All over New Zealand, Citrus trees can be commonly found in the backyards of many homes. However, these trees are not without challenges as they often suffer from pest attacks and diseases. For a healthy citrus tree and great fruit crops, it is important to know how to treat them, what signs to look for and how best to feed them.
A citrus tree is said to be deficient in iron if it has yellow leaves with darker, green veins. This disease is commonly known as chlorosis. It is a common disease that is particular to trees where the nature of the soil is alkaline.
The best time to check a citrus tree for magnesium deficiency is in Autumn. Citrus plants require magnesium in large quantity. This is because magnesium is an essential nutrient for the formation of green leaves (chlorophyll) in leaves. Citrus plants will not be able to produce sugars and starches without possessing enough magnesium which can lead to poor growth.
Magnesium deficiency is usually more prominent during the autumn season because it is highly required for the development of fruits while many citrus species are known to produce fruit over the cooler months. Due to the high mobility of magnesium in citrus plants, magnesium can be easily withdrawn from older leaves to tender ones that are just springing up when there is a shortage of this essential element.
Chlorosis is majorly treated with iron chelates. Ensure to follow the packet instructions to mix it. After the solution has been properly mixed, pour it into a sprayer and spray the foliage. Changes should be observed within 3 – 4 days in a warmer climate. Preferably a watering can should be used to apply treatment for a large tree by watering around the tree’s root zone. Before applying the iron chelates, ensure to remove any ground cover that can be found around the roots of the tree.
Sometimes lack of fertilizer or overwatering can cause yellowing foliage. If the problem is not corrected, total defoliation can occur. Since citrus plants are heavy feeders, they require a continuous steady source of nitrogen so they can be productive and healthy. Perform regular fertilizing of the plant according to the stipulated directions. A higher amount of fertilizer is essential in any fertilizer ratio that should be applied.
Alternaria Brown Spot
Another cause of leaf yellowing in a citrus plant is Alternaria brown spot. It’s a fungal disease that affects shoots and young leaves of various citrus trees. Leaves tend to develop yellowish halos around brown spots. For treatment, apply copper fungicides when the leaves are expanded by half in spring while a second treatment would be required when the foliage is fully expanded. This treatment process may be regularly required from September through to December for effective results.
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