International Soft Fruit Conference s Hertogenbosch 11.01.2018 Tracking the blackberry mite (Acalitus essigi) Phenological observations and control Matthias Bernhart Landratsamt Ortenaukreis Amt für Landwirtschaft Prinz-Eugen-Str. 2 77652 Offenburg Tel.: 0781-805 7106 Fax: 0781-805 7200 matthias.bernhart@ortenaukreis.de 15.01.2018 1
Ortenau district fruit production Southwest of Germany Rhine valley and black forest (150-500 m) One of the warmest regions in Germany (9,8 C average temperature, 500-1.000 mm precipitation) 4500 ha fruit production, most in open field: pomefruit, stonefruit and soft fruits
Introduction: Blackberry gallmites in Ortenau district Every year blackberry growers find fruits with symptoms, which could be origin from mites. On such fruits we could not find mites (Microscopic observation). 2014: heavy damages on Loch Ness,, cultivated in a glasshouse => frequent applications with Vertimec short effect 2015: only some sites with damage; in autumn 2015 control of canes origin from different blackberry sites:discovery of lots of mites behind the basic flakes of new buds on different varieties: Loch Ness & Loch Tay in the field and glasshouse Chester from open field 15.01.2018 3
2016: More exact examinations Glasshouse plantation Loch Ness Microscopical observation of buds and lateral shoots (interval of 1 week/ 3 weeks): presence of mites Field test: effect of sulphur applications on the blackberry mites 15.01.2018 4
15.01.2018 5
Microscopical observation of buds LANDRATSAMT ORTENAUKREIS 15.01.2018 6
Autumn 2015: control of buds (11.09.2015) House 2 left and right side Ø mites alive/ bud Ø mites dead/ bud H2li (n=20 buds) 2 4 H2re (n=18 buds) 4 0 Spring 2016: first control of buds (23.02.2016) House 2 left and right side Ø mites alive/ bud Ø mites dead/ bud H2li (n=20 buds) 2 4 H2re (n=18 buds) 4 0 Some canes with high numbers of mites/ bud: 25-50 mites/ bud 15.01.2018 7
Observation on base and in the axils of lateral shoots Bilder: Bernhart Bild vom 03.05.16 Bild vom 17.03.16 15.01.2018 8
date LANDRATSAMT ORTENAUKREIS 2016: observation of lateral shoots average number Mites/ bud 23.02.16 4 Oviposition on a few buds 01.03.16 5 Mites behind basic flakes 08.03.16 ~ 10 Mites behind basic flakes 17.03.16 ~ 25 Mites behind basic flakes 23.03.16 ~ 50 Movement to the axils 01.04.16 ~ 70 increasing oviposition 15.01.2018 Bild vom 17.03.16 9
Observation of lateral shoots: average LANDRATSAMT number ORTENAUKREIS of mites 08.04.16 N= 6 / 15.04.16 N= 6 / 03.05.16 N= 3 / base untreated 275 460 117 0 27.05.16 N= 3 / 1. leaf/ axil untreated 25 65 3 0 2. leaf / axil untreated 62 41 15 0 3. leaf/ axil untreated 22 75 12 0-20 tot 4. leaf/ axil untreated 7 25 155 0-20 tot Blossoms/ flowers untreated 0 0 0 0-5 tot oviposition untreated Strong on base On base and in axils strong in 4. axil no 15.01.2018 10
Is there an effect of sulphur applications on gallmites? Test in the glasshouse 1. application on 10.03. with 7 kg/ ha Kumulus WG 2. application on 26.03. with 4 kg/ ha Kumulus WG Control of the evolution of the mite population on treated plants compared to untreated 15.01.2018 11
Observation of lateral shoots: average LANDRATSAMT number ORTENAUKREIS of mites Position of the bud Variante 08.04.16 N= 6 / 10 15.04.16 N= 6 / 2 03.05.16 N= 3 / 9 27.05.16 N= 3 / 2 Base untreated 275 460 117 0 sulphur 44 50 38 0 1. leaf untreated 25 65 3 0 sulphur 0 0 1 0 2. leaf untreated 62 41 15 0 sulphur 0 2,5 0 0-30 tot 3. leaf untreated 22 75 12 0-20 tot sulphur 0,5 0 6 0-20 tot 4. leaf untreated 7 25 155 0-20 tot sulphur 0,5 0 16 10-30 tot flowers untreated 0 0 0 0-5 tot sulphur 0 0 63 0 oviposition untreated Strong on base On base + axils strong in 4. axil none sulphur a few on base a few on base none None 15.01.2018 12 Grünberg - Beerenobstberater 2016
15.01.2018 13 Bilder: Beuschlein vom 18.03.16
Bild: Bernhart Bild: Pfundstein, vom 02.03.16 08.04.16 15.01.2018 14
15.01.2018 15
Symptoms on Chester in begin of September Bilder: Bernhart (1), Beuschlein (2) 15.01.2018 16
Bilder: Beuschlein 15.01.2018 17
Conclusion Blackberrymites occur often in the blackberry production in the Ortenau region in open field and glasshouse production Blackberry mites live covert in axils or behind flakes of buds Symptoms described in literature as origin from Acalitus essigi can be confirmed Glasshouse production: 2 applications of sulphur within two weeks can stop the evolution of blackberrymites up to six weeks There were no phytotoxical reaction after the application of sulphur in the glasshouse production in 2016 (cloudy weather) The effect of sulphur applications in the open field must not be the same as in the glasshouse sulphur may be washed away by rain 2017: large field trial to check the efficacy of different acaricides no symptoms, too little numbers of mites during the growth period 15.01.2018 18
Thank you for your attention!