My blackberry bushes and raspberries are within 10 feet of each other. Is this too close for the sharing of disease? The raspberry canes are producing small pebbly fruit and leaves are yellowing. I put on sulphur, have sprayed miracle grow, mulched with leaves, added compost. All to no avail. Ideas???
For the first part of your question, blackberries and raspberries planted 10 feet apart should be fine. According to the Ontario Ministry of Agriculture, Food and Rural Affairs Factsheet on Raspberries and Blackberries (https://www.omafra.gov.on.ca/english/crops/facts/99-033.htm) “Rows should be spaced 2-2.5m (6 to 8 feet) apart, depending on available space, machinery needs and plant vigor. Plant red raspberries 60 cm (2 feet) and all others 75-90cm (2.5 to 3 feet) apart in the row.”
And for the second part, the yellowing of leaves and pebbly fruit could be symptoms of any of several causes. Again according to OMAFRA, usually the yellowing of plant leaves is caused by the inability of the plant to take up enough iron from the soil to keep the leaves green. This condition, called iron chlorosis, is worse when we have a lot of rain or water heavily. With iron chlorosis the leaves will be yellow but the veins in the leaves will be a greener color.
To treat this condition, iron supplements are available in both the liquid and powdered form. The liquid form when mixed with water works well on low growing plants and shrubs but has short term results. The powder which needs to get down to the roots is slower acting but has longer term results.
However, this could also be a symptom of raspberry bushy dwarf virus, a pollen-born virus that affects red and black raspberries and occurs naturally in wild raspberries.
Raspberry bushy dwarf virus (RBDV) can cause a variety of symptoms, and may cause no symptoms in some cultivars. One common symptom is yellow, interveinal chlorosis on emerging primocanes in the spring. Another is crumbly fruit, and a reduction in vigour. Leaves may exhibit yellow blotches, rings and lines.
The best way to diagnose raspberry bushy dwarf virus is early in the season, when temperatures are fairly cool and symptoms are most evident. Collect a few young but fully expanded leaves with symptoms and send to a diagnostic laboratory. ELISA test kits have been developed to diagnose this virus and most diagnostic labs will provide this service.
Raspberry bushy dwarf virus is a big problem because it is spread to new plants in pollen from infected raspberry plants. Some varieties are more tolerant than others, and some plant breeders have developed varieties with resistance to this disease. Primocane fruiting varieties are prone to RBDV because of their long bloom period. Remove bloom in the establishment year of a raspberry planting.
Tomato ring spot virus is another common virus in Ontario raspberries, and the one I see most often. Tomato ring spot virus is spread by the dagger nematode. Symptoms include crumbly fruit, and reduction in plant vigor. This virus can also be diagnosed using the ELISA test.
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