TOMATO - DISORDERS

LOW TEMPERATURE, PHOSPHORUS DEFICIENCY

Aetiology: low temperature, phosphorus deficiency
Importance: The leaves of plants, young ones in particular, turn purple when the temperature and/or the substrate is too wet.
Symptoms: Both leaves and stems get a reddish to purple tinge, particularly pronounced on the underside of leaves. If the unfavourable conditions persist, plants turn yellow and eventually may even die. These symptoms must not be confused with the initial symptoms of the stolbur disease, which usually appears much later in the field.

Treatment:

• increase temperature,
• use substrate with better structure and provide balanced nutrition.

Source: project number: HU/02/B/F/PP-136012

Treatment: There is no suitable solution.

CATFACES

Aetiology: low or very high temperatures during flowering and the early development of fruits
Importance: This disorder is relatively frequent especially at the beginning of the season. Fruits with more locules are more susceptible. Affected fruits are not marketable.
Symptoms: The irregular necrotic spots are found mainly on the apical part of the fruit, extending towards the basal part. The spots may be invaded by sooty mould in wet weather, but the mould does not cause them. Do not confuse these symptoms with those of calcium deficiency - see below.

Source: project number HU/02/B/F/PP-136012

Treatment:
- cannot be controlled under field conditions
- select less susceptible varieties

CALCIUM DEFICIENCY

Aetiology: Blossom and root

Source: project number HU/02/B/F/PP-136012

Slight calcium deficiency causes only light symptoms. In this case, the apical part of the fruit appears to be injured.

Source: project number HU/02/B/F/PP-136012

In the case of severe calcium deficiency, cells in the apex of the fruit collapse resulting in necrosis. Sometimes this necrosis is only visible inside the fruit. Necrotic spots may be invaded by sooty mould in wet weather. Plum-shaped fruits are more susceptible. As leaves and fruits compete for calcium, the fruits of more vigorously growing varieties may suffer more damage.

Source: project number: HU/02/B/F/PP-136012

Blossom end rot only affects the apex and its vicinity. Necrotic spots are usually round and slightly sunken. Catface may also appear on the apical parts, but its symptoms are usually not restricted to that zone only. The spots caused by catface are of irregular shape and extend to the upper parts of the fruit; their edges appear to be torn.

Sooty mould, though thriving on these spots, does not cause the disorder.
These symptoms must not be confused with those of catface.

Treatment
Liming does not always solve the problem. Instead, the conditions of calcium uptake should be improved:

• balanced irrigation (avoid water surplus or water stress),
• balanced fertilization (avoid excess nitrogen and other elements),
• application of foliar fertilisers containing calcium.

RUSSETING

Aetiology: low temperatures during fruit development, phytotoxicity of some pesticides.
Occurrence and importance: Russeting commonly occurs at the beginning or at the end of the season when temperatures are lower.
Symptoms:

Source: project number: HU/02/B/F/PP-136012

The skin of the fruit is rough and corky, with small cracks.
Do not confuse these symptoms with the cracking of fruits caused by erratic watering      conditions. In the latter case, the cracks run very deep and do not affect the skin of the fruit only.

Treatment: It cannot be controlled under field conditions.

POTASSIUM DEFICIENCY - YELLOW TOP

Aetiology: excessively low or high temperatures or great differences between day and night temperatures during fruit development, especially around maturation.  
Importance: Yellow top is a very frequent disorder, but the impacted fruits often remain marketable, because consumers usually do not recognize the damage.
Symptoms:

Source: project number: HU/02/B/F/PP-136012

The maturation of the upper part (around the calyx) is delayed and remains green or yellow even when the apical part is already quite ripe. Sometimes this symptom is only visible when the fruit is cut. The flavour of the damaged part is inferior.

Source: project number: HU/02/B/F/PP-136012

The picture illustrates the internal symptoms in the fruit.

SUNSCALD

Aetiology: sudden exposition to direct sunshine
Importance: Sunscald on leaves occurs relatively frequently after transplanting. Fruits are damaged much less frequently. Fruit damage usually occurs when the leaves covering fruits are removed by the grower or destroyed by some disease and the weather is sunny afterwards. Damaged fruits are unmarketable, though damaged leaves are soon replaced by new ones.
Symptoms:

Source: project number: HU/02/B/F/PP-136012

Relatively large, almost white spots appear on the fruit, usually on the upper parts. Their surface is firm and leathery.

Source: project number: HU/02/B/F/PP-136012

Spots on the leaves are whitish and have a papery appearance. Both on fruits and leaves, the spots have very sharp edges. The spots may be invaded by sooty mould in wet weather, but the      ty mould, does not cause the spots.

Treatment:

• proper hardening of transplants before planting,
• control of foliar diseases,
• do not remove the leaves if sunny weather is expected.