. Mulch the soil surface
   A light layer of mulch (dry leaves, straw, or bark) under the plant helps stop spores in the soil from splashing back up onto leaves.

5. Consider a fungicide only if it keeps spreading
   If, after pruning and better care, new leaves still get spots, you can use a fungicide labeled for leaf spot on ornamental plants (like a copper or sulfur-based spray). Follow the label carefully and keep pets and kids away until it dries.

How to prevent it

• Keep foliage as dry as possible. Drip or soaker watering is best.
• Prune lightly each season to keep the plant open and airy.
• Clean up fallen leaves around the base, especially after rain.
• Avoid heavy nitrogen fertilizer, which can cause lots of soft, disease-prone growth.

When to worry

• If new growth is also quickly spotting and dropping.
• If stems start to turn black, mushy, or crack.
• If several nearby plants develop similar spots.

In those cases, take a close-up photo of a few spotted leaves (front and back) and the stems, and check with a local nursery or extension service—there may be a more aggressive disease that needs targeted treatment.