[email protected] [email protected] Spatial and Population Dynamics of Patches of Wild-oats Nicola Perry and Peter Lutman IACR-Rothamsted

[email protected]@bbsrc.ac.uk

Spatial and Population Dynamics of Patches

of Wild-oats

Nicola Perry and Peter Lutman

IACR-Rothamsted


Background:

• Important grass weed

• Patchy distribution

• Patch stability unknown

Wild-oats:


Experiment details

• Patch size 3x3 m

• Two sowing densities:– 10 plants/m2 and 50 plants/m2

• Ploughing, cultivations and combining in same direction each year

• +/- wild-oat herbicide in 2000


Experiment design

SLD

SHDLDSHD

LDSLDHD

HD

HD = high density; LD = low density; S = sprayed

arrows indicate cultivation & combining direction

N

30m

12m

3m

3m


Monitoring

• Panicle distribution

• Seed movement

• Patch shape

• Location of outliers


Panicle and seed distribution 1999

Panicles / m2

Seeds / m2

0

5

10

15

20

25

30

35

40

-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Distance (m)

Pa

nic

les

/ m

2

0

200

400

600

800

1000

1200

1400

Se

ed

s /

m2

Direction of cultivation & combining


Panicle and seed distribution Sprayed Treatments 2000

Panicles / m2

Seeds / m2

0

20

40

60

80

100

120

-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24

Distance (m)

Pa

nic

les

/ m

2

0

500

1000

1500

2000

2500

3000

3500

Se

ed

s /

m2

Direction of cultivation & combining


Seed distribution after harvestSprayed v Unsprayed 2000

0

2

4

6

8

10

12

14

16

18

-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24

Distance (m)

Pe

rce

nta

ge

of

tota

l s

ee

ds

Sprayed UnsprayedDirection of cultivation & combining

Total no. seeds/m2

Sprayed: 17,860

Unsprayed: 139,410


Low Density Sprayed Patch

1998 (9 m2)

1999 (20.3 m2)

2000 (20.6 m2)m

harvesting &

cultivation

0 1 2 3


m

1998 (9 m2)

1999 (29.5 m2)

2000 (41.0 m2)

High Density Unsprayed Patch

harvesting &

cultivation

0 1 2 3


513260 513280 513300213180

213190

213200

213210

213220

213230

213240

213250

213260

213270 1999

Patch outline

Outliers


513260 513280 513300 513320213180

213190

213200

213210

213220

213230

213240

213250

213260

213270

213280

2000

Patch outline

OutliersS

S

S

S

S Sprayed plots


Conclusions

• Majority of seeds move 1-2 m– movement due to cultivations and plants

leaning in wind

• Isolated plants occur up to 30 m away– movement by combine– may lead to future infestations / new

patches


Conclusions

• Wild-oats need frequent re-mapping

• Patches not stable and new patches may form from isolated plants

• Presence of outliers make decisions on patch spraying complicated


Limitations of manually mapping

weed patches

Nicola Perry and Peter Lutman

IACR-Rothamsted


Methods of manually mapping weed patches

• Visual detection (human)– mapping on a grid– ATV, tractor/sprayer, combine– walking around patches


Weed attributes which can be recorded

• Presence / absence

• Approximate levels (high / low)

• Weed numbers

• Weed vigour / ground cover


Weed attributes which can be recorded from a vehicle or using quadrats

Vehicle Quadrat

Presence/Absence

Levels (high/low) ?

Counts x

% cover x


Timing of visual assessments

Winter EarlySpring

Summer Harvest

Black-grass

? Y Y N

Cleavers ? Y Y ?

Wild-oats ? ? Y Y

Couchgrass

N N ? Y


Activities on Warren Field(winter wheat)

Crop drilled 16 Sept 99

Quadrat mapped 2 Dec 99

ATV mapped 27 Jan 00

Sprayed ‘Grasp’ 13 Mar 00

Sprayed ‘Topik’ 30 Apr 00

Tractor mapped 30 Jun 00


Warren Field black-grass comparison of mapping methods

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

Correlation : 0.82

Quadrat threshold 20 plants/m2 (Dec 99)

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

Black-grass

No Black-grass

ATV (Jan 00)



0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

Correlation : 0.60


Black-grass

No Black-grass

ATV (Jan 00)

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90



Correlation : 0.37


Black-grass

No Black-grass

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

Tractor (June 00)



Correlation : 0.84


Black-grass

No Black-grass

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

Tractor (June 00)


Warren Field wild-oats comparison of mapping methods

ATV (Jan 00)

Correlation : 0.74


0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

Wild-oats

No Wild-oats


Warren Field wild-oats comparison of mapping methods

Tractor (June 00)

Correlation : 0.58


Wild-oats

No Wild-oats

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 900

10

20

30

40

50

60

70

80

90


Broad Mead black-grass comparison of mapping methods

ATV (Jan 00)

Correlation : 0.70


Black-grass

No Black-grass0 20 40 600

20

40

60

80

100

120

140

0 20 40 600

20

40

60

80

100

120

140


Black-grass distribution in Cashmore Field

Mapped from ATV Nov 99

Mapped from combine July 00

black-grass

no black-grass

508450 508500 508550 508600 508650 508700 508750

235450

235500

235550

508500 508550 508600 508650 508700 508750

235450

235500

235550

508450 508500 508550 508600 508650 508700 508750

235450

235500

235550

Mapped on foot May 00


Conclusions

• Limitations to manually mapping weeds

• Discrete quadrat sampling too time consuming for mapping on a whole-field scale

• Continuous visual detection from a vehicle is less accurate, & may be restricted to tramlines, but is quicker


Conclusions

• Need to make more progress with optimum visual detection in absence of automated detection

Documents

[email protected] [email protected] Spatial and Population Dynamics of Patches of Wild-oats Nicola Perry and Peter Lutman IACR-Rothamsted