What's wrong with our raspberries?

[PaulF]

Wife is concerned about the state of our raspberries - I'm not a gardener but apparently the leaves don't look right.


Sick Raspberries? by paulfulford, on Flickr

[Kathy]

As the old agricultural research joke went, show that to an entomologist and they'll say "insect damage", ask a soil chemist and they'll claim a nutrient deficiency, and a plant virologist will swear that it's a virus.

I'd reckon a virus, but then I used to be a plant virologist...

[L CC]

I'd expect yellowing with a virus, rather than brown-ing.

Most common diseases of raspberries: Rust (I'd expect to see orange, well, rusty-looking, spots); mites (die back, mite visible to the naked eye); blight (affects canes first- black fungal patches on the canes).

Your leaves seem very pale (could be my monitor settings) which would imply a systemic problem eg drought or waterlogging, either of which will weaken the plants and make them more susceptible to disease. Where are they situated in the garden? What's your soil like?

[PaulF]

They're in a sunny part of the garden - our soil is supposed to be 'good' (I'm not the gardener though!) as as we're just off the Ridgeway is probably chalky. Soil is dry, I'll try and run a hose up there this evening.

[Kathy]

I'd expect yellowing with a virus, rather than brown-ing.

Browning follows yellowing - first chlorotic, then necrotic. But having looked at pictures of Raspberry Mosaic Disease, the pattern looks wrong for that.

[L CC]

(Obviously) my gardening 'expertise' is years out of date, I haven't grown a plant (apart from mustard-and-cress, and they died) for about 10 years. It doesn't change that much tho'.
This is what I'd do:
1) throw shit in the soil- nothing too fresh, that'll burn the roots, but a hefty top dress of well rotted FYM over a soil that's sodden will keep things righteous. On chalk you're unlikely to be waterlogged, so drought is my suspicion
2) check over the plants with a fine tooth comb for aphids (vector for the viruses), mites, scale insects. If you see 'em, squish 'em.
3) make up a weak washing up liquid solution and squirt all over the leaves

[ferret]

is there any sign of disease to the canes or is it just the leaves ?