Caraway (Carum carvi) seeds contain biologically active essential oils, which have shown potential in controlling Phytophthora infestans (P.i.). An attempt is being made to develop a P.i. control strategy for organic farming based on caraway oil

Fabritius, A.-L.

Hakala, K.

Hannukkala, A.

Keskitalo, M.

Ketoja, E.

Lehtinen, A.

Mikkonen, P.

Vuorema, A.

English

Organic Eprints

Nordic Associationof Agricultural ScientistsNJF Report • Vol. 1 • No 1 • 2005NJF-Seminar 369Organic farming for a new millennium-status and future challengesReport_vol1_no1_2005  02.06.05  10:06  Side 1Published by Nordic Association of Agricultural Scientists (NJF),Section I: Soil, Water and Environment Swedish University of Agricultural Sciences Alnarp, Sweden June 15-17, 2005Electronic version available at www.njf.nuISSN 1653-2015      We are grateful for financial support to the seminar from these sponsors!  Control of potato late blight by caraway oil in organic farming  M.Keskitalo1, A-L.Fabritius2, K.Hakala1, A.Hannukkala1, E.Ketoja3, A.Lehtinen1, P.Mikkonen1 and A.Vuorema1 1MTT Agrifood Research Finland, Plant Production Research, 31600 Jokioinen, Finland 2 University of Helsinki, Department of Applied Biology, Plant Pathology, P.O. Box 27, 00014 Helsinki, Finland 3MTT Agrifood Research Finland, Research Services, 31600 Jokioinen, Finland  Abstract  One of the most severe threats to organic potato production in Finland is potato late blight (Phytophthora infestans, P.i.), because there are currently no compounds available for its direct control. Caraway (Carum carvi) seeds contain biologically active essential oils, which have shown potential in controlling P.i. An attempt is being made to develop a P.i. control strategy for organic farming based on caraway oil. In addition, knowledge is sought on the interactions among the essential oil-based anti-fungal agents, the plants sprayed with them and the P.i. pathogen. The economic feasibility of controlling P.i. with caraway oil will be also surveyed. Caraway essential oil delayed the onset of P.i. for about 10-14 days under field conditions. The efficacy of the oil is based on the prevention of P.i. spore production and growth already at a low oil concentration. In contrast to previous findings, caraway oil had some systemic effect on potato plants. Formulation decreased volatilisation of the caraway oil and changed its adhesiveness to spores, but efficacy against P.i.  was not improved in greenhouse tests.  Keywords: plant protection, Phytophthora infestans, potato growth, caraway essential oil, carvone  Introduction  A new sexually reproducing potato late blight (Phytophthora infestans, P.i.) population characterised by early oospore-derived epidemics is one of the most severe threats to organic potato production (Fry et al, 1993; Lehtinen & Hannukkala, 2004). The first symptoms of the new P.i. are apparent in the field about one month earlier than was the case ten years ago. Currently control is based on crop management practices that delay the onset of epidemics. These include methods such as: using only healthy seed, implementing crop rotation, taking care of sanitation during composting (Zwankhuizen et al, 1998), increased aeration in potato stands by wider row spacing (Karalus 1998; Glass et al, 2001) and favouring varieties with early tuber formation capacity and reasonable tolerance to leaf and tuber blight (Karalus & Rauber, 1997). However, blight management based on cultural practices alone results in considerable yield losses even under a moderate disease pressure. In Finland there are no compounds available for direct blight control in organic production.  Different plant and compost extracts have been studied for their efficacy against foliar pathogens of vegetables and ornamental plants, including P.i. on tomato and potato. The overall results of these studies have been variable but on several occasions a reasonable delay in onset of a blight epidemic has been achieved, resulting in higher yield compared with an untreated crop (Jackel et al, 1995; Schmitt, 1996; Blaeser et al, 1999). One of the successful examples is crude steam distillate from the herb, Ocimum gratissimum on the pathogen Phytophthora palmivora on cocoa pods (Awuah, 1994). 77 Caraway products are used as sprouting inhibitors, and they also considerably reduce losses caused by storage fungi (Bång, 1995a, 1995b, 1999). However, very limited published data on the efficacy of caraway oil based extracts against P.i. are available.  The aim of the research is to develop a P.i. control strategy for organic farming based on caraway oil. We also want to obtain knowledge about the interactions among the essential oil-based anti-fungal agents, the plants sprayed with them and the P.i. pathogen.  Materials and methods  The research includes several experiments started in 2000, some of which are still continuing. During the initial stage laboratory, greenhouse and field experiments were carried out to study the effects of caraway oil on P.i. Possibilities for different oil extraction methods were also investigated. The aims of the second stage of the research were to improve the efficacy of caraway oil through oil formulation, and to reveal its mode of action on the pathogen and potato plant.  Results and discussion  Caraway essential oil delayed the onset of late blight for about 10-14 days under field conditions (Hannukkala et al, 2002; Keskitalo, 2002). The control activity of the oil is based on the prevention of late blight sporangia production and growth already at a low oil concentration. In contrast to previous findings, caraway oil had some systemic effect on potato plants. Formulation decreased volatilisation of the caraway oil and changed its adhesiveness to spores, but efficacy against P.i. was not improved in greenhouse tests.  Conclusions  It is possible to delay the onset of P.i. for 14 days by using caraway oil. The aims of the ongoing studies are to find ways to delay it further. This improves the economic feasibility to control  P.i. with caraway oil. Use of caraway oil in combination with other plant-based extracts is being studied.  References  Awuah, R.T. (1994). In vivo use of extract from Ocimum gratissimum and Cymbopogon   citratus against Phytophthora palmivora causing blackpod disease of cocoa. Annales   Applied Biology 124: 173-178.   Blaser, P., Steiner, U., Lyr, H., Russel, P.E., Dehne, H.W. and Sisler, H.D. (1999). Antifungal   activity of plant extracts against potato late blight (Phytophthora infestans). Modern   fungicides and antifungal compounds II Friedrichroda, Thuringia, Germany 24th-29th   May 1998. 491-499pp. Bång, U. (1995a). Natural plant extracts – control of fungal pathogens of potato.   Proceedings of the Swedish crop protection conference: Svenska   Växtskyddskonferencen: Jordbruk Skadedjur, växtsjukdomar och ogräs. 371-381pp. Bång, U. (1995b). Essential oils as fungicides and sprout inhibitors in potatoes. Proceedings   of the EAPR pathology section meeting "Phytophthora infestans 150", Dublin, Sept 10-  16 1995. Eds Dowley, L. J., E. Bannon, L. Cooke, T. Keane & E. O´Sullivan, 318- 324pp. 78Bång, U. (1999). Control of seed borne pathogens by natural volatile substances. Abstracts of   the EAPR 14th triennial conference, Sorrento, Italy, 2-7 May 1999. Fry, W.E., Goodwin, S.B., Dyer, T.T., Matuszak, J.M., Drenth, A., Tooley, P.W., Sujkowsk,   L.S., Koh, Y.J., Cohen, B.A., Spielman, L.J., Deahl, K.L., Inglis, D.A. and Sadlan, K.P.   (1993). Historical and recent migrations of Phytophthora infestans: Chronology,   pathways and implications. Plant Disease 77, 653-661. Glass, J.R, Johnson, K.B. and Powelson, M.L. (2001). Assessment of barriers to prevent the   development of potato tuber blight caused by Phytophthora infestans. Plant Disease 85:  521-528. Hannukkala, A., Keskitalo, M., Laamanen, J and Rastas, M. (2002). Control of potato late   blight with Caraway and Dill extracts. In: H.T.A.M. Schepers and C.E. Westerdijk,   editors. Proceedings of the sixth workshop of a European network for development of   an integrated control strategy of potato late blight. Edinburgh, Scotland, 26-30   September 2001. PPO-special report 8: 279-280. Jackel, B., Schmidt, H.U. and Lemke, K. (1995). Plant strengtheners - possibilities and   limitations for the application in the hobby garden. I. Efficacy against phytopathogenic   fungi. Gesunde Pflanzen 47: 15-22. Karalus, W. (1998) Effect of plant density on diseases of potatoes in organic farming.   Gesunde Pflanzen 50: 97-100. Karalus, W. and Rauber, R. (1997) Effect of presprouting on yield of maincrop potatoes   (Solanum tuberosum L.) in organic farming. Journal of Agronomy and Crop Science  179:  241-249. Keskitalo, M. (2002). Production and composition of antimicrobial extracts from caraway.   Abstract book, 5th European Symposium Industrial Crops and Products, 24-26.4 2002   Amsterdam, the Netherlands, 95p. Lehtinen, A. and Hannukkala, A. (2004). Oospores of Phytophthora infestans in soil provide   an important new source of primary inoculum in Finland. Agricultural and Food   Science 13:000-000 (in press). Schmitt, A. (1996). Plant extracts as pest and disease control agents. Atti convegno   internazionale: Coltivazione e miglioramento di piante officinale, Trento, Italy 23   giugno 1994. 265-272pp. Zwankhuizen, M.J. (1998). Potato late blight epidemics and population structure of   Phytophthora infestans. 1998. 147pp.  Acknowledgements  These projects are funded by the Finnish Ministry of Agriculture and Forestry.      79

Control of potato late blight by caraway oil in organic farming

Control of potato late blight by caraway oil in organic farming

Abstract

Similar works

Full text

Available Versions

Organic Eprints