Chlorosis prevents a plant’s leaves from producing sufficient chlorophyll. Once affected, they discolour and turn pale, yellow, or yellow-white…
Chlorosis most commonly occurs when leaves do not have enough nutrients to synthesise all the chlorophyll they need. The plant cannot then manufacture the carbohydrates it needs through photosynthesis and may die unless the cause of its chlorophyll insufficiency is treated…
Causes of Chlorosis
Although unusual in hedging plants, should symptoms appear the most likely causes are:
• Waterlogged roots due to poor drainage
• Damaged and/or compacted roots
• Overuse or misuse of pesticides and/or herbicides which are commonly formulated to cause chlorosis in target weeds
• A mineral deficiency in the soil. A lack of iron, magnesium, nitrogen or zinc is probable
Other, less likely causes include:
• Deficient nitrogen and/or proteins
• A high soil pH that prevents roots from absorbing minerals
• Exposure to sulphur dioxide
• Ozone injury to sensitive plants
• An attack by bacterial pathogens
Treatment for Chlorosis
As the plant’s decline is gradual, there is usually enough time to remedy the situation.
Waterlogging. With hedging plants, first check for waterlogging, a main cause of Chlorosis. If this appears to be the case, check and clear the drainage holes of smaller containers and stand them on feet or bricks. If they are too heavy to lift, remove as much compost as you can without damaging the root system and replace with dry compost. If the plants are in the ground, dig channels from the plant to help the water flow or leech away. If the soil is clay or generally heavy, dig in organic matter around the plants once the water has gone.
Mineral Deficiency: If drainage is good, the problem is most likely to be a mineral deficiency, probably triggered by a high soil pH. Apply a proprietary feed containing iron (as a chelate or sulphate), magnesium, nitrogen and zinc.