Epidemiological aspects and control of Powdery scab Leah Tsror (Lahkim) Agricultural Research Organization (ARO, Volcani) Gilat Research Center EAPR Pathology & Pests Section Meeting, 2016, Dundee, UK
Overview Background potato and the disease in hot-climate Pathogen transmission\inoculum bank seed tubers monitoring, regulation soil infestation aerial dispersal weeds/rotational crop Disease management resistant/tolerant cultivars manipulation of planting date monitoring soil and seed soil/seed treatments
Evap Temp. Potato Production in Israel Evap T.max T.min North-West Negev 7.0 40 6.0 5.0 4.0 3.0 2.0 35 30 25 20 15 10 annual rain fall 30-300 mm; (Nov-Mar); avg max temp. 30 C; evaporation 5-8 mm/day poor soils - <0.5% organic matter 1.0 5 0.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month
Potato Production in Israel Powdery Scab Occurrence in IL Imported seed Export Local market processing 6% 44% First reported in IL in 1984 Since 2005, PS significantly increased due to phase out of Methyl bromide, intensification of potato production, use of susceptible cvs., neglecting prevention measures. Prevalent in sandy, loess and terra-rosa soils. 50% [PER CENT AGE] 33% EU UK Estern Europe 59% Causes economic damage by downgrading tuber quality rejectin contaminated seed lots for the winter season
Powdery scab and root gall symptoms
Monitoring seed borne inoculum in imported lots Sample of 200 tubers/lot Black dot Silver scurf Black scurf Powdery scab IL permit for powdery scab : 1% of the tubers <1/8 of surface; zero tolerance to cankerous form
Soil borne inoculum Disease incidence (%) Field infestation with PS 90 80 70 60 50 40 30 20 10 0 # commercial potato plots infested sand loess sand loess sand loess sand loess 2012 2013 2014 2015 0 0.1-10 >10 Survey Soil samples taken from commercial potato plots W-shape sampling; 30 cm depth; 1kg/ha 200 gr soil grinding and sieving; DNA extraction using Gene MATRIX Soil DNA Purification Kit (0.25 grx2) Analysis of 2 reps by TaqMan RT-PCR (Lees et al, 2003) 100 80 60 40 % PS-infested plots 100 50 Disease incidence (%) 2012 20 0 sand loess sand loess sand loess sand loess 2012 2013 2014 2015 0.1-10 >10 0 2012 61 דגימות 2013 140 דגימות 1E-3 0.01 0.1 1 Soil inoculation (ng DNA/gr Soil) 50 plots (commercial farms); Pearson's r =0.50657
Dispersal of Spongospora sporosori by wind?
Dispersal by wind 14.2.2014-6.4.14 נווה - 8-9 חלקת ניסוי חיטוי 2013 31.12.13-9.1.14 נווה 5 )חלקה נגועה(
Dispersal by wind Spatial distribution of PS Ground traps, 0.5 km from infested field Wind traps, 0.5 from infested field
Dispersal by wind Presence of Spongospora in traps
Host range of Spongospora subterranea in IL weeds and rotational crops Shikma, plot 185; high soil-inoculum Spontaneous/natural infections Sampling of plants in infested plots located in the Negev (based on history of crops and soil testing) weeds (217 plants) rotational crops (38 plants) potato volunteers (13 plants)
Host range of Spongospora subterranea in IL Artificial inoculation Weeds typical to the region of potato production in Negev ; seeds were obtained from the Israeli Gene Bank, Faculty of Agriculture & weed research lab@aro Crops rotated with potato Wheat (3 cvs), barley (2 cvs), oat (2 cvs), peanut, carrot, radish, onion, lucerne, Inoculation of seedlings with sporosori [in Hogland solution or in pots (soil+peat+vermiculite)] - first 2 weeks at 15C, then 21C. Testing at 14, 30, 90 dai.
Host range of Spongospora subterranea in IL Methodology Plant roots were surface sterilized and cut for: 1: staining & microscopic observation 2: freeze dried, ground in liquid nitrogen, stored -20C Total DNA of each root (0.03gr dried tissue) was extracted using MasterPure TM Yeast DNA Purification Kit, RT-PCR analysis (van de Graaf et al. 2003)
Spontaneous infections of weeds and rotational crops Out of 49 weed species (from 18 families) 18 are positive in RT-PCR testing; in microscopic testing, so far, only 7 positive Family Scientific name % infec. Amaranthaceae Amaranthus albus 57% (4/7) Asteraceae Verbesina encelioides 67% (2/3) Brassicaceae Diplotaxis erucoides 100% (5/5) Brassicaceae Brassica tournefortii 67% (6/9) Brassicaceae Matthiola longipetala 67% (2/3) Chenopodiaceae Chenopodium murale 93% (14/15) Chenopodiaceae Chenopodium opulifolium 100% (5/5) Chenopodiaceae Salsola soda 100% (1/1) Fabaceae Medicago radiata 100% (1/1) Solanum nigrum Solanum elaeagnifolium Fabaceae Astragalus hauraensis 50% (1/2) Malvaceae Malvella sherardiana 17% (1/6) Poaceae Rostaria cristata 100% (1/1) Poaceae Phalaris minor 25% (1/4) Poaceae Cynodon dactylon 29% (2/7) Ranunculaceae Adonis dentata 50% (1/2) Matthiola longipetala Brassica tournefortii Solanaceae Solanum elaeagnifolium 50% (1/2) Solanaceae Solanum nigrum 88% (7/8) Zygophyllaceae Tribulus terrestris 100% (1/1) Poaceae Triticum aestivum 40% (12/30) Poaceae Hordeum vulgare 25% (2/8) Solanaceae Solanum tuberosum 77% (10/13) Phalaris minor Astragalus hauraensis Medicago radiata
Artificial inoculation of weeds and rotational crops Rotational crops: out of 10 species (from 6 families) 6 were positive in RT-PCR testing: wheat, radish, oat, barley, tomato, potato Weeds: out of 14 species (from 7 families) 6 positive. Microscopic testing is on-going Family Scientific name Poaceae Setaria verticillata 33% (2/6) Poaceae Phalaris paradoxa 22% (2/9) Poaceae Phalaris minor 43% (3/7) Brassicaceae Sinapis arvensis 33% (1/3) Brassicaceae Diplotaxis erucoides 17% (1/6) Solanaceae Solanum nigrum 8% (1/12) Poaceae Triticum (C9) 43% (3/7) 43% (3/7) Poaceae Triticum (Galilee) Solanaceae Solanum lycopersicum 56% (5/9) Brassicaceae Raphanus sativus var radicula 33% (2/6) Poaceae Avena sativa (Paeya 4) 36% (5/14) Poaceae Hordeum vulgare (Noga) 33% (2/6) Solanaceae Solanum tuberosum 100% (4/4) Solanum nigrum X400
Updated host range of Spongospora subterranea Naturally-infected plants: Nightshade weeds (Solanum physalifolium, S. sarrachoide) Nitzan et al. 2009. Am. J. Pot. Res.; Shah et al. 2010. Aust. Plant Pathol. Wheat Barley S. nigrum, S. elaeagnifolium, Medicago radiate, Verbesina, Diplotaxis, Matthiola, Salsola, and more Artificially-inoculated plants: Tomato, Oat, Rapeseed, Buckwheat, Radish, Red clover, Rye; S. ptycanthus, Brassica, Dactylis, Datura; Chenopodium, Cyperus, Ambrosia, Amarnthus, Phleum Celery, Carrot, Corn, Cabbage, Parsley, Bean, Cucumber, Onion, Pea, Maize; Datura,S. nigrum, S. quitese, Sonchus Qu & Christ. 2006. Am. J. Pot. Res.; Aristizibal et al. 2013. Rev.Fac.Nal.Agr.Medellín Wheat, Barley Setaria, Phalaris, Sinapis, Diplotaxis
Assessment of cultivars to PS Vivaldi Dita Naturally-infested plots Complete randomized blocks, 4-5 replicates Replicate size 4 m long X 2 rows (1.95m) Valor Maris peer Annabelle Nicola Charlotte Winston Rosanna
Rating scale tuber lesions (Falloon et al., 1995)
Field trial Negev, winter 2015/16 PS incidence (%) and severity index (0-6) at haulm killing
Field trial Negev, winter 2015/16 Root galls incidence (%) and gall severity at haulm killing
Field trial Negev, winter 2015/16 PS on tubers and root gall incidence (%)
cultivar susceptibility/tolerance PS incidence 2008-2016 (2-5 trials for each cv.)
October 10 October 25 November 15 Temp 55 DAP (tuber initiation) Planting Date Min Temp Max Temp Oct 7 15.1 o C 26.9 o C Oct 25 13.0 o C 24.0 o C Nov 15 10.3 o C 20.8 o C Planting date Effect of planting date on Powdery Scab Field trial, Winter 2012-13 Avg Max Temp 23 o C; Min Temp-11 o C
Soil/seed treatments Chemical control
PS incidence (%) Soil treatments Pre-planting soil fumigation Winter 2012-13; + /- plastic Field trial; naturally infested sandy soil; cv. Exquisa
Soil/seed treatments Pre-planting soil and seed treatments Field trial, Shikma, winter 2015/16 Infested plot; clean seeds; cv. Allians Complete randomized blocks, 5 reps (10m long, 4 rows) Planting: Nov 15, 2015; Haulm killing: Mar. 16, 2016; Harvest: Mar. 20, 2016 Root gall assessment: Mar 6,1206; A B C D E F G H I J K Control Seed spray Ohio (fluazinam 500 g/l) - 500 ml/ton + in-furrow Commodor [chlorothalonil (400 g/l)+ azoxystrobin (80 g/l)] - 3 L/ha Incorporation/broadcast Ohio (fluazinam 500 g/l) - 5 L/ha In-furrow Nebijin (flusulfamide 50 g/l ) - 7.5 L/ha In-furrow Nebijin (flusulfamide 50 g/l) - 15 L/ha Foliar spray (45&90 dap) Nebijin (flusulfamide 50 g/l) - 15 L/ha In-furrow+foliar spray Nebijin (flusulfamide 50 g/l) - 15 L/ha Incorporation/broadcast Banjo-Forte (fluazinam 200 g/l + dimethomorph 200 g/l) - 5 L/ha Incorporation/broadcast Mirador (azoxystrobin 250 g/l) 10 L/ha in-furrow Adama Fluz (fluazinam 500 g/l) 5 L/ha In-furrow Topaz (thiophanate methyl 70%) 1 L/ha + Cymcositop (cymoxanil 8% + mancozeb 64%) 3 L/ha
Soil/seed treatments Powdery scab incidence (%) Shikma, winter 2015/16 K In-furrow Topaz (thiophanate methyl 70%) 1 L/ha + Cymcositop (cymoxanil 8% + mancozeb 64%) 3 L/ha J In-furrow Adama Fluz (fluazinam 500 g/l) 5 L/ha I Incorporation/broadcast Mirador (azoxystrobin 250 g/l) 10 L/ha H Incorporation/broadcast Banjo-Forte (fluazinam 200 g/l + dimethomorph 200 g/l) - 5 L/ha G In-furrow+foliar spray Nebijin (flusulfamide 50 g/l) - 15 L/ha F Foliar spray (45&90 dap) Nebijin (flusulfamide 50 g/l) - 15 L/ha E In-furrow Nebijin (flusulfamide 50 g/l) - 15 L/ha D In-furrow Nebijin (flusulfamide 50 g/l ) - 7.5 L/ha C Incorporation/broadcast Ohio (fluazinam 500 g/l) - 5 L/ha B Seed spray Ohio (fluazinam 500 g/l) - 500 ml/ton + in-furrow Commodor [chlorothalonil (400 g/l)+ azoxystrobin (80 g/l)] - 3 L/ha A Control
Root galling and severity index Shikma, winter 2015/16 Pearson's r 0.79821 No statistical differences
SUMMARY IPM management for reducing the risk for powdery scab under favorable conditions is a must Tools provided to the grower enable getting a better decision: soil infection levels, seed lots infection, levels of cultivars susceptibility, planting date Transmission of the disease by infected seed tubers, wind dispersal Weeds and rotational crops may play an important role Chemical control by pre-planting soil fumigation (MS/PIC) is effective and other soil and seed treatments should be further investigated
Acknowledgments Sara Lebiush, Asaf Rosenberg, Orly Erlich, Marina Hazanovsky ARO, Gilat Research Center Uri Zig - M aon Enterprises Jonathan Binnefeld- Atzmona Enterprises Gilan Maharshak - Ego Enterprises Funding: Chief scientist Min Agriculture Potato growers organization THANKS FOR YOUR ATTENTION
Seed borne inoculum Monitoring seed lots