TIL GAVN FOR GARTNERE

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1 1 Red core in strawberry Agenda GartneriRådgivningen (HortiAdvice Scandinavia) A/S Who are we? Brief introduction to production of strawberries in Danmark Acreage, status, planting systems Main strawberry varieties used in DK What are our main problems regarding diseases and what to do about it? Plant quality Soil quality Red core/red stele in strawberry in Denmark Preventive actions Curative actions Whoam I and whoarewe? OLE H. SCHARFF Adviser since 18 years: Strawberries and Vegetables (cabbage and lettuce) Our team in GartneriRådgivningen, HortiAdvice A/S: 6 advisers on vegetables, 2 on strawberries 3 Danish production historically 20 years ago: ha with strawberry for processing (Senga Sengana!) After 1990 no production for processing! Today: 1000 ha with strawberry including 5 % organic production Stable acreage, but depending on prices on cereals! Trend: Production in tunnels (with or without substrate) and greenhouse now > 50 ha and still growing 1

2 Production systems Denmark Flat fields without raised beds Still dominating, > 90 % of total acreage plants per ha. Almost all plants are Frigo A Typically 2 or 3 years of picking per plant Raised beds with plastic Slowly growing in acreage Mainly on soils of clay Table Top with or without protection Substrate, peat or coir Trendy Normal culture Raised beds before covering with black plastic 6 Photo: Nauja L. Jensen 2

3 7 Table Top Varieties in Denmark, retail Harvest Early Middle Late Main variety Honeoye Rumba? Flair? (Elsanta) Sonata Florence Malwina? 9 Photo: Bodil Damgaard Petersen 3

4 Diseases in DK in order of priority Verticillium wilt 2. Crown rot 3. Black root rot 4. Rhizoctonia solani 5. Red core 6. Antracnose 11 Status of Red core in Denmark Historically: First time recorded in Denmark 1988, around the introduction of frigoplants from abroad Current situation (My feeling or guess): % of fields with visible red core Latent infections could be much more widespread As far as I know Nobody gone bankrupt nor given up production - because of red core We seem to have learned to live with red core! 12 What triggers Red core Planting out infested plants of course the main source Bad crop rotation (cykles with strawberries after strawberries) Wet conditions (low oxygen) Temperatures in soil beneath 15 C, optimum for disease development C The case for long periods in our climates! 4

5 Photo: Bodil Damgaard Petersen 13 Strawberry Fields Forever 14 Once Red core in your field: It will last forever Maybe a little exaggerated!!! But nevertheless it can stay in the field for at least years Experienced strawberry growers always say to me: NEVER strawberries on a field with strawberry before!!!!!! 15 Root diseases from plants or soil? Good question We can t answer.. Anthracnose Fruit Rot, Colletotrichum acutum Mainly from plants, but can last in the fields in debris or latent on weeds Phytophthora fragraria, Red core (Red stele disease) Introduced with plants, but stays in the soil Phytophthora cactorum, Crown rot (Leather rot), especially Sonata very susceptible Often spread by plant material, but will survive some years in infested soil Verticillium wilt, Visnesyge 50/50 from plants or in soil???? Strawberry black root rot? Complex of more fungi (Rhizoctonia spp., Pythium spp., and Fusarium spp) From soils or plants? Triggered by plant stress and waterlogged soil? 5

6 Remember! Check out your plants Contract, deal Make a deal on how the plants must be delivered, grading of plants and so on Save your plant passport and delivery documents for every lot and variety Look for the little sign on the boxes Some danish growers visit their plants in the soil by the propagator! A matter of trust! Foto: Nauja L. Jensen Complain immidiately! Photos for documentation or pathological test 16 Check out your plants 17 When you receive the frigo plants they must: be cold and slightly frozen But not icecubes (since plants can t stand temperatures below 5 C) be without new, white root tips Vitality is going down smell like fresh forest soil be without fungus mold Indicates alternating temperature during transport be without black, rotten or rat tail roots have totally white crowns inside, (and without red steles in the roots!) always cut a few plants from different bundles 18 Photo: Bodil Damgaard Petersen 6

7 19 How to avoid Red core Soil quality Avoid waterlogged areas Avoid hilly and sloping fields if possible Soil preparation Gentle soil handling, avoid compaction Planting in the right depth Timing of soil handling, better wait for right conditions Raised beds on plastic better drainage and soil not compact creating an environment less favorable for the fungi 20 How to avoid Red core, 2 Proper hygiene Dipping or drenching with Aliette and/or phosphite (e.g. Resistim) Think about your transport, if possible always start in the new planted fields or fields without visible symptoms Rødmarv kan smitte via overfladestrømmende vand ned ad bakke, men smitter nærmest ikke op ad bakke. Vand er en kardinalfaktor for spredning og sygdomsopformering Only to a small degree spread by machinery, boots etc. Spoil the plants! max 8 days of storage at 1 C after reception, refreezing avoid stressing of plants before planting ( sun and wind before plantning out) don t give excess water for the first irrigations (and not the next either ) Are new growing systems the solution? 21 7

8 22 What do they do elsewhere? Norway: Excluding plant material from abroad Quite efficient, but makes intro of new varieties difficult Germany: Same as Denmark, but apparently some use of Perlka, (Kalkstickstoff) as a sanitary action Holland/UK: Renewing plants after one picking! Or chemical control by use of Fenomenal, Aliette, Ridomil, Revus etc. 23 Aliette WG 80, fosetyl-al Systemic compound taken up by the roots as well as the leaves mode of action not really known! Approved in most countries incl. Denmark with 4 kg/ha Band application optimal especially in the start of the culture (also to save money..) Can control the disease, but maybe 2-3 treatments a year (spring and autumn) Also applied by dipping plants into a 0,25 % solution Can be combined with phosphite products No resistance known yet! metalaxyl is known to cause resistant strains of fungi. 24 Phosphite? Quote from the label: Is not a fungicide but an alternative to fungicides against phytophthora and downy mildew (phycomycetous disease). It does not itself kill the fungus but induces the production of natural phytoalexins Many trade names: Resistim, Hortiphyte, Micodux etc. 8

9 What have we done to prevent spreading the disease? 25 Earlier on some control with imported plants quarantine rejection if Tried to keep good crop rotation Tried to prevent planting in waterlogged fields Used a standard fungicide treatment either before planting or after planting Taken out infested areas if very bad attack growing grass for some years not touching the soil 26 New test, Real time PCR Known PCR teknology based on plant DNA Next generation sequencing or pyrosequencing 2012: GartneriRådg. and the University of Aarhus are developing a test for identifiing diseases in soils for strawberry and vegetable production Target species in strawberries Verticillium dahliae /albo-atrum, Phytophthora cactorum & P. fragariae, Red core 27 New test, Real time PCR This technology will be able to identify all fungi and nematodes quantify the attack establish thresholds And is expected to be quite cheap and very fast The aim: to offer the growers a commerciel soil testing method BUT, Why not test new plants the same way????????? Dutch DNA based test already available with answer within 4 days 9

10 28 Wake up, please Thank you for your attention 10