Effects of reduced pesticide use on flora and....., Danish Environmental Protection Agency

Effects of reduced pesticide use on flora and fauna in agricultural fields

Appendix E.1.
Densities of weed species occurring with more than 5 plants per square meter after spraying in winter wheat (A) and spring barley (B) field trials. The maximal yield decrease (%) at reduced or zero dosages compared to yield at normal dosage is mentioned. In addition, the weed density for all species after spraying is listed as a mean for all treatments. Placement of the weed species on the line between strong and weak competitors is relative and based on data of crop equivalents from Wilson (1986), Wilson and Wright (1990), Jensen (1991, 1996) as well as the authors' knowledge about the species. Galium aparine is a very strong competitor even in small densities and are therefore always mentioned in the table. Each value is a mean of 12-16 plots.

A Winter wheat				Strong competitors ¬ ----------------------------------------------------------------- Weak competitors
Farm	Year	Max. yield decrease (%)	Total weed density after spraying (mean of all treatments)	Galium aparine	Sinapis arvensis/ Brassica napus/ Raphanus raphanistrum	Poa pratensis/ trivialis	Stellaria media	Myosotis arvensis	Aethusa cynapium	Veronica arvensis/ agrestis/ persica	Viola arvensis/ tricolor ssp. tricolor	Polygonum aviculare	Trifolium sp.	Poa annua	Capsella bursa- pastoris
Nøbøllegård	98	11.0	207				149							46
Lekkende	98	10.0	34	0.5										21
Nordfeld	99	9.7	95	5.7	12		7					59
Gjorslev	98	9.3	28	5.2			18
Nordfeld	98	8.3	147			17						37	18	57	16
Oremands- gård	98	8.0	5
Lekkende	99	6.8	59				17	7		6	9			11
Oremands- gård	97	4.5	23			22
Gjorslev	99	4.2	90						16		15	51
Gjorslev	97	3.2	18	2.4			9
Oremands- gård	99	2.3	21						9
Nøbøllegård	99	2.1	146				121						12
Nordfeld	97	0.5	134											132
Lekkende	97	0.3	56									20		30

B Spring barley				Strong competitors --------------------------------------------------------------------------------------------------------------------------------® Weak competitors
Farm	Year	Max. yield de- crease (%)	Total weed density after spraying (mean of all treat- ments)	Galium aparine	Sinapis arven- sis/ Bras- sica napus/ Rapha- nus raphani- strum	Poly- gonum avicu- lare	Trifoli- um sp.	Cheno- podium album	Bilder- dykia convol- vulus	Chamo- milla recutita/ suaveo- lens/ Matri- caria perfo- rata	Lamium amplixi- caule/ hybri- dum/ purpu- reum	Stel- laria media	Vero- nica arven- sis/ agrestis/ persica	Viola arven- sis/ tricolor ssp. tricolor	Aethusa cyna- pium	Poa annua	Ana- gallis arven- sis	Plan- tago major	Euphor- bia helio- scopia	Euphor- bia peplus	Euphor- bia exigua	Cap- sella bursa- pasto- ris
Oremands- gård	99	34.6	513		242		39		11		14		169	23
Nordfeld	98	13.4	150	6.0	45	64													12
Nøbølle- gård	98	11.5	243				154					49				14
Gjorslev	99	8.3	350			193			45						43		24		15		16
Gjorslev	98	7.4	291			95						35		140	16
Oremands- gård	97	6.7	7	3.5
Oremands- gård	98	5.5	147				8		8		7			12	32			37		14	10
Lekkende	98	4.4	102						14	14			17	39		6
Nøbølle- gård	99	4.3	313	3.9		45		17	106	36		59		8			19
Lekkende	99	3.6	188			43								16		120
Nordfeld	99	2.6	65								7					43
Nøbølle- gård	97	1.0	85					7	13			16	22			20
Nordfeld	97	0.3	75										14			43						11
Gjorslev	97	0	49	1.0								31
Lekkende	97	0	105	1.7							8		15			65