Diagnosis and Correction Methods for Nutrient Deficiency in Orchids
Diagnosis and Correction of Nutrient Deficiency in Orchids...
When an orchid lacks a certain nutrient, it will show signs on the plant. Based on these signs, the nutrient deficiency can be diagnosed and corresponding measures taken to correct it. ① Nitrogen deficiency. It shows as new leaves being shorter and narrower than old leaves, thin in texture, pale yellow in color and lacking luster. It can be corrected by watering the roots with a 500-fold dilution of potassium sulfate compound fertilizer or potassium nitrate compound fertilizer, and spraying a 0.2% urea solution on the leaf surfaces and undersides in the evening. Spray once every three to five days, for 3 consecutive sprays, and it will be corrected.② Phosphorus deficiency. It shows as slow growth of leaf buds, roots failing to emerge for a long time, and leaf margins slightly curling backward. It can be corrected by watering the roots with a 2% superphosphate extract, or a 3%-5% bone meal solution, or an 800-fold dilution of monopotassium phosphate, once every 10 days, for 2 consecutive waterings; and by spraying a 600-fold dilution of monopotassium phosphate, or a 1000-fold dilution of Huabao No. 3, on the leaf surfaces and undersides in the evening, once every three to five days, for 3 consecutive sprays.
③ Magnesium deficiency. It shows as old leaves turning yellow; the leaf tips and margins of middle-aged leaves turning yellow and curling toward the leaf surface (commonly known as "gong-luo margin"). It can be corrected by spraying a 0.5% magnesium sulfate solution on the leaves in the evening, once every three to five days, for three to five consecutive sprays.
④ Potassium deficiency. It shows as leaf margins and leaf tips turning yellow (old leaves first, then new leaves), then turning brown; the main and lateral veins of the leaves being rather thin; the leaf texture being soft and prone to bending and drooping; and if exposed to strong light and low temperatures, the new leaves showing slight dehydration. It can be corrected by first watering the roots and spraying the leaves with a 0.5% potassium sulfate solution, or by broadcasting plant ash.
⑤ Manganese deficiency. It shows as sunburn-like spots appearing even with proper shading, with spotted markings within the spots, flower buds not developing; leaves shriveling, losing green color, and lacking luster. Neutral, calcareous and sandy soils are more prone to manganese deficiency symptoms. It can be corrected by spraying a 0.3% manganese sulfate solution on the leaves 3 times.
⑥ Calcium deficiency. It shows as leaf tips taking on a hooked shape (except where this is a varietal characteristic). It is commonly seen in plants given acidic fertilizers. It can be corrected by watering the roots once with a 1.0% lime solution, or by watering once with a 3% solution of livestock-grade calcium powder.
⑦ Iron deficiency. It shows as the mesophyll of young leaves turning yellow to white, and the middle veins, leaf margins and leaf tips showing scorched brown necrotic spots. It can be corrected by spraying a 0.5% ferrous sulfate solution on the leaves, once every 3 days, for two to three consecutive sprays.
⑧ Zinc deficiency. It shows as pure rust-like spots appearing in the middle section of the bottom leaves and gradually spreading toward both ends of the leaf; and the petiole ring of new growth being noticeably lower than that of old leaves. It can be corrected by spraying a 0.1% zinc sulfate solution on the leaves, once every three to five days, for 3 consecutive sprays.
⑨ Copper deficiency. It shows as the leaf tips losing green color, gradually turning grayish-white and spreading to the whole leaf, with growth stagnating. It can be corrected by spraying a 0.2% copper sulfate solution, once every 7 days, for 2 consecutive sprays.
⑩ Boron deficiency. It shows as the base of young leaves being damaged, the petiole ring being extremely brittle and breaking easily, the number of flowers per scape being noticeably reduced, flower buds opening slowly and looking listless when open, and the lasting period of the flowers after opening being noticeably shortened. It can be corrected by spraying a 0.3% borax or boric acid solution, once a week, for 3 consecutive sprays.
Molybdenum deficiency. It shows as new growth being noticeably dwarfed even without the application of chlormequat; old leaves losing green color, then turning withered yellow, wilting and finally necrotic. It can be corrected by spraying a 0.1% ammonium molybdate solution, once every 3 days, for 3 consecutive sprays.
If fertilizer is supplemented according to what the orchid plant lacks, so that the nutrient elements in the plant are relatively balanced, then the functions of each organ of the plant can be fully brought into play and coordinated, which is very beneficial for improving both yield and quality.