Blueberry plants care.
Watering blueberry bushes
If you decide to set transplants of high-bush blueberry on your site, be sure to keep the planting hole moist, not allowing its drying. If you have only a few blueberry bushes, it is very convenient and effective to use a watering pot. Thus you will not wash out the mulch as during watering with a hose under high pressure. Soil moisture should be 60-70% of the total water field capacity. In the country, water blueberry bushes 2 times a week using one bucket of water per mature bush twice a day (preferably in the evening). Abundant watering is required in July and August, because at this time blueberry yields and sets flower buds of the further yield. In case of non-enough moisture, you will lose the yield significantly, not only for this year, but for the next year as well.
If the outside air temperature is high within several days, then, besides watering, spray the bushes after 4PM to cool them. Spraying reduces the overheat stress and increases the photosynthetic rate.
Mulching blueberry bushes
Mulching represents a coating of the ground surface around the plant with different materials to preserve moisture in the topsoil. Blueberry bushes can be mulched with straw, leaves, pine needles and – even better – with decomposed pine sawdust or bark. Mulch layer can be from 4 to 15 centimeters.
With mulching you get rid of weeds and create optimal conditions to maintain optimal humidity of the substrate, wherein blueberry bushes grow. Because of the mulch layer buds come out later in the spring, which helps blueberry withstand winter and spring temperature fluctuations.
When mulching blueberry bushes with fresh sawdust, an intensive consumption of nitrogen from the soil, which blueberry needs, occurs. Because of this, blueberry bushes start growing poorly. Therefore, before mulching apply double nitrogen fertilizer to the soil (for spring mulching; do not apply nitrogen fertilizers for winter mulching).
Mineral nutrition and fertilizer application:
High-bush blueberry requires mineral fertilizers. The amount and composition of the applied fertilizers should be determined based on the soil characteristics on each country site.
Determination of lack or excess of fertilizer elements during blueberry bushes inspection.
At sufficient amount of nitrogen, plants have relatively large dark green leaves and strong growth. At deficiency of this element, the growth of shoots decreases at the beginning, then old leaves become yellowish-green. At significant nitrogen deficiency, the plant becomes yellow-green, its leaves ting a kind of red color, the growth is slowed, the berry yield and size are sharply reduced. Young shoots that grow at nitrogen deficiency have a distinct pink color, and after the growth cessation they become pale green.
Excess nitrogen causes the active growth of shoots, which lasts until late autumn. As a result, the shoots have no time to ripen and lignify, which bring to their freezing over or death during winter. Quite often manufacturers overfeed the blueberry transplants with nitrogen trying to accelerate their growth. As a result, shrubs look very high and are sold as a 3- or 4-year shrub, but, in fact, it is a 2-year shrub. This is not dangerous, but such shrubs/bushes can be lost during winter or a part of shoots can significantly freeze over. It is very simple to determine the overfed bushes in October-November, when all qualitative bushes have a beautiful decorative look: foliage is red. The overfed bushes have green or dark green leaves and shoots. Have you met such bushes?
At phosphorus deficiency the leaf apex becomes purple-green, and its base – dark purple. Over time, all leaves become purple and get leathery texture. The intensity of symptom depends on the bushes lighting/illumination: purple color is clearly visible at bright sunlight, and it can disappear at shadowing or cloudiness. At deficiency phosphorus leaves hug the stem (while usually they are normally disposed).
At potassium deficiency the leaf apex initially dies, and then necrotic spots appear in the middle and on the edges of a leaf. With the potassium deficiency increase the leaf apex warps. From time to time, yellowing between the veins is observed on young leaves. The overgrown shoots die back and the black apex becomes clearly distinguished. Sometimes, a strong growth of shoot branching from lateral buds, which after some time also die, is observed.
Calcium. There are no bright signs of this element deficiency. Warping leaves with yellowed edges are the most notable. Light yellow-green spotting appears on the apical leaves and the edges grow yellow. From time to time leaves form a rosette. The leaf tip warps and can fall off.
Magnesium deficiency is easily recognized by the bright red edges of old leaves. Red color on the edges and between the veins strongly contrasts with the green color, which dominates in the leaf center near the midvein (resembles a Christmas tree). At intense sunlight necrotic spots are observed, and yellow or brown shades appear instead of the red color.
Boron deficiency is recognized by the blue color of the apical leaves, which abruptly stop growing. Then, a slight yellowing between the veins is found on old leaves and yellow dots on the young ones. Leaves become curved. Shoots stop growing and dry. From time to time the shoots death leads to “witches broom” formation (shoots from the lower buds begin to develop and then also die).
Yellowing near the veins of young apical leaves indicates the presence of iron deficiency. Further symptoms are manifested themselves as a set of green veins against lemon coloring of the whole leaf on the shoot apex. Iron deficiency has an extremely negative impact on the plant growth and berry-bearing.
Manganese deficiency, as well as iron deficiency, is manifested on young leaves as yellowing between the veins. The difference is that the green color near the veins has a wider border. Over time, the yellowed areas on the leaf edges die off. Necrotic dots, which gradually merge, appear on the whole leaf and later the leaf dies.
Zinc deficiency manifests itself as yellowing of young leaves, thus the whole leaf becomes lemon-yellow. Leaves do not grow, become small and narrow, form rosettes as interstices are reduced as well.
Sulfur. Chlorotic spots on leaves manifest the deficiency symptom. At acute deficiency yellow-white color appears. In severe cases, leaves become whitish-pink or even white. Sulfur deficiency in the soil leads to pH increase (acidity of the soil) and mycorrhiza degradation. 50 grams of sulfur should be applied if the soil pH is 5; and 100 grams of sulfur per 1 m2 if the soil pH is 6.0. Usage of sulfate fertilizer is an additional source of sulfur. Soil acidification with sulfuric acid (or electrolyte) has the same effect.
Symptoms of copper deficiency are manifested primarily on the leaves. They grow small andoften curl up. Older leaves grow brown and die, branch apex dries up. Sometimes, as well as at boron deficiency, numerous small branches – “witches broom” – grow from lateral and dormant buds.
Molybdenum deficiency manifests itself on young leaves of the growing shoots as chlorosis between the veins.
When to apply mineral fertilizers for high-bush blueberry?
– fertilizers should be applied in early spring (at the beginning of sap flow) or at the beginning of buds swelling.
Ammonium sulfate at the rate of 10-15 grams per 1 m2 should be applied to soils with acidity (PH) above 4.8 twice per season at intervals of 6-7 weeks.
To soils with optimum pH apply 90 grams of ammonium sulfate, 40 grams of potassium sulfate and 110 grams of superphosphate per mature blueberry bush or 200-250 grams of “Kemira Universal” fertilizer (currently, Fertiko company produces it) or Florovit, Polish fertilizer.
Scheme of mineral fertilizer application.
Apply 1 tablespoon of complete mineral fertilizer to a two-year bush, 2 – to a three-year bush, 4 – to a four-year bush, 8 – to a five-year bush, 16 – to a six-year or elder bush.
Do not apply to the soil and do not fertilize the high-bush blueberry with organic fertilizers (manure, chicken manure, even compost).
How to protect blueberry transplants from frosts?
High-bush blueberry can withstand frost up to -23-25° C (some varieties, such as Earliblue – up to -27-30° C).
Bushes can freeze over during severe snowless winter.
In garden plots bind the blueberry bushes with spruce branches or cover with spunbond and burlap (do not use polythene film) after making a frame near bushes from sticks or two crisscross arch wires.
During the growing season (plant growth) do not apply a high dose of nitrogen fertilizers under blueberry bushes, especially after flowering, thus avoiding shoots growth in late autumn. At excess of nitrogen a part of shoots will freeze over during winter (the whole bush can die).
During flowering high-bush blueberry withstands frosts up to -7° C. Therefore, rare protection is required during spring. In autumn, during blueberry ripening, frost can harm the late-ripening varieties of blueberry. Green berries are injured at -2° C. Therefore, to protect the blueberry bushes in autumn apply sprinkling or covering using any materials at hand: spunbond or burlap.
When and how to start pruning high-bush blueberry bushes?
2-4-year plants are pruned to build a strong skeleton of the bush. All berry buds available on the plant should be removed.
Further pruning is required after the 3-rd year of planting (i.e. it will be a 5- or 6-year plant). Remove only small bushy growths at the bush bottom, all diseased branches and branches lying on the ground.
Annual pruning plan, starting with 4-year blueberry cultivation:
1) low branches spreading near the ground should be pruned, keeping only the upright growths;
2) weak and very old branches inside the bush should be pruned if the middle of the bush is thickened;
3) remove the majority of small thin branches, leaving strong boughs and shoots. Leave 5 strongest one-year shoots.
Blueberry yields on the previous year growths. The degree of pruning depends also on the intensity of shoots growth. Heavy pruning is required for varieties, which are liable to strong tillering (such as Rencocas blueberry). Prune the blueberry in early spring, before the bud break. It is better to remove the pruned branches (shoots) from the site and burn them to prevent the development of diseases and pests after winter, which can infect the blueberry bushes.
If you plan to grow high-bush blueberries on a commercial scale, then create orchard-protecting belt near blueberry plantation to protect the bedding. Use pine or alder as plants for forest protective belt. Do not use spruce and birch, because their roots lie shallow in the soil and may eventually become serious competitors to blueberry roots.
A fence located on the north side, hedges and walls of the house and structures serve as protection in a garden plot. The main thing is that protective structures should not block the bush lighting.
Blueberry yield is partially reduced in the absence of screen plantings and an unpleasant whitish bloom appears on the berries.
High-bush blueberry requires cross-pollination. Therefore, set 2 or more bushes of different varieties, but with identical time of flowering. For example, if you decide to buy early and late-season blueberry transplants, then make sure you have 2 early and 2 late varieties on your site, that is 4 pieces, because the late varieties of blueberry will not pollinate the early varieties due to the difference in time of flowering. Mixed planting of different varieties provides better berry setting and contributes to their earlier ripening. In addition, the berries from cross-pollination become bigger and have a better taste and a delicate skin.
Insect pollinators are needed to increase the blueberry yields and improve the berries quality.
There should be no weeds near the bushes. Mulching will partially help you with this. A thick layer of mulch prevents the growing of weed seeds and greatly reduces the number of perennial shoots. Weed shoots that grow through the mulch layer can be easily eradicated by hand.
Keep in mind that the blueberry roots are located (growing) not deeply, therefore, the inter-row cultivation should be shallow (not deep, no more than 3 centimeters).