What causes nutrient deficiency disorders in greenhouse strawberries?
How should strawberries be managed in spring? Please guide on removing the mulch to harden the seedlings. 1. When the daily average temperature stabilizes at around 10°C, the winter cold protection coverings should begin to be removed. 2. Be careful when removing to prevent breaking the flower buds. If covered with agricultural film, it should first be removed during the day and covered at night, then gradually remove the film to avoid excessive temperature differences affecting the normal... of strawberries.
What is nutrient deficiency disorder in greenhouse strawberries? An introduction is requested.Strawberry nutrient deficiency has the following symptoms:
I. Nitrogen deficiency
1. Symptoms. When nitrogen deficiency generally begins, especially during the peak growth period, the leaves gradually change from green to light green. As nitrogen deficiency worsens, the leaves turn yellow, with local scorching, and are slightly smaller than normal leaves. In young leaves, as nitrogen deficiency intensifies, the leaves actually become greener. The petioles and calyxes of old leaves appear slightly red, and the leaf color is paler or shows serrated bright red. Nitrogen deficiency is likely to occur in poor soil without proper fertilization, with extensive management and overgrown weeds.
2. Control methods. Apply sufficient base fertilizer to meet the short and concentrated growth characteristics of the spring growing period. If nitrogen deficiency is found, apply 11.5 kg of ammonium nitrate or 8.5 kg of urea per mu as a top dressing, and irrigate immediately after application. During the flowering period, foliar fertilizer of 0.3%-0.5% urea solution can also be sprayed 1-2 times, with 50 kg of fertilizer solution per mu, or 0.2% potassium dihydrogen phosphate solution 2-3 times.
II. Phosphorus deficiency
1. Symptoms. Plants grow weakly, develop slowly, and the leaf color takes on a bronze dark green. When phosphorus deficiency worsens, the upper leaves show purple-red spots, and older leaves also have this characteristic. Flowers and fruits on phosphorus-deficient plants are smaller than those on normal plants. Phosphorus deficiency is likely to occur in soil with high calcium content or high acidity, as well as in loose sandy soil or soil with much organic matter.
2. Control methods. When symptoms begin to appear on the plants, spray the leaves with 1% clarified superphosphate solution or 0.1%-0.2% potassium dihydrogen phosphate solution 2-3 times, once every 7-10 days, with 50 kg of fertilizer sprayed per mu.
III. Potassium deficiency
1. Symptoms. The symptoms of potassium deficiency in strawberries often begin on newly matured upper leaves. The leaf margins often show black, brown and dry scorching, and this also develops between the veins toward the center in most leaves, with old leaves being severely damaged. Light intensifies leaf scorching, so potassium deficiency is often confused with "sunscald." The true petioles of scorched leaves often develop brown to dark brown coloration, with mild damage, and then gradually wither. Strawberry fruits from potassium-deficient plants are pale in color and poor in taste.
2. Control methods. Apply sufficient organic fertilizer, and apply about 7.5 kg of potassium sulfate per mu as a top dressing; foliar spraying of 0.1%-0.2% potassium dihydrogen phosphate solution 2-3 times is also possible, once every 7-10 days, with 50 kg of fertilizer solution sprayed per mu each time.
IV. Magnesium deficiency
1. Symptoms. Initially, the edges of the upper leaves become yellow and brown and scorched, then the areas between the veins lose green color and dark brown spots appear, with some spots developing into necrotic lesions. As scorching worsens, the leaves on the stem appear light green and swollen, and the scorching develops with increasing leaf age and worsening magnesium deficiency. Magnesium deficiency generally occurs easily when strawberries are cultivated on sandy soil or when nitrogen and potassium fertilizers are applied excessively.
2. Control methods: Spray 1%-2% magnesium sulfate solution on the leaves 2-3 times, once every 10 days or so, with 50 kg of fertilizer solution sprayed per mu each time.
V. Boron deficiency
1. Symptoms. In early boron deficiency, young leaves appear shrunken and leaf-scorched, the leaf margins turn yellow, and the growing point is damaged. As boron deficiency worsens, the veins of old leaves lose green color or the leaves curl upward. Flowers of boron-deficient plants are small, pollination and fruit set rates are low, and the fruits are deformed or tumor-shaped, small, with many seeds and poor fruit quality. Boron deficiency is likely to occur in boron-deficient soil and when the soil is dry.
2. Control methods. Water in a timely manner to increase the content of soluble boron in the soil and facilitate plant absorption. For boron-deficient strawberries, spray 0.15% borax solution on the leaves 2-3 times. When supplementing boron during the flowering period, the spraying concentration should be appropriately reduced, with 50 kg of fertilizer solution sprayed per mu each time.
VI. Iron deficiency.
1. Symptoms: Young leaves become yellow or lose green color, and turn white as the degree of yellowing worsens. In moderate iron deficiency, the veins are green and the areas between the veins are yellow-white. In severe iron deficiency, newly grown leaflets turn white, and leaf margins become necrotic or the leaflets yellow. Iron deficiency is likely in alkaline soil or strongly acidic soil.
2. Control methods. Adjust the soil pH so that it reaches 6-6.5, and spray 0.2%-0.5% ferrous sulfate solution on the leaves 2-3 times.
VII. Zinc deficiency
1. Symptoms. As zinc deficiency worsens, old leaves become narrower. In particular, the more severe the zinc deficiency in the basal leaves, the more the narrow-leaf portions elongate. However, zinc deficiency does not cause necrosis. In severe zinc deficiency, new leaves become yellow, the veins are slightly red, and the leaf margins have obvious serrated edges. Zinc-deficient plants bear few fruits.
2. Control methods. Apply more organic fertilizer, improve the soil, and spray 0.05%-0.1% zinc sulfate solution on the leaves 2-3 times. The spraying concentration must not be too high to avoid phytotoxicity.
VIII. Molybdenum deficiency
1. Symptoms. In the early stage of molybdenum deficiency, the leaves uniformly change from green to pale, and whether young leaves or mature leaves, they ultimately appear yellowed. As molybdenum deficiency worsens, scorching appears on the leaves and the leaf margins curl.
2. Control methods. Spray 0.03%-0.05% ammonium molybdate solution on the leaves 2 times, with 50 kg of fertilizer solution sprayed per mu each time.
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