Wednesday, 12 August 2009

ABC Wednesday 5: D is For...

... Deficiency

For the past couple of years my raspberry foliage up at the allotment has tended to look rather sick and this year is no exception. I've ruled out a virus as these tend to give the foliage a mottled appearance rather than the distinctive veined patterning you can see in my picture. I'd also ruled out the usual mineral deficiencies, such as iron or manganese I've previously seen in my garden as these tend to affect the younger foliage first. In my photo, the younger foliage at the top of the plant is a healthy green and the problem gets worse the further down the plant you go.

But then I got pondering the ideal conditions for growing raspberries: a neutral to acid soil and loamy, perhaps with some sand. Mine's the complete opposite as it's lime with clay. Clay soils are notoriously fickle about hanging onto their nutrients, even though they're considered to be a nutrient rich soil. Time for a bit of Googling...

...and there you have it. Looks like I have what's called Lime-induced chlorosis, which is a posh way of saying you're-growing-an-acid-loving-plant-in-alkaline-conditions-which-is-poorly-adapted-for-absorbing-the-trace-elements-it-needs-from-that-kind of-soil. And it turns out I have a magnesium deficiency as this affects the older leaves first. Magnesium, iron or manganese are the usual minerals which are deficient and the clay soil isn't helping as it tends to hold onto these elements quite firmly. According to the link, waterlogged conditions don't help either, which makes me wonder if that's why I've only spotted the condition in the past couple of years. Whilst I grow my raspberries at the top of the slope, last month's rainfall and the past couple of wet summers have been rather extreme. The saving grace in my book is that I haven't noticed any drop in yield.

As it's a magnesium deficiency, I could try a foliar feed of Epsom salts using crystals obtained from the chemist to counteract it. For iron or manganese deficiencies, those specially formulated feeds for acid-loving plants available at garden centres could be used instead. However, that would only cure the problem for this season. I could also put something like flowers of sulphur around the plants to acidify the soil, but I suspect the 'power of clay' would soon return pH levels back to alkaline and thus I might shell out my cash for very little return.

So, I'm planning on carrying on as usual, especially as I'm getting oodles of raspberries at the moment. However, I am pondering the large conifer tree at the end of my plot. It sheds rather a lot of needles which I can't really compost as they're too acid for the health of my heap. I'm wondering whether a well-rotted mulch of needles, might help in the longer term especially as I'll have a pretty constant supply. Time to rescue some of my pallet stash from the nettlebed at the bottom of the plot to make a nice 'needlemould' bin methinks.

For more Decidedly Delicious posts, do visit the ABC Wednesday blog.

18 comments:

  1. It's a shame about the soil. I have blackberry thickets (under control) which do very well in our supposedly clay area. It's probably due to the previous owner adding who knows what to the planting beds.
    I've been toying with the thought of making a pine needle composting pile for those acid loving plants, but not just yet.

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  2. Well, as long as you get those oodles of raspberries...

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  3. Send some fo those pien needles across the pond. I have very heavy clay soil (moist in spring, then can't even shovel it in summer it's so dry). I have a couple trees which are either ticking me off as they try to establish. We can't fix the clay unless we haul it all away. I'm gonna go rent a tractor.

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  4. I am going by my book rather than by proper knowledge but . . . the picture in my book suggests manganese deficiency which (when talking about roses . . . but, well, anyway) it says, unlike with iron deficiency, affects the older leaves worst. (Only with better grammar.)

    I'm interested in the pine needle solution. I hadn't previously known one can compost pine needles. Sometimes there's a suggestion that they might contain some kind of plant poison . . . ?

    Interesting too that, on the whole, soft fruit discussions tend to think that everything which ails a raspberry comes down to a virus. But, again, that depends on which books one happens to have on one's shelves!

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  5. I love your solution, VP, doing nothing. We call that the Semi school of gardening after my daughter Semi. She does absolutely nothing, the weeds are sky high and the blooms are amazing. Sometimes life isn't fair. ;-) Come to think of it, when we lived in alkaline sandy soil of Texas, we added gypsum to the soil, which was supposed to help the nutrients get into the roots better, somehow.
    Frances

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  6. Hi Jacob and welcome! Blackberries don't seem to have the same kind of problem as raspberries do.

    Mara - welcome too. Oh yes, we have oodles of raspberries. I'm making raspberry jam tonight :)

    Benjamin - we have exactly the same kind of soil, Sometimes I've had to hammer out my late potato crop, and hammer in my later plantings such as leeks. Unfortunately I can't take your approach, so I'm stuck with digging in lots of organic matter...

    3C - my book (RHS Pests and Diseases) lumps both of them together, but I vaguely remember something about one deficiency affecting young leaves and the other older. However, I can't remember which deficiencies they are. The pine needle solution's a bit of an experiment. I think they'll need a while to compost. I've used them previously as part of my weed suppressing path mulch, so I know they do rot down eventually. I'm not sure about the plant poison bit, I've only ever seen them as a no-no for composting because of their effect on acidity levels and therefore suppressing the good hard working bugs and animals that help to breakdown the compost. Perhaps that's the poison? My RHS book suggests acidic materials such as composted bracken or conifer bark when planting raspberries, hence my sudden interest in what conifer leaves might be able to do...

    Frances - I like the Semi solution! Gypsum's suggested as a solution for clay soils here as it helps to clump the clay particles together, so they're no longer clay. However, I think getting hold of some gypsum might be a more expensive solution than lots of good old hard work and organic matter...

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  7. Oh and 3C - I was going to talk about viruses too, but found I didn't have any up at the plot to take a picture of for comparison. However, I did find this useful link about raspberry viruses when I was researching this post.

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  8. Sounds as if you have deduced what the problem is VP. Glad to hear that it has not interfered with raspberry production.

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  9. Anna - I'm having to make lots of jam, so that tells you how well the crop's doing!

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  10. Note

    I had a couple of spam comments yesterday asking for visits to blogs of a certain nature. I've removed these comments as soon as I found them and I've also reported the spam blogs to Blogger.

    This blog is a spam no go zone!

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  11. How about you use some peat-based grow bags for short term crops like tomatoes or lettuce, then dig the peat into the soil around the raspberries? It's a win-win situation .. except for the peat bogs.

    You could also save all your old tea bags to mulch the raspberries, or dig old pea and bean roots into the area. Apparently nitrogen acidifies soil too!

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  12. Hiya VP

    I sprinkle sulphur chips around the base of my rhododendrons and camellias to keep them happy. I have slightly alkiline soil, and this seems to work extremely well – shrubs look very healthy. Also the sulphur chips are fairly cheap and last for ages. May work for your raspberries.

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  13. I'm not a horticulturalist, but you seemed to suss it out yourself, so bravo to you.

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  14. A plant doctor, you are! I have several raspberry stalks and they produced well this year, so guess I should be knocking on wood - Nice post!

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  15. Jay - nice try, but as you say, not so good for the peat bogs.

    Soilman - thanks for the tip. I'll keep a look out for those. I'm not sure if I've seen them locally, but that's probably because I've not been looking. See you in October?

    Roger - thank you :)

    Tumblewords - I'm glad you like them too. We've just had some of the jam I made yesterday :)

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  16. You are a star! I now know what the problem is on the Isle of Dogs. I guessed it was some kind of deficiency but had not linked it with the alkalinity of the soil. Never heard of sulphur chips before and will be on the look our henceforth.

    Thanks all...

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  17. Colleen - brilliant! I do like it when a post and its comments help someone else :)

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  18. Update - further research shows it's a magnesium deficiency as the older leaves are affected, so I've updated the article to reflect this new-found knowledge.

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