Sour cherry (Cerasus vulgaris) comes from Asia Minor and is a cultivated species resulting from the crossing of wild cherry (bird cherry) and dwarf cherry. Sour cherry fruit are small to medium size (about 1.5 cm in diameter), spherical, juicy drupes that are suitable for direct consumption, but are mainly intended for industrial and home processing. Sour cherries should be harvested when fully ripe and immediately delivered to customers. The earliest varieties ripen at the end of June, the fruits of late varieties are harvested even at the beginning of August. Sour cherries are not long-term cold-stored fruit.
Poland is one of the largest sour cherry producers not only in Europe but also in the World.
The best soil for growing sour cherries is sandy or sandy loam soil, with a pH of 6.2–6.8. Sour cherry does not tolerate heavy, wet and flooded soils. The groundwater level should be up to 1.5 m. Sour cherry trees grow well in sunny and warm sites. Sour cherry is a crop whose trees are quite resistant to drought – therefore they do not require regular watering (except in periods of prolonged drought). The roots of sour cherry trees are shallow and are sensitive to lack of oxygen, therefore periodic flooding is very dangerous for them. Sour cherry trees are relatively resistant to frost (they tolerate temperature drops to -30°C which depends on the variety). On the other hand, spring frosts are a particular threat due to early flowering (late April / early May).
To counteract the effects of frosts, fruit growers use various methods, including spraying trees with preparations that increase the concentration of mineral salts in plant cells, thanks to which they become more resistant to freezing (PLONVIT® KALPRIM, ALKALIN™ K+Si).
In stone trees – in contrast to pome trees – flower and leaf buds are formed separately. Stone trees first develop flowers, pollinate them, and simultaneously develop leaf buds.
Therefore, in stone trees it is very important to stimulate the best possible development of leaves (TYTANIT®, PLONVIT® NITROMAG, GROWON®), because when there are too few of them or they are not well developed, a significant drop of fruitlets may occur.
Obtaining an high yield and high-quality of sour cherry fruit depend on many biological and cultivation factors. One of them is the proper supply of trees with nutrients. Stone tree crops have greater nutritional requirements compared to pome crops. The selection of the method of fertilization of sour cherries and the dose of fertilizers should be adjusted to the condition and age of the trees and the soil’s fertility status, the level of which can be determined by chemical soil analysis.
An important supplement to soil fertilization is foliar plant nutrition. Its main advantage is the quick and effective supply of the most-required nutrients to trees at particular stages of development.
Presently, foliar treatments are an integral part of the mineral nutrition programs for sour cherry trees, because:
- support supplying plants with major nutrients: nitrogen (PLONVIT® NITRO or PLONVIT® NITROMAG), phosphorus (PLONVIT® PHOSPHO or PLONVIT® FOSTAR), potassium (PLONVIT® KALI or PLONVIT® KALPRIM), magnesium (MIKROKOMPLEX™) and sulphur (PLONVIT® SULVIT or PLONVIT® BOROSULF)
- provide plants with ingredients that are difficult to be taken from soil, e.g. boron (MIKROVIT® BORON TURBO or MIKROVIT® BORON)
- provide plants with ingredients that directly affect the fruit color and firmness: phosphorus (PLONVIT® PHOSPHO or PLONVIT® FOSTAR), potassium (PLONVIT® KALI or PLONVIT® KALPRIM)
- support supplying sour cherry trees with calcium, which is a low-mobility nutrient in the plant (OPTYCAL®, PLONVIT® CALCIUM TURBO – calcium increases the flexibility of the peel, reduces fruit cracking and increases their shelf life in market trade).
Sour cherries are less likely to crack than sweet cherries, but rains during fruit ripening and harvesting can cause such damage.
One of the methods of reducing cherry crops cracking is spraying trees with a solution of calcium fertilizer (PLONVIT® CALCIUM TURBO). There are recommended standard spraying each time directly before the expected rainfall or during rainfall.
Sour cherry is a crop that requires proper care after fruit harvesting, i.e. in the period from the end of harvesting to the end of vegetation in autumn (for a period of about 3 months).
- The first goal of these treatments is to keep the leaves in good condition on the trees, because premature defoliation (caused by diseases or nutrient deficiency) leads to tree weakness, a decrease in their resistance to frost and a significant drop in yield.
Therefore, first (after standard tree pruning), it is recommended to feed trees with nitrogen (PLONVIT® NITROMAG or PLONVIT® NITRO), magnesium (MIKROKOMPLEX™) and boron (MIKROVIT® BORON TURBO or MIKROVIT® BORON). In the next treatment, the plants should be provided with a set of NPK with microelements (PLONVIT® OPTY or PLONVIT® GEL) and magnesium (MIKROKOMPLEX™).
The foliar treatments with the use of copper products (MIKROCHELAT™ Cu-15) are also used to increase tree resistance to diseases.
- The second important goal of feeding sour cherry trees before winter dormancy is to enable trees to accumulate nutrients needed for their development in early spring.
In spring, low temperature limits the effective uptake of nutrients from the soil. Therefore, before the beginning of leaf discoloration, trees should be fed with a fertilizers containing zinc and boron (BORZIN ™TURBO) and potassium (PLONVIT® KALI or PLONVIT® KALPRIM).
These treatments are the first ones to prepare trees for the new growing season.
The good condition of sour cherry trees throughout the growing season determines the yield of cherries. Even short-term nutrient deficiency may have a negative impact on plant growth and yield. Therefore, it is necessary comprehensive assessment of the requirements of the plants at any stage of their development. This will allow them to be properly fed and biostimulated.
INTERMAG’s wide range of products, allows you to develop your own individual foliar fertilization and biostimulation program, considering local soil conditions, crop intensity, stage of plant development and availability of various products.
Particularly noteworthy are the highly alkaline line of fertilizers ALKALIN™, which, in addition to the basic functions of bringing in nutrients, have shielding properties for plants: ALKALIN™ K+Si, ALKALIN™ KB+Si, ALKALIN™ PK 10:20.
All of these discussed actions significantly affect the yield increase and its quality parameters.
