5 Causes & Cures - Yellow leaves on tomato plants
Yellow Leaves On Tomato Plants - An Overview
Yellowing of tomato leaves is natural and not a cause of worry. On the contrary, you need to be vigilant if you notice the leaves are yellowing prematurely or yellow right from the time they appear.
It could be something as silly as excess water to essential nutrient deficiencies, both of which are easy to fix once detected. However, if your tomato plants are under a pest attack, it could turn ugly.
It's not just a deficiency of nutrients that can cause foliage to lose color and deform, but also an excess of certain nutrients. An excess of these nutrients can lead to something most gardeners refer to as 'a burn' which manifest as deformed yellowish leaves and fruit.
If it's your first time growing tomatoes, problems such as this can be detrimental to your confidence and many people give up on growing tomatoes after their first crop fails. Instead of quitting it would be wise to find out the problem and learn how to fix it, so that the next crop if not the present one grows well. Growing tomatoes or any other plant to perfection is a matter of skill and all skills need to be developed.
Causes For Yellow Leaves On Tomato Plants
As stated earlier, yellow leaves are the result of a variety of problems, all that I know of are listed below. Just make sure that you go through the entire list before you go to your garden to fix the issue, because, very often there can be multiple causes and you'd want to fix them all.
- Moisture Content - One of the leading causes is water levels. Tomato plants need perfect soil moisture levels. The soil shouldn’t be too damp nor too dry, always maintain the Goldilocks level. Water your crop based on your weather conditions, the soil and the level of mulch you use. In some cities you're going to need to water multiple times a day, whereas there are others where watering just a few times a week is best. For more on perfect watering techniques, I'd suggest checking out my article on watering tomato plants.
- Soil Texture - The first time I planted tomatoes I planted seeds directly into the garden skipping the nursery stage. This resulted in the plants turning yellow when they were around a foot tall. After some research I found out that the soil wasn't aerated well and it was too compact. The plants recovered after I dug up and loosed the soil a bit. Loosening the soil gave the plants enough room to spread their roots and breathe.
- Viral, Fungal or Bacterial Attacks - It's not that common, but there are times where the cause of yellowing leaves is a viral, fungal or bacterial attack. If you notice just a few plants exhibiting this problem, it's best to uproot them and burn them since these pathogens are likely to spread to the plants that are doing well. If you want to find out a way to treat these issues you're going to need professional help, your garden center may be able to guide you on this.
- Pests - Pests unlike Viruses, fungi and bacteria can be controlled using predators or other natural methods. Pests are not always obvious, maybe you need to look closely at the stem or turn over the leaves. I've had some sought of white insects (research tells me they are Mealybugs) and at other times aphids. Soapy spray gets rid of mealybugs and ladybugs feast on aphids. You may want to search for natural ways to get rid of mealybugs if you're going the organic route.
- Nutrient Deficiencies - Macro and Micro-nutrient deficiencies are a leading cause of yellow leaves in plants, not just tomato plants. It does not necessarily mean that your soil is lacking, there are instances where the plant is simply incapable of absorbing them. You can read my article on fertilizing tomatoes to learn more about making sure your plants get exactly what they need. This article goes on to focus on the different kinds of nutrients and the problems associated with a lack of each of them.
Yellow Streaks On A Tomato - Low Nitrogen In The Soil
Yellow tomato leaves due to nutrition deficiency
Yellow tomato leaves are often caused due to nutrition deficiency. They can easily be prevented if you ensure the right nutrients in your garden soil.
Yellow leaves on tomatoes due to lack of absorption:
Tomato plants can absorb nutrients only through their roots. If this is prevented for any reason whatsoever then your tomato plants are going to lack key nutrients. Water is the medium through which tomato plants absorb nutrients from the soil. Therefore, you need to ensure the presence of sufficient water – not excess; problems related to excess water have already been discussed.
Is your soil pH acidic or alkaline? Tomato plants are very timid and need the right pH range for successful absorption of nutrients. So don’t add excess of fertilizers to your garden. Excess fertilizers lead to high pH. But for the proper growth of your tomato plants you’ll need to add a little fertilizer.
- Lack of Nitrogen: -
Yellow leaves on tomato plants can be caused do to the lack of Nitrogen. Due to the deficiency of Nitrogen the older leaves at the bottom usually turn yellow whereas the upper new leaves remain bright green as though there’s no problem at all. However, you’ll notice that the overall growth rate drops and your tomato plants will be shunted. You could add urea or ammonium to the soil or any other form of manure.
- Deficiency of Potassium: -
· Yellow leaves on tomatoes can be caused due to the lack of Potassium as well. The leaf as a whole doesn’t turn yellow; the area between veins turns yellowish and the leaves may wilt. You could add potash to your soil in case this is the cause.
- Calcium deficiency: -
A deficiency of calcium could be the cause of your tomato plant leaves turning yellow. The growing tips of the tomato plant may turn yellow and die within a few days. This is known as blossom end rot. Adding any compound containing calcium will work wonders.
- Lack of Magnesium: -
Yellow tomato leaves could very well be caused because your garden soil is poor in Magnesium. This will result in stunted growth and the outer edges of your tomato leaves may end up becoming pale and yellow. Epson salts are a good source of Magnesium to your soil.
- Sulphur deficiency: -
· The new leaves are yellow and the older foliage remains fresh and green. The tomato plant suffers from stunted growth.
- Zinc deficiency: -
Deficiency of Zinc is a big cause of yellow tomato leaves. Lack of Zinc leads to the area between veins turning yellow especially in the new leaves. This often leads to a bunch of small leaves at the top (a rosette)
Learning From Other Gardeners Out There
Yellow leaves on tomato plants – Not always a cause of worry
If you observe any plant eventually all the older leaves wilt and die. Similarly your tomato plant will also have yellow leaves at the bottom. Also it could be due to the lack of sunshine due to shading by the higher leaves. As long as the plant continues to grow healthily and produce fruits you need not worry about yellow tomato leaves.
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