Tuesday, April 8, 2014

In need of nematodes?

While doing a spot of weeding the other day, in preparation for potato planting, I came across an alarming number of slug eggs in the soil. Doing a bit of internet research on the subject made for worrying reading:
  • A slug can lay 20-100 eggs several times a year
  • Slug eggs can remain dormant in soil for many years, hatching when conditions become suitable.
  • A cubic metre of garden can contain upto 200 slugs
  • Slugs are hermaphrodite (possessing both male and female reproductive organs) so can mate with any slug of the same species they come across.
  • They can also reproduce without a mate by producing eggs without the male gamete being transferred (parthenogenesis).
  • Only 5% of a slug population will be above ground at any time. The remaining 95% will be below ground, laying eggs, feeding on roots and seed sprouts, and digesting your newly emerged seedlings.
(slug facts courtesy of slugoff.co.uk) 

Last year was just awful - I'd never seen such a rampage of slime-secreting leaf-eaters that ploughed through my seedlings last spring. Previous years I've not had such a big problem. They occasionally hit a particular plant – salad leaves are usually popular – but 2013 was notable for virtually nothing being safe. They worked their way through so many of my crops – they put paid to the first sowing of rocket salad and of beetroot. I sowed carrot seeds three times and had the grand total of two carrots reach true leaf stage. They took down a lot of my pea, borlotti bean and sugar snap plants when they were first planted out, they nibbled lots of the potato haulms and had a really good go at the courgette and squash plants. I feared they might have finished off my Hooligan pumpkin plant but thankfully it rallied and went on to produce a single fruit. One after one they decimated my baby nicotiniana plants. I kept some replacements in the greenhouse, but even there they didn't seem to be safe – a few nibbled leaves and even telltale trails on my 4 foot tall tomato plants. It seems there is nowhere a slug won't go for some dinner.

Having had such a mild winter, I fear for the 2014 crops already. A less than frosty winter means that the slug population has avoided the natural population control of freezing temperatures, so I may well employ the services of nematodes to keep the hungry hordes at bay. My finger is hovering over the 'Buy' button as the weather warms up and hoping that there will not be a shortage of the product as many fellow gardeners do the same.

14 comments:

  1. I wasn't too badly affected last year buy the slugs but I agree with you, after having such a mild winter Nematodes are the way to go.

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    1. It's the little ones that seem to do the worst damage Joanne. I was so annoyed when they totally razed a crop of lettuce seedlings I planted out last year - I'm determined they're not going to get the chance again!

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  2. Ugh, you're right, there are going to be loads this year I think. It's SO disappointing when you've sown a seed, watered it, nurtured it, potted it on, hardened it off, planted it out and, oh, it's gone and all that's left is a little raggedy stump.

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    1. I know, it just seems such a waste of all that time and effort. This year, the suburban veg plot may well be renamed Fort Knox as far as those darn molluscs are concerned.

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  3. I think there'll be many pests about this year after the mild winter. I resorted to growing all my potatoes in containers because of the slug damage to them on the plot, but now I'm on a new site, I'm going to give them another go in the ground. You've made me wonder now if this is the best year to be trying it.

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    1. I've been lucky in that they've never actually affected my potato crops, it's the above ground damage that's been the worst. I guess you could make sure you dig and turn the soil well on your plot on a nice sunny day in the hope that the local bird population will feast on the critters and their eggs.

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  4. I thought slugs still had to mate but that both ended up with fertilised eggs. In the garden our problem is snails which can;t be dealt with by nematodes, Trouble also is that to deal with a garden full of slugs you would need a lorry loaf of nematodes too

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    1. When they mate, only one ends up with fertilised eggs as each slug can use only one set of reproductive organs at a time. I was mixing up 2 facts though (as I've corrected in the post) in that the ability to produce eggs without fertilisation is thought to be used in times of plentiful food, where a sudden boom in population occurs to take advantage of the conditions. A bit like the aphid explosion in good summers where one minute there's none, the next they're everywhere. Aphids are even worse in that the females (without any intervention from males) give birth to live young (termed vivipary).

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  5. It's a new lesson for me. Thanks for sharing

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    1. Wherever we garden, we all have our most dreaded pests. A friend only a few miles away suffers most from wild rabbits and deer that come in from the surrounding woodlands.

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  6. Is your finger still hovering or did you press the buy button? The extent of mollusc damage here varies from year to year. I was out last night torch in hand and rounded up a good few :)

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    1. It hovered only for a short time before the buy button was pressed. Growing crops for my Gardeners' World Live plot means that I can't afford to lose many at all. So far, the chickens have been enjoying the feast of slugs and snails daintily served to them on the end of a trowel each morning!

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  7. Very informative! I have snail problem in my garden especially during monsoon!

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  8. I think we read the same slug research! it made for some pretty daunting reading. I wasn't too bothered by slugs last year but have been finding loads this year. May have to look into the nematode thing as I've just been picking them off so far but I fear they're winning!

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