Temporal dynamics of actual weed infestation
in the sugar beet canopies

Časová dynamika aktuálnej zaburinenosti porastov repy cukrovej

Štefan Týr, Tomáš Vereš, Jozef Smatana - Slovak University of Agriculture in Nitra
Ivica Ðalović - Institute of Field and Vegetable Crops, Novi Sad, Serbia.
Dragiša Milošev - Faculty of Agriculture, University in Novi Sad, Serbia.

Corresponding author: Ing. Štefan Týr, PhD.,  Department of  Sustainable Agriculture and Herbology, Faculty of Agrobiology and Food Resources, Slovak University of Agricultural in Nitra, Trieda A. Hlinku 2, 949 01 Nitra, Slovak Republic, e-mail: Stefan.Tyr@uniag.sk

Abstract

The aim of this study was to detect the most harmful weeds in the canopies of sugar beet during the years 1999–2009 in the Slovak Republic. The actual weed infestation was evaluated by a counting method per square. The four randomly established sample quadrants were situated minimally 20 m from field margin and apart each other, respectively. Temporal dynamics of all weed species in the canopies of sugar beet were statistically analyzed. In the sugar beet fields the most problematic weeds were: perennial weed (Cirsium arvense (L.) SCOP, Elytrigia repens (L.) DESV, Convolvulus arvensis (L.)), annual weeds (Chenopodium spp., Amaranthus spp., Atriplex spp., Persicaria spp., Echinochloa crus galli (L.) Beauv., Datura stramonium (L.), Mercurialis annua (L.), Panicum capillare (L.), Iva xanthiifolia Nutt.) and cultural crops winter oilseed rape (Brassica napus (L.)). Temporal dynamics of actual weed infestation depend on climate conditions of production region, forecrop and canopy health condition. The most dangerous weed species were Persicaria spp., Amaranthus spp., Atriplex spp., Chenopodium spp. and Echinochloa crus galli (L.)P.Beauv, which infested more than 90% of sugar beet fields in maize and sugar beet production region. 

Keywords: mapping, temporal dynamics, actual weed infestation, sugar beet.

Súhrn

Cieľom tejto štúdie, vykonávanej v rokoch 1999–2009, bolo zistiť najnebezpečnejšie buriny v porastoch repy cukrovej v Slovenskej Republike. Aktuálna zaburinenosť bola hodnotená početnou metódou. Hodnotené boli 4 náhodne usporiadané kvadranty, ktoré boli od seba a od okraju poľa vzdialené minimálne 20 m. Časová dynamika zaburinenosti porastov cukrovej repy bola štatisticky vyhodnotené. Na poliach s cukrovou repou boli najproblematickejšie nasledovné druhy burín: trváce buriny (Cirsium arvense (L.) SCOP, Elytrigia repens (L.) DESV, Convolvulus arvensis (L.)), jednoročné buriny (Chenopodium spp., Amaranthus spp., Atriplex spp., Persicaria spp., Echinochloa crus galli (L.) Beauv., Datura stramonium (L.), Mercurialis annua (L.), Panicum capillare (L.), Iva xanthiifolia Nutt.) a kultúrne plodiny – výmrv kapusty repkovej pravej (Brassica napus (L.)). Časová dynamika aktuálnej zaburinenosti závisí od klimatických podmienok v produkčnej oblasti, predplodiny a zdravotného stavu pestovanej plodiny. Najnebezpečnejšími burinnými druhmi boli Persicaria spp., Amaranthus spp., Atriplex spp., Chenopodium spp. and Echinochloa crus galli (L.)P.Beauv, ktoré zaburiňujú viac ako 90% pestovateľských plôch cukrovej repy v kukuričnej aj repárskej výrobnej oblasti Slovenska. 

Kľúčové slová: mapovanie, časová dynamika, aktuálna zaburinenosť, repa cukrová.

Sugar beet is not very competitive crop, until it has at least 8 true leaves (Hembree, Norris, 2010; May, 2001). Because of this weed infestation of sugar beet fields should be monitored. Ideally, sugar beet fields should be monitored for weeds in the winter, spring, summer and fall. If it is not feasible, monitor fields at least twice per year: in late winter to determine the cool season weed population and in late summer to determine the warm season weed population. While monitoring, it is particularly critical to note any weeds that have escaped control in the previous crops and were able to set seed. Because seeds can remain viable in soil for years, monitoring done over a period of years, can provide the means to predict which species are likely to be present (Hembree, Norris, 2010).
Thus weed control is a decisive and one of the most difficult agricultural arrangements in sugar beet growing. Especially where sugar beets are planted at final density and will not be thinned. Main reason include slow early growth of sugar beet, its very low competitive ability at the beginning of vegetation, high sensitivity to herbicides (mainly in early growth stages), and also high cost of special herbicides. Uncontrolled weeds can reduce sugar beet yield by over 90 %; even one barnyard grass in 10 feet of row can cause about a 5 to 15 % yield loss. Dense weeds make hoeing, the use of electronic thinners, cultivation and harvest difficult (Abdollahi, Ghadiri, 2004; Hembree, Norris, 2010; May, 2001)

Methods and materials

	The assessment of the most dangerous weed species and their dynamic in canopy of sugar beet was conducted at the Slovak fields in 1999–2009. The fields were selected in maize and sugar beet production region. Common chemical weed practices were used. Present study assessed the actual weed infestation of weed species in canopy of sugar beet and their dynamic during the years 1999–2009. 
An actual weed infestation was evaluated before application of herbicides with concordance to modified international scale. Screening of each field was made on the quadrant of 1 m2 area with four replications. One quadrant of each replication was (1.0m x 1.0m). The four randomly established sample quadrants were situated minimally 20 m from field margin and apart each other, respectively. The fields with same history were selected. Standard mechanical and chemical weed control have been used. The level of infestation was evaluated according to average density of weeds per square meter (Table I). Received dates from farms were computed to whole area of growing crop and statistically analysed by correlation analysis in Statistica 7.0.

Tab. I. Evaluation scale of actual weed infestation

Group of weeds*	Actual weed infestation	
	none	weak	low	medium	heavy	
	Infestation level	
	0	1	2	3	4	
	Number of weeds per m2	
Excessively dangerous	-	£ 2	3-5	6-15	≥ 16	
Less dangerous	-	£ 4	5-8	9-20	≥ 21	
Less important	-	£ 8	9-15	16-30	≥ 31	
*- weed species checklist Hron-Vodák, 1959, modified by authors

Tab. II. Characteristic of evaluated production region of the Slovak Republic

Characteristics	Maize production region
 (MPR)	Sugar beat production region (SBPR)	
Share of total arable land	24%	16.2%	
Altitude	up to 200 m	up to 350 m	
Average year temperature	9.5-10.5°C	8-9°C	
Average year precipitation	550-600 mm	550-650 mm	

Results and Discussion

Weed survey at the Slovak fields in the years 1999-2009 showed that in maize and sugar beet production region were at the sugar beet field presented following weeds: Datura stramonium L., Persicaria spp., Iva xanthiifolia Nutt., Echinochloa crus galli (L.)P.Beauv, Amaranthus spp., Galium aparine L., Atriplex spp., Setaria spp., Chenopodium spp., Avena fatua (L.), Tripleurospermum perforatum (Mérat) M. Lainz, Cirsium arvense (L.)Scop., Abutilon Theophrasti Medik., Panicum capillare (L.), Convolvulus arvensis (L.), Elytrigia repens (L.)P.Beauv, Polygonum aviculare (L.), Xanthium strumarium (L.), Volunteer winter oilseed rape and volunteer sugar beet. Only in maize production region were detected: Anthemis arvensis (L.), Mercurialis annua (L.), Conium maculatum (L.), Fallopia convolvulus (L.)A. Loeve, Fumaria officinalis L., Volunteer sunflower.
The most frequently weed species in the mapping of actual weed infestation at the European fields in the canopies of sugar beet were: Chenopodium album L., Solanum nigrum L., Stellaria media (L.)Vill., Echinochloa crus galli (L.)P.Beauv, Polygonum persicaria L., Polygonum aviculare L., Cirsium arvense (L.)Scop., Amaranthus retroflexus L., Poa annua L., Atriplex patula L., Fallopia convolvulus (L.)A. Loeve, Fumaria officinalis L., Galium aparine L., Sonchus arvensis L., Elytrigia repens (L.)P.Beauv. (Schroeder et al., 1993).
The main weeds found in sugar beet in Europe include the perennial species Elytrigia repens (L.)P.Beauv and Cirsium arvense (L.)Scop., whilst common annual weeds include Chenopodium album L., Polygonum aviculare L., Matricaria chamomilla (L.), Fallopia convolvulus (L.)A. Loeve, Sinapis arvensis (L.) and Stellaria media L.Vill.. Crop volunteers of potatoes and oilseed rape are present in many countries. Weed beet (an annual form of Beta vulgaris L.) is a problem of many countries but particularly the UK where it is present in approximately 60 % of sugar beet fields (May, 2001).
The ten most dangerous weed species at the sugar beet fields are presented according to production region in the table III. The highest level of weed infestation in the maize production region achieved: Chenopodium spp., Amaranthus spp., Atriplex spp. and Persicaria spp., which infested sugar beet with more than 16 plants per m2 and caused serious yield and quality losses and problems with sugar beet harvest. The troublesome weed at sugar beet fields in sugar beet production region was Echinochloa crus galli (L.)P.Beauv, which infested every field with more than 16 plants per m2. In this production region were also dominant: Chenopodium spp., Amaranthus spp., Atriplex spp. and Persicaria spp..
	Temporal dynamics of weed species (during the years 1999-2009) infested sugar beet fields in maize and sugar beet production region were completely different. In maize production region was detected significant increase of weed infestation percentage at three weed species Persicaria spp., Chenopodium spp. and Panicum capillare (L.). Very significant increase of weeds frequency was detected at Anthemis arvensis (L.), Mercurialis annua (L.) and Iva xanthiifolia Nutt.. Weed species like Datura stramonium (L.) and Fallopia convolvulus (L.)A. Loeve decreased their sugar beet fields’ infestation significantly or very significantly.
	Weed like Amaranthus spp., Echinochloa crus galli (L.)P.Beauv, Mercurialis annua (L.) and Chenopodium spp. can produce high amount of seed which are presented in the soil seed bank for long time. It could be reason why they increased their infestation of sugar beet canopies. Another reason of increasing weed infestation by these weed species is an unsuitable choice of herbicides, wrong term of application or bad establishment of sugar beet canopy (Jursík et al., 2004; Jursík et al., 2008; Mesbah, 1993; Storkey, 2004; Wellmann, 1999)
As for sugar beet production region there was detected significant increase of sugar beet canopies at two weed species – Echinochloa cruss galli (L.)P.Beauv and Chenopodium spp. and very significant increase of Atriplex spp. and Setaria spp. occurrence (Tab. IV).

Tab. III. Top 10 of most dangerous weed species in the Slovak sugar beet fields

No.	Maize production region	Sugar beet production region	
1.	Chenopodium spp.	Echinochloa crus galli (L.)P.Beauv	
2.	Amaranthus spp.	Chenopodium spp.	
3.	Atriplex spp.	Amaranthus spp.	
4.	Persicaria spp.	Atriplex spp.	
5.	Datura stramonium (L.)	Cirsium arvense (L.)Scop.	
6.	Echinochloa crus galli (L.)P.Beauv	Elytrigia repens (L.)P.Beauv	
7.	Cirsium arvense (L.)Scop.	Persicaria spp.	
8.	Iva xanthiifolia Nutt.	Convolvulus arvensis (L.)	
9.	Mercurialis annua (L.)	Volunteer winter oilseed rape	
10.	Panicum capillare (L.)	Datura stramonium (L.)	

Tab. IV. Correlation coefficient of the most important weed species in the sugar beet fields during years 1999–2009

Weed	Maize production region	Sugar beet production region	
Datura stramonium (L.)	-0.6630 S	0.1045 NS	
Persicaria spp.	0.6170 S	0.3132 NS	
Iva xanthiifolia Nutt.	0.8237 VS	0.5978 NS	
Echinochloa crus galli (L.)P.Beauv	-0.3251 NS	0.6876 S	
Volunteer winter rape	-0.4681 NS	0.4800 NS	
Amaranthus spp.	-0.0516 NS	0.5855 NS	
Atriplex spp.	0.5301 NS	0.7552 VS	
Setaria spp.	0.5125 NS	0.9069 VS	
Chenopodium spp.	0.7110 S	0.6025 S	
Avena fatua (L.)	-0.2739 NS	-0.5404 NS	
Tripleurospermum perforatum (Mérat) M. Lainz	-0.0296 NS	-0.1190 NS	
Cirsium arvense (L.)Scop.	-0.3421 NS	-0.2161 NS	
Abutilon Theophrasti Medik.	-0.2048 NS	0.3077 NS	
Panicum capillare (L.)	0.6497 S	0.5314 NS	
Weed	Maize production region	Sugar beet production region	
Convolvulus arvensis (L.)	-0.4877 NS	0.2599 NS	
Elytrigia repens (L.)P.Beauv	0.5422 NS	0.2371 NS	
Anthemis arvensis (L.)	0.8051 VS	-	
Mercurialis annua (L.)	0.8162 VS	-	
Fallopia convolvulus (L.)A. Loeve	-0.7362 VS	-	
Legend: NS – non significant; S – significant, VS – very significant

Conclusions

In the last decade very significantly increased the percentage of sugar beet fields weed infestation with Anthemis arvensis (L.), Mercurialis annua (L.) and Iva xanthiifolia Nutt. in maize production region and in sugar beet production region with Atriplex spp. and Setaria spp.. Only significant increase was detected at three weed species in maize production region Persicaria spp., Chenopodium spp. and Panicum capillare (L.) and two weed species in sugar beet production region Echinochloa crus galli (L.)P.Beauv and Chenopodium spp.. In maize production region was detected also significant decrease at weed infestation of sugar beet fields with Datura stramonium (L.) and very significant decrease at Fallopia convolvulus (L.)A. Loeve.

Acknowledgements

This paper was supported by VEGA project 1/0466/10 “Adaptation of sustainable agriculture and mitigation of impact of climate change”, and project VEGA 1/0804/11 “Výskum udržateľných agroekosystémov, inovatívnych technológií pre produkciu bioproduktov a ich vplyv na nutričné a zdravotné parametre ľudí”.

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