Category: Pests and diseases


I recently had a ‘tweet’ from fellow Norfolk resident, Claire in Thetford. She was wondering what the growths on these leaves were.

I must admit to being a bit puzzled at first, but some further research suggested that they are some sort of Gall, which Wikipedia describes as:

‘…abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites. Plant galls are often highly organized structures and because of this the cause of the gall can often be determined without the actual agent being identified. This applies particularly to some insect and mite plant galls.’

My guess from the pictures was that these were galls possibly created by some sort of parasitic wasp (in this case on the leaves of a Lime Tree). Claire’s own research came up with a more precise description: a ‘Nail Gall’ formed by a small mite Eriophyes tiliae. These microscopic mites overwinter in the bark of lime trees and crawl on to the underside of the foliage in spring to feed. The mites secrete chemicals into the leaves causing them to produce the unusual projections into which the mites move to continue feeding during the summer. Infestations of mites and the nail galls they induce don’t appear to affect the health of the trees and there’s no way of controlling or preventing them. The galls caused by this mite are said to be yellow-green or red in colour (see picture below). It may be that the whitish nails in Claire’s picture have been be caused by another mite (Aceria lateannulatus), which affects both the small-leaved lime (Tilia cordata) and the Common Lime (Tilia x europaeus), but not the large-leaved lime (Tilia platyphyllos).

Nail Galls cauised by Eriophyes tiliae

Nail Galls cauised by Eriophyes tiliae

Galls are fascinating phenomena. As Wikipedia continues, those created by insects are:

‘…highly distinctive plant structures formed by some herbivorous insects as their own microhabitats. They are plant tissue which is controlled by the insect. Galls act as both the habitat and food source for the maker of the gall. The interior of a gall can contain edible nutritious starch and other tissues. Some galls act as “physiologic sinks”, concentrating resources in the gall from the surrounding plant parts. Galls may also provide the insect with physical protection from predators.

Insect galls are usually induced by chemicals injected by the larvae or the adults of the insects into the plants, and possibly mechanical damage. After the galls are formed, the larvae develop inside until fully grown, when they leave. In order to form galls, the insects must seize the time when plant cell division occurs quickly: the growing season, usually spring in temperate climates, but which is extended in the tropics.

The meristems, where plant cell division occurs, are the usual sites of galls, though insect galls can be found on other parts of the plant, such as the leaves, stalks,branches, buds, roots and even flowers and fruits. Gall-inducing insects are usually species-specific and sometimes tissue-specific on the plants they gall.’

Galls are also caused by fungi, bacteria, viruses and nematodes. It seems that in many instances these growths do not cause any significant harm to the plants they infest, though in some cases long term harm can be caused to some species, for example by affecting their overall shape and vigour.

Crown Gall on apple- RHS

Crown Gall on apple- RHS

Crown gall affects a wide array of plants and roses are definitely one of them. It is a plant disorder caused by the bacterium Agrobacterium tumefaciens, that interferes with the plants ability to take up water and nutrients. This results in poor growth and weak plants that are easily stressed and injured- the only remedy in this case is to dig up the plant and dispose of it.

The study of plant galls is called cecidology. While these weird structures have intrigued humans for many years, there is still much that we don’t know about them.

Wiches Broom Gall - picture Rosser1954

Wiches Broom Gall – picture Rosser1954

While some galls are well hidden and hard to spot, others are much more conspicuous. Have you ever looked up into a birch tree (Betula spp.) and noticed what looked like large, dense birds’ nests? In some cases these may well be nests, but very often they are actually galls called ‘witches’ brooms’. These are caused by a fungus (Taphrina betulina), which stimulates the tree to produce numerous extra shoots, resulting in a dense nest-like cluster. The fungus can then feed on the shoots. It was once believed that they were caused by witches flying over the tree!

If you spot an odd-looking growth on a dog rose (Rosa canina) it could well be a Robin’s pincushion gall, caused by a wasp (Diplolepis rosae). There was once a belief in England that these were caused by the woodland sprite, Robin Goodfellow or Puck. It is hardly surprising that people ascribed supernatural causes to some galls – they look pretty strange, and their causes aren’t exactly obvious.

'Robins Pincushion' gall on a Wild rose

‘Robins Pincushion’ gall on a Wild rose

The real gall specialists include gall midges, gall flies and gall wasps. Perhaps one of the most familiar galls is the oak apple, caused by a tiny wasp (Biorhiza pallida).

Oak apples

Oak apples

There are actually hundreds of species of oak gall wasps and they cause a fantastic variety of galls on oaks (Quercus spp.). A single oak tree may support many thousands of galls. Each gall wasp species creates its own unique and outlandish structure: some resemble cotton wool or marbles, pineapples or tiny UFOs!

Here’s a gallery of some of the other amazing galls to be found.

This slideshow requires JavaScript.

Sources and further information:

Galls- Wikipedia

Eriphyes tiliae- Wikipedia

British Plant Gall Society

Trees for Life- Galls

RHS- Crown Gall

Old School Gardener

If you’ve enjoyed reading this post and others on this blog, why not comment and join others by signing up for automatic updates via email (see side bar, above right ) or through an RSS feed (see top of page)?

Advertisements

mole hills‘The worst ENEMYES to gardens are Moles, Catts, Earewiggs, Snailes and Mice, and they must be carefully destroyed, or all your labor all the year long is lost.’

The garden book of Sir Thomas Hanmer 1653

To what extent can we ‘control’ these pests in ecologically sound ways, or is destroying them the only effective method? Old School Garden is suffering from major mole damage at present and I’m stopping short of acting other than to clear up the (increasingly annoying) mole hills in the grass and putting down some powder that’s supposed to encourage them to move elsewhere (the neighbour’s garden?!). I have been tempted to get the garden fork and plunge this along the runs, but I’ve resisted the temptation- so far. What methods of ‘pest control’ do you use?

Old School Gardener

I featured a range of ‘hotels for the discerning’ earlier this year, and here are a few more ideas for desirable residences for the bugs you want in your garden.

Old School Gardener

snail‘…the snail, whose tender horns beign hit,
Shrinks backward in his shelly cave with pain,
And there, all smother’d up, in shade doth sit,
Long after fearing to creep forth again:’

William Shakespeare

Blackfly-C‘Sometimes we try to be a bit too clever in this world. Take the poor old gardener who’s plagued by blackfly. He’ll spend a small fortune on sprays and things when all he need do is take a little soil from the bottom of the plant and sprinkle it like powder all over those blessed blackfly. That’ll finish them off…it gets in their teeth you know!’

Fred Streeter

greenfly‘Greenfly, it’s difficult to see

Why God, who made the rose, made thee.’

A.P. Herbert (1890-1971)

Look Back and Laugh

Gardening-Boots2Two new rounds of my courses on Garden Design and Grow Your Own Food for Beginners start soon, and I’m also offering a new, one day course on Wildlife Gardening. I ran the last Garden Design course earlier this year and had great feedback on it (I even had a thank you present from the students!). All the courses feature a lot of group discussion and some practical tasks as well as useful tips and tricks to help particpants apply what they learn to their own plots.

The Garden Design course takes students through a customised design process, prompting a fresh look at participants’ own gardens, giving them the opportunity to develop their own ideas in a systematic way and benefitting from ideas generated in the whole group. I support participants to draw up their own scale plan design for their garden and supply plenty of useful background information and links to helpful web sources as well as the opportunity to borrow from my own garden book library. The course can also feature a visit to a well known garden to look at design ideas in practice.

The ‘GYO’ course is aimed at food-growing beginners or novices and gets off to a flying start with making paper pots and sowing broad bean seeds. It also prompts students to look at what they want to eat/grow and how they might do this most effectively in their own plots – this can include growing in containers for those with little or no garden.The course includes a visit to Old School Garden to look at my own approach to food growing, and covers topics like soils and soil improvement, growing under glass, encouraging beneficial wildlife into your garden and how to effectively control pests and diseases.

Narrow beds in the Kitchen Garden at Old School GardenNarrow beds in the Kitchen Garden at Old School Garden

The one day Wildlife Gardening course, taking place at Gressenhall Farm and Workhouse Museum, makes use of the Wildlife Garden at the Museum and includes some practical work to help develop the wildlife -friendly features there as well as helping participants to focus on their own gardens and gardening practices. The aim is for them to develop  their own action plans for the future.

The Wild life Garden at Gressenhall Farm and Museum

The Wild life Garden at Gressenhall Farm and Museum

The courses are fast filling up but there are some places still available if you’re quick!

They are running as follows:

Garden Design–  6 Monday evenings, 7pm-9pm at Reepham High School & College, commencing on 12th May.

Grow Your Own Food for Beginners – 6 Wednesday evenings, 7pm-9pm at Reepham High School and College, commencing 14th May.

Get more details and how to enrol at www.reephamlearningcommunity.co.uk

Wildlife Gardening- Sunday 18th May, 10am-4pm at Gressenhall Farm and Workhouse Museum, near Dereham.

For more information on this and other short courses at the Museum see www.museums.norfolk.gov.uk

Old School Gardener

aristonorganic

In keeping with the organic gardening concept, it is always preferable to seek natural solutions to garden problems such as pests and common diseases.. Should you have any ideas to share on this topic please send them to us for passing on to others.

Please also note that dish-washing liquid is called for in most of these ‘recipes’. It serves as a ‘wetter’ enabling the liquid solution to adhere to the plant for maximum effect. The environmentally friendly non-toxic dish-washing liquid is ideal for this purpose. snail

Insect Spray Concentrate

This is an all-purpose natural insecticide.

  • · 3 unpeeled garlic cloves 1 tablespoon dish-washing liquid
  • · 3 teaspoons of liquid paraffin 2 cups of hot water

In a small bowl, crush garlic heads and add paraffin. Leave to stand for 24 hours then add the dish-washing liquid to the mixture.

Sieve the mixture, discard the solid bits and store the liquid…

View original post 354 more words

Pest or Pal?

Pest or Pal?

This week’s question is on an issue that I’m in two minds about. Lorne Bowles from Teddington asks:

‘On damp days in Autumn (and Spring) my grass becomes covered with earthworm casts. I’d like to get rid of them somehow. What do you recommend?’

There are many species of earth worms but only 3 of them make casts. Worm casts are a sign that you have a fairly active soil with good aeration and humus content. Earth worms are useful for mixing and aerating soil, but those which cast can create a muddy and uneven surface on grass and can also encourage weeds, as their casts make excellent seed beds!

Charles Darwin spent a lifetime studying worms, and estimated that up to 40 tons of worm casts per acre can be added to the soil (representing between 45 and 170 worms per square metre!). These casts are invariably richer, finer and less acidic than the surrounding soil, and contain around 50 per cent more calcium, nitrogen, phosphorus, potassium and bacteria.

Earthworm activity is encouraged if cuttings are left on the turf. Worms also pull fallen leaves and plant debris into their burrows and, in doing so, they add organic material to the soil, improving its structure as well as its fertility. For borders and beds, if you are short of compost, a mulch of leaves, preferably chopped up, will not only add structure to the soil, but will also dramatically increase the worm population and therefore the health and fertility of your soil. The use of alkaline or organic fertilisers and dressings can also encourage Worms in lawns. Monty Don tells an amusing anecdote about a grass tennis court which demonstrates worms’ love of alkaline soil:

‘A grass tennis court had been laid on acidic soil and marked out with chalk. Over the years, the calcium in the chalk neutralised the acid soil beneath it, making extremely narrow strips that attracted earthworms. Long after the chalk had been washed away, ‘runways’ made by moles attracted by their favourite food – earthworms – followed the line of them, without realising that they were mirroring exactly the original chalk lines of the court!’

This raises the topic of moles in lawns. A real issue for me here at Old School Garden, despite me trying to persuade the ‘little burrowers’ to take themselves next door. If you have moles, as the tennis court story indicates, this is a sure sign that you have worms in your lawn.

worm casts on lawn

Worm casts on a lawn

So what can you do?

Well one approach (but not one I’d recommend myself) is to try to deter the worms from casting using a fungicide. The law does not permit long life residual chemical build up in the soil, so gone are the days when formulations like Chlordane could be used to wipe out the worms (and possibly some gardeners too). However, Carbendazim is a chemical which is primarily used to deal with fungal diseases such as Fusarium but which also appears to interrupt the feeding of worms near the surface, by making the organic matter in which they feed unpalatable. Deeper feeding, non casting worms are apparently unaffected and continue to benefit the soil structure as normal.

Applying the chemical, which has a non hazardous classification, is said to be most beneficial in Spring and Autumn and must be carried out when the soil is already wet as it needs help in dispersing through the soil. However, be aware that whilst Carbendazim is approved for use in the UK and some other countries, some organisations argue that it is a dangerous substance.  Other options exist such as adding sulphur to the lawn, so reducing its alkalinity, and therefore reducing the attractiveness of it to worms. Manufacturer’s of this type of solution claim that this does not harm the worms or the soil.

However, I’d be a little wary of this, and other chemically – based solutions and try a more organic approach.

This does mean, however, that you’ll need to adopt a more relaxed attitude to worm casts (and mole hills, though it pains me to say so…). Worm activity, on the whole, is extremely beneficial to your lawn, so the best way to deal with the casts is to wait for them to dry and then brush them into the surface, spreading evenly with a Besom or similar broom. In doing so, you are adding to your lawn some fine compost and helping to improve its future appearance. There are also a few other things you can try to reduce the problem of casts:

  • Avoid leaving leaves on the lawn surface during the autumn and winter because this warm blanket of organic matter is an ideal ‘restaurant’ for the worms.

  • Do not allow a build up of thatch as again this decaying matter is digested by the worm which leads to casting deposits – so scarify your grass in the autumn and possibly also the spring.

  • Keep the grass at a reasonable height.

  • Avoid unnecessary watering as this attracts more worms. In dry weather the worms will move deeper, and by aerating regularly and ensuring good drainage, you will discourage activity.

If, like me you have a mole problem, I think the only safe, direct (but from experience, not necessarily successful) solution is to trap them, which might involve the services of a mole catcher unless you fancy a go yourself! I’ve found that other ‘solutions’ like noise/ vibration emitting devices seem only to have a temporary effect, if that!

Mole hills on the Old School Garden lawn

Mole hills on the Old School Garden lawn

More generally, lawns are not attacked by pests, though you may at some point see the effects of the ‘Leather Jacket’ (the larva of the Crane Fly or ‘Daddy Long Legs’) and Chafer grub.

These can cause damage to the roots and stems of grass resulting in poor, stunted growth and bare patches. When a pest problem like this is suspected, the turf should be examined thoroughly to find the culprit. Pests are often found first in stressed areas, such as the edges of lawns or in shady or wet areas. They are not usually distributed evenly so it is advisable to look for spots that have discoloured, stunted or distorted turf. Insects tend to proceed outward from a central point; therefore they are generally most active on the outside edge. In both cases a lawn insecticide could be applied to kill the grubs/larvae….

Chafer Grub damage to grass

Chafer Grub damage to grass

However, an alternative, organic solution is to wait for heavy rain (or thoroughly watering any yellow patches in the lawn yourself). Then cover the affected areas with black plastic sacks and leave overnight. The Leather Jackets and grubs will come to the surface and can be collected in the morning and disposed of – or left to natural predators such as spiders and garden birds (especially Starlings). You could also use the biological control Steinernema feltiae, which should be applied while the ground is still moist and warm in late Autumn.

Old School Gardener

If you’ve enjoyed reading this post and others on this blog, why not comment and join others by signing up for automatic updates via email (see side bar, above right ) or through an RSS feed (see top of page)?

Pardon My Garden

Part of the fun of encouraging biodiversity is seeing all the little critters this time of year.  I try to have something blooming from March through November, if possible, and that gives opportunities for many species to survive.
Garden 09 22 13 121

The sedum is even busier this weekend.  This praying mantis has been sitting on the sedum all weekend.  It did not actually snatch anything while I was watching.  The painted lady butterfly was on the sedum all weekend, too.

Garden 09 22 13 099

Side view of painted lady butterfly on sedum.

Garden 09 22 13 081

Also on the sedum were this little skipper butterfly and many kinds of bees and flies.  I can see why the praying mantis hangs out here.  There was also a little yellow sulphur butterfly, I am not exactly sure which kind of sulphur it was.  I can’t show pictures all the species that were on the sedum!

Garden 09 22 13 095

Praying mantis blends in on miscanthus “morning light” ornamental grass.  This one has a…

View original post 331 more words

PushUP24

Health, Fitness, and Relationships is a great way to start living again.

TIME GENTS

Australian Pub Project

Vanha Talo Suomi

a harrowing journey of home improvement

How I Killed Betty!

The Diary and blog on How to Tackle Depression and Anxiety!

Bits & Tidbits

RANDOM BITS & MORE TIDBITS

Rambling in the Garden

.....and nurturing my soul

The Interpretation Game

Cultural Heritage and the Digital Economy

pbmGarden

Sense of place, purpose, rejuvenation and joy

SISSINGHURST GARDEN

Notes from the Gardeners...

Deep Green Permaculture

Connecting People to Nature, Empowering People to Live Sustainably

BloominBootiful

A girl and her garden :)

gwenniesworld

ABOUT MY GARDEN, MY TRAVELS AND ART

Salt of Portugal

all that is glorious about Portugal

The Ramblings of an Aspiring Small Town Girl

Cooking, gardening, fishing, living, laughing.

aristonorganic

"The Best of the Best"

PetalPushin

Thoughts from a professional Petal Pusher

Free Spirit Publishing Blog

An idea exchange for kids' education

%d bloggers like this: