Due to their durability and uses in the garden, currants are one of the most popular shrubs among German gardeners. Currants rarely get sick, but the plant is not immune to any disease. There is a large number of diseases that have a negative effect on the vitality of the plant and can even lead to its death. For this reason, it is important to know how to recognize and deal with these based on damage images.
Diseases of currants
If you are the proud owner of a currant in the garden, you definitely do not want to lose it to disease or forego your harvest. Currants are considered to be extremely robust and can therefore even be kept in unsuitable locations. However, the plants are not safe from all diseases and it can happen that you suddenly face a big problem.
The most common reasons for currant disease are care errors and unfavorable locations. Fortunately, these can be treated with the right measures. The most susceptible to the 8 diseases that are described in detail in the following sections are redcurrants (bot. Ribes rubrum), while the black variety (bot. Ribes nigrum) is significantly more resistant.
American gooseberry powdery mildew
American gooseberry powdery mildew is also under the name currant mildew known and one of the most serious diseases of currants. Especially in Central Europe, powdery mildew is a danger that should not be underestimated, since many regions have damp weather and for this reason support the spread of the fungi. Podosphaera mors-uvae is not only dangerous for the ribes in your own garden. Mildew counts as a problem for the economic cultivation of the berries. The following symptoms indicate powdery mildew:
- white coating forms on leaves
- can also affect fruit
- this looks mealy
- slowly turning brown
- Leaves begin to wither
- Leaves dry up and fall off
- Shoot tips wither
- Shoot tips die off
- Fruits are inedible
You can prevent infestation by regularly spraying the plants with a decoction made from either stinging nettles (bot. Urtica) or field horsetail (bot. Equisetum arvense). For first aid, follow these steps:
- remove affected leaves
- remove affected shoots
- alternatively spray nettle stock
This way, you can get mildew under control quickly. Refrain from using milk to wipe off the mildew, as removing the infected areas is healthier for the crop.
tip: If you don't want to deal with gooseberry powdery mildew, consider growing resistant varieties that don't have a problem with the fungi. These include the sweet and sour 'Neva', the juicy 'Black Marble', the sweet 'Blackbells' and the tart 'Late Night', all of which are ideal for establishing yourself in your own garden.
weave
Lichens are a combination of algae and fungi that result from neglecting your currants. As such, the growths of lichens recover when they become ill from them. The damage can still be alarming:
- Flowering fails
- Crop failure follows
Lichens are fairly easy to spot and can be kept at bay with regular trimming. Make sure you do this, because many pests use lichens as protection.
column grate
Column rust is a disease of currants that you can hardly fight. The cause of this is the fungus Cronartium ribicola, which survives in fruit trees over the summer and changes to five-needle pines over the winter:
- Arolla pine (bot. Pinus cembra)
- Bristlecone Pine (bot. Pinus aristata)
- Flexible pine (bot. Pinus flexilis)
- Japanese pine (bot. Pinus parviflora)
- Teardrop pine (bot. Pinus wallichiana)
- Rumelian pine (bot. Pinus peuce)
If you have any of the above species around, the pillar rust will strike year after year. Only cutting down the pines can help here, so that your specimens do not get sick again. You can remove only the affected leaves to prevent the spread of spores. The symptoms as follows:
- pustules on the leaves
- these are red-orange
- Leaves can dry up
red pustular disease
Red pustule disease can be curbed by removing the affected shoots. In addition, you can regularly distribute a stinging nettle decoction on the soil and the plants over spring and autumn. Currant disease caused by the fungus Nectria cinnabarina can be recognized by the following symptoms:
- dying shoots
- Spore deposits form on shoots
- Spore pustules are yellow to pale red
- Fruiting bodies at the base of the bush are formed
- these are violet in colour
nettle leafiness
The trigger for this disease is Currant leaf gall midge (Dasineura tetensi), which transmit a virus to the currants through their sucking behavior. This causes the following damage, which draws attention to the infestation by mosquitoes:
- Shoots and leaves change color
- weak formation of flowers
- Flower formation weakens with each passing year
If this is the case, you have to cut the currants thoroughly and leave only a little material. After pruning, the bush is sprayed with a decoction of tansy (bot. Tanacetum vulgare), which you repeat more often. That drives away the mosquitoes. You should also cut back the shrub strongly before autumn.
Colletotrichum fruit rot
Colletotrichum fruit rot is caused by the fungus Glomerella cingulata in weather conditions above 15°C when wet conditions prevail. The symptoms of fruit rot are noticeable in the berries, which begin to lose their color from the disease and turn a milky red before they dry up and remain on the plant. The stems also turn brown and dry out. As soon as you notice the fruit rot, here's what you should do:
- remove berries
- Cut back affected shoots
- optionally use a nettle decoction
The only way to prevent fruit rot, apart from a location that is not too damp, is regular pruning, as a lot of foliage increases the infestation.
leaf fall disease
Leaf fall disease is one of the most common diseases affecting currants, as many gardeners do not know what causes the disease and therefore do nothing to prevent it. This currant disease is caused by the fungus Drepanopeziza ribis, which has mainly focused on plants within the genus and can only be noticed on these. You can recognize Drepanopeziza ribis by the following symptoms:
- brown spots on the leaves
- dots connect
- turn yellowish
- leaf edges dry up
- Leaves curl up
- leaves fall off
- Shoots turn brown
The damage can progress so severely that the entire shrub is largely defoliated. Since the disease already shows up in summer, the leaves can be missing until harvest, which can have a negative effect on the currants. For this reason, you should absolutely prevent the fungus from spreading in the first place. The fungi overwinter in damp fall leaves that were not collected before winter and disperse spores the following spring. These then settle on the still young leaves of the currant in spring and attack them. For this reason, you must collect autumn leaves from under the bushes as best you can before winter, especially if you live in a humid region, as the weather there is extremely favorable for the spread of fungi. In the event of an infestation, proceed as follows:
- remove affected shoots
- Use clean, sharp scissors for this
- then clean the scissors
You can prevent the fungus from spreading even more effectively in the spring if you prune the currant bushes in your garden spring pruning undergo. This will remove most of the mushrooms.
tip: Do not dispose of the leaves on the compost but in the residual waste or burn them. This will prevent the fungi from spreading and another season of bare shrubs.
dieback
Dieback is another of the numerous currant diseases caused by fungi. The shoot dieback is caused by the fungus Botrytis cinerea, which is not only transmitted via the autumn leaves like leaf fall disease. It also sets up its winter quarters in diseased berries and on shoots, which makes the entire currant a veritable hotbed of infection possibilities. The damage picture of drive death is as follows:
- Leaves are not formed
- developed leaves turn yellow
- Shoots sprout badly
- young shoots wither
- the shoots die off
- loss of fruit
As you can see, the death of shoots is a guarantee of a bad harvest. For this reason, it is imperative that you do something about Botrytis bark blight. Botrytis bark blight is just another name for the disease. To prevent this, follow the steps below:
- Cut back currants
- choose autumn for that
- reap all the fruits
- even inedible or rotten ones
- Remove fall leaves
- pick up fallen berries
In this way, as with leaf fall disease, you prevent an infestation. If the plant is sick and you need to treat it immediately, you should remove all affected leaves, shoots and fruit as soon as possible. Be generous here and cut at an angle to prevent further infestation by the fungi. Do not dispose of the infested parts of the plant on the compost either. This is the only way to protect your ribs from the fungus so that they no longer get sick. As long as you keep the fungus under control, it will no longer show up on your bushes.