Filed in Gardening & Maintenance, Latest News, Pest control, Soil Health, The Environment on February 14, 2011 with 3 comments
Potential problems you may encounter with growing and caring for citrus.
An important aspect for your citrus tree is the area between the trunk and the drip line. This is the area where you want micro organisms to work and thrive, so avoid using any Herbicides, chemical sprays and fertilisers it this area. Instead hand weed or cut the weeds off at ground level with a sharp knife. Use natural food such as blood & bone, animal manures (I give mine chicken manure plus Fruit and Flower Power along with Bio Boost).
Now let’s look at some of the problems that can occur:
Aphids: usually clusters of black insects on young leaves. Spray with Neem Tree Oil and Key Pyrethrum to control.
Mealy bug: often the presence of black, sooty mould will be the first noticed signs. Small, mealy insects found in protected cavities. Spray with Neem Tree Oil and sprinkle Neem Granules under the tree and water in to kill the root mealy bugs.. You can also drench Neem Oil over the granules to make them more effective at the rate of 25ml per litre of water.
Scale: poor growth, pale dehydrated leaves will be noticed. Fruit will be small and dry.
The cause is hard scale-like insects on woody and green stems. Scale numbers build up in dry seasons, spray with Neem Tree Oil over summer months.
Leaf roller caterpillar: leaves tightly rolled and foliage and surface of fruit eaten. Spray with Neem Tree Oil as needed from October to March.
Soft wax scale: snow white, soft scale likely sooty mould present. Treat as Scale.
Thrips: show as silvering of foliage and fruit. Black spots of excrement maybe seen especially under leaves. Spray with Neem Tree Oil spray from November to March.
Spider Mites: leaves go yellow and hydrated. Minute insects under leaves. Common in hot dry weather, spray with Neem Tree Oil or Wallys Liquid Sulphur spray (but not these two products together).
Lemon tree borer: tree shows poor growth, are dehydrated and branches die. Holes can be seen in branches and sawdust indicates presence of borer. Remove infected wood where practical and burn, sprinkle Neem Tree Granules under the tree. Wrap felt pad soaked in Neem Tree Oil around base of trunk or affected branches. It is a good idea to fill in the borer holes with an acyclic paint. This prevents adults entering the holes and laying more eggs. It also means that it is easy to detect new holes and further problems. I have also solved the borer problem by injecting a strong solution of Neem Oil into the borer holes (50:50 ratio).
There are a number of diseases that can affect citrus trees also which are:
Citrus brown rot: fruit develops brown rot and drops from tree. Prune out lower branches of tree to increase air circulation, spray with Liquid Copper and Raingard.
Verrucosis/scab: irregular, grey, scabby, wart-like growth on fruit or stems. Spray with Liquid Copper at monthly intervals.
Brown Spot: spots on leaves, fruit and stems of mandarins. Common in damp weather. Spray with Liquid Copper, prune dead material and burn it.
Melanose: small dark, red-brown spots on leaves and fruit, often merging. Skin may crack. More common on older trees in warm humid weather. Prune off dead twigs and branches. Spray with Liquid Copper at monthly intervals.
Even if you have no known diseases present it is good practice to spray the trees with Liquid Copper and Raingard twice a year, spring and autumn for prevention.
Deficiencies in a tree maybe caused by lack of food, pale small leaves. Mulch with an animal manure based compost and blood and bone. Sheep manure pellets are very good also.
Lack of iron: light green leaves fading to pale yellow or white. Veins remain green. Apply mulch and Sulphate of Iron or use Bio Boost for feeding.
Zinc: new leaves small and narrow, growing close together. Spray foliage with Matrix Reloaded and apply Ocean Solids to the drip line.
Magnesium: older leaves yellow from outer edge and yellow area between the main veins on younger leaves. Spray foliage with Matrix Reloaded and sprinkle Fruit and Flower Power to the drip line.
Citrus trees are pruned only in late summer by removing total branches from within the frame work of the tree to open the tree up and allow for better air circulation. Do not trim off the ends of branches as this causes further branching and a denser tree. February or March is the best time when borer on the wing have finished for the season.
Citrus trees can be mulched in the spring to feed and conserve moisture through the dry months.
Mulches that retain soil moisture should be scrapped back as winter sets in so the soil can breathe and dry out faster during wet times. Remember that wet feet are the biggest killer of citrus trees.
During flowering and fruiting periods apply Fruit and Flower Power once a month. This will create fruit with great flavour and ample juice.
Lemon trees can be grown throughout New Zealand in home gardens, but in some areas, which are more exposed to hard winters than others, some little tricks are needed.
Most home gardeners know about protecting young citrus trees from air frosts with a tent of clear plastic or sprays of Vaporgard.
Gardeners can be tricked in winter by lemons and other citrus fruits which grow quite yellow or orange, appearing to be ripe. But usually the white pith is thick; lacking in juice the fruit can be dry. Sheer cold will turn green fruit a bright yellow/orange in some conditions on some soils.
Give the plant more warmth because there is some warmth in the low winter sun (if it can be trapped) and the fruit will ripen better. An almost total plastic enclosure, making a small glasshouse round the trees, is worthwhile if the gardener is serious about ripening fruit in midwinter. At the price of horticultural plastic these days it is not an expensive option either.