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When growing petunia, a grower may encounter various problems, such as chlorosis. This disease has different causes, but in any case it harms plants. Information about what causes petunia chlorosis and how to combat it will be useful to those who grow seedlings or adult plants.
What does chlorosis look like in petunia and why is it dangerous?
Healthy specimens have green or dark green leaves and stems. Characteristic signs of the disease are gradual yellowing of the leaf blades, while the veins of the leaves remain their natural color. Over time, they curl and die, new ones grow small, and the tops dry out. Chlorosis can also affect the root system. Growth and development slow down, and if measures are not taken, it may die.
The disease can affect both seedlings and adult plants, that is, it can be encountered at any period of their growing season. What chlorosis of young petunia seedlings looks like can be seen in the photo.
Chlorosis usually affects young leaves first.
Types of chlorosis
This disease causes a disruption in the formation of chlorophyll in leaf cells, which inhibits photosynthetic processes.The plant cannot produce substances important for itself, which affects its development and growth. Chlorosis cannot be considered a harmless disease. Without treatment, petunias, especially young ones, may die.
Chlorosis can be infectious and is caused by microorganisms, viruses and fungi. Pathogens enter plants through damage left by insect pests. This type of disease occurs in petunias, but not as often as the functional one.
Reasons for appearance
Functional chlorosis is the result of an imbalance of mineral elements in plant tissues, especially iron, magnesium, nitrogen, zinc, and proteins. The reason may be a deficiency of these components in the soil or a shift in soil acidity towards increasing or decreasing, which makes the elements unavailable for absorption by the roots, even if they are present in the soil. In most cases, this petunia disease is caused by precisely these reasons.
Treatment of petunia chlorosis should begin with determining which element is missing in the soil or determining acidity. The cause of deviations is most often the incorrect use of fertilizers. Many widely used fertilizers, for example, ammonium nitrate, urea, superphosphate, potassium and phosphorus - oxidize the soil, sodium and calcium nitrate, phosphate rock, ash - alkalize. If you get too carried away with any of them, it may turn out that the acidity will be impaired. The same applies to microelements; a deficiency of any of them can be caused by excessive or, conversely, insufficient use of certain fertilizers.
In the case of petunia seedlings and flowers growing in pots, the cause of chlorosis may be an insufficient volume of substrate in which each plant is located, excessive watering when the soil becomes sour, or high room temperature.
You should also pay attention to the water that is used to water the petunias. Ideally, it should be distilled, that is, have a neutral reaction. Tap water is considered alkaline due to the trace elements dissolved in it. This also needs to be taken into account when trying to create optimal conditions for plants.
The likelihood of developing chlorosis will decrease if petunia grows in a spacious pot
How and how to treat chlorosis in petunia
Methods of treatment are watering at the root or spraying with fertilizer solutions that contain the necessary element. Moreover, foliar application works faster than root application, because microelements, absorbed with moisture into the leaf tissue, begin to be used by them immediately.
The best preparations for chlorosis in petunia are those in which the elements are in chelated form. Of these, iron and other elements are absorbed faster and completely. You can buy chelates in a store or make your own. They are sold in liquid form and in small volumes, just convenient for use in the household.
Here's an example of how to make chelated iron at home:
- Dissolve 8 g of iron sulfate in 2 liters of clean (preferably distilled) water.
- In another 2 liters of liquid, dilute 5 g of citric acid.
- Add iron sulfate to the acid solution, constantly stirring the entire liquid.
- Add another 1 liter of ordinary water to the four liters obtained.
You will get 5 liters of chelated fertilizer.The mixture should be transparent, without sediment, and orange in color. It must be used immediately after preparation. The fertilizer must not be diluted. If more is needed, a fresh batch should be prepared. Homemade iron chelate is not effective for long - its shelf life is no more than 14 days. The frequency of spraying is 2-3 times a week until recovery, then for prevention - 1 time a week.
If the cause of chlorosis is in alkaline soil, which can be determined after checking the acidity level, it is necessary to acidify it in order to move the indicators in the right direction. To do this, you need to water petunia seedlings or adult plants with a weak solution of citric acid. Preparation process: dissolve 3-5 g of powder in 10 liters of water and water the flowers as usual.
You can reduce acidity by using ash, phosphate rock, calcium or sodium nitrate. Prepare solutions in accordance with the concentration standards offered by the manufacturers of these fertilizers.
Chelates are the best form of fertilizer that can be used to feed petunias.
Prevention
To prevent chlorosis in petunias, you need to correctly select fertilizers that can be used for feeding, and ensure that the concentration of solutions is within normal limits. Fertilizers should also be applied according to recommendations, no more often and no less often than required.
Instead of synthetic fertilizers, you can use ash for fertilizing; it contains almost all the necessary elements, except nitrogen.
To reduce the likelihood of developing chlorosis in petunia seedlings, you need to take care even when sowing the seeds: choose pots for the plants of such a volume that they do not feel a lack of nutrients until transplantation. Adult flowers should also not grow in small containers; on average, 1 petunia requires at least 3 liters of substrate. If the soil is depleted, you need to transplant the plants into a new soil mixture and increase the volume of the pot. For irrigation, use settled tap water, well water, rain water or melt water. Water so that the liquid does not stagnate.
To prevent infectious chlorosis, you need to disinfect equipment, pots, substrate, seeds with fungicides or at least 1% Bordeaux mixture. If the disease does develop, you need to immediately water the soil with fungicides and spray the plants at the same time. Treatments should be carried out until the petunias show no signs of disease. To prevent diseases and damage from pests that can spread diseases, you must remember to do preventive spraying with fungicides and insecticides. It is not necessary to use agrochemicals right away; first, using folk remedies is enough.
Varieties resistant to disease
Resistant varieties are those that belong to the multi-flowered group, for example, “Fantasy”, “Avalanche”, “Mirage”, “Plamcrystal”. Large-flowered petunias are more susceptible to the disease - “Pikoti”, “Hit Parade”, “Pearl Pirouette”.
Multi-flowered petunias are considered chlorosis resistant
Conclusion
Petunia chlorosis can affect plants at any time during their growing season if errors are made in feeding or creating growing conditions. The fight against this disease must begin after identifying the causes of its occurrence. Without help from the grower, petunias will not be able to recover on their own, which will lead to their death.
