Symptoms
The older leaves become chlorotic, later necrotic, starting from the leaf edges.
At severe deficiency, the intercostal areas of the leaves may become chlorotic, too.
Whitish, necrotic dots develop within the chlorotic areas.
Reasons
Potassium deficiency on the leaves.
Excess salinity may cause similar symptoms, this can be controlled by measuring the electrical conductivity (EC) of the nutrient solution.
Tomato - Chlorosis
Symptoms
The older leaves become chlorotic, later necrotic, starting from the leaf edges.
At severe deficiency, the intercostal areas of the leaves may become chlorotic, too.
Light brown and whitish, necrotic dots develop within the chlorotic areas.
Reasons
Potassium deficiency on the leaves.
Excess salinity may cause similar symptoms, this can be controlled by measuring the electrical conductivity (EC) of the nutrient solution.
Tomato - Discolouration
Symptoms
Glasshouse grown tomatoes will often express potassium deficiency as blotchy ripening. When fruits turn red some areas around the peduncle remain green or yellow. The flesh underneath is hard and tasteless.
The symptoms are sometimes visible in field grown tomatoes, too.
Reasons
Potassium deficiency on fruits
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
Coenzyme functions
Protein synthesis
Stomatal function
Tugor potential
Sugar degree
Yara recommended fertilizers for Potassium
YaraMila™ UNIK™ 16
Tomato (field grown):
Apply 5 grams per hill at transplanting. 3-45 days after transplanting, apply 5-10 grams per hill. Repeat application after every 7 days thereafter.