Citrus trees were an integral part of an Australian backyard and still have an important place in today’s garden. Not only does the Vitamin C in their fruit protect against colds and flu in the colder months, citrus are also highly productive. Citrus trees don’t require a lot of attention throughout the year (they can be virtually neglected, and still weigh down their branches with fruit, season after season) and they are a fruit most children enjoy, especially mandarins.
Try incorporating some citrus trees and chooks in your backyard to create a mini ecosystem, and a great source of interest for your kids. In Don’s own garden he has planted citrus trees next to the chook shed. The tree roots have grown under the shed to get at the continuous supply of rich chook manure. Additionally, the chooks act as mobile compost heaps, devouring all the kitchen scraps and adding manure to the soil. They also help clean up pests.
Best citrus varieties
Mandarins: Mandarins are fast health food – they peel easily and cleanly, and are not at all messy. Their sweetness makes them a great favourite with kids, and of all the citrus trees, the ‘Emperor Mandarin’ would be the finest addition to your backyard.
Oranges: While many people love the taste of Navel orange juice, the seedless Valencia is also great for juicing and has fewer problems. It is the better growing tree for backyards as it crops over a longer period.
Lemons: The ‘Eureka’ lemon is great for the warmer areas in Australia, while ‘Lisbon’ or ‘Meyer’ lemons suit cooler climates. Of all varieties, the ‘Meyer’ is the best choice for planting in a tub in any climate (Diagram 1).
Lime: ‘Tahiti’ produces very juicy fruit, and is used in drinks or as a lemon substitute. The fruit is small and green when ripe, and seedless.
Cumquat: The ‘Nagami’ cumquat with its oval shaped fruit has a sweeter taste than other cumquats and is very decorative to look at on the tree. Another good container plant in a small garden.
- Full sun.
- Before planting, dig in plenty of chook, cow or horse manure into the ground.
- Ideally, citrus should be fertilised in August and February. It is good to alternate fertilisers – say Dynamic Lifter in August/September and Complete Citrus Food in February.
- Keep citrus trees well watered when young fruit is forming in spring and early summer. Use a sprinkler twice a week to deep water trees in the warmer months.
- Grass and citrus don’t mix. Keep the area beneath your citrus free of grass and weeds. Cover with a mulch such as lucerne, composted leaf litter or compost, but keep the mulch away from the tree trunk to avoid collar rot.
Citrus in pots
- Trimmed and rounded citrus trees in pots are one of the main components of the fashionable Mediterranean or Tuscan garden. They have the added advantage of being able to be moved from place to place to enjoy the sunshine.
- Ensure that citrus in pots are well watered – once or twice a week in warmer months.
- Fertilise every six to eight weeks with a complete citrus food, alternated with Dynamic Lifter or use 3-4 month Osmocote applied in spring and early summer.
Citrus trouble shooting
Sour oranges. May be caused by:
- harvesting the fruit too early (leave fruit longer on the tree).
- insufficient sunlight (it may be necessary to replant your tree in a sunnier position or remove surrounding growth to allow more sun to reach the tree particularly in winter).
- nutrient deficiency (treat the soil around the tree with a matchbox-full of copper sulphate. If that fails, try spreading a small handful of super phosphate about the root zone in spring).
- Older leaves that yellow in the centre may be an indication of magnesium deficiency. Treat the soil around the tree with epsom salts (magnesium sulphate).
- Leaves that yellow at their tips can indicate a lack of fertiliser (use a complete fertiliser).
Dropping fruit. Caused by:
- strong winds during flowering or shortly after while fruit is forming.
- too much water or too little (at flowering or while fruit is forming). To remedy this, check drainage if soil too wet, or put the sprinkler on twice a week to give adequate water.
Bronze orange bugs (also known as stink bugs) and other sap sucking insects. The larger insects such as bronze orange bugs can be removed by hand, or by using a vacuum cleaner (with a disposable vacuum bag). These insects can squirt an irritating substance, so take care to protect your eyes and skin. Alternatively, spray with Pest Oil or Folimat (in an aerosol can).
Citrus gall wasp: Lumps on the branches are caused by little wasps. It does not kill the tree but remove any bits of the tree with lumps. Dispose of these in the garbage. Affects coastal Queensland and New South Wales and some inland areas (see maps). Prune galls by the end of August to control this pest (Diagram 2).
Citrus scab. Lumps and brown scabs on the skin of citrus (particularly lemons) are symptoms of a disease called Citrus Scab but not one that affects the fruit.Remove the scabs if using the rind or just use pulp or juice. Ignore the disease, or treat by spraying with a solution of copper oxychloride and white oil around October to get rid of the disease before scabs form.
It is not necessary to prune citrus to produce fruit. The trees can be pruned however if it is necessary to shape them in some way, for example to remove low hanging branches, or to remove branches that are rubbing and can cause bark damage and allow an entry point for disease. Use secateurs (for small branches) and a pruning saw (thicker stems) for the task. Tip: Make a small cut underneath the branch first then cut through from the top. This will stop the bark tearing.
Citrus may also require pruning if too heavy a crop is produced. A heavy crop can weigh down branches to the point where they can break, especially after heavy rain. In this situation either remove some of the fruit to lighten the weight or cut out some of the smaller branches. The heavy crop can be avoided again by removing some of the young, developing fruit before it gets too big. The tree will then produce larger fruit.