Let me tell you a little about the disease itself. Powdery mildew is a fungal disease. It is caused by various types of fungi, each crop having its own specific pathogen. However, currants and gooseberries are both affected by the same species: Sphaerotheca morsuvae.
The white coating, which first appears on the leaves, gradually spreads to other parts of the plant. If left untreated, the fruit will eventually become covered. This will deprive you of at least half your harvest, and if the condition is severe, the entire crop.
How to combat powdery mildew on gooseberries and currants
There are different ways to combat this scourge: from folk methods to chemical ones.
It all depends on whether you can treat the bushes every two weeks; if so, you won’t need any chemicals.
I've heard that hot water (+90°C) is often used, dousing all the bushes with it in early April. I haven't tried this method myself yet, as it's difficult to carry boiled water from home. I use an ash infusion (1 kg, dilute it in 10 liters of water and leave it for 5 days, stirring occasionally). I strain the mixture and pour it into a spray bottle. By the way, to make the solution stick better, add a little soap to the infusion. Don't leave the solution for too long, as it will lose its properties.
Another option is to use mullein or manure. To do this, dilute one with water 1:10, let it sit for 4 hours, and then spray it on all the bushes. This is best done in the morning or evening on a warm, dry day.
If you don’t have time for regular care, use chemicals (copper sulfate, colloidal sulfur).
Methods of disease prevention
But it's best to prevent this kind of illness from developing. To do this:
- Do not plant bushes in a shaded area.
- Do not thicken the plantings.
- Try to place currant bushes away from gooseberries.
- Don't overdo it with nitrogen application.
- Feed with phosphorus-potassium fertilizers.
Better yet, plant disease-resistant plant varieties. For example:
- gooseberry - Kolobok, Ural grapes, Kuibyshevsky, Harlequin;
- black currant - Binar, Bagheera, Black Pearl, Moscow;
- white currant - Boulogne, Dutch;
- Red currant - Boulogne, Red Cross.
