Plant Doctor Archive

Fruit drop

I have an orange tree which had heaps of little oranges growing well. One morning when I came out most of the oranges were on the ground — do you know what may have caused this? There is a lemon tree and a grapefruit tree planted next to the orange and they have not suffered like this; also it is sheltered from the frost. I live in Canterbury.

Fruit drop is usually caused by dry conditions, over fertilising, or it could be something unique to some varieties. Over summer, if the tree went through a period of drought, especially during flowering and fruit set, this could lead to fruit drop. A surge of rapid growth due to an over zealous application of fertiliser can also lead to fruit dropping off.

Some citrus varieties are more prone to fruit drop than others and in the first few years after planting, before trees are established, it is quite common. Frost can also cause fruit to fall in the early stages.

To prevent fruit drop:

• Protect plants from frost with frost cloth;
• Mulch plants in early spring and again in late winter with bark, compost, straw or similar well-rotted organic material;
• Water regularly, especially during dry periods and during flowering and fruit set;
• Feed plants in late winter and late summer with a specially blended citrus fertiliser at the recommended rate. Water in well. Avoid feeding citrus in autumn in your region as this will encourage soft new growth that will be cut back by frost.

Advice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

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