Trouble shooting Citrus

No fruit

Failure of trees to set fruit may be due to lack of water, lack of fertiliser, lack of sun or lack of bees for pollination. In dry conditions immature fruit may fall from the tree. If the tree is only producing fruit every second year, try removing some of young fruit to channel some energy back into tree growth.

Yellow leaves

Most likely due to lack of food. Apply citrus fertiliser. Yellow or pale leaves may also be due to poor drainage, nutrient or pH imbalance in the soil, cold weather or sucking insects.

Leaves dropping

Poor drainage, lack of water, lack of food or too cold.

Blackened or white leaves and stems

Frost damage Black coating on leaves Sooty mould on the foliage is the work of sucking insects, such as aphids, white fly and scale insects whose sticky honeydew excretions feed the mould. If you kill the insects you get rid of the sooty mould. Spray with a mixture of soapy water and oil, neem oil, or an easy-to-use product such as Yates Bug Oil or Tui Insect Control. Ants, also feed on the honeydew, and will nurture and protect the aphids.

Puckered curling leaves

Sucking insects such as aphids. See above.

Scabby ‘warts’ on fruit

Citrus scab (verrucosis) is a fungus that spreads in damp conditions. Mainly a problem in humid climates, it generally only affects the skin of the fruit and can be prevented by spraying with copper in spring and early summer.

Holes in branches

Borer beetles burrow into the wood leaving telltale sawdust in their wake. Prune and burn infected wood and avoid unnecessary pruning in spring.