Recognize & combat raspberry diseases

If raspberries have diseases, it can endanger the harvest. We present the most common raspberry diseases with pictures and show countermeasures.

raspberries (Rubus idaeus) are excellent for growing in the home garden. Unfortunately, the raspberry is not spared from plant diseases either. Surely you have already asked yourself which disease your raspberry has. We will show you how to recognize and treat these diseases on raspberries and how to prevent an infestation.

Crumb fruitiness in raspberries

The raspberry is an aggregate drupe. This means that what we call raspberries are actually many small stone fruits that stick together. The name "crumb fruitiness" explains very well what this disease is about: The individual drupes no longer hold together and the raspberry falls when picked or stored apart.

Recognizing crumb fruitiness in raspberries

Crumb fruitiness can be recognized before the harvest by the smaller fruits, which consist of a few drupes. The individual drupes that form a raspberry are often thickened. When harvesting, the crumb fruitiness is very easy to recognize, as the fruit breaks down easily when picked.

Combat crumb cravings

Unfortunately, the cause of the crumbly fruitiness, which is occasionally also described as crumbly fruitiness, has not yet been finally clarified. Inadequate fertilization of the flowers, the influence of vegetative propagation and location factors are suspected of triggering this disease. Likewise, viruses cannot be ruled out as a cause. As long as the cause of the crumb fruitiness has not been clarified, there are unfortunately no ways of combating it. However, some raspberry varieties are less susceptible to crumb fruitiness, for example 'Prussia', 'Polka', 'Borgund' or 'Zefa 3'.

In order to prevent crumb fruitiness, we recommend that you ensure that your raspberries are supplied with nutrients in line with their needs. It is also conceivable that other diseases weaken the raspberry and promote crumb fruitiness. Therefore, you should take care to keep your plants healthy overall. The site preparation, possibly with a high-quality potting soil like ours Plantura organic universal soil, as well as a suitable fertilization are important elements here.

Root rot in raspberries

Raspberry root rot is an infestation of the raspberry roots by the fungus Phytophthora fragariae var. ruby. As a result of the infestation of the roots, the water supply to the plant is disrupted and there are severe yield losses up to and including the death of the plant.

Identifying root rot in raspberries

The first symptoms of root rot in raspberries are usually visible from May. In the case of new shoots, leaf discoloration and wilting of leaves and the shoot tip occur. The base of the young shoot often turns dark. In early summer, the first new shoots often die off. Due to an infestation of root rot in two-year-old bearing canes, the sprouting is weaker and fewer fruits are formed. Here, too, leaf discoloration and drying of leaves occur. When pulling a rod out of the ground, dark discoloration and the absence of fine roots can be noticed. The symptoms are usually first visible in plants in moist locations.

Prevention and control of root rot

Since there is no pesticide to combat raspberry root rot, we recommend you take steps to prevent it from spreading and to get the infestation under control. Infested plants should be dug up with the roots as soon as possible and disposed of in the residual waste. Please do not put the plants on the compost as spores of the fungus may remain in the compost.

The fungal spores can survive in the soil for years. Therefore, no raspberries should be planted for a few years on areas that are already infested. In another spot, as far away from the infected soil as possible, you can plant raspberry varieties with high resistance to root rot, such as the 'Rubaca' variety.

Preventing waterlogging is particularly helpful. You should therefore avoid compacted or very moist soil as a location. Cultivation on embankments is also possible, which also reduces waterlogging.

Cane disease in raspberries

The rod disease is a clinical picture and can be caused by the fungi Didymella applanata,Leptosphaeria coniothyrium or Fusarium avenaceum be evoked. Even Botrytis cinerea (grey mold) and Elsinoe veneta can cause similar symptoms. These summarized cane diseases are among the most important diseases in raspberries. The fungus usually enters the plant through injuries. An infestation weakens the raspberry, resulting in a reduced yield in the infested year. In addition, budding is greatly reduced in the following year.

Recognize cane disease in raspberries

Rod disease, also known as rod dieback, can be recognized from early summer by purple to black spots on new shoots. The spots often appear first in the leaf axils and grow larger over time and can develop into streaks that extend across the entire shoot. In late summer, the entire shoot is usually affected, the bark appears black and shines silver in the light. The leaves of infected canes turn yellow faster than on healthy shoots. In addition, the bark begins to peel off the wood.

Prevention and control of cane disease

In order to specifically combat the various pathogens of rod disease, it would be necessary to identify the exact pathogen. Unfortunately, this is not usually possible, which is why we advise against the use of pesticides for cane diseases. Infested rods should be removed as soon as possible and disposed of in the residual waste to slow down further spread.

As a precautionary measure, we recommend that you avoid too dense a stand. A good row spacing is 2.5 meters, there should be at least 50 cm space between the plants. In addition, regular weed control contributes to a well-aerated stand. With all care measures it is important to avoid injuries to the rods. If you cultivate the raspberries with a climbing aid, you should therefore make sure that the rods are not injured.

Needs-based fertilization will help you to keep the raspberries healthy. We recommend that you ensure a good supply of potassium and phosphorus when fertilizing. However, you can keep the nitrogen fertilization reduced. A primarily organic long-term fertilizer like ours Plantura organic universal fertilizer promotes the fruiting of your raspberries. Diseases are also prevented in this way.

Anthracnose of raspberry

The anthracnose in raspberries is caused by the fungus Elsinoe veneta caused. This affects leaves, shoots and fruits. An infestation is usually only recognizable at the time of harvest from fruits that tear off unevenly, deformed berries and pink spore deposits on the fruit. The pathogen overwinters as spores on affected parts of the plant and infects healthy tissue in humid and warm weather.

Unfortunately, pesticides are not available to combat it. The spread of the disease on raspberries can be reduced by cutting back the affected parts of the plant. As a preventative measure, we recommend a row spacing of around 2.5 meters and a planting spacing of at least 50 cm, as well as good weed control. You should also remove all fruit, including inedible berries, before winter.

raspberry rust

Raspberry rust is one of the most common diseases affecting raspberries and is caused by the fungus Phragmidium rubi-idaei caused. The plant is weakened by an infestation and there can be a reduced yield. The fungus overwinters on fallen leaves, with the risk of infestation being greatest in May and June when the weather is damp.

The best way to identify a raspberry rust is by the yellow-orange spots or dots on the upper side of the leaf. Orange dots can also be seen on the underside of a fresh infestation, but these quickly turn black. Once you have identified an infestation, we recommend that you regularly monitor your raspberries and consistently remove infested leaves. It is best to dispose of the infected leaves in the residual waste to prevent the fungus from spreading. Several synthetic agents such as tebuconazole, azoxystrobin or difenoconazole are available to treat infested plants. Tebuconazole is not considered to be harmful to beneficial insects, but is suspected of being carcinogenic, i.e. causing cancer. For example, difenoconazole has a damaging effect on the beneficial chalcids (Trichogramma cacoeciae), whereas the active ingredient azoxystrobin is described as not damaging to beneficial insects and is therefore less problematic for the home garden. You can avoid the use of such synthetic active ingredients by consistently removing infested leaves and taking preventive measures.

As a preventive measure, we recommend that you ensure an airy stand where the leaves dry quickly. You can achieve this with regular weed control and wide row spacing. In the case of infested plants, the fallen leaves should be disposed of, as the fungus overwinters there.

Botrytis fruit rot in raspberries

The blossoms or ripe fruits on your raspberries are covered with gray mold? Then it is the Botrytis fruit rot. This disease is caused by the fungus Botrytis cinerea caused.

Especially in damp weather, the flowers or fruits are quickly attacked by gray mold. It is spread by conidial spores, which get onto the healthy plant from other infected plants or from the soil. The affected parts of the plant should be removed as soon as possible and disposed of in the residual waste. However, please do not throw the affected parts on the compost to prevent reinfection. Synthetic pesticides containing the active ingredient fenhexamid are available to treat an infested plant. This is not dangerous to bees, but we recommend keeping its use as low as possible to protect the environment.

We advise you to prevent an infestation by Botrytis. An open stand with good air circulation and a wide row spacing of 2.5 meters is very effective. The fungus enters the berry through injuries or via uninjured tissue. You should therefore avoid injuries and keep the cells resilient with needs-based, potassium-rich fertilization. By fully harvesting in the fall, you prevent forgotten or inedible fruit from being infested and facilitating infection in the spring. In the event of a severe Botrytis infestation, we recommend not growing berries at this location in the following year.

tip: An optimally supplied raspberry with perfect site conditions is more resistant to raspberry diseases. You can find out more about the fact that raspberries need a sunny, airy location with humus-rich soil in our article on the subject plant raspberries read. There it is also described how enormously important the planting distance is and you will find out more tips.