Blotchy ripening, spotted ripening or chocolate in the language of farmers is one of the problems that spread in tomato fields cultivated with some varieties that are susceptible to light, especially during the winter growing season and during short days, long nights and low temperatures. Consequently, this problem negatively affects and reduces the price of tomatoes in the market. Since marketable yield is more important than the total yield, physiological problems such as “blotchy ripening” often have minimal effects on the total yield but can significantly reduce the marketable yield, putting the grower at risk. Hence the importance of the farmer’s awareness of how to identify the problem of tomato coloration, the factors that contribute to its development, and the steps that can be taken to reduce its occurrence.
Blotchy Ripening Symptoms
Poorly colored areas of irregular shape appear on the surface of tomato fruits affected by blotchy ripening with no clear separating border between them and the rest of the surface of the fruit, which is normally colored in the characteristic color of the cultivated variety. These areas vary from small scattered spots to large areas covering the surface of the fruit.
What are the most important causes of blotchy ripening on tomato?
1- Low heat, high humidity, poor lighting
Symptoms of infection on tomato fruits increase when the fruits are exposed to low temperatures (where the fruits do not color well at a temperature less than 10 degrees Celsius), poor lighting, or shading, especially at high relative humidity. A large percentage of infection has been observed in cluster fruits. Primary, in which the shading is increased by the vegetative growths of tomato plants.
2- Tomato varieties
There are varieties of tomatoes that are highly sensitive to the symptoms of irregular ripening when grown in conditions that favor the emergence of this physiological symptom.
3- Lack of nutrients
Deficiency of potassium, boron, and an imbalance in nitrogen fertilization increases the symptoms of irregular ripening on tomato fruits … Iron deficiency, which is an important factor for the formation of lycopene pigment
4- Increasing the nitrogen fertilization rate at the expense of potassium fertilization, which leads to an increase in vegetative growth and an increase in the shading rate, and thus a decrease in the formation of the red lycopene pigment.
5 – Increasing the irrigation rates for what the plant needs and the type of soil.
6- Increasing the salinity of the irrigation water at times beyond the appropriate limit.
7 – Excessive use of growth-promoting hormones such as gibberellins and cytokinins.
8- Do not spray with sulfur, which greatly stimulates the coloration.
9- Infection of tomato plants with Tobacco mosaic virus causes them to produce fruits that show symptoms similar to those of irregular ripening (spotted – stained).
How to overcome blotchy ripening?
1- Cultivation of the appropriate tomato variety.
2- Applying balanced fertilization programs:
A good, balanced fertilization program must be applied; To feed tomato plants, in which all factors determining the cultivation of tomato plants are taken into account, and focus on adding potassium in the appropriate balanced quantities.
3- Follow an appropriate irrigation program:
Work must be done to add the appropriate amounts of irrigation water according to the factors regulating the irrigation programs, and to avoid increasing the ground moisture for a long time under and around the plants.
4- Not to use growth regulators and plant hormones, except within the narrowest limits.
5- Rationalizing the use of pesticides, especially copper compounds, especially during the coloring stage of fruits.