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Source: Jerzy Opioła, Drepanopeziza ribis a1 (2), Edited by Plantopedia, CC BY-SA 4.0

How do I recognize leaf fall disease and how is it combated? Is she dangerous? This article will tell you what to do if currant leaves curl.

In a nutshell

  • Disease occurs particularly in wet periods, but is not life-threatening, but control is still recommended
  • first characteristics: spots/dots on upper side of leaves, initially yellow, later brown-black, progressively larger
  • later leaves curl, edges dry up and finally premature leaf fall follows
  • Control: pruning measures, strengthening with plant manure, renunciation of artificial fertilizers and disposal of diseased leaves
  • Preventive measures: sunny and airy location, light pruning, plant strengthening and use of resistant varieties

Leaf fall disease explained

It is a fungal disease caused by the fungus Drepanopeziza. It only affects the gooseberry family, more precisely their only genus currants, botanically Ribes. This in turn consists of various types of currants and gooseberries. The fungus does not spare any Ribes Art. In a home garden, the following types of currants are mainly grown:

  • Redcurrants (Ribes rubrum)
  • Blackcurrants (Ribes nigrum)
  • Gold currants (Ribes aureum)
  • Alpine currants (Ribes alpinum)
  • Blood currants (Ribes sanguineum)
Gooseberries (Ribes uva-crispa)

Notice: The popularly cultivated gooseberries (Ribes uva-crispa) and jostaberries (Ribes x nidigrolaria) can also suffer from this disease.

time window of the disease

Currants are attacked between May and July. The harvest time also falls within this time window, which, depending on the variety and the current weather, lasts from mid-June to around the beginning of August. But it is by no means said that this disease has to occur frequently or even every year. Many currants in the home garden are even spared from it for the rest of their lives.

Favorable Conditions

This fungus needs moisture to thrive. Damp, rainy spring days are the greatest risk of infection. It is also beneficial if the temperature is around 12 °C at the same time. The fungus lurks in the soil, where it usually got through diseased leaves that were thrown off the previous year, where it survived the winter unscathed and formed new spores in the spring. It first reaches the nearby lower leaf specimens and is then carried higher and higher by the wind, up to the tips.

symptoms

If ignored entirely, this disease will eventually lead to leaf drop. But long before that, she shows other symptoms. In the first place, no curling of the leaves, but mainly spots form on them. But a reassurance first: As frightening as this disease may seem, it is not life-threatening for Ribes.

Gooseberry leaf affected by Drepanopeziza ribis
Source: Jerzy Opioła, Drepanopeziza ribis a2 (1), Edited by Plantopedia, CC BY-SA 4.0

These are the visible signs by which you can recognize leaf fall disease:

  • small, round spots (dots) on leaf surfaces
  • first yellow, later brown-black in colour
  • speckled leaves
  • Spots grow larger, flow together
  • until they cover almost the entire leaf
  • Leaves curl or curl up
  • sometimes this is referred to as leaf curling
  • Leaf edges yellow and dry up increasingly
  • Result: premature leaf fall

If the owner fails to fight the disease for any reason, the affected currant will be left with bare branches shortly after harvest time. But she drives out again in due course.

Identify other diseases

Leaf spot is one of the common symptoms of plant diseases. But if you take a closer look, you'll quickly spot the telltale features. The timing of the illness is also important:

  • Nettle foliation: Leaves slowly turn brown to black
  • is accompanied by weak shoots and weak formation of flowers
  • only affects blackcurrants
  • Column rust occurs only in autumn
  • appears with red pustules on the leaves
  • Red pustule disease occurs in midsummer
  • she also shows up with red pustules
Black currant (Ribes nigrum)

Tip: In the case of currants, it should also be checked whether leaf changes were caused by drought. However, the entire sheet usually turns yellow without really appearing blotchy.

fight in time

Although this fungal disease keeps the shrubs alive, you should still fight it as soon as you discover it. It is not necessary that the vitality of the plant suffers and the yield decreases. Also, the mottled leaves are not a sight that an industrious gardener would want to put up with. By combating it, you also reduce the risk of being infected again in the following year or of spreading to healthy bushes.

Grab a pair of scissors in the early stages

If the fungus is still in the early stages of its conquest, the easiest way to contain it is with scissors. Cut off heavily affected branches completely. Closely inspect all the leaves on the remaining branches and remove any stained specimens. If a currant is still young and only has a few shoots, do not cut it off. Instead, remove each affected leaf by hand.

Tip: Disinfect the cutting tool before and after use to avoid spreading fungal pathogens. Experts disagree on whether plant material infected with this pathogen can be composted. You play it safe if you dispose of it as residual waste.

strengthen plant

Freshly prepared nettle manure

With plant broths, you can specifically strengthen the resistance of currants so that they can better defend themselves against the fungus. You can use nettle manure, horsetail broth, garlic broth, or onion skin broth, depending on which broth is easiest for you to make.

  • splash on warm, sunny days
  • but not in the blazing midday sun
  • Process can be repeated several times a week

Avoid artificial fertilizers

Immediately after discovering the disease, refrain from using nitrogen-heavy artificial fertilizers if you are not already doing so. This is how you reduce the infestation pressure.

Collect leaves when infestation is severe

If the symptoms of the disease appeared late and only moderately, the foliage is allowed to rot on the spot. If the disease progresses severely, you should collect and dispose of the fallen leaves promptly.

Prevent early

You can prevent this disease from occurring or spreading if you plant the currant in a suitable location, take care of it properly and, if possible, take appropriate measures to strengthen its vitality.

Red currant (Ribes rubrum)

In summary, you should implement the following points:

  • choose a sunny, airy location
  • Do not plant the bed too closely, ensure there is sufficient planting distance
  • if necessary, remove or replant a few shrubs afterwards
  • thin out vigorously when cutting if necessary
  • Also thin out shady trees

Tip: By doing without nitrogen-heavy artificial fertilizers, you should not only act in the event of illness, but also generally prevent an infestation. Organic fertilizer and the aforementioned manure are ideal fertilizers for ribes.

Rely on hardy varieties

If you want to get a few new currant bushes in the garden, get advice on resistant varieties from specialist retailers. Although these varieties are not completely resistant, they fall ill less often or survive the disease better.

Tip: The black currant is less likely to suffer from this disease than the red currant or white currant. It is the better choice, especially in rainy regions of the country.

A few words about fungicides

No fungicides against this fungal pathogen are currently approved for the home garden. Given that it's not dangerous, there's no need to resort to toxic and polluting agents either. Better meet the curling leaves on the paths described above.

frequently asked Questions

Do gooseberries get this fungal disease at the same time?

The gooseberries get sick later in the year. The visible symptoms usually appear after harvest.

Can I harvest and eat the fruit of diseased currants?

Even if you don't recognize and/or fight the disease, the fruits remain unaffected. They are edible without restrictions, and their taste does not suffer either. However, it may be that the harvest quantity is somewhat reduced.

Which red currant species is less susceptible?

There are a few varieties, for example 'Rondom', 'Stanza', 'Tatran' or 'Rote Vierländer'.

Is this disease also called leaf curl because the leaves curl?

There is a fungal disease called curling disease. But this refers to a different disease that affects almond, peach and nectarine trees.

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