Lettuce - Deformation
Symptoms
Tips and margins of older leaves get chlorotic spots with increasing size which become necrotic later on. On account of scorched leaf margins leaves are deformed.
With more severe deficiency the leaf color turns to mottled dark green and the plant appears wilted. Occasionally leaves are less crinkled than normal and shape of the leaves becomes more rounded.
Growth of the plants is restricted, they do not form heads or the heads remain loose.
Causes
Potassium deficiency
Symptomes may be confused with high salt concentration of the growing substrate. In this case the veins of the leaves become brown in addition to dry leaf margins.
Lettuce - Discolouration
Symptoms
Potassium deficiency causes longer main roots than normal and only few secondary roots. They show yellowish color. Often roots are slimy .
Causes
Potassium deficiency on roots
Lettuce - Deformation
Symptoms
Tips and margins of older leaves get chlorotic spots with increasing size which become necrotic later on. On account of scorched leaf margins leaves are deformed.
With more severe deficiency the leaf color turns to mottled dark green and the plant appears wilted. Maybe leaves are less crinkled than normal and shape of the leaves becomes more rounded.
Growth of the plants is restricted, they do not form heads or the heads remain loose.
Potassium deficiency causes longer main roots than normal and only few secondary roots. Often roots are slimy and yellowish in color.
Causes
Potassium deficiency on head and roots
Lettuce - Deformation
Symptoms
Tips and margins of older leaves get chlorotic spots with increasing size which become necrotic later on. On account of scorched leaf margins leaves are deformed.
With more severe deficiency the leaf color turns to mottled dark green and the plant appears wilted. Maybe leaves are less crinkled than normal and shape of the leaves becomes more rounded.
Growth of the plants is restricted, they do not form heads or the heads remain loose.
Causes
Potassium deficiency (right) compared to optimum supply(left)
Symptoms may be confused with high salt concentration of the growing substrate. In this case the veins of the leaves become brown in addition to dry leaf margins.
Lettuce - Necrosis
Symptoms
Symptoms of potassium deficiency start on older leaves. The leaf color turns to mottled dark green and the plant appears wilted. Tips and margins get chlorotic spots with increasing size which become necrotic later on. On account of scorched leaf margins leaves are deformed. On the photo necrotic areas appear along the main veins. More typical are scorched zones on the margins.
Occasionally leaves are less crinkled than normal and shape of the leaves becomes more rounded.
Causes
Potassium deficiency on leaves
Potassium deficiency made worse by
- Acidic soils (low pH)
- Sandy or light soils (leaching)
- Drought conditions
- High rainfall (leaching)
- or heavy irrigation
- Heavy clay (illite) soils
- Soils with low K reserves
- Magnesium rich soils
Potassium is important for
- Internal water regulation
- Vigorous growth and healthy foliage
- Required in large amounts
Yara recommended fertilisers for Potassium deficiency
YaraVita FOLIAR POTASH
Lettuce (field grown): 5 l/ha 14 to 20 days after the 4 to 6 leaf stage. Repeat if necessary at 10 day intervals. Note: Final application to be made at least one month before harvest. Water rate: 500 l/ha.
Read more about YaraVita FOLIAR POTASH