The following nine diseases occur in many raspberry crops and can cause lasting damage. Careful controls and regular reviews of the stocks help to identify and treat diseases as quickly as possible.
Table of Contents
The botrytis fruit rot
If there is a pronounced period of wetness during the fruit development phase, there is a risk of fruit rot. The damage can be recognized by a grayish, dusty coating on the fruit. In the late stage, the berries shrivel and harden.
How does the disease develop?
The fungus can hibernate on the raspberry canes with the help of its sclerotia (spores). The fruits become infected during flowering when the spores are spread by heavy rain. In particular, if there are aging parts of the flower, an infection or infestation can occur.
What preventive measures are there?
Fruit rot can best be prevented if the rods are thinned out regularly and in good time. A clean harvest is also important. If the weather is warm and humid for a long time, the use of a fungicide should be considered during the flowering period. Here it is necessary to choose preparations that are suitable for combating fruit acids.
The raspberry rod disease
Fungi are also responsible for causing raspberry rod disease. In the event of an infestation, the yield can be very sparse. The symptoms become visible in spring when the shoots are around 40 cm high. amounts to. At the points of attachment and buds of the plant, purple spots appear that expand quickly. The affected bark dies or turns silver-gray. An infected bud remains behind, does not continue to grow and dies in the following winter.
How does raspberry rod disease spread?
Raspberry rod disease infection can occur throughout the growing season. The spores are spread especially in strong wind and rain. If there are injured rods, the fungus can colonize them completely and lead to death.
How can the disease be prevented?
Timely thinning of the stands is one of the most important precautionary measures, including avoiding weeds. It is also useful to ensure that there are no injuries to the rods, because these form a gateway for the mushrooms. The use of fungicides can usually contain and treat raspberry rod disease.
The Phytophthora root rot
Root rot is an endangering disease that can lead to the collapse of entire raspberry plants. The risk is particularly high on wet floors.
How can the disease be recognized?
The symptoms mainly appear on the young shoots or the crop branches. There is discoloration of the leaves, necrosis on the leaf edges and signs of wilting. If the infestation is severe, the entire plant growth appears poor. If young shoots are affected, they usually die by early summer, the rest takes place in autumn. Dark brown discoloration on the base of the rod is also a symptom of root rot.
A clear sign of root rot are yellow leaves with clear necrosis on the edges. The root system is affected by rot. Raspberry bushes are infected via the roots, the main source of infection is already infected plants. The pathogen can spread very quickly, within a year it can spread up to seven meters.
The symptoms at a glance:
- discolored leaves with necrosis and wilting
- poor growth
- dead young shoots
- Discoloration at the diamond base
How can you prevent root rot?
The best way to prevent root rot is to ensure that young plants are free from infestation. In addition, a well-drained soil should be chosen as the location, the soil moisture of which is sufficient.
The raspberry mosaic
The term raspberry mosaic encompasses various viruses that can result in a high loss of yield.
Symptoms of the
stain mosaic There are three different types of the viral disease, which are known as stain mosaic, vein ligament and vein chlorosis. The main symptom of the stain mosaic is stains, which are clearly separated from the rest of the leaf tissue.
Symptoms of the vein ligament
With a vein ligament, on the other hand, only the areas around the main veins of the leaf change color. In addition, there are puckered deformations that can spread over the entire edge of the leaf.
Symptoms of vein chlorosis
In vein chlorosis, network-like lightening of the lateral veins occurs over the entire leaf.
How can the infestation be prevented?
The viruses of the raspberry mosaic are transmitted by different species of aphids. To prevent infestation, it is advisable to use aphid-resistant varieties from the start. New plants should also not be planted in the immediate vicinity of contaminated old plants.
The dwarf disease
The so-called dwarf disease affects not only raspberries, but also blackberries. If a raspberry crop is infected with this disease, the culture is no longer profitable.
How do you recognize dwarfism disease?
Affected plants appear stocky and develop the optical image of a witch’s broom. A large number of thin annual shoots form, which are normally not common in a raspberry bush. Shortened side shoots sprout from the axillary buds, and the carpels are increasingly fading. The existing sepals seem longer than usual, the fruits are inedible.
The symptoms get worse with increasing age of the plants, after a few years the affected raspberry bushes die. The disease is transmitted by a species of leaf hoppers and the incubation period is up to eleven months.
What are the options for combating it?
Unfortunately it is not possible to fight dwarf disease, only the selection of still healthy mother plants is an option. In the case of a new plant, it should be checked in advance whether the young plants are free from infestation.
The raspberry beetle
Raspberry beetles are one of the common pests that can quickly lead to large losses. Consumers do not buy larval-laden fruit, so the harvest is no longer useful.
The beetle eats the flower buds and flowers, while the larvae eat them damage the fruit.
How does the raspberry beetle spread?
The approximately 5 mm will appear from mid-May. large beetle with yellow-gray hairs. The eggs are laid inside the raspberries from June onwards. The beetle’s damage to eat is enormous, especially in shady regions; the larvae pupate outside of the fruit. The beetles can overwinter outside the plants in the ground.
How is the beetle controlled?
Insecticides which can be used against biting insects are suitable as control. Application is permitted shortly before and during flowering, but only insecticides that are not harmful to bees may be used.
The raspberry gall mosquito
Not only diseases, but also pests such as the raspberry gall mosquito are causing problems for raspberry populations. Considerable damage is to be expected in the area of the rods, especially if the raspberry gall mosquito occurs together with the raspberry rod disease.
How does an infestation with the raspberry gall mosquito express itself?
Brown spots and discoloration appear especially in the regions of the raspberry rod close to the ground. The damaged tissue sinks into the soil, the places where the larvae eat show up with dark gray to purple spots. The affected areas are occupied by numerous, red larvae.
How is the damage created?
Mosquitoes begin to fly in mid-May, the eggs are mainly laid by the insects in the cracks in the bark of young rods. Most larvae are between 20 and 40 cm. Rod height, they live under the top layer of bark and destroy the rod piece by piece. Fungi have easy play due to the injuries and can penetrate the tissue.
How can the infestation be prevented?
The best method of prevention is an adequate supply of water and regular thinning of the stocks.
The raspberry blossom cutter
Raspberry blossoms only become dangerous to the stocks if they are found in large quantities. The small beetles gnaw on the stem of the flower buds, so that they wither and fall off. The dark brown beetle appears just before flowering begins and lays its eggs.
How is the damage developing?
As soon as the eggs are deposited in the closed flower bud, the flower stalk is gnawed. The buds wither and fall off. Inside the flower bud, the larva continues to develop and plaster itself. The young beetles finally retreat to their winter quarters in late summer.
How can you act in the event of an infestation?
In order to rule out an infestation, it is necessary to check the buds for beetle infestation shortly before the flowering period. Treatment with contact insecticides shortly before the start of flowering is quite possible.
Raspberry rust
One of the most common diseases is raspberry rust, which is shown by yellow dots and spots on the top of the leaves. On the underside of the foliage, the spots are orange and turn dark brown to black after a very short time. The entire spots are quite small, mostly only points can be seen. In the case of heavily infested bushes, the leaves are thrown off early.
How does the raspberry rust spread?
The raspberry rust can overwinter on the leaves that have already fallen and develop numerous new spores in spring. When wet weather prevails, new, healthy leaves will be infected from the fallen leaves on the ground.
What treatment methods are there?
Once the raspberry rust has been identified, the foliage should be checked for yellow spots and spots. The foliage must be removed at the slightest signs. Treatment with a chemical fungicide is also advisable. Young rods must be treated a total of three times to combat raspberry rust. The treatment should take place every seven days.
Infected rods with affected leaves should be cut off and carefully destroyed. In addition, the stock should be checked for injured young rods and any waterlogging. Tall weeds have to be weeded, and dense stands of plants should be separated.
Raspberry rust treatment at a glance:
- Control for infestation
- Removal of leaves from the smallest of traces
- Use of chemical fungicide is recommended
- Treatment is done every seven days
- affected rods are cut off and destroyed
- the entire stock must be checked
- Weed removal required
- dense stands of plants must be separated
