Ontogenetical resistance of grapes - a chance to reduce fungicide residues in wines?

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1 Ontogenetical resistance of grapes - a chance to reduce fungicide residues in wines? Karl Bleyer and Walter K. Kast Weinsberg/Germany IOCB/OILB Meeting of Working Group Integrated Protection and Production in Viticulture October 2013 Ascona, Switzerland Staatliche Lehr- und Versuchsanstalt für Wein- und Obstbau Weinsberg

2 Residue limits regulation (EG VO 149/2008) Maximum limits at fruit and grapes: 2-5 mg/kg (depending on the active substance) - also applies to must and wine No problem if the rules for the last spraying are observed!! in comparison with other products, residues in grapes and in wine are very low

3 Pesticide residues in wines in Germany Image of wines with residues is poorly made from magazines even if they are extremely low Newspapers get the information by PAN (Pesticide Action Network) In the wine region Baden-Wuerttemberg about 60% of the wines are sold by supermarkets Supermarket chains analyze residues to beat down the price The cooperative vineries and their vine growers are under considerable strain to produce grapes with very low pesticide residues

4 Powdery Mildew: Ontogenetic Resistance of Grape Clusters Kast, Stark-Urnau; 1999 severity grapes % Trollinger Lemberger

5 Open window period (OWP) for initial infections of powdery mildew at grapes Same period is also important for infections of downy mildew at grapes

6 10 years trials only by spraying into open window period (OWP) Result of field trials - Cabernet Dorsa % severity grapes untreated Standard-OiDiag 3x powdery mildew Standard-OiDiag 3 x w indow window 1. Sulfur 2. Vivando (Metrafenone) Vivando 3. Cabrio Top (Pyraclostrobin) Cabrio Top OWP 4. Talendo (Proquinazid) Talendo 5. Vento Pow er 6. Systhane 7. Systhane

7 Downy mildew grapes get ontogenetically resistant when berries are like peas Needs stomata for infection process The stomata loose their function if the berries reach pea-size Only a few stomata on rachis are left These are mainly infected by high spore numbers from upper parts

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10 Residues of active substances in wines Trial - Botrytis, W. Riesling, 2009 Switch (Cyprodinil, Fludioxonil), Cantus (Boscalid) wine (mg/kg) must (mg/kg) Cyprodinil Fludioxonil Boscalid Cyprodinil Fludioxonil Boscalid 03. july < 0,01 < 0, Switch before bc Cyprodinil, Fludioxonil, Boscalid Switch before bc Cyprodinil, Fludioxonil, Boscalid plus Cantus last spray Cyprodinil, Fludioxonil, Boscalid - - 0, plus Cantus last spray Cyprodinil, Fludioxonil, Boscalid - - 0, plus Cantus late Cyprodinil, Fludioxonil, Boscalid - - 0, plus Cantus late Cyprodinil, Fludioxonil, Boscalid - - 0, aug. < 0,01 0,04 < 0, aug. - 0,07 increase maximum amount VO (EG) Nr. 396/2005 detectation limit not detectable 5 mg/kg 0.01 mg/kg n.d.

11 Downy mildew experiment 2010 an example Residues of Folpet on grapes*) *)No residues detected in wine Folpan 80 WDG Folpan 80 WDG 7 sprays at grapes; last BBCH 79 Folpan 80 WDG, last spray upper part only (not on grapes) Folpan 80 WDG, last spray upper 6 part sprays only at grapes; (not last on BBCH grapes) 77 Folpan 80 WDG, last two sprays upper part only (not on grapes) Folpan 80 WDG, last two 5 sprays sprays at grapes; upper last part BBCH only 73-75(not on grapes) 0.06 mg/kg 0.12 mg/kg n.d. n.d. n.d. n.d. maximum amount VO (EG) Nr. 396/2005 detectation limit not detectable 5 mg/kg 0.01 mg/kg n.d.

12 Powdery mildew 2010 an example Residues of Myclobutanil and Quinoxifen on grapes*) Cabernet Dorsa; 2 replications *)No residues detected in wine Myclobutanil Quinoxyfen OiDiag - Standard 0.02mg/kg n.d. OiDiag - Standard 0.01mg/kg n.d. OiDiag, last spray upper part only (not in grapes) n.d. n.d. OiDiag, last spray upper part only (not in grapes) n.d. n.d. 1. Sulfur 2. Metrafenone activ substances 3. Pyraclostrobin 4. Proquinazid 5. Myclobutanil + Quinoxifen 6. Myclobutanil 7. Myclobutanil maximum amount VO (EG) Nr. 396/2005 (Myclobutanil) detectation limit not detectable 1 mg/kg 0.01 mg/kg n.d.

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14 Downy mildew leaves Example 2010 Riesling, Ranzenberg incidence severity untreated Folpet Folpet-last spray not on grapes Folpet-two last sprays not on grapes

15 Downy mildew grapes Example 2010 Riesling, Ranzenberg incidence severity untreated Folpet Folpet-last spray not on grapes Folpet-two last sprays not on grapes

16 Powdery mildew grapes Example 2009 Cabernet Dorsa incidence severity untreated OiDiag Spraying OiDiag-last spray not on grapes OiDiag-two last sprays not on grapes

17 Powdery mildew grapes Example 2012 Cabernet Dorsa incidence severity LSD 5%: 6, untreated OiDiag Spraying OiDiag-last spray not on grapes 5.6

18 Results and Conclusions In wine the residues which were found are very low (lower than 1% of the maximum limit of grapes) Spraying not into the grape zone the last or two last sprayings reduce residues in grapes and the persistent active substances in must and wine We suggest only to treat the canopy above the grapes for Downy mildew: last or two last sprayings are no problem for Powdery mildew: it is only possible if there are no previous infections

19 Thanks to all colleagues and for your Attention