White Spots on Raspberries – Reasons & Remedies

Introduction

Very few things say ‘summer’ quite like the taste of sweet, juicy raspberry. Everything seems okay until these juicy raspberries get some unwanted troubles.

White spots on raspberries are one of them.

When you see the white drupelets, you may ask yourself, ‘are they edible?’ or ‘what exactly causes the white patches?’ or ‘how can I fix this?’ Well, this is very normal to be anxious but it can’t be the end of the earth, huh?

So, relax! From this article, you will find all of the answers. Moreover, there is a FAQ section so that all of your confusions can be gone in a flash.

Let’s jump in!

What Causes White Spots on Raspberries?

So, here you go with details. We compiled some common problems and solutions here so that you don’t need to beat your brain out to understand what’s happening with your raspberries.

Problem 1: Sunscald (Sunburn)

This is the most common reason for Raspberries with white spots. Raspberries often develop small white spots to hot weather and exposure to direct sunlight. At first, the affected drupelets have a bleach, but eventually, they become dry or collapse and are visually unattractive.

Not only these, but sections of the fruit also become brown and dry. In fact, berries that are shaded by a canopy may also develop sunscald in the absence of direct sunlight when exposed to high temperatures.

Hence, a thing is worth mentioning that sunscald only affects those berries that ripen shortly after the weather warms. But berries that ripen a day or two later will be pretty normal. In both cases, affected fruit can still be eaten, you just won’t be selling them.

Solution: To reduce this, make the area sheltered from intense heat and wind. But another point to be remembered, don’t cover the plants completely otherwise, bees won’t be able to reach them to pollinate them.

In fact, an orientation of your rows in a north-south facing position will help the plants to minimize the effects of sunscald.

A question about watering the plants may rear its head. So, the answer is, watering twice a day to cool the plants during hot weather, for 15 minutes between morning and afternoon is helpful to alleviate sunscald. Yes, keep in mind that this method is not recommended in the evening hours. Because limited watering should cool the plants but evaporates quickly.

Problem 2: White Drupelet Disorder

This also happened as a result of solar injury, a combination of exposure to ultraviolet radiation, and high temperature. These white drupelets can occur singly or in groups.

As berries with white drupelet disorder vary from normal fruit only when there is a lack of pigment, they remain suitable for processing. But the only problem here is, they are quite unacceptable for fresh market sales.

Solution: The same suggestion will go for this, yes, shading plants to reduce UV radiation will lessen the problem.

Problem 3: Pests/ Insects

Yes, pests can play a role in the white spots in the raspberries. Such as stink bugs, red mites are often responsible for leading to white drupelets.

But hence, the discoloration from feeding damage won’t look the same as it looks for the sun scaled or hot temperatures. In this case, the drupelets will take a more random patterning of white spots instead of a large general area.

There is another case, the drupelets won’t be white but small yellow/white ‘raspberry fruit worms’ larvae may be seen clinging to the harvested fruit. These whitish larvae will burrow into the fruit and destroy it. Moreover, there will be holes in the leaves of the plants indicating the presence of adult beetles.

Solution: Insecticides are used primarily to control these insects.

Additional Information

This part is about gray mold (Botrytis cinerea). It sometimes causes confusion whether your raspberries are facing white drupelet disorder or gray mold because they almost look the same.

In wet seasons, gray mold causes a significant loss of flowers and fruits. Infected berries become covered with a gray, dusty fungal growth. Another point to be noted, mature berries are more susceptible than the younger ones. Moreover, berries sometimes do not show gray mold until after harvest and they can quickly become a rotted mass in storage.

Solution: This problem is managed through an integrated program including:

  • Cultural practices that promote rapid drying of fruits and flowers such as, site selection, maintenance of narrow plant rows, trellising, and cane thinning.
  • On-time (regular) harvesting of fruit to prevent a build-up of gray mold spores on overripe fruit.
  • Fungicide sprays as necessary. In particular, sprays are most important just before rainy periods that occur during bloom and before harvest.

White Spots on Raspberries – FAQs

Question: How should I water my raspberry plant?

Answer: Mostly, they need water every 5-7 days during establishment. Remember, keep the soil moist but not waterlogged. When irrigation is needed, apply 1 or 2 inches of water per week. During fruiting, plants may need additional water to promote larger barriers.

Question: Are raspberries with white drupelets edible?

Answer: Yes, they are. But berries with brown (rotting) drupelets are not edible, they should be picked and discarded.

Question: When white drupelets typically occur?

Answer: When temperatures are fairly steady around 70 degrees Fahrenheit suddenly go above 90 degrees Fahrenheit.

Question: What about applying fertilizers?

Answer: Sandy soil will need more nitrogen than clay soil. A general recommendation for an establishing plant is to apply 3-5 pounds of urea (45-0-0) or ammonium sulfate (21-0-0) per 100-row feet. Apply fertilizer in the early spring.

Conclusion

So, that’s all we stored for you. Hopefully, after reading this article, you are no longer confused about what causes white spots on raspberries and how to fix it.

In the end, we’d like to say that you should always take extra care of your raspberry plants as they are vulnerable to sunlight, heat, diseases, and pests. Apart from this, you now know everything about troubleshooting the issues.

So, don’t overthink, you are going to fix it. Good luck!

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