What Is Cane Blight on Blackberries?

Cane blight is a fungal disease caused by Leptosphaeria coniothyrium that produces dark brown to black lesions at the base or along the length of blackberry canes, followed by sudden wilting and death of the cane above the lesion. The disease enters through wounds — pruning cuts, insect damage or mechanical injury — and the infected cane often wilts suddenly in summer during the season it was expected to fruit. If a healthy-looking cane suddenly collapses at the base, cane blight is the most likely diagnosis.

Symptoms of cane blight

The first visible sign is often a dark brown-black discolouration at the base of a cane or at a pruning cut, spreading up and around the cane. The cortex (outer bark layer) may show small dark fungal pustules on the surface of the lesion. Above the lesion, the leaves wilt suddenly and the cane dies rapidly — typically over a few days. The wilting is fast and complete, distinguishing it from slow nutrient-deficiency yellowing.

Cutting out infected canes

Cut out infected canes as soon as you identify them, cutting well below the lesion into clean, healthy wood. If the lesion extends to the base, cut the cane out at ground level. Disinfect tools before and after the cut. Remove cut canes from the site — do not leave them on the ground as they continue to produce spores that can infect other canes. Burn or bag the removed material.

Prevention

The most important prevention is tool sterilisation. Clean pruning cuts also help — ragged cuts from blunt secateurs create a larger wound surface and are more susceptible than clean cuts from sharp tools. Avoid pruning in wet conditions if possible, as the fungus enters and spreads more readily when surfaces are wet. Make sure cut ends are clean and slanted to shed water.