There are multiple reasons that your radish leaves may be turning yellow. It can be something as benign as overwatering, or something more serious such as pests and disease. No matter what the cause, it is affecting the radish enough to cause it stress, which is why it changes color.
Other common causes of yellowing radish leaves are overcrowding, lack of light, weeds, underwatering and lack of nutrients.
In this article, we will discuss all these causes of yellowing radish leaves and also how to fix each one.
Why are my radish leaves turning yellow?
Overwatering
Most newbie gardeners make the mistake of being overzealous when it comes to watering their plants. This is a bad thing for your radish plant, and for most plants in general, and can lead the leaves on your plant to turn yellow.
If you are able to catch your overwatering early enough, the plant should be able to recover with no lasting damage, but if you have been overwatering for an extended time, it may be too late to save the plant.
Plants need time between watering for the soil to dry out so that air can circulate around their roots. If they are in soggy water for too long, the roots will drown.
Correct your watering techniques; keep the soil moist but do not make it boggy. In time, you will master just the right amount of water as well as the correct watering frequency.
Underwatering
Not giving the plant enough water can also cause its leaves to turn yellow. Radishes need to be watered lightly five times a week. Water just enough to make the soil moist, but do not make it soggy. Keeping the soil moist can be made easier by placing mulch over the soil around the radish plant. You can make your own mulch using grass clippings.
It is also easy to dry the plant out in summer, especially if you keep to the same watering schedule as during the cooler months. The soil will dry out much faster during the hotter months, so be sure to keep a constant eye on your plants.
Overcrowding
Another reason your radish leaves may be turning yellow is because the plants are crowded. You might have planted the radishes too close to one another so they end up not having enough room to thrive.
You can fix this by uprooting each plant and spacing them more apart. This way, the plants will no longer have to compete for resources such as water and nutrients.
Lack of light
Radishes need at least six hours of sunlight every day. If the plant is unable to get this required amount, its leaves will start to turn yellow.
This effect can be seen in radishes that were planted in areas with too much shade.
You can fix this problem by simply transferring the plant to another location where it can get six hours of light every day.
Weeds
Weeds are bad to have around any of your plants, because they are plants themselves and require many of the same things our plants do. If there are weeds anywhere near your radish plant, they are taking water and nutrients from the soil that should have been for the radish. The radish leaves will turn yellow and its growth can even become stunted as it is deprived of its resources.
Check the area around your radish plants and, if there are visible weeds, remove all of them.
Lack of nutrients
Nutrient deficiencies can also cause radish leaves to turn yellow. Soil that does not contain the nutrients required by the plant will severely affect it, and you will need to apply fertilizer around the plant to restore nutrients to the soil. Over time, even soil that was once rich in nutrients will become depleted if it has been planted many times.
Radish plants like sandy soil that is rich in nutrients. You can also mix compost into the soil to replenish its nutrients.
Though several nutrient deficiencies can be blamed for yellowing leaves, the most probable reason is a lack of nitrogen. Fortunately you can correct this using fertilizer – specifically one that is high in nitrogen.
Pests and diseases
There are multiple pests that can attack your radish plant.
Leafhoppers can spread the Aster yellow virus to your plant. These insects can cause plenty of damage to your radishes in a short amount of time. The mycoplasma disease it can give your plant is a kiss of death, because there is no known treatment.
Harlequin bugs can suck the moisture from your plant’s cells and ultimately cause the plant to wilt. Yellowing leaves are a sign that the pests have already been on your plant for quite some time, and that plenty of damage has been done. Other signs of a harlequin bug infestation are white or yellow spots, dotted marks, deformed leaves and wilting.
Diseases
There are a host of fungal diseases that can cause yellow leaves on your radish plant, some of which are discussed below:
- Club root
This disease gets its name from the large, tumor-like galls that form due to the swelling of the radishes.
This is caused by overwatering and can pose a serious threat to your radish plants.
This fungus thrives in a garden that is overwatered and has a low pH. It can survive in your soil for up to 18 years, making it very difficult to eradicate.
- Septoria leaf spot
This disease is very common among root vegetables. It causes yellow spots on the leaves which look like water blotches with gray centers.
This disease can affect the radish plant in all stages of its life cycle. It starts its cycle in wet conditions, but spreads more effectively during the summer. It may not kill your radish plants, but it can definitely hinder their growth and further weaken the plants against other possible infections.
- Blackleg
Yellowing radish leaves that become brittle could have Blackleg. This is a fungal infection that causes the radish under the soil to become slimy and turn black. The longer the disease is left unchecked, the higher up your plant it will travel.
Blackleg spreads from one radish plant to the next without you even suspecting anything. The leaves will curl up and turn brown and eventually the plant will die.
- Stem rot
This disease is also caused by overwatering and soggy soil. It is also called Fusarium rot, and will cause the leaves of the plant to turn yellow with red streaks along their body.
Conclusion
Radish plants that have yellow leaves usually have a problem pertaining to a certain environmental factor that is causing them stress. You need to identify the cause of the discoloration as soon as possible in order to remedy the problem quickly.
The most common causes of yellowing radish plants are overwatering, underwatering, overcrowding, lack of light, weeds, lack of nutrients, pests and disease.
Image: istockphoto.com / Dinesh Ahir