Potato Blight

Blight usually hits our potatoes in warm, damp weather in August.

Some time in August, especially when the weather is warm and damp, our potatoes plants start showing signs of blight.
 
How do I know if I’ve got it?
Black spots on the leaves, surrounded with a watery looking “halo”, quickly spreading and turning the potato tops to mush – not to be confused with normal die-back when the plants are mature.
Blight just starting.
Advanced blight, killing off whole plants.
NOT blight. Normal yellowing and die-back.
What should I do if (when!) my plants get it?
Cut the tops off, clear up all blighted bits and bury them in your compost to decay over the winter.  The spores only live for a couple of weeks without living potato tissue.  Do not move blighted tops around the site and infect other peoples’ crops.  Leave the potatoes in the ground for two or three weeks before you dig them so that any spores on the surface die off before they reach the tubers. Check potatoes in storage every month or so for signs of rotting tubers.
 
You can still dig a few any time for immediate use.
 
How can I avoid potato blight?
You can either grow early varieties, like Kestrel and Charlotte, which are ready before the blight strikes, or grow resistant main crop varieties like Sarpo Mira.
 
For more information, see the RHS web site:  https://www.rhs.org.uk/advice/profile?pid=217 .
 
 

Peat Free Composts

A report by Rosie Hall for Hollin Lane Allotment Association

A report by Rosie Hall for Hollin Lane Allotment Association

Background

Peat only started to be used in garden composts in the 1950s with the rise of popular gardening. Humans have used peat for centuries as a fuel, a building material, for animal bedding and, more recently, for horticulture. In the UK, gardeners and commercial growers get through 3.5 million cubic metres of peat a year. To meet this demand, areas of lowland bog are being stripped of their peat, destroying valuable habitats both here and abroad (65% of our peat is now imported). Because peat bogs take so long to form they are an unsustainable resource. If we continue to destroy these peat habitats we will ruin a vital part of our natural heritage, lose many rare plants and animals, and valuable information about our planet’s past.

While some of our remaining peatlands are protected, there are many in other European countries that aren’t, and it is these which now supply most of our garden peat.

Peat in the garden

Peat has three uses in the garden: as mulch, as a soil improver and as a growing medium.

Mulches
A mulch is a layer of material spread on top of the soil to keep down weeds, conserve moisture and insulate the earth. Peat-based mulches do a relatively poor job as they break down quickly in dry conditions and often just blow away. Better mulches are based on bark, leaf mould, recycled wood waste, spent mushroom compost or garden compost.
Soil improvers
Peat adds no nutrition to the soil. Better products for this are manure, compost, spent mushroom compost (though this is of variable nutritive value)
Growing media
All growing media should be peat free by 2020 according to Government targets.  Growing media do not have to be based on Peat. They can have the following as a basis: composted bark, coir, leaf mould, garden compost, screened green waste and screened composted manure

Peat-free Products

Clearly we need different grades of media for different jobs in the garden; the differences in water retention are also very important.

In researching the available peat free products it is clear that one product will not fit all. Multipurpose works all right up to a point, but often the products are far too coarse for seed sowing.  In looking at available products I have tried to take the following into account, but there are sure to be other factors- it is a huge task!

  1. Have the products been tested by reputable trials?
  2. Are products available locally? How much do they cost?
  3. Do we know what the products contain?
  4. Are the companies involved in production of peat-containing products? I added this as something we might like to consider.
  1. Have the products been tested by reputable trials? The Royal Horticultural Society has some useful pages on peat free gardening. The main points for my purposes were:
    • In their trials they found that there was very little information on the main components of the composts.
    • They found considerable variations in quality between batches.
    • The more expensive composts tended to perform better.
    • Water management is critical.
    • How best to feed was a subject for further research.

    Other trials:
    Which? Test scores for 2010 as a percentage of germination in the following peat free composts:

    • New Horizon Multi-Purpose: 80% (also top in 2011)
    • Westland Multi-Purpose: 80%
    • J Arthur Bowers Multi: 74%
    • Levington Multi: 74%
    • Vital Earth Multi: 74%
    • Murphy Multi: 73%
    • Vital Earth Tub/Basket: 70%
    • New Horizon Growbag: 65%
    • Shamrock Multi: 63%
    • B&Q Tub/Basket: 53%
    • J Arthur Bowers JI no. 3: 50%
    • B&Q Multi: 49%
    • Westland Earth Matters: 48%
    • B&Q Peat-Free Multi: 46%
    • Westland Multi: 43%
    • Westland Container/Basket: 39%
    • Miracle Gro Peat-Free: 28%

    The previous Which? Score put B&Q multipurpose and New Horizon organic and peat free growbag along with B&Q sowing and cutting compost as top 3 for sowing composts. They suggested that Homebase multipurpose and Vital Earth were not worth buying as the germination was< 40%. (Compare with results above)
    A report in The Ecologist suggested that Petersfield and New Horizon both scored 90% germination.
    The trials are difficult to interpret. They do seem to illustrate that there is sufficient variation between batches to lead to variable germination rates, all else being equal.

  2. Are products available locally? How much do they cost?
    • New Horizon Multipurpose Peat Free is widely available; High Trees would deliver any amount for £18; a bag costs £5.99. Garden Goodies (Bingley) would deliver eg 30 x 60 litre bags for £186+VAT including delivery.
    • Moorland Gold (see below) from West Riding Organics priced as follows: 20-64 x 40 litre sacks £5.34 each (individual price £7.99), full pallet £4.79 each (max 65 sacks) delivery £42 + VAT
    • Knotford Nook (Lancashire) bulk loads up to 5 tons (£40/ton -£60/ton depending on whether screen size and whether manure based)equivalent to a builder’s 1 cubic metre sack) £40 delivery + VAT
    • Petersfield which received good reviews, is based in Leicester so is not considered further here.
    • These are the ones I enquired about as a ‘taster’. Most on the Which? list are available locally.
  3. Do we know what the products contain?
    • New Horizon Peat Free: bark, timber residues, green waste, limestone, hoof and horn, rock potash, Vinasse (?) bone meal. Will need more watering then peat, and extra feeding after 4-6 weeks.
    • Moorland Gold: This is not peat free, being made of a mixture of entrapped peat from water purification + sharp sand. It is therefore a by product using a waste material, so not reliant on peat extraction. It is Soil Association Certified.
    • Knotford Nook: There are various types based on either green waste, mature compost or farmyard manure. They are screened to 40/30/20/8 mm, so suitable for different purposes.
  4. Are the companies involved in the production of peat containing composts?
    • New Horizon makes peat-containing composts. Since all compost will have to be peat free by 2020, this is going to change the picture considerably.

Conclusions

  • It would be good to encourage the use of peat free composts on the allotment site.
  • We should invite comments on this report from the plot holders.
  • We should consider buying a bulk load of compost or a couple of bags of several types to do our own trial.
  • Making our own means allocating an area , collecting leaf mould etc
  • We should make sure that every plot holder is helped to produce garden compost for use in mulching, soil improving and as a growing medium.
  • We should try to make Hollin Lane Peat Free as soon as possible

Pea and Bean Weevil

The pea and bean weevil is hard to spot, but its damage to peas and beans is easy to see …

The pea and bean weevil is a horrible little creature called Sitona lineatus. It is quite small (5mm) and hard to spot, but its damage to peas and beans  is easy to see:  neat half-round notches cut out of the edges of the leaves of young plants.

Pea and bean weevil damage
Damage from pea and bean weevils.

They overwinter in the soil near peas and beans (and winter tares), and come out in warm weather.  They lay lots of eggs on the host plant during May, June and July, and the tiny larvae then find their way into the soil and feed on the roots.  They are annoying, but don’t usually cause serious damage.  The best advice seems to be to keep the young plants well fed so they can outgrow the danger, as the weevils don’t climb very high.  Rotating your crops helps, too.

Joe Foster

Good Varieties for Hollin Lane

Here are some vegetable varieties that do well here. Please give us your own favourites with a few words saying why you like them.

VegetableVarietyQualitiesAuthor
CabbageGreyhoundTasty and trouble-free cabbage for early summerPeter Byass
CabbageMarner White StoringHuge dense round heads that stand well through the winterPeter Byass
KaleNero di ToscanaFairly hardy - delicious dark green leaves late summer and autumnJoe Foster
KalePentland BrigVery hardy - pick leaves in autumn and winter and sprouting shoots in springJoe Foster
OnionCenturionRound, good cropper, keeps well in storePeter Copeland
PotatoCharlotte2nd early, ready before blight and slugs hit, salad typeJoe Foster
PotatoColleen1st early, yellow flesh, good baker, good blight resistance.Jayne Harnett
PotatoJazzy2nd early, ready before blight and slugs hit, salad type. Better eelworm resistance than CharlotteJoe Foster
PotatoHarmony2nd early, some blight resistanceJenny Ward
PotatoKestrel2nd early, ready before blight and slugs hit, delicious baked or mashed and a good cropperJoe Foster
PotatoNadine2nd early, some blight resistanceJenny Ward
PotatoNicolaEarly main crop, salad variety, some blight resistanceJenny Ward
PotatoRecordMain crop, floury, some blight resistanceJenny Ward
PotatoRemarkaEarly main crop, some blight resistanceJenny Ward
PotatoSanteMain crop, some blight resistanceJenny Ward
PotatoSarpo AxonaLate, good blight and slug resistance, good cropper and keeperJoe Foster
PotatoSarpo MiraLate, good blight and slug resistance, good cropper and keeperJoe Foster

Not So Good Varieties for Hollin Lane

Some fruit and vegetable varieties just don’t work here. Please give us your own experience with a few words about what the problem was.

VegetableVarietyQualitiesAuthor
PotatoMarfona2nd early. The slugs love it.Joe Foster
CabbageHispiNot very tasty. Attractive to slugs.Peter Byass
Brussels SproutEvesham SpecialThe sprouts are mostly blown – hardly any solid ones.Joe Foster
OnionGolden BearNOT tolerant of downy mildew!Joe Foster

Make Your Own Seed and Potting Compost

Make your own seed and potting composts …

You can make your own organic, peat-free seed and potting composts using leaf mould, garden compost and loam. You can make it up as you need it, in large or small quantities. Leaf mould needs to stand for two years. Loam is basically just good garden soil. If you are bothered by weed seedlings you can pasteurise the loam at 80 degrees C for about half an hour. I just pull the weeds up.

The recipes are by volume: shovel-fulls, scoops, or whatever.

  • Sowing compost: 1 part sieved leaf mould + 1 part sieved loam.
  • Potting compost: 1 part sieved leaf mould + 1 part sieved loam + 1 part sieved garden compost.
  • Tomato compost: 3 parts loam + 1 part leaf mould + 1 part garden compost or manure.

Joe Foster

Compost Heaps

Gillian North’s recipe for success!

Use lots of nettles or comfrey to activate and provide extra nutrient in the form of trace elements. Layers of shredded bark also aids decomposition. Intersperse with grass cuttings.

Gillian North

Potatoes

Extend the season for earlies and avoid blight on maincrops…

Plant just one short row of earlies as soon as conditions allow in order to get your first new potatoes of the season. Then plant maincrop and second earlies so they have a long growing season before blight strikes. Continue with the rest of the earlies, staggering the planting so not all are ready at once.

Gillian North

Sowing Seeds

Gillian’s ‘three for one’ planting tip…

Sowing: It is necessary to sow three seeds, or plant three plants – one for the slugs, one for the weather and one for yourself. If the first two survive, they can go to the annual bring and buy sale.

Gillian North