Infinite Gardening

At first, I only noticed the holes.

Several leaves on my balcony raspberry had small, irregular gaps, but I could not see what was causing them. The plant was still full of berries, so the damage was easy to dismiss at first.

Then I turned one of the leaves over.

The damage was easy to spot, but the cause was hidden underneath the leaves.

The larvae were hiding under the leaves

On the undersides were small, pale-green, caterpillar-like larvae. Based on their appearance and the feeding damage, they were most likely raspberry sawfly larvae.

Their colour matched the leaves so well that I found them only after checking each leaf from below.

The plant kept producing

Some leaves had been badly eaten, but the berries were untouched.

I have grown this ‘Maurin Makea’ raspberry in a fabric pot on an open balcony in Finland. It has survived three Finnish winters outdoors, and this year it has produced its largest crop so far.

The damaged leaves made the problem look more serious than the harvest suggested. The berries continued to ripen, and I did not find larvae in the fruit.

What I am doing now

I removed the most heavily damaged leaves, but I did not remove every leaf with a hole. I also thinned the new growth and kept around six or seven of the strongest canes for next year. Once the current fruiting canes have finished producing, I will remove them.

Now I inspect the undersides of the leaves every day. A new hole tells me where to look, and any larvae I find are removed by hand.

Raspberry sawfly larvae can drop into the growing medium and overwinter in cocoons. Because this pot has a bark mulch layer, I plan to remove the old mulch and top up the pot with fresh potting mix. This may remove some possible hiding places, but I will continue checking the plant rather than assuming the problem is gone.

For now, daily checks and hand removal are enough. The leaves show clear damage, but the berries remain untouched.