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Spots on Leaves of Roses and Pear and Problems with Raspberries

Every week I email a gardening question to the panel of experts at BBC Radio Norfolk’s The Garden Party  and then eagerly listen to the programme the following day, scribbling down the gems of information they kindly offer. Sometimes Laila sends a question or two as well. This is a transcript of the advice the garden party is giving on this weeks gardening challenges we are facing;

Bridget’s questions:

Hello gardeners!

I’ve noticed over the last few weeks that the leaves on several of my Autumn Bliss raspberries have changed and are not looking ‘normal’ any more. Is this a cry for help and perhaps they need feeding? If no action is taken, will the harvest be affected?

Also the leaves on my Shocking Blue floribunda rose plants are smitten with black spots. The flowers have been plentiful this summer but are now petering out… Please advise me what I should do and tell me whether this disease can spread to other plants nearby.

Thank you in advance.

Bridget

Raspberry leaf

 

The Garden Party’s answer:

Q1 Markings on raspberry leaves

Alan: Deficiency in something is there but I don’t know what is though, do you Richard?

Richard: Yes, they’re hungry. Also I think they’ve gotten dry. You can’t do anything now about this year’s crop at all, what you do now will not affect this years harvest but what I would do is two things; when you cut them down, which will be before Christmas, I would then get some well rotted manure or garden compost or whatever you use, preferably well rotted manure and I would add fish blood and bone or bone meal, something like that, to it and I’d put a good old mulch on top of the whole bed.

Alan: Six inches is not too deep is it?

Richard: No, not all. The photo we see shows this very pale colour coming from the veins and that is almost certainly because it is a bit short of one of the minerals. I would use something like a balanced liquid fertiliser but I wouldn’t put that on until the end of April or early May next year.

Ian: Yes. Fundamentally raspberries are ericaceous loving plants as well, so it’s primarily going to be something like magnesium for the iron deficiency and a good compost, leaf mold which is slightly acidic, composted pine needles or a bag of ericaceous compost form the garden centre…

Alan: There are specific liquid fertilisers for acid loving plants they release the iron chelates in the soil so just go to the garden centre and ask.

Leaf spot on rose

Q2 Black spots on rose leaves

Ian: I would say she shouldn’t worry for now, I mean it’s quite late in the season. I’d make sure I remove any leaves at the end of the season – clear up that leaf litter and bag it, burn it or put it in the brown bin because it goes off to the council where it gets heated up to such a high temperature that it kills off any spores and next year you’ve got to feed your plants with potash fertiliser. Potash thickens up leaf cells and it makes leaves much less susceptible to things like black spot, isn’t that right, Mr Hobbs?

Richard: Yes and also we’re back to air circulation so make sure that you prune your roses every year to make sure the air can circulate

Alan: …and just another little note – it’s still not too late to prune it just above a leaf node and you’ll hopefully get some more flowers this year.

Thunderfairy: …and  like any plants, they  respond well to regular watering, regular feeding, roses are very greedy!

Laila’s question:

Hello Garden Party,

About 2 months ago friends gave me a pear tree in a pot which they bought at a nursery.  I am of course very happy with the tree since it is the first fruit tree in the orchard we are going to create and am determined to take care of it and pull it through the summer.

We planted the tree out in a field with some fruit bushes like raspberries in the vicinity.

However, right away I noticed a few brown spots which quickly spread and it’s now almost on every leaf. I really would like to know what this might be, if it is hurting the tree and if necessary what to do about it.

Thank you so much for helping me save my pear tree!

Kind regards and greetings from Belgium!

Laila

Pear leaves with spots Pear tree with spots

The Garden Party’s answer:

Alan: It looks like a fungal rust doesn’t it, Richard?

Richard: It’s rusty in colour and it’s definitely fungal, no question about that and I would actually say, at this stage in the proceedings, don’t worry. Same as for the black spots on the rose leaves, just gather them up and be as hygienic as you can in that way. It’s a nice young looking plant which will cope with this and I suggest next year you feed it.

Alan: I think, Laila, that if you notice the spots come back next year that you spray it with a fungicide. You may have to repeat the treatment every fortnight.

Richard: When the spots are pin head size is when you want to catch them.

Thunderfairy: If Laila is by any chance an organic gardener and didn’t want to use fungicide, could she just pick off any infected leaves?

Richard: She could but as I said – hygiene is the key. Collect and dispose of infected leaf litter, making sure it doesn’t end up on the compost heap!

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