What is Wrong with my Lemon Tree? Expert Answers to Top Asked Questions

It is most likely that your orange tree needs fertiliser. Citrus trees require feeding on a regular basis in order to grow well. Feed your tree with a balanced citrus fertiliser every couple of weeks and see if the tree improves. If you live in a cold climate it may be better if you overwinter your tree in a warm greenhouse.

When citrus fruit split and inside flesh is exposed it can be due to lack of nutrients such as copper and calcium, moisture stress, frost and general health of the tree. This often happens when a tree receives a sudden soaking of water particularly after a long dry spell. Citrus trees require plenty of water while the fruit is developing, so ensure that the tree receives sufficient watering. Good nutrition, and application of lime around the tree every few years will help prevent fruit splitting. If soil is alkaline, add gypsum rather than lime.

This sounds like scale insects and sooty mold. The scale insects feed on new growth by sucking the sap and exude a sticky, sugar substance called honeydew. This accumulates on the leaves and feeds the black mold. If left untreated, the insects and mold weaken your tree. If you control the insects you will stop the mold. To do this, spray the tree with pest oil every 6 weeks until the infestation clears.

This is caused by the citrus leaf miner insect. These minute insects feed by tunnelling their way through the leaves. They do not usually cause a problem for large trees but it is best to treat younger trees. Prune off the infected growth and then spray the tree with a pest oil every 3 weeks during summer and autumn, making sure to cover the top and underside of the leaves.

Some citrus varieties tend to bear fruit well one year and little or no fruit the following year. This is also referred to as biennial bearing habits’. Varieties such as Valencia oranges, mandarins and kumquats are alterative. The condition may be influenced by factors such as nutrition and water supply. To reinstate regular bearing of fruit, prune during the ‘on’ year when a large crop is expected and ensure good feeding and watering and you may receive a more regular harvest.

The citrus gall wasp insect has caused the swelling on your branches. It attacks all citrus, but lemons, grapefruit and the Rough lemon suffer most. The wasp is only about 2mm long and shiny black in color. It lays eggs in soft new shoots and as the hatching larvae feed, they cause the infected tissue to swell gall. In spring, adult wasps emerge from the gall. Galling reduces tree growth, and when new shoots become galled, leaf and fruit production is severely affected. Cut off the galls and destroy them by the end of winter before the wasps emerge in spring and lay eggs in the new shoots.