Orchid virus? or is it a chemical deficiency
Several years ago I found an article in an orchid magazine about leaf markings and fertilizer deficiency in orchids.
I lost the article for quite some time and during a bit of a clean-up I found it again and thought that some of it needs to be shared.
So here is a condensed version of the article in My words.
All plants need the main/basic chemicals for growth/flower, Nitrogen, Phosphorus and Potassium (The NPK rating on the packet), but they also need the other chemical elements – Calcium, Sulphur, Magnesium, Manganese, Boron, Molybdenum, Zinc, and copper , just look at the list of ingredients to make a mix for flasking.
So let’s have a look at these individually.
Nitrogen (N) – needed for plant growth (new cell growth). Effects of deficiency – slow or stunted growth, Plants pale, rapid yellowing of the lower /older leaves.
Solution – Use any fertilizer containing a higher value of ‘N’ until fixed.
Phosphorus (P) – necessary for photosynthesis, it also works as a catalyst for transferring energy within the plant .It helps to build strong roots, and is essential for flower and seed production. The deficiency shows itself as slow or stunted growth – All the same symptoms as for Nitrogen. Use a fertilizer with higher phosphorus. Leaves that have been affected will not recover but the new growths will appear corrected.
Potassium (K) – stimulates the manufacture and movement of sugar and starch within the plant as well as growth and cell division. It also increases the chlorophyll in the leaves and helps the stomata opening and closing, enabling the plant to better use the light and air movement.
Apart from that potassium encourages stronger roots, better water uptake and therefore enables the plants to fight disease.
The Symptoms shown here are – the plants are usually the tallest and appear to be the most vigorous. Necrotic spots form on the lower leaves and the leaves appear pale in colour. The solution here is to use a fertilizer that has increased potassium.
Calcium (Ca) – fundament for cell manufacture and growth, some use dolomite lime to keep the mix sweet. Calcium moves slowly within the plant and tends to concentrate in the roots and the older growths.
A lack of calcium results in the mix becoming to acid, which leads to magnesium and iron deficiency and slow or stunted growth. The best solution here is to use dolomite lime (also known as dolmag) sprinkled on the top of the mix. Dolomite is the best and safest here as when the potting mix is back to neutral the dolomite becomes inactive.
Sulphur (S) – is a component of plant protein and plays a part in root growth and chlorophyll production. Plants suffering from a lack of sulphur show yellowing of new growth. One way to fix this is to mix Epsom salts at the rate of 1Tb per 5 litres (1.3 US gallons),(1.1 UK gallon) of water until the condition improves.
Magnesium (Mg) – found as the central atom of the chlorophyll molecule, it is essential to the absorption of energy from light. It helps with use of the nutrients. It also neutralizes acids and other toxic compounds that the plant produces. The symptoms here are that of the lower leaves turning yellow and in the end they may even turn white while the veins remain dark green. An excellent fix for this is a foliar feed of a liquid fert containing magnesium – use the sulphur solution.
Iron (Fe) – Iron is a major catalyst in chlorophyll production and is used in photosynthesis Here leaves turn pale and veins remain dark green. PH imbalance in the potting mix makes iron inaccessible to plants. Water with rusty water is the safest solution.
Manganese (Mn) – This element works with the enzymes in the plant to reduce nitrates before producing proteins. Leaves have necrotic yellow spots form on top. Foliar feed with a fert with manganese.
Boron (B) – necessary for the division of plant cells as well as protein formation. It also appears to play a major role in pollination and seed production. New growths turn grey, look burned and can die. Use 1tb of boric acid per 5 litres (1.3 US gallons),(1.1 UK gallon) of water.
Molybdenum (Mo) – helps form proteins and aids the plants ability to fix nitrogen from the air. Here the middle of the leaves turn yellow. Foliar feed with a fert that contains Molybdenum
Zinc (Zn) – this just a catalyst but MUST be present in minute amounts for plant growth. The deficiency shows as the tips of the leaves and between the veins turning white. The article suggests the burying of galvanised nails in the mix as a treatment or use a fert containing zinc.
Over fertilization – shows as the leaf tips to appear yellow or burnt. Repot the plant or the pots must be thoroughly flushed with water.
Like I said at the beginning does the plant have a virus or is it a chemical deficiency. Hope this helps, but it may raise more questions, on fertilizers, water quality and the different potting mixes that we use.
Happy growing folks
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Originally Posted by raybark
