High Temperature

High Temperature, High Temperature Damage, Extreme Temperature, Sun Scald, Heat Canker

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Sun scald orchid leaf
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Extreme temperature does not complement plants well. In particular, intense sun and high temperatures can cause a handful of disorders in plants. Sunscald is when the sun shines directly on plants for a prolonged period, causing tissue temperatures to rise, or too much water is lost from the plant before its replaced. Sunscald is a disorder which affects thin-barked trees such as beech, cherries, maples or poplars. Fruits can also be affected by similar causes; tomatoes, gooseberries, apples and pears are some of the first affected fruits. Greenback can arise when the fruit of trees are exposed to strong sunlight, resulting in brown burnt parches on the crop. In addition, high temperatures can cause heat canker in woody plants, and a similar disorder called 'strangles' in root veg and other leafy plants.
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Symptoms

Dead patches of bark may be evident on trees such as beech, cherries, maples or populars.
Sometimes the whole South facing side of tree bark can be killed.
Fruits can also be scalded, producing patches of red-brown on fruits.
Fruits can develop green-yellow papery patches.
Bulbs left in the sun can be damaged, and may prevent flowering when planted.
The foliage of indoor and outdoor plants can become scorched if left in direct sunlight for too long.
Hot soil can damage the stem bases of plants, resulting in canker.

Prevention

Please note: with every 18°F increment, the amount of water lost by plants is doubled. For this reason, during hotter periods of the year, the temperature should be monitored closely and irrigation adjusted accordingly. Try not to water during the hottest periods of the day. It's been proposed that water droplets can act as a magnifying glass, focusing light from the sun on a small surface area. It can sometimes be possible to purchase plants resistant to some of the disorders mentioned.
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Knowledge and advice

Search our ever-growing knowledge base to find plants and information. Find out about pests and diseases you should be keeping an eye out for. Watch How to videos or follow step by step guides for tasks in the garden. Free download for your phone or tablet.
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