by Sometimes, when growing tomatoes, gardeners encounter an incomprehensible problem: the “shoulders” (the upper part near the stalk) of the tomato remain hard and yellowish-green, although the rest of the berry ripens and turns red on time. Why does this happen?
Let’s say right away – there are certain varieties of tomatoes for which such uneven, “spotty” coloring of the fruit is normal (Stripe Herman, Black Crimea, Siberian Tiger, Indigo Blueberry, Geranium Kiss, Siberian Kiwi, Amethyst Jewel, Sergeant Peppers, Bison Black, Truffle, De Barao Black and others). In this case, there is no need to sound the alarm – everything is going according to plan, this varietal characteristic does not have any effect on the taste of tomatoes.
If such unripe yellowish, yellow-green, and sometimes frankly dark green areas and spots remain at the stem of tomatoes, which should be completely red, pink, orange or yellow when ripe, something has definitely gone wrong. Most often, large fruits on the lower brushes of tomato bushes “suffer”, as well as tomatoes with a low dry matter content. The pulp at the stem in areas under the greenish or yellowish skin remains hard, rough and unripe, the tomatoes lose their taste and attractive appearance.
Who is to blame and what to do?
Such uneven coloring of tomato fruits is most often associated with physiological disturbances in the development of the plant, and they are associated with errors in the cultivation of your favorite vegetable. And what kind of errors and how to try to avoid such a situation in the future, we will figure it out together.
So, partial unripening of tomatoes can be associated with several factors.
Degeneration of the variety
Many novice gardeners do not know that the variety fund of their tomatoes should be updated from time to time, purchasing new seeds from a trusted manufacturer. That is, even when you once purchased tomatoes of a particularly successful variety and year after year plant only the seeds collected from them, there is a high probability of its degeneration, the appearance of some “breakdowns”, undesirable signs.
This is especially true for varieties of so-called amateur folk selection, where selection based on qualities and characteristics is mostly chaotic and random, and characteristics are not properly fixed.
Of course, if your tomato plant has already produced numerous fruits with such light, unripened “shoulders”, it is especially not worth letting such tomatoes “go to seed”.
Poor soil and/or improper fertilizing
This is the most common and probable cause of light, unripe spots in the area of the tomato stalk.
In this regard, the uneven coloring of tomato fruits is primarily due to the imbalance of the amount of nitrogen and potassium in fertilizers and soil – namely, an excess of the former against the background of a deficiency of the latter. It is this combination at the time of filling tomatoes that gives the effect of their unripening, like green or yellow “shoulders”.
Both of these elements are, of course, needed by plants – but at a certain time and in a certain quantity.
Nitrogen is primarily responsible for the growth of green mass of plants and is involved in protection against pathogenic microorganisms. Potassium maintains the water balance of crops, promotes their drought and frost resistance, increases the shelf life of fruits and the plant’s resistance to diseases.
Let us recall that nitrogen fertilizers (ammonium nitrate, urea, carbamide, ammonium sulfate, manure, etc.), to which tomatoes are quite sensitive, are mainly applied in spring or early summer, necessarily being incorporated into the soil. Potassium fertilizers (potassium sulfate, potassium nitrate, potassium humate, potassium magnesium sulfate, wood ash, etc.) dissolve well in water and are usually applied to the soil in summer and autumn.
It is better not to use potassium chloride for fertilizing tomatoes, as chlorine inhibits this crop.
The same wood ash (can be combined with other fertilizers – chicken manure and rotted manure, superphosphate, eggshells, onion peels, etc.) is useful to add to the hole when planting tomato seedlings.
Sharp fluctuations in temperature and humidity during the growing period
Everyone knows that tomatoes do not tolerate over-watering – the bushes need to be watered only as the soil dries out. However, in poorly ventilated greenhouses, the air humidity often increases significantly, which the plants do not like. The same applies to sprinkling, which should not be used in the case of growing tomatoes – it negatively affects flowering, causes flowers to fall off, and delays the setting of fruits and their ripening.
Excessive soil and air humidity adversely affect the ability of this crop to fully absorb the necessary nutrients – as a result, you will get poorly ripening fruits with impaired pigmentation.
By the way, it is regular rains and/or excessively abundant and frequent watering that can literally wash potassium out of the soil, even if you added it additionally in the form of fertilizers – and we wrote above about the consequences of this for ripening tomatoes.
Another reason why tomatoes do not ripen and do not turn red at the stalk may be extremely high or low temperatures at the time of fruit filling. In many varieties of tomatoes, tissues that are constantly strongly illuminated (and heated) by sunlight lose the ability to form red pigments – and then those same yellow “shoulders” are formed. What is interesting is that even at low temperatures, pigments can form unevenly, creating a “spotty” color.
In addition to the very high values of temperature and humidity, the same problems described above can also be caused by their sharp fluctuations during the ripening of tomatoes.
Lack of lighting
Dense plantings and, as a consequence, insufficient lighting of some ripening plant clusters can also be the cause of delayed fruit ripening in general and the appearance of unripe light spots (yellow and green spots) in the area of the tomato stalk on such clusters in particular.
To ensure that all the bushes receive enough sunlight evenly, do not forget about the rules for planting tomato seedlings or about subsequent proper thinning of the plantings (if they have become too dense), about pinching the tops, about stepchildren, about removing excess leaves, about shaping tomato plants.
Prevention
So, if you have problems with the full ripening of tomatoes:
- Update your seed stock from time to time, buy varietal seeds of factory selection, not amateur selection, and in a proven place.
- Choose tomato varieties with a high dry matter content (sweet and fleshy), which are less susceptible to the vagaries of the weather – Finger, Revenge, Evgenia, Chernomor, Enchantress and more.
- Plant tomatoes in prepared fertilized soil.
- Do not plant too densely; carry out sanitary pruning of plants in a timely manner.
- Review your tomato plant feeding regimens – perhaps you should reduce the percentage of nitrogen in your fertilizers and at the same time increase the percentage of potassium.
- Maintain optimal temperature, lighting and humidity conditions for the crop.
It is also important to understand that similar color spots on tomato fruits can sometimes form in the initial stages of many fungal or bacterial diseases (cladosporiosis, anthracnose, late blight, alternaria, gray mold, etc.), but a competent gardener can easily distinguish them from unripened spots by the appearance of these spots, their dynamics, and accompanying symptoms.
