Zinc deficiencies are one of the most common micronutrient deficiencies in plants and are usually associated with dry climates and alkaline (pH 7 or more) soils.
Why Is Zinc Important?
Zinc works with magnesium, manganese, and iron to promote enzyme, chlorophyll, sugar, and protein production so it is necessary both in the vegetative phase and flowering phase of your crop cycle. Although zinc is a mobile micronutrient, its deficiencies do not appear in older growth first like other mobile nutrients like nitrogen. Since it’s instrumental in making chlorophyll for new growth with iron and manganese, which are immobile micronutrients, zinc deficiencies begin in the younger leaves and can easily be confused for deficiencies in the other two elements. It is vital to catch a zinc deficiency early because it is easily overlooked.
Identifying Zinc Deficiencies In Plants
Early zinc deficiencies appear in the newest leafy growth through interveinal chlorosis. Interveinal chlorosis can be identified by the darkening of veins throughout the leaf while the rest of it grows lighter. The newest leaves look weak, thin, and may grow horizontally. Bud and leaf production grind to a halt and you may not notice any new growth at all for weeks.
Since iron and manganese are the usual culprits when spotting deficiencies in new growth, zinc is easily overlooked. Remember, zinc is a mobile nutrient, meaning that the plant can move it from old growth to new, while iron and manganese are immobile, meaning it only affects new growth. This means that the early deficiency can be addressed with just iron and manganese because your plant will pull zinc from its older leaves. Eventually, the missing zinc will continue to delay progress on your plant. The leaf tips and margins of the older growth will begin to darken and appear burned. Dead spots may begin to appear and as the deficiency grows unchecked, the older leaves may turn pale and exhibit severe interveinal chlorosis. If you are in the bloom cycle, your buds or flowers can grow in a twisted, gnarled, pattern and be very dry and brittle.
- Yellowing of older leaves
- Old leaf tip burns
- Young leaves wrinkle and curl
- Necrosis spots appear in really bad cases
Examples Of Zinc Deficiency
How To Correct Zinc Deficiency
The pH of your medium dictates what nutrients can be absorbed by your plant’s roots. You can have all the zinc in the world and none of it will get used by your plant without the right pH range. Most plants prefer a pH range between 5.5 and 6.5 for best results.
If your pH is in the right range, you can nip a zinc deficiency in the bud by flushing your medium with a diluted fertilizer appropriate for your grow medium. Be sure that it contains chelated trace micronutrients, especially zinc, iron, and manganese. It is best to supplement with a complete profile of nutrients, so stay away from the temptation of supplementing heavily with just zinc because it can be toxic to your plants. Too much zinc can prevent iron from being used effectively and will kill your plants very quickly.
If you are growing organically, it is best to amend your soil with a rock dust like azomite or greensand to prevent zinc deficiencies. However, it can take months before the minerals break down and become available to your plant, so if you are in the middle of a deficiency, you may want to consider using an organic liquid fertilizer. Be sure to read the label to make sure that it has a complete micronutrient profile. Compost tea is also an excellent way to supplement naturally.
The roots are the transport system from your medium to your plant. If they are in bad shape, no amount of zinc or change in pH will make a difference. Check for root rot, which can come from over-watering, and be sure that the medium is free from pests such as root aphids that can hinder the your crop’s nutrient absorption.
After diagnosing and administering the above steps, monitor your plant’s growth. It could take up to a week for it to recover and show signs of vigor. The mobile nature of zinc will mean that your older growth will still appear damaged, but if the new growth is coming in healthily, then your plant is on the road to recovery.
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