We have only listed infections we have been confronted with ourselves, and describe how we eventually controlled the problem.
Problem profiles are illustrated by fotographs and are grouped according to the causing agent.
Larvae of the yellow sawfly are the most common leaf eaters on gooseberries, although some varieties/species are not infested by this insect.
It is a larvae of a yellowish sawfly (Nematus ribesii or Pteronidea ribesii).
The -caterpillar like- larvae is about 2 - 2.5 cm long, often with brown/black spots on a greenish background.
Sawfly larvae can defoliate a shrub very rapidly.
Best prevention is to look for these larvae and dispose of them. When they are to abundant you can use a bacterial spray or use a pyrethrum based product.
The sawfly has 2 or 3 generations a year.
When the small larvae just hatched they start to eat with a lot together and make typical perforations in the leaf. Just using your fingers to clean the leaf will destroy the 3 mm long larvae...
(for a detailed picture see also here)
You can also find larvae of the black sawfly eating the leaves of your gooseberry plants. They can be distinguished from the yellow sawfly as they are a dull green, where the yellow sawfly larvae are lightgreen with all types of coloured dots on their body. Aphids:
Aphids are a common problem. There are different kind of aphids, but they all cause the same problem, i.e. curling up the young infested leaves. The young shoot also will be twisted. Often infections will disappear as they come. We keep a close eye on these infestations as they are told to pass over virus infections. In that case the danger does not come so much from the mass of wingless insects, but from the winged ones that easily can fly over to other bushes taking possible virusses with them.
We try to keep the infestations at bay by using a soft soap solution combined with basalt flour. When we notice no improvement the next day, we will respray with a herbal fungicide (nettle extract) or in the worst cases with a pyrethrum solution...
Gooseberry fruitworm
Gooseberry fruitworm is in reality the caterpillar of a moth (fruitmoth or Zophodia convulutella).
Eggs are placed on the flowers or on young berries.
It takes the caterpillar about 2 months to develop to a puppa by end of July. The caterpillar drops on the ground and hides under the ground to become a pupa.
There is only one generation during the year.
The moth flies from April till mid May.
The small caterpillar penetrates the first berry, then it weaves silk threads around several berries and might penetrate other berries. Generally one gooseberry is sufficient. The berry decolors and infection is easily recognised.
It is a common infection of red currants and is rather rare on gooseberries. Till today we did not have to take action against this insect.
Anthracnose or leafdrop might be caused by Drepanopeziza ribes and Gloecospridiella ribes.
Symptoms are small dark brown, round or irregular leaf spots that appear on the leafs.
In some cases it may lead to leafs turning yellow and shed to the ground.
Small, grayish knobs develop in the leaf lesions.
The disease reduces the plants vitality, growth and productiveness. Repeated infections can finally kill the shrub.
Controlling of the disease can be obtained by removing the leaves from under the bushes when leaves drop during mid-season. These leaves need to be burned or composted at high temperatures to kill the spores.
Adding a mulch layer at regular times avoids the ascopspores to be released in the air and so no new infection can take place.
It is best to apply open pruning to have sufficient air flowing through the bush.
When necessary also chemical treatment of this infection is possible with the correct fungicide
Mildew
American mildew
Originally this gives a white powdery coverage of the tops of the shoots. Later this becomes a thick grey layer that also gives patches on the berries. In a further stadium the berries become completely covered by a thick brown cover. The young shoots also turn brown. The new leaves are small and disformed, in a later stage (often already in june), the young shoots will dy back at the top. Often dry warm summer wheather makes that the bush starts forming new shoots, but as sson as the wheather becomes more humid, the mould will again cover the new growth....
When infection occurs it is advised to remove the infected parts. You can also try to spray against this disease, but American mildew is very though to control, even with professional products not available to the home gardener. It is strongly advised to grow only mildew tolerant varieties (the home gardener should only consider these). see tolerant gooseberry list.
Powdery mildew
This is a similar infection as above, but only covers the plants (and sometimes also the berries) with a white powdery cover. As a result of infection with powdery mildew plants will slow down in grow, but rarely young growing points will dy back. It is also more difficult to detect the infection during winter compared to the 'American' mildew.
Often infections will come back year after year and so plants will loose their growing abilities. So it is recommended to spray with sulfer (or systematic fungicide).
Grey mildew
Grey mildew (Botrytis) is a grey, powdery coverage of the (mostly) young shoots, very similar to the above. You can spray with systemic fungicides, sulfer or even better grow only tolerant varieties see tolerant gooseberry list
Rust
In our collection, trial fields we were not yet confronted with rust infections. Often it appears as yellow/orange dots on the leafs. In that case it are the sporangia that break trough the leaf and spread the coloured spores. Infections can be very severe as that leaves seem to be covered with rust. When confronted with rust, it is best to spray with sulpher early in the season (when leaves start to pop out from the buds) and repeat this every two-three weeks during the season. Skipping the flowering period and the fruit picking time...
There are several known virus infections. In most cases they appear as different colours on part of the leaves or veins. In some oocasions only the young leaves are brightly yellow, this colour disappears when the leaves become older. In most cases virus infections cause no visible harm to the gooseberry bushes. Although it is advised to prevent the virusses to spread from one bush to another bush (see e;g; aphids, mites,...), certainly in collections or nurseries should take the necessary actions to stop spreading the virusses from one variety to another.
Be aware that (dis)colouring of leaves can also be an indecation of the lack of a certain nutrient in the soil...
Mites are tiny spiderlike creatures. Like aphids they only cause harm when they appear in large quantities. They are also suspected from transferring virusses from one plant to another.
It can become necessary to treat the bushes against mites. This can be done by setting out assassin bugs or by spraying with an acaricide (less preferential).
Larvae of the yellow sawfly are the most common leaf eaters on gooseberries, although some varieties/species are not infested by this insect.
Best prevention is to look for these larvae and dispose of them. When they are to abundant you can use a bacterial spray or use a pyrethrum based product.
Aphids are a common problem. There are different kind of aphids, but they all cause the same problem, i.e. curling up the young infested leaves. The young shoot also will be twisted.
Often infections will disappear as they come. We keep a close eye on these infestations as they are told to pass over virus infections. In that case the danger does not come so much from the mass of wingless insects, but from the winged ones that easily can fly over to other bushes taking possible virusses with them.
Gooseberry fruitworm is in reality the caterpillar of a moth (fruitmoth or Zophodia convulutella).
In some cases it may lead to leafs turning yellow and shed to the ground.
Originally this gives a white powdery coverage of the tops of the shoots. Later this becomes a thick grey layer that also gives patches on the berries. In a further stadium the berries become completely covered by a thick brown cover. The young shoots also turn brown. The new leaves are small and disformed, in a later stage (often already in june), the young shoots will dy back at the top. Often dry warm summer wheather makes that the bush starts forming new shoots, but as sson as the wheather becomes more humid, the mould will again cover the new growth....
There are several known virus infections. In most cases they appear as different colours on part of the leaves or veins. In some oocasions only the young leaves are brightly yellow, this colour disappears when the leaves become older. In most cases virus infections cause no visible harm to the gooseberry bushes. Although it is advised to prevent the virusses to spread from one bush to another bush (see e;g; aphids, mites,...), certainly in collections or nurseries should take the necessary actions to stop spreading the virusses from one variety to another.
Mites are tiny spiderlike creatures. Like aphids they only cause harm when they appear in large quantities. They are also suspected from transferring virusses from one plant to another.
It can become necessary to treat the bushes against mites. This can be done by setting out assassin bugs or by spraying with an acaricide (less preferential).