Raspberry Leaf Curl

Fresh-from-the-garden raspberries are a real treat. Once canes are established, they can be relatively maintenance-free. But if you happen to notice that some of your raspberry leaves are starting to crinkle, curl, or change color, you may have a problem.
 
There are several reasons raspberry leaves start curling. Aphid, leafroller, leafhopper, and psyllid feeding can cause leaf curling, as well as chemical overspray and some viral diseases.
 
Raspberry leaf curl is a viral disease carried by aphids.
 
Symptoms of raspberry leaf curl
 
At first, there are no symptoms. This is a slow-moving disease. You will eventually see mild downward leaf curling at the tips. The next year, you will see more pronounced symptoms.
 
As the virus gets serious about reproducing inside the phloem tissue of your plants, canes will become branched, brittle, stunted, or develop into a rosette. Fruits will be small, deformed, and crumbly. Leaves of infected red raspberry plants will turn yellow, while black raspberry leaves turn a dark, greasy green. In both cases, the leaves on young and old canes will curl downward. [Leafhopper feeding causes upward curling.]
 
Infected plants are highly susceptible to winter damage.
 
Managing raspberry leaf curl
 
Unfortunately, there is no cure for raspberry leaf curl. It may take two or three years, but infected plants will die.
 
The only thing you can do once a plant is infected with raspberry leaf curl is remove it. Double-bag and trash infected plants or burn them if you have a fire pit going anyway. As you cut away infected canes, be sure to disinfect your pruners between each cut to prevent the spread of disease.
 
To avoid raspberry leaf curl in the first place, install certified pest- and disease-free plants. If you have any wild brambles growing nearby, you may want to remove them. You can monitor for aphids using yellow sticky sheets, and insecticidal soap sprays can help keep aphid populations in check.
 
Other plants susceptible to raspberry leaf curl include purple raspberries and wineberries, Himalaya blackberries, Pacific coast trailing blackberries, and wild blackberries. Tropical black raspberries, ‘Lucretia’ dewberries, and Alpine strawberries may also be vulnerable to this disease.
 
As of 2023, raspberry leaf curl disease was predominantly found in Canada and northern-tier US states. Of course, high mobility rates and changing climates can make new areas appealing to the small raspberry aphid (Aphis rubicola), responsible for spreading the disease.