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Plum Tree Leaf Spot and Fruit Drop in New Zealand

A 60-year-old plum tree dropping leaves with circular yellow spots during fruit set suggests a fungal disease (like shot hole or bacterial spot) exacerbated by stress. Heavy cropping can stress the tree, making it susceptible.

Immediate Steps

Collect affected leaves and take to a local horticultural advisor or Ministry of Agriculture office for lab diagnosis.
Thin fruit to reduce stress—remove 30-50% of developing plums.
Rake and destroy fallen leaves to reduce inoculum.
Ensure adequate water and nutrition.

Long-Term Care

Old trees benefit from rejuvenation pruning over several years, proper fertilization, and disease-resistant rootstocks if replanting.

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