Vole species, especially Arvicola terrestris and Microtus arvalis cause significant economical damage in organic pomiculture by gnawing the root system of trees. The importance of voles as pest organisms is well known. Nevertheless, the estimation of financial loss caused by voles is difficult for German fruit growers. We conducted a survey among organic fruit growers to get data on kind and amount of annual damage. Using the available publications and official statistics we calculated economical values of organic apple trees for different types of orchard processing and tree ages. Furthermore we calculated the number of trees lost due to voles in one year

Fülling, O.

Malevez, J.

Pelz, H.-J.

Walther, B.

English

Organic Eprints

330How expensive is vole damage? B. Walther 1,4, O. Fülling 1,2, J. Malevez 3and H.-J. Pelz 4AbstractVole  species,  especially  Arvicola  terrestris  and  Microtus  arvalis  cause  significant economical  damage  in  organic  pomiculture  by  gnawing  the  root  system  of  trees.  The importance  of  voles  as  pest  organisms  is  well  known.  Nevertheless,  the  estimation  of financial loss caused by voles is difficult for German fruit growers. We conducted a survey among organic fruit growers to get data on kind and amount of annual damage. Using the available publications and official statistics we calculated economical values of organic apple  trees  for  different  types  of  orchard  processing  and  tree  ages.  Furthermore  we calculated the number of trees lost due to voles in one year. Keywords: survey, organic farming, pomiculture, economical loss, Germany IntroductionVole  species,  especially  the  Water  vole  (Arvicola  terrestris)  and  the  Common  vole (Microtus  arvalis)  cause  significant  damage  in  German  orchards  (Klemm  1958,  1964; Wieland, 1973; BBA, 1978). Both species gnaw on the root system or trunks of trees. The affected trees mostly die and a persistent crop failure is the consequence. In some organic apple orchards dramatic effects are reported culminating in total losses (Kopp 2002). The knowledge about frequency, distribution and the resulting economical losses caused by voles in German organic pomiculture is poor. In order to get a more precise data basis we started a survey among German organic fruit growers and compared the results with data from Statistisches Bundesamt (2003, 2004) and KTBL collection (2005). Material and Methods Our survey among German organic fruit growers asked for information about farm location and size, kind of apple cultivation, the importance of vole damage and the applied vole management.  We  focused  our  analysis  on  value  and  economical  significance  of  vole damage. The questionnaire was distributed in February 2003 by consulting services and organic farming associations among their members and also by federal crop protection agencies.  75  questionnaires  returned  until  June  2003  covering  698  ha  of  fruit  growing acreage.  This  represents  13%  of  the  nationwide  organic  fruit  cultivation  (Statistisches Bundesamt, 2004). Nevertheless, returns from the different fruit growing areas in Germany were  not  evenly  distributed.  The  majority  of  returns  came  from  the  central  and  south western parts of the country.                                                1University Münster, Institute of Landscape Ecology, Robert-Koch-Straße 26, D-48149 Münster, Germany, walther.bernd@web.de, 2University of Bern, Zoological Institute, Community Ecology, Baltzerstraße 6, CH-3012 Bern, Switzerland, olaf.fuelling@zos.unibe.ch3Topcat GmbH, 9, chemin des Grangettes, CH-1454  L’Auberson VD, Switzerland, info@topcat.ch 4 Federal Biological Research Centre for Agriculture and Forestry, Institute for Nematology and Vertebrate Research, Toppheideweg 88, D-48161 Münster, Germany, j.pelz@bba.de  Archived at http://orgprints.org/13744/331How expensive is vole damage? B. Walther 1,4, O. Fülling 1,2, J. Malevez 3and H.-J. Pelz 4AbstractVole  species,  especially  Arvicola  terrestris  and  Microtus  arvalis  cause  significant economical  damage  in  organic  pomiculture  by  gnawing  the  root  system  of  trees.  The importance  of  voles  as  pest  organisms  is  well  known.  Nevertheless,  the  estimation  of financial loss caused by voles is difficult for German fruit growers. We conducted a survey among organic fruit growers to get data on kind and amount of annual damage. Using the available publications and official statistics we calculated economical values of organic apple  trees  for  different  types  of  orchard  processing  and  tree  ages.  Furthermore  we calculated the number of trees lost due to voles in one year. Keywords: survey, organic farming, pomiculture, economical loss, Germany IntroductionVole  species,  especially  the  Water  vole  (Arvicola  terrestris)  and  the  Common  vole (Microtus  arvalis)  cause  significant  damage  in  German  orchards  (Klemm  1958,  1964; Wieland, 1973; BBA, 1978). Both species gnaw on the root system or trunks of trees. The affected trees mostly die and a persistent crop failure is the consequence. In some organic apple orchards dramatic effects are reported culminating in total losses (Kopp 2002). The knowledge about frequency, distribution and the resulting economical losses caused by voles in German organic pomiculture is poor. In order to get a more precise data basis we started a survey among German organic fruit growers and compared the results with data from Statistisches Bundesamt (2003, 2004) and KTBL collection (2005). Material and Methods Our survey among German organic fruit growers asked for information about farm location and size, kind of apple cultivation, the importance of vole damage and the applied vole management.  We  focused  our  analysis  on  value  and  economical  significance  of  vole damage. The questionnaire was distributed in February 2003 by consulting services and organic farming associations among their members and also by federal crop protection agencies.  75  questionnaires  returned  until  June  2003  covering  698  ha  of  fruit  growing acreage.  This  represents  13%  of  the  nationwide  organic  fruit  cultivation  (Statistisches Bundesamt, 2004). Nevertheless, returns from the different fruit growing areas in Germany were  not  evenly  distributed.  The  majority  of  returns  came  from  the  central  and  south western parts of the country.                                                1University Münster, Institute of Landscape Ecology, Robert-Koch-Straße 26, D-48149 Münster, Germany, walther.bernd@web.de, 2University of Bern, Zoological Institute, Community Ecology, Baltzerstraße 6, CH-3012 Bern, Switzerland, olaf.fuelling@zos.unibe.ch3Topcat GmbH, 9, chemin des Grangettes, CH-1454  L’Auberson VD, Switzerland, info@topcat.ch 4 Federal Biological Research Centre for Agriculture and Forestry, Institute for Nematology and Vertebrate Research, Toppheideweg 88, D-48161 Münster, Germany, j.pelz@bba.de  ResultsVole damage in organic fruit growing is a wide spread phenomenon. 83% of the farms reported damage caused by voles in 2002. In the decade before, 95% of the farms were confronted with vole problems.Apples were the most important fruit covered by the replies to our survey. They grow on 75%  (526  ha)  of  the  surveyed  acreage.  In  2002  voles  caused  damage  in  230  ha  of pomiculture (Tab.1) representing 44%. On 17% of the farms no damage occurred although one or both vole species were present. 55% of the farmers reported a loss of up to 10 % of apple trees/ha. 19% of the farmers lost up to a fourth and 2 farmers suffered from a total loss of trees (Tab. 2). Damage occurred although the vole populations were controlled permanently. 71% of the farms could not specify the total economical losses arising from vole damage. The remaining farmers estimated losses between 50 € and 40.000 €/ha. In the category “up to 10% damaged trees/ha” the losses in 2002 varied between 50 € and 2.000 € per hectare with a mean around 1.000 €/ha (Tab. 2). Table 1: Returned surveys, covered apple acreage, and occurred vole damage.  Federal State  Number of returnedsurveysPercentageof returned surveysTotalacreageof apple (ha)Acreagewith vole damage(ha)Percentageof damagedacreage(%)Baden-Württemberg  36  48  314  140  45 Rhineland-Palatinate  12  16  72  31  43 Hesse  11  15  61  26  43 Saarland  9  12  29  6  21 Bavaria  5  7  32  15  47 Lower Saxony  1  1  3  3  100 North Rhine-Westphalia  1  1  15  9  60 Total  75  100  526  230  - Table 2: Degree of vole damage and variation of estimated total economical loss (TEL) in organic apple orchards  Damagedapple trees/ha Number of farms  Percentage of farms Range of estimated TEL (€/ha) No damage  7  9  0 Uncertain  8  10  1.000 -10%  41  55  50 - 2.000 -25%  14  19  2.600 - 15.000 -50%  3  4  20 - 40.000 -75%  0  0  no data  -100%  2  3  no data Total  75  100  50 - 40.000 Archived at http://orgprints.org/13744/332Discussion The results of our survey confirmed the results of Klemm (1958, 1964) and Wieland (1973) and showed the importance of Water voles and Common voles as vertebrate pests in German organic pomiculture. 44% of the reported acreage suffered from vole damage and in most oft the affected orchards the farmers lost up to 10% of apple trees/ha. In a survey covering the decades from 1940s to the 1980s, Gemmeke & Pelz (1987) found that the total  annual  loss  of  trees  was  between  10-20%  in  the  apple  growing  region  around Hamburg. The Federal Biological Research Center (BBA, 1978) and Gaudchau (1983) found a damage of 50% and more in conventional pomiculture caused by voles. However, damage of much more than 20% seems to be infrequent. In our survey three farmers had up  to  50%  damaged  trees  and  two  farmers  suffered  from  total  loss.  Kopp  (2002)  got similar results comparing 12 organic farms in Southern Germany. Most of these farms lost only about 1% of trees/ha but in one case 80% were damaged.Estimations of the economical value of tree losses are rare in literature. For the period from  1958  to  1963  Wieland  (1973)  gave  a  total estimation  of  6.5  Mio  Mark  losses  on territory  of  the  GDR.  According  to  Teutsch  (1979)  the  average  of  financial  losses  per hectare  was  4.610  DM  after  a  vole  peak  in  conventional  apple  orchards  around  Bad Neuenahr-Ahrweiler. In the 1990s Wieland (1997) calculated 21.55 DM as the value of a single tree damaged by voles. To get this value he took the loss of crop yield for one year and the price for a new seedling into account. Wielands  tree  value  reflects  the  calculation  farmers  have  in  their  minds.  However,  we found that the value of a tree is a function varying in time (Tab. 4). It depends on the costs of orchard plantation, orchard processing, personal costs and expected total crop yields for the  whole  period  of  orchards  usage  (Tab.  3).  Therefore,  we  started  our  calculation estimating the value for a new tree in its first year. This value based on data published in the KTBL collection (2005). An orchard of one hectare contains 3.000 apple trees and stands  for  15  years.  We  calculated  with  two  different  scenarios.  The  first  is  a  simple orchard with just trees and protection devices excluded. The second scenario, the complex orchard, uses hail-nets, irrigation, anti-freeze protection and deer fences. In both scenarios the crop yield rises for the first five years and reaches 4,63 € per tree from the 6th year of cultivation  onward.  All  costs  were  added  and  divided  by  the  number  of  apple  trees (3000/ha).  Accordingly  the  value  of  one  apple  tree  in  the  first  year  is  98  €  in  simple orchards and 117 € in complex orchards (Tab. 4). Table 3: Items for the calculation of the tree value in its first year (KTBL, 2005). The data based on a 1 ha orchard with 3.000 apple trees and a life cycle of 15 years. A simple orchard includes just trees. A complex orchard includes hail-net, freeze-protection, irrigation and deer fence.   Item  Simple orchard (€)  Complex orchard (€) Expected crop yields  165.500  165.500 Plantation costs    23.140    47.913 Processing costs    27.185    61.259 Machinery costs    10.510    10.510 Personal costs    67.028    67.028 Total  293.363  352.210 Archived at http://orgprints.org/13744/333Table  4:  Varying  value  of  apple  trees  and  total  economical  losses  during  orchard  lifetime. Examples given for the 1st, 6th and 12th year of an orchard with a total life span of 15 years.    Value of a single tree  Range of total economical losses/ha  Simple orchard  Complex orchard Simple orchard  Complex orchard1st year  98 €  117 €  2.058 - 20.188 €  2.457 - 24.102 € 6th year  72 €  81 €  1.512 - 14.832 €  1.701 - 16.686 € 12th year  29 €  31 €  609 - 5.974 €  651 - 6.386 € According to Kopp (2002) the usual damage of trees per hectare in an orchard is around 1%. Farmers participating in our survey choose at most the category “up to 10% trees/ha damaged”.  This  indicates  that  an  annual  damage  between  1  and  10%  is  common  in German organic pomiculture. Our calculation of tree values based on the number of 3.000 trees per hectare. This is the number of trees usually planted in a today’s orchards. In the nationwide survey “Baumobstanbauerhebung 2002” (Statistisches Bundesamt, 2003) the average number of apple trees per hectare is 2.058. The difference of almost 1.000 trees appears because the “Baumobstanbauerhebung 2002” includes orchards of different ages, structures and degrees of damage. Given an actual number of 2.058 trees/ha and 1 to 10% of damaged trees per year, farmers have to face a loss of 21 to 206 trees/ha each year. In simple orchards the resulting total economical loss is between 2.058 € and 20.188 €/ha in the first year and 609 € and 5.974 € in the 12th year. For complex orchards the losses are 2.457 € to 24.102 € in the first and 651 € to 6.386 € in year twelve (Tab. 4). Our calculated losses per hectare would allow an estimation of the economical importance of voles in organic pomiculture of Germany. However, there is no statistic available that gives  the  acreage  of  organic  pomiculture.  According  to  the  German  wide  survey “Agrarstrukturerhebung  2003”  (Statistisches  Bundesamt  2004)  a  total  of  5.407  ha  is cultivated with organic fruits. Among organic fruit growers in our survey 75% of the total acreage  were  cultivated  with  apples.  Assuming  that  this  is  a  plausible  ratio  for  whole Germany, 4.055 ha should be organic apple orchards. Taking the fraction of 44% from our survey, in 2002 a total of 1.784 ha was affected by voles. With an average of 2.058 trees per hectare and 1 to 10% of the trees lost due to vole damage, 36.715 to 367.147 organic apple trees were destroyed by voles in one year.  There is no doubt that the annual economical losses caused by voles count into millions of Euros. Unfortunately, it is impossible to calculate the exact yearly economical losses due to tree values varying with the age and kind of cultivation and the number of damaged trees ranging from 1 to 10%. We conclude that due to the difficulties of calculation farmers, consultants and officials often  underestimate  the  value  of  a  single  organic  apple  tree  and  consequently  the economical losses caused by voles. A modern ecological and economical management of vole populations is essential. Acknowledgements We  are  grateful  to  all  participants  of  the  survey  and  also  to  the  “Fördergemeinschaft Ökologischer  Obstbau  e.V.,  “Beratungsdienst  Ökologischer  Obstbau  e.V.”  and  �Öko-Obstbau Norddeutschland Versuchs- und Beratungsring e.V.“. The work was funded by the Federal Ministry of Food, Agriculture and Consumer Protection and the Federal Office for Agriculture and Food (Bundesprogramm Ökologischer Landbau, project 02OE108). Archived at http://orgprints.org/13744/334References BBA (1978). Erhebung über die von Säugetieren und Vögeln in der Bundesrepublik Deutschland an Kulturpflanzen verursachten Schäden. Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft 186: 144 pp. Gaudchau, M.-D. (1983). Die Schermaus und ihre Bekämpfung. Stuttgart: Eugen Ulmer Verlag  Gemmeke, H., Pelz, H.-J. (1987). Ergebnisse des Forschungsvorhabens “Wühlmausbekämpfung in Obstanlagen. Nachrichtenblatt des Deutschen  Pflanzenschutzdienstes 39: 65-70. Klemm, M. (1958). Die Große Wühlmaus (Arvicola terrestris L.) – Verbreitung, Schadgebiete und Auftreten in Deutschland. Nachrichtenblatt für den Deutschen Pflanzenschutzdienst 1: 1-19 Klemm, M. (1964). Beitrag zur Kenntnis des Auftretens der Feldmaus (Microtus arvalis Pall.) in Deutschland in den Jahren 1928-1941. Zeitschrift für angewandte Zoologie 51: 419-49 Kopp, B. (2002). Wühlmausprobleme unter den Rahmenbedingungen des ökologischen Landbaus (Schwerpunkt  Obstbau).  Berichte  aus  der  Biologischen  Bundesanstalt  für  Land-  und Forstwirtschaft 104: 6-9 KTBL (2005). Daten für den Ökologischen Obstbau in der Landwirtschaft. Darmstadt: Kuratorium für Technik und Bauwesen in der Landwirtschaft e.V.  Teutsch,  H.  (1979).  Ermittlung  von  Schäden  durch  Wühlmäuse  in  Apfelerwerbsanlagen. Mitteilungen der Biologischen Bundesanstalt für Land- und Forstwirtschaft 191: 218 Statistisches Bundesamt (2003). Baumobstanbauerhebung 2002. Wiesbaden Statistisches Bundesamt (2004). Agrarstrukturerhebung 2003. Wiesbaden Wieland,  H.  (1973).  Probleme  und  Möglichkeiten  der  Bekämpfung  der  Großen  Wühlmaus (Arvicolaterrestris L.). Nachrichtenblatt für den Pflanzenschutzdienst in der DDR 1:19-21. Wieland, H. (1997). Untersuchungen zur Migration der Feldmaus (Microtus arvalis PALL.) und ihrer Auswirkungen auf dei Fluktuation im Rahmen einer veränderten Agrarstruktur zur Ableitung von  Strategien  einer  integrierten  Schadensabwehr. Abschlussbericht  Forschungsauftrag 93HS021. Bonn: Bundesministerium für Ernährung Landwirtschaft und Forsten.  Archived at http://orgprints.org/13744/

How expensive is vole damage?

Abstract

Similar works

Full text

Available Versions

Organic Eprints