Common Name: Lemon.
Etymology: Citrus: From Latin where it referred to either the plant now known as Citron (C. medica) or a conifer tree (Thuja). This may be due to perceived similarities in the smell of citrus leaves and fruit with that of cedar. limon: Old French word for citrus fruit.
History: The Lemon is thought to have originated in Assam a region in north eastern India. Citrus has a long history of cultivation and it is a generally accepted view that the roughly 170 (hybridized) species today arose from three primordial Citrus species—Citrus medica (citrons), Citrus maxima (pumelos), and Citrus reticulata (mandarins). The Lemon is a cultivated hybrid derived from Citrus medica (citron) and Citrus × aurantium (bitter orange) bitter orange, itself, being a hybrid derived from Citrus maxima (pumelos), and Citrus reticulata (mandarins). Lemons entered Europe via Italy no later than the turn of the century. We know they were around during Ancient Roman times as they are depicted in paintings from Pompeii destroyed by that was destroyed Mount Vesuvius in 79AD. It was introduced to Persia, Iraq and Egypt around 700AD and distributed widely through the Mediterranean and Arab regions between 1000 and 1150AD. The Lemon was brought to the Americas in 1493 by Christopher Columbus and through the New World by Spanish conquest. James Lind (Scottish physician 1716-1794) experimented with seaman, suffering with scurvy, in 1774 and wrote a book ‘A treatise of the scurvy’ that described citrus and in-particular lemon as the best cure for the disease. The first substantial cultivation of lemons in Europe began in Genoa in the middle of the 15th century but, interestingly, of the roughly 13,000,000 tonnes that is produced today, India (where it all began) still produces the majority.
10 Uses of Lemons: Lemons are an excellent source of vitamin C which is one of the most important antioxidants in nature. They also contain smaller amounts of the B vitamins, particularly B1, B2, and niacin. Vitamin C travels through the body neutralizing any free radicals with which it comes into contact with both inside and outside cells. For this reason it reduces inflammation in the body that cause the symptoms of osteoarthritis and rheumatoid arthritis. It also strengthens the immune system reducing the likelihood and severity of colds and flu’s and is associated with the reduction in the risk of death from heart disease, stroke and cancer.
- Can be used in a multitude of recipes for cooking and refreshing drinks.
- As a marinade for meats (acid helps break down meat so other flavours can penetrate it).
- Blood purifier and blood pressure reduction.
- Breath freshener.
- Hair and nail lightener.
- Making ‘Corona’ beer taste better.
- Mild cleaner and grease remover.
- Reduces risk of developing Kidney Stones.
Basic description: Tree, can grow up to 10 meters but usually much smaller. The branches are thorny and form an open crown. The leaves are green, shiny, and elliptical-acuminate. Flowers are white on the outside with a violet streaked interior and have a strong fragrance. On a lemon tree, flowers and ripe fruits can be found at the same time
Lemon requirements & maintenance: pH 6-7 (slightly acid – neutral), large variations on this can cause vital nutrients to be locked out or over-supplied. Full sun position, citrus trees are best grown in warm to hot climates with a mild winter in well drained soils. They will tolerate extremely hot weather provided adequate water is supplied and mature trees will tolerate short periods low as -5 degrees Celsius with minimal damage. They do not like high winds and have a low salt tolerance.
Growing season: All year round although fruiting may vary depending on variety.
- Alfalfa (adds nitrogen to the soil).
- Clover (adds nitrogen to the soil).
- Dill (attracts beneficial predatory insects).
- Fennel (attracts beneficial predatory insects).
- Lemon balm (attracts beneficial insects).
- Lucerne (adds nitrogen to the soil).
- Marigolds (covers tomato smell from eating insects).
- Mint (attracts beneficial insects).
- Nasturtium flowers (attracts and traps aphids).
- Parsley (attracts beneficial predatory insects).
- Peas (adds nitrogen to the soil).
- Thyme (attracts beneficial insects).
- Yarrow (attracts beneficial predatory insects).
Problem Solving without chemicals:
- Armilaria root rot: fungus growth under bark and toadstools growing bottom of trunk. Clear native bushland thoroughly two years prior to planting lemon tree and if present in existing tree, remove and burn tree, do not replant in area again.
- Aphid: Small black sap sucking insect 1mm-2mm usually clustering around new growth. Spray with soapy water, White oil, Neem oil or blast off with hose. Introduce predatory insects such as ladybirds, hover-flies and lacewings. Ants will discourage predators so need to be controlled as well.
- Collar rot: Gum oozing from bark at bottom of trunk followed by wet patches and later becoming brittle and splitting effectively ring-barking tree. Improve circulation near trunk by remove any smaller plants growing near trunk, improve drainage and avoid watering directly on trunk. Soil should never be built up on trunk or near graft.
- Copper deficiency: Dark brown gum pockets on young shoots & shoot dieback. Peel may be brown, with gum stained areas. Fruit splitting more likely. Copper becomes less available in alkaline soil so adding organic matter will increase microbial activity and decrease pH.
- Crusader bug: Wilting and death of young shoots and flower heads caused by sap-sucking only. Remove bugs by hand, this will be easier when they are nymphs. Where gloves to protect yourself from foul-smelling fluid bugs produce when disturbed.
- Fullars rose weevil: Small greyish-brown weevil (7mm long) that chews ragged holes around the edges of leaves and also attack buds and shoots. Removal by hand.
- Fruit fly: In summer flies lay their eggs in small groups just beneath the skin of the fruit, larvae make their way to centre of fruit and destroy it. Fruit will be full of maggots and inedible. Burn and destroy all fruit or seal fruit in plastic bag and leave in the sun for several days. The ‘Cera Trap’ and ‘Eco-Naturalure are new and effective organic fruit fly baits.
- Gall wasp: Large calluses or gall on tree branch. It is caused by wasp (size only 3mm) laying eggs under bark of new shoots and emerging 9-12 months later as adults. There is no reversal or cure. Avoid high nitrogen fertilizer in spring that produces soft new growth perfect for egg laying, fertilize in late autumn or winter, remove all new galls that don’t already have exit wound, yellow (attractive to wasp) sticky traps can be used from late winter but these can also catch beneficial insects and even small birds.
- Iron Deficiency: Yellowing of new leaves, can even go from yellow to white in extreme cases. Low winter soil temperature, poor drainage and high pH.
- Leaf miner: Thin blister-like lines under leaf surface. Remove leaf when spotted. Spray new growth with white oil (until new growth matures and goes hard) as a preventative.
- Lemon scab: Scabby irregular, slightly raised growths on fruit, leaves and twigs, grey or pinkish at first and becoming darker with age. Spread easily by rain and overhead sprinklers. Apply copper fungicide to whole of infected area up to 25% growth when it becomes resistant (copper spray although considered organic will damage plant if used during hot dry weather and is highly toxic to aquatic life).
- Manganese deficiency: Magnesium deficiency produces a very distinct yellowing towards the apex of the older leaves, with a triangular area remaining green at the leaf base. Check pH to ensure it is not too acid.
- Mealybug: Oval shaped white to pink insects. Spray with white oil, squash by hand or introduce preditory insects like ladybirds and lacewings Avoid any type of chemical as it will do a better job at killing preditory insects than the mealybug.
- Mites: Deformed leaves at tips of shoots, deformed flowers and fruit, ‘Eureka’ lemon is the most commonly attacked. Spray tree in mid winter and again in Summer with wettable sulphur.
- Nitrogen deficiency: Yellowing of leaves beginning in older leaves, can happen towards end of winter or early spring when plants nitrogen levels are low and soil is cool. Add nitrogen rich fertilizer to correct problem.
- Phosphorus deficiency: Reduced growth, older leaves will loose their deep green colour. Leaves are small and narrow with purplish or bronze discoloration, leaf shed, fruit drop, limited flowering and fruit yield (fruit will be coarse and rough in texture with a coarse, thick rind and a hollow core). Phosphorus will become unavailable in very acid soils and leached out in high rainfall areas. Correct pH, add (P) water-soluble fertilizer.
- Potassium deficiency: Hard to recognise, symptoms include slow tree growth, small leaves and heavy leaf fall, leaves turning yellow or bronze, weakened twigs and decreased bloom. Fruit are small; the skin is thin and smooth, tends to colour early, and splits easily. Add organic ‘sulfate of potash’ (Muriate of potash tends to be cheaper but the chlorine it contains can hurt the helpful microbes living in your garden’s soil).
- Scale: Small black, brown, pink or white insects that have either a hard or soft outer shell and attach themselves (usually) to underside of leaves (in veins) and along branches. Use White-oil at recommended dose on bottle, control ants that also help spread them.
- Spined citrus bug: Has projecting horns on either side of its head, the young change colour from yellow to orange and then green. They attack the fruit, causing shedding of the young fruit and dry patches in mature fruit. Control by hand picking.
- Thrips: Adults are very small (1-2mm) straw-colored or black slender insects with two pairs of feathery wings. They damage the plant by sucking resulting in leaves turning pale, splotchy, and silvery before dying. They also scrap at fruit, flowers and leaves. Injured plants are twisted, discolored, and scarred. They can be controlled by removing and disposing of infected foliage and flowers, spray with Neem oil.
- Zinc deficiency: A yellowing between the veins of new leaves, veins may turn yellow particularly at the tips. Zinc can be added as a trace element in a foliar spray or as part of a kelp solution spray. Soil may be too alkaline.
Growing lemons: Majority of Lemons that you purchase from your local nursery will be grafted onto suitable root stock so ensure you cut off any growth that appears below the graft. The popular varieties for growing in Australia are ‘Eureka'(4m tall, does better in warmer climates, relatively few seeds, fruits all year round and virtually thornless),’ Lisbon’ (3-4m tall. It is cooler climate tolerant, hardier to drier conditions and fruit is less likely to be damaged by wind due to fruit growing towards middle of tree. It does have thorns, more seeds and doesn’t fruit all year round) and ‘Meyer'(2m tall, the most cold tolerant but does equally well in tropics, excellent for pots and relatively sweet fruit but has an inferior zest).
- What Garden Pest and Disease is That (Judy McMaugh)
- Yates Garden Guide.