Zeitschrift für Pfianzenkrankheiten und Pflanzenschutz Journal of Plant D i s e a s e s and Protection Sonderheft XIX, 3 9 9 - 4 0 3 ( 2 0 0 4 ) , ISSN 0 9 3 8 - 9 9 3 8 © Eugen Ulmer GmbH & Co., Stuttgart
Using GPS in weed prediction P. REISINGER 1 *, É . LEHOCZKY 2 , S . N A G Y 3 , T . KOMIVES
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'Faculty of Food and Agricultural Sciences, University of West-Hungary, H-9200 Mosonmagyaróvár, Vár u. 2., Hungary, e-Mail:
[email protected] 2 Georgikon Faculty of Agricultural Sciences Keszthely, Veszprém University, H-8360 Keszthely, Deák F. u. 16., Hungary, e-Mail:
[email protected] 3 Faculty of Food and Agricultural Sciences, University of West-Hungary, H-9200 Mosonmagyaróvár, Vár u. 2., Hungary, e-Mail:
[email protected] 4 Plant Protection Institute of the Hungarian Academy of Sciences, H-1022 Budapest, Herman O. u. 15., Hungary, e-Mail:
[email protected] *Corresponding author
Summary Precision management of weeds is based on information technologies such as the global positioning system (GPS) and geographic information systems (GIS). In this study we investigated the weed community developed on winter wheat stubble and identified the sampling sites of the survey by GPS. We found that the weed population of the cereal stubble, with the exception of some species such as barnyardgrass (Echinochloa crus-galli) and volunteer sunflower (Helianthus annum) showed great similarity to the weed flora in maize sown next year. Thus, a weed survey carried out before harvesting in cereal fields without herbicide-treatment can provide a basis for the forecast of weeds in cereals. We concluded that an evaluation of data of systematic weed surveys carried out repeatedly at locations identified by geographical coordinates allows the prediction of weeds and the reduction of herbicide use thereby resulting in a reduction in financial and environmental costs. Keywords: Weed prediction, cereal stubble, maize, GIS, GPS, herbicide use, weed survey, negative weed prognosis Zusammenfassung Nutzung von GPS bei der Unkrautvorhersage Präzisionsunkrautmanagement erfordert Informationstechnologien wie das globale Positionierungssystem (GPS) oder geographische Informationssysteme (GIS). Diese Studie befasst sich mit der Untersuchung von Unkrautgesellschaften auf Getreidestoppeln. Die Probenahmestellen wurden mit Hilfe von GPS bestimmt. Dabei zeigte sich, dass die Unkrautpopulation auf dem Getreidestoppel mit Ausnahme einiger Arten wie z. B. Hühnerhirse (Echinochloa crus-galli) und Ausfall-Sonnenblumen (Helianthus annuus) eine sehr große Ähnlichkeit mit der Unkrautflora des Maises des Folgejahres zeigte. Eine vor der Ernte durchgeführte Unkrautbestimmung in Getreide ohne Herbizidbehandlung kann eine gute Grundlage für die Unkrautvorhersage sein. Es ist anzunehmen, dass die Daten der systematischen Unkrautbestimmung, die aufgrund der ermittelten geographischen Koordinaten an den gleichen Probestellen wiederholt durchgeführt wurde, die Vorhersage des Auftretens von Unkräutern ermöglicht. Dadurch ist eine Reduzierung der zu verwendenden Herbizidmenge zu erwarten. Dies kann zu ökonomischen und ökologischen Vorteilen führen, was wiederum zur Reduzierung der Ausgaben und Umweltkosten fuhren kann. Stichwörter: Unkrautvorhersage, Getreidestoppel, Mais, GIS, GPS, Herbizidanwendung, Unkrautbestimmung, Unkrautprognose
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Introduction Molecular biological and traditional crop breeding programs increasingly contribute to reduce the crop plants sensitivity to diseases and insect pests, but offer little help to increase the plants ability to compete with weeds. Therefore, weeds continue to have major impacts on crop production in spite of efforts to eliminate them. The shift from centrally planned to free market agriculture in Hungary and in other Central Eastern European countries in 1990 led to dramatic increases in weed problems. For example, weed seed content of soils in Hungary increased about tenfold, occasionally reaching 5 0 , 0 0 0 viable weed seeds per square meter (LEHOCZKY and BOROSNÉ-NAGY 2 0 0 2 , LEHOCZKY et al. 2 0 0 3 ) . As a result even well-established weed control methods often fail in our region, especially in lose-standing crops (such as maize (Zea mays L.), sunflowers (Helianthus annuus L.) and potatoes (Solarium tuberosum L.), where early, massive appearance of weeds leads to harmful competition (LEHOCZKY et al. 2 0 0 3 ) . The purpose of this investigation was to find out whether the appearance of certain weeds at a location in a field is predictable from results of weed surveys regularly carried out in previous years. For these studies we used selected sampling sites and assigned them with GPS coordinates.
Materials and methods The field experiment was carried out at Baracska, Hungary, on a 9.2 ha wheat field project area (soil properties are listed in Table 1) in 2 0 0 1 and 2 0 0 2 . Wheat was harvested on July 16, 2 0 0 1 and the stubble was left undisturbed. The project area was divided to 18 x 222 m blocks (altogether 21, numbered from 102 to 122) and within the blocks 2 x 2 m sampling areas were assigned and identified by GPS coordinates using a Trimble Pathfinder instrument (USA; accuracy < 1 m). Weeds were first surveyed (weed species and relative weed cover) at the sampling sites on September 13, 2001 by using the BalazsUjvarosi coenological method. In the next two years maize was sown in the project area (April 2 6 , 2 0 0 2 and April 2 9 , 2 0 0 3 ) and before the application of postemergence herbicides weeds were surveyed again at the sampling sites on May 2 5 , 2 0 0 2 and May 2 2 , 2 0 0 3 .
Tab. 1: Soil properties (mean, variance) of the project area (Baracska, Fejer county; Hungary) Tab. 1: Bodeneigenschaften (Mittelwert, Varianz) der Versuchsjlache (Baracska, Fejér; Ungarn) Type FAO USDA Calcaric Mollisol phaeosem
Texture Loam
Organic matter (%)
pH
3.2 [0.83]
7.5 [1.8J
CaC03
(%)
P2O5
K2O
mg k g '
5.7 [1.2] 283 [54] 314 [39]
Results and discussion Weed seedling emergence is known to be highly variable, depending on environmental factors that control the breaking and re-imposition of seed dormancy and germination (DEKKER et al. 2 0 0 1 , DEKKER and HARGROVE 2 0 0 2 , GRUNDY et al. 2 0 0 3 ) . Therefore, reliability of weed forecasts strongly depends on the environmental conditions as wells as on the weed seed bank of the site. Coverage of weeds surveyed in 2 0 0 1 in wheat stubble, and in 2 0 0 2 and 2 0 0 3 in maize is shown in Table 2. Good correlation exists between coverage values of weeds in different years (r > 0.73 in each case), suggesting that from the weed populations in a field in one year the weed population of the following year(s) can be predicted. The data clearly indicate that Datura stramonium is the dominant weed in the project area. However, the distribution of Datura stramonium in the project area is far from even: the weed is found in stable patches of different size and different plant density as indicated by data in Table 3.
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(seeds, rhizomes, etc.) of a weed in the soil. Constancy values of the dominant weeds in our project area are summarized in Table 3. Tab. 4: Constancy* of dominant weed species at the sampling sites (Baracska, Fejer county, Hungary; number of sampling sites: 21) Tab. 4: Konstanz der dominierenden Unkräuter auf den Probenahmestellen (Landkreis: Baracska, Fejer; Ungarn; Anzahl der Probenahmestellen: 21) Constancy (2002 to 2003) % 91 77 58 53 58 78 72 72 year to the next year.
Constancy (2001 to 2002) %
Weed species
Datura stramonium 76 48 Cannabis sativa Panicum miliaceum 58 Helianthus annuus 48 Echinochloa crus-galli 53 Amaranthus retroflexus 62 Chenopodium hybridum 58 Chenopodium album 77 *Reappearance of a weed in the project area from one
Constancy (2001 to 2003) % 100 91 81 77 86 62 77 62
Tab. 5: Presence of Helianthus annuus at the sampling sites Tab. 5: Vorkommen von Helianthus annuus Sampling site No. 102 103 104 105 106 107 108 109 110 111 112 113 114 116 ; 117 118 119 120 121 122
September 12, 2001 (wheat stubble)
4.68 6.25
6.25
May 25, 2002 (maize) 3.12 12.50 0.10 4.68 0.18 6.25 6.25 6.25 4.68 0.62 0.62 6.25
May 22, 2003 (maize)
0.1 0.1 0.1 0.1 3.12 0.1 0.1
3.12
3.12 6.25 3.12
1.87 0.62
Using GPS in weed prediction
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A specific case in pest management is the so called "negative prognosis" that involves the prediction of pest-free areas and/or periods of time, thereby eliminating unnecessary pest control measures. Since in weed control negative prognosis locates weed-free areas where weed control is not required it is a valuable tool in precision weed management ( N O R D B O et al. 1 9 9 5 ) , as well. We found that repeated sitespecific weed surveys allow negative predictions of weed emergence. For example, an evaluation of the weed cover data of Helianthus annuus (Tab. 4) reveals that the probability of emergence of this weed at sampling sites where it had been absent for two consecutive years is less than 4 % and, even if this plant appears, its weed cover remains below the economic threshold level (3 % weed cover in September). Our studies led to the conclusion that repeated and accurate weed surveys allow the prediction of the emergence of dominant weed species at a given sampling site as well as its negative prognosis (i.e., a prediction of its absence). In case of perennial weeds (e. g. Cirsium arvense) it is necessary to localize the patch precisely by identifying its contours with GPS coordinates. Further research is necessary to characterize the optimum size of the management blocks and the sampling sites.
Acknowledgement Financial support of this work was provided by the Hungarian OTKA Research Fund (T029121 and T43476).
References R . G . HARTZLER, F . FORCELLA; Weed seed bank dynamics: Implications to weed management. Journal Crop Production 1, 145-168, 1998. CHRISTENSEN, S., T . HEISEL, J . V . BENLLOCH: Patch spraying and rational weed mapping in cereals. In: ROBERTS, P . C . , R . H . R U S T , W . E . LARSON (eds): Precision Agriculture Part A, 7 7 3 - 7 8 6 , 1 9 9 8 . COLBACH, N., F. FORCELLA, G.A. JOHNSON: Spatial and temporal stability of weed populations over five years. Weed Science 48, 366-377, 2000. DEKKER, J . , M . HARGROVE: Weedy adaptation in Setaria spp.: V . Effects of gaseous atmosphere on giant foxtail (Setaria faberii) (Gramineae) seed germination. American Journal of Botany 89, 410-416, 2002. DEKKER, J . , L . LATHROP, B. ATCHISON, D . T O D E Y : The weedy Setaria spp. phenotype: How environment and seeds interact from embryogenesis through germination. Proceedings of the Brighton Crop Protection Conference -Weeds, 65-74, 2001. BUHLER, D . D . ,
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F. FORCELLA: Emergence of Chenopodium album and Stellaria media of different origins under different climatic conditions. Weed Research 43, 163-176, 2003. LEHOCZKY, É . , A. B O R O S N É - N A G Y : Effect of early competition between barnyardgrass (Echinochloa crus-galli L.) and maize on the growth of plants. Hungarian Weed Research and Technology 3, 13-20, 2002. LEHOCZKY, É . , P. REISINGER, T. KOMIVES: LOSS of nutrients caused by excessive weediness at the early stage of maize vegetation period. Communications in Soil Science and Plant Analysis 2003 (in press). NORDBO, E„ S . CHRISTENSEN, K . KRISTENSEN: Teilflâchen-Unkrautmanagement. Zeitschrift fiir Pflanzenkrankheiten und Pflanzenschutz 102, 75-85, 1995. A.J. MURDOCH,
