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Green Shoulders

Zvi Howard Wener is well know to farmers in Australia and New Zealand, and as an online crop consultant can be contacted through www.agrisupportonline.com
 

What are persistent green/yellow shoulders?
This phenomena occurs when tomato varieties with green shoulders undergo ripening but the shoulders remain dark green or turn to yellow but do not turn to red.

When does this happen?
This phenomena, can take place when the temperature of the fruit becomes very high. These high temperatures can result from the fruit being exposed to the sun during the stages of ripening. Frequently, when tomatoes are grown in very high temperatures, unexposed fruit can simply heat up and this phenomena will also occur.

Why does this happen? 
The chlorophyll in the green shoulder of the fruit is slow to break down during the ripening phase. The result is a patch that can remain green and may turn to yellow but will not turn to red. This happens on fruit that has been exposed to high temperatures during maturation and ripening.

 

Control 
1. When fruit is picked green and ripened in the dark there is no problem with the shoulders. If the problem is great then the tomatoes may be picked as mature greens and ethylene ripened in the dark. 

2. Use varieties that are resistant to this phenomena, either with or without green shoulders. 

3. Avoid causing the fruit to be exposed unnecessarily to the sun. Proper nutrition, pruning and de-leafing are the best protection against persistent green/yellow shoulders. The leaves protect the fruit from the sun and help create a favourable microclimate. Leaves should only be removed when it is necessary to facilitate the picking.

Russeting

Symptoms:
It is the appearance on the skin of the fruit of a number of small cracks which are often concentric.

Causes:
1.
When chemical sprays are applied in excessive quantities or under poor conditions, the cuticle can become more corky and as a result, less elastic. As the fruits grow, the cells are not elastic enough and small cracks start to appear.

2. Large variations in temperature, when daytime temperatures are high (accompanied by relatively low humidities) and night temperatures are low. The cuticle cells are not elastic enough to cope with the changes. 

3. Poor light intensity in the greenhouse caused by cloudy weather or even excessive shading with nets, whitewash or thermal screens. 

4. Low levels of Electrical Conductivity (EC) around the root system. 

5. Sensitivity varies with different varieties.

Control:
1. Use proper chemical concentrations when spraying crops. Spray only under proper conditions. Use the correct equipment. 

2. Use proper water management to control growth; water at fixed intervals and reduce when necessary. 

3. Apply a good fertilizer programme to avoid overly succulent plants. 

4. Keep leaves healthy for as long as possible by properly managing diseases and by supplying adequate fertilizers. 

5. Do not excessively remove leaves. Leaves create a micro-climate for the fruit which helps prevent russeting. 

6. Use varieties that may be more resistant to russeting.

 
 
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