White spots on raspberries can appear due to the growing conditions of your plants and also some environmental factors.
Well, these spots can be fixed so long as you know their cause. To learn the cause of white spots on your raspberry plants and how to fix them, read this article.
Contents
Why Are There White Spots on Your Raspberry Plants?
There are white spots on your raspberry plants because of sunscald, white drupelet disorder, fungal attacks, high humidity, insufficient light, insect and invertebrate pests, Achenes and possible lack of nutrients. It is important to first diagnose the reason behind the spots before moving on to treatment.
– Sunscald
If your raspberry leaves and fruits are exposed to too much sunlight, the plant can get sunscald. Sunscald is the damage to your plants’ tissues due to the high temperature and UV rays of the sun. To know if your raspberries have sunscald, carefully observe the entire plant.
Plants with sunscald will only have white spots on their upper leaves or those facing the sun. If a part of the fruit is white, it can only be sunscald if that part is facing the sun. Do not conclude that your raspberries have sunscald if the white spots appear in places without access to the sun.
– White Drupelet Disorder
Asides from sunlight, other factors that can make your raspberry fruits have white spots are high temperature, low humidity, and too much wind.
When you see some drupelets or individual balls of your raspberry fruits turning white, you can tell that the plant has white drupelet disorder. The drupelets that are exposed to harsh environmental factors are those that will turn white.
Are you growing your raspberries at the right temperature? How often does wind disturb your plants? What is the average level of humidity in your garden? Answering these questions can help you to decide if your raspberry fruits are turning white because of environmental factors or not.
– Fungal Attacks
There are so many types of fungi that can cause white spots on your raspberry plants. For example, the raspberry leaf spot (Sphaerulina rubi) initially causes dark-green spots on the leaves. After some days, the spots become pale, gray, or white.
There is also the powdery mildew fungus (Sphaerotheca macularis) that covers the entire underside of your raspberry leaves.
These fungi usually attack weak raspberries or plants that grow in poor growing conditions. For example, raspberries growing in a place with excessively high humidity can get attacked easily by fungi.
You can tell that the white spots are caused by fungi when you see them spreading from one plant to the next every day until your entire garden has fungi.
– Insufficient Light
While exposure to too much sunlight can burn your raspberry leaves and fruits, growing the plants in a place without enough light is equally damaging.
Every plant relies on sunlight for photosynthesis so that it can get energy. The process of photosynthesis also gives plants their green leaves. This means that without a source of light, your raspberry leaves will not be as green as they should be.
When you see that your raspberry leaves are pale, white, or yellow or have large pale or yellow spots, you need to check the amount of light that the plants receive daily. Raspberries suffering from a lack of light also have stunted growth.
– Lack of Nutrients
Just as in a lack of sufficient light, a lack of nutrients can also cause white spots on your raspberry leaves. These spots will first appear on the lower leaves of your raspberries before they spread to the upper ones.
Nutrients that you should watch out for are nitrogen, iron, magnesium, and potassium. You may also notice the fruits falling off early, especially if the plant is lacking phosphorus.
When last did you feed the raspberry plants? What are the components of the fertilizer that you used to feed your raspberries? The answer to these questions can tell you if your raspberries are truly lacking nutrients or not.
– High Humidity
High humidity is the cause of so many bad things that can happen to raspberry plants. High humidity encourages the growth of fungi that can attack your plants.
High humidity also causes plant edema on your raspberry plants. Plant edema is a condition whereby water droplets are trapped in your raspberry leaves because the humidity level is too high to permit transpiration in the plants.
How often do you check the humidity level of your garden? What is the average daily humidity? Even though some gardeners do not care about the humidity level of their garden, you need to check that of your garden regularly.
– Insect and Invertebrate Pests
Have you had a close look at the spots to see if they are mobile or not? Some insects such as weevils lay white eggs on raspberries.
When these eggs hatch, their larvae actively eat your raspberry leaves. Spider mites are red, but they cover themselves with white silk. There are also white insects such as scale insects, aphids, and others that attack your raspberries.
While some of these insects create holes in your raspberry leaves, others only suck nutrients from the leaves and turn the plant pale and weak. If you see one pest on your raspberry plant, there is a high chance that other plants are being attacked as well.
– Could Be the Achenes
Raspberry plants produce multiple fruits and their achenes are tiny hair-like appendages that appear between each drupelet. Before the achenes grow out of the fruit, they first appear as white dots between the drupelets.
This means that you have nothing to worry about if the white spots only appear between drupelets in the fruits of your raspberries. If you continue to observe the fruits for a few days, you will see that the achenes would have grown into the hair-like appendages that they are.
How Do You Fix Your Raspberry White Spot Problems
To fix your raspberry white spot problems you can prune the sick plants, increase air circulation or ensure you don’t overwater. If your raspberries have white spots or you want to prevent the plants from getting white spots, choose the correct cause and the corresponding cure.
– Prune Sick Plants
As soon as you see white spots on your raspberry plants, you want to remove the affected leaves, branches, or fruits.
You should remove the leaves and branches so that other leaves do not get white spots if the spots were caused by a disease. As for the fruit, they have become undesirable (even though they may still be edible), so you do not need them anymore.
After pruning the leaves or fruits, do not throw them away immediately. Carefully examine them to find out the cause. Using the symptoms listed in some reasons above, you can know what is wrong with your raspberry plant if you carefully study the spots.
– Increase Air Circulation
Air circulation is important, especially for raspberries that were attacked by fungi, bacteria, and other types of microbes.
Most microbes grow best in places with high humidity, so you can prevent them from reaching your raspberry plants when you reduce the humidity. You can reduce the humidity by installing a fan near and opening the windows for indoor plants.
As for those growing outside, ensure proper spacing between plants. Also, make sure that you wait until their substrate is dry before you water them so that too much water does not evaporate at a time.
– Use Fungicides
Fungicides are products with which you can kill fungi that are attacking your raspberry plants. If the white spots on your raspberries are caused by fungi, go to a gardening store and buy a fungicide. If you can identify the specific fungus attacking your plants, it will be better, as you can now buy a suitable product.
When you get the fungicide, please be sure to carefully read the instructions before using it so that you do not harm your raspberries. Using too much of the fungicides can kill your raspberries and using too little may not be effective enough for the fungus to attack the plants.
– Grow Your Plants in the Right Spot
The right place to grow raspberries is one with the correct environmental conditions for the plants. Here are some factors that you should consider:
- Temperature: If the temperature is too high, your raspberries can get sunscald or lose their leaves. They can also get stunted growth if the temperature is too low. The ideal temperature for raspberry plants is 70-75 degrees Fahrenheit.
- Light: Grow your raspberry plants in a place with six to eight hours of direct sunlight daily. In the summer months, you can protect the plants from the sun by using shade cloth.
- Humidity: Grow your plants at 60-80 percent humidity. Remember that if the humidity is too high, your raspberries can get attacked by fungus. They can also get the drupelet disorder if the humidity is too low.
So long as the raspberry requirements are met, your plants will grow to be very healthy and hardy.
– Do Not Overwater Your Raspberry Plants
Overwatering raspberry plants do not just lead to root rot, it can also attract many types of fungi that attack raspberries.
You want to keep your raspberry plants free from fungi by only watering them when they need water. Check the soil and only water the plants when you see that the soil is almost dry. Aim to grow your raspberries in evenly-moist soil.
– Repel Insects with Homemade Products
If the white spots on your raspberries are caused by insects, you can help the plants by repelling the insects.
While there are so many products that you can use, two products that are easy to make yet effective are soapy water and neem oil. With soapy water which is made with just soap and water, you can kill insects on the leaves of your raspberries.
You can use soapy water on your raspberries whenever you want. Just make sure that you do not overwater the plants. As for neem seed oil, you can dilute it and use it in the evening or morning. Do not use it when the temperature is high so that your raspberry leaves do not get burnt.
– Use Chemical Insecticides
Insecticides are products that help to kill insects in your garden. While neem oil and soapy water are effective to some extent, their effects do not last for long and they are not as effective as chemical insecticides.
To get rid of the insects quickly and be sure that the insects do not return to your raspberry garden, make use of chemical insecticides.
As always, be sure to read the instructions. Also, make sure that the products that you buy are plant-safe. This means that you should ask the shop owner if you can use the insecticide in a garden with plants that are already growing.
– Fix Your Plants’ Substrate
After finding the cause of white spots on your raspberry plants, you should fix the soil if the plants had white spots because of fungi and other types of microbes. Fix the soil because these microbes are usually soil-borne and can attack future plants if the soil is not fixed.
You can fix the soil by mixing some fungicides with it, especially after your plant’s growing season is completed. You can also fix the soil by collecting the top 4-6 inches and baking it in an oven.
Whatever you do, just make sure that your next batch of plants do not grow in the same soil in which the previous plants had diseases.
– Dispose of Dying Plants
If a raspberry plant is not responding to treatments, it may not recover. Therefore, you do not need to keep it. Remove the plant from your garden so that it does not transmit its disease (if any) to other plants.
Well, ensure that you have amended your soil and reduced your watering rate so that you do not expose other plants to the cause of white spots in the initial plant.
Conclusion
White spots on raspberries may get you worried, but you can now fix them with the help of this article.
Here are some things that you should remember:
- If the white spots only appear on some drupelets, it means that the fruits are exposed to high amounts of sunlight.
- Lack of light can also cause your raspberry leaves to turn pale or get pale spots. The plants may also become weaker.
- As soon as you see white spots on your raspberry plants, prune off the leaves, branches, and fruits to be certain that the spots do not spread to other plants.
- You want to grow your raspberries in the right spot so that they can have optimal growth free from causes of white spots.
- Just in case a raspberry plant is not responding to treatment, remove it from your garden so that you can keep other plants safe.
Now you can grow healthy raspberries without the fear of them getting white spots and if they do, you know what to do!
References
- https://rubus.ces.ncsu.edu/2015/06/white-drupelets/
- https://hortnews.extension.iastate.edu/raspberry-leaf-spot
- https://blogs.cornell.edu/berrytool/raspberries/raspberries-leaves-have-a-white-powder-on-them/
- https://extension.umn.edu/plant-diseases/raspberry-leaf-spot
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