dormancy of charlock

[Devil's advocate]

Local folklaw is that charlock will live in the soil for 100 years.

As a brassica grower including swedes under nets, I certaily have fields that will never be used for swedes in my lifetime.

I do dispute the 100 year figure, my Dad bought land in 1986 totally infested. It has been arable every since Winter barley, potatoes, spring barley, winter barley, leaf brassica, spring barley ever since. Now no charlock is seen although we went through a phase of Shepherds purse & are now battling with fat hen & sterile brome.

But heavier land with similar rotation but swedes (under nets) instead of leaf brassica charlock has put some land out of business for swedes, fat hen in decline thanks to Dual Gold.

My theory is heavy land makes the charlock seed much more dorment wheras light land more germinate & are easily killed.

We have ploughed up heavy loam after 40 years of grass sometimes charlock sometimes not, but never a severe infestation.

Light may be a factor because stale seed beds work very well, sadly without insecticide we can't use them because of cabbage root fly eggs in the soil before netting. Maybe GPS bed tilling in the dark?

 

[Bogweevil]

Modules planted through biodegradable mulch, then netted. Might pay with organic premium?

 

[CORK]

Local folklaw is that charlock will live in the soil for 100 years.

As a brassica grower including swedes under nets, I certaily have fields that will never be used for swedes in my lifetime.

I do dispute the 100 year figure, my Dad bought land in 1986 totally infested. It has been arable every since Winter barley, potatoes, spring barley, winter barley, leaf brassica, spring barley ever since. Now no charlock is seen although we went through a phase of Shepherds purse & are now battling with fat hen & sterile brome.

But heavier land with similar rotation but swedes (under nets) instead of leaf brassica charlock has put some land out of business for swedes, fat hen in decline thanks to Dual Gold.

My theory is heavy land makes the charlock seed much more dorment wheras light land more germinate & are easily killed.

We have ploughed up heavy loam after 40 years of grass sometimes charlock sometimes not, but never a severe infestation.

Light may be a factor because stale seed beds work very well, sadly without insecticide we can't use them because of cabbage root fly eggs in the soil before netting. Maybe GPS bed tilling in the dark?

I don’t have the same soil type comparison as you but I would dispute the 100yr figure too although perhaps it states “up to” 100 yrs?
We have some light land that was in continuous spring barley for 20 yrs, it certainly cleaned up.
On the other hand, I’ve heard stories of people digging a hole for a gate pier and seeing a forest of Charlock begin growing on the soil they dug out.

I work for a seed company and I do know that seeds stay viable longer if they are exposed to less air and also less temperature fluctuation.
Could heavy land have less air in it?

 

[Nearly]

@Devil's advocate
I made 4 grass fields into one 25 years ago at Shepley. Removed the odd elder bush and a lot of old posts and rusty wire.
From the garden centre at Shelley the yellow cross on a green background looked a picture.

 

[Lincsman]

On clay here, dig a trench in the road verge and leave it a month... covered in charlock, poppies are 100 years so charlock could also be, we never see one in a crop other than OSR, but over 50 years of 100% control in most crops and its still there in big numbers.

 

[Steevo]

I always thought it was 7 years.

 

[Devil's advocate]

I always thought it was 7 years.

I think it depends on cropping & soil type. Certainly we took a few walls out 30 years ago & there was red stripes of poppies where the wall bases were ploughed.

If down to grass, maybe 100 years but I suppose no one really knows exactly.

There is supposed to be a allopeith (sorry spelling) effect where seeds can sense if others have already germinated. So if seeds detect an oppuntity they take it, but stay dorment if others of there kind have already germinated.

 

[Bogweevil]

Thank heavens for the interweb thingy;

Seeds can remain dormant in soil for many years (Long, 1938) and may still be viable
even after 60 years (Mulligan & Bailey, 1975). Seed recovered from excavations and
dated at 20, 25 and 80 years old is reported to have germinated (Ødum, 1974). Seed
longevity in dry storage was 12 years and in soil 35 years (Guyot et al., 1962).
Charlock seeds gave 87% germination after 10 years in soil and 24% after 10 years in
dry storage (Brenchley, 1918). Seed stored dry for 5 years gave up to 80%
germination (Kjaer, 1940). The viability of seed buried in soil was 75% after 1 year
and there was little change over the next 4 years. Edwards (1980) gave the half-life
for the buried seed population as 3 years. Charlock can appear and become prevalent
on land ploughed after being under grass for decades (Anon, 1935). Charlock plants
appeared in cart tracks made across permanent pasture that had been undisturbed for
23 years (Goss, 1924). Viable charlock seeds have been found in the soil under a
pasture that had been undisturbed for 40 years (Fogg, 1950). The number of charlock
seeds germinating did not decrease as the number of years under a ley and hence the
age of the seed increased (Thurston, 1966). Most variation in seedling numbers was
the result of rainfall events in the period after ploughing. A single unchecked seeding
every 11 years is sufficient to maintain charlock the weed seedbank (Grime et al.,
1988).

The biology and non-chemical control of Charlock (Sinapis arvensis L.)
W Bond, G Davies, R Turner
HDRA, Ryton Organic Gardens, Coventry, CV8, 3LG,

 

[Flat 10]

The oilier a seed is the longer it lasts.....

 

[Bogweevil]

The oilier a seed is the longer it lasts.....

there is something in that but some oily seeds such as beech mast remain viable for only a few months.

 

[Devil's advocate]

Thank heavens for the interweb thingy;

Seeds can remain dormant in soil for many years (Long, 1938) and may still be viable
even after 60 years (Mulligan & Bailey, 1975). Seed recovered from excavations and
dated at 20, 25 and 80 years old is reported to have germinated (Ødum, 1974). Seed
longevity in dry storage was 12 years and in soil 35 years (Guyot et al., 1962).
Charlock seeds gave 87% germination after 10 years in soil and 24% after 10 years in
dry storage (Brenchley, 1918). Seed stored dry for 5 years gave up to 80%
germination (Kjaer, 1940). The viability of seed buried in soil was 75% after 1 year
and there was little change over the next 4 years. Edwards (1980) gave the half-life
for the buried seed population as 3 years. Charlock can appear and become prevalent
on land ploughed after being under grass for decades (Anon, 1935). Charlock plants
appeared in cart tracks made across permanent pasture that had been undisturbed for
23 years (Goss, 1924). Viable charlock seeds have been found in the soil under a
pasture that had been undisturbed for 40 years (Fogg, 1950). The number of charlock
seeds germinating did not decrease as the number of years under a ley and hence the
age of the seed increased (Thurston, 1966). Most variation in seedling numbers was
the result of rainfall events in the period after ploughing. A single unchecked seeding
every 11 years is sufficient to maintain charlock the weed seedbank (Grime et al.,
1988).

The biology and non-chemical control of Charlock (Sinapis arvensis L.)
W Bond, G Davies, R Turner
HDRA, Ryton Organic Gardens, Coventry, CV8, 3LG,

So yes it makes the point the more the land is disturbed the quicker the half life of the charlock, ie how we cleared them on light land.

One year in 11 of poor control (thats hard to measure too) keeps the seed bank topped up.

3 year half life so to go from a ton/acre to zero, flipping long time.

 

[Devil's advocate]

Modules planted through biodegradable mulch, then netted. Might pay with organic premium?

I think rent land or go nucleur & use Basamid to reset the clock, where we use insect netting on swedes.

Biodegradable mulch, did not know it was used in this country. Have seen the Italian built MAS speed planters used to have an option to put a giant roll of reycled paper down on the bed & the planter punch holes through it. In fact in their dry climate, they were also rolling out drip tape irrigation & then had a machine to lift lettuce up with the paper, to a semi automatic harvester.

MAS now taken over by Hortus & lots of those ideas dropped.