Non-fumigant options for replant disease/nematode management OSU Replant Discussion March 17, 2017 Tom Forge
Replant management for cherry Soil factors causing poor establishment of replanted fields/orchards Very costly Replant disease complex Pratylenchus penetrans Cylindrocarpon/Ilyonectria, Rhizoctonia, Pythium species Restricted availability of nutrients and water to small root systems Replant syndrome
Migratory endoparasites Root-lesion nematodes Pratylenchus species Ubiquitous chronic pests of horticultural crops
Replant management Preplant fumigation targeting pathogens has been primary control strategy 2013 regulatory changes: Fumigation has become more difficult and costly Alternatives to conventional fumigants are needed
An organic matter intensive soil health approach to replant management compost mulch By optimizing soil health Suppress pathogens without fumigants? Optimize root growth despite pathogens? Improve water relations & P availability? passive OM NH 4 + NO 3 - PO 4 - nematodes Fungal pathogens active OM Enhanced Soil food web and soil health
Ongoing question: Does soil organic matter/soil health management lead to PPN suppression?
Cherry replant 2014 experiment w/d. Neilsen, G. Neilsen, T. Watson, L. Nelson D. O Gorman, J.R. Urbez-Torres 2014 experiment Amendment subplots: 1. Control 2. Fumigated fall 2013 3. Compost 50 Mg ha -1 4. Mulch - ~5 cm fir bark mulch 5. Compost + Mulch Irrigation whole-plots: Microsprinkler vs- drip
TCSA (cm2) Early tree growth 250 200 150 Fumig Control Mulch Amend A+M ab b ab a 100 50 0 2014 2015 2016 Ph.D. Thesis work of Tristan Watson
P. Penetrans / 100 ml soil P. penetrans populations 250 200 150 a ab Fumig Control Mulch Amend A+M 100 ab --a-- 50 --b-- --b-- a 0 Spring 2014 Fall 2015 Spring 2016 P. penetrans / g root Fall 2014 Spring 2015 Fall 2015 Spring 2016 Harvest 2016 Fall 2016 Soil Treatment Control 2570 a 338 ab 2149 a 1286 a 1176 2241 a Fumigation 1082 ab 463 a 1238 ab 1501 a 2228 1731 ab Compost 315 b 131 bc 555 b 779 ab 1490 1221 ab Mulch 236 b 100 bc 407 b 468 b 1164 1374 ab Compost + Mulch 108 b 56 c 281 b 403 b 1110 514 b Irrigation Drip 747 197 600 b 608 982 1106 b Microsprinkler 977 238 1252 a 1167 1885 1840 a Soil Treatment <0.001 <0.001 0.033 0.020 0.365 0.003 Irrigation 0.490 0.413 0.001 0.091 0.122 0.011 Soil Treatment x Irrigation 0.191 0.427 0.057 0.149 0.116 0.053
Rhizosphere microbiology Tristan Watson et al. 2017. Applied Soil Ecology. In press. End of second growing season Total Bacteria (log 16S gene copies g -1 soil) Total Fungi (log 18S gene copies g -1 soil) Pseudomonas spp. (log 16S gene copies g -1 soil) DAPG+ Bacteria (log phld gene copies g - 1 soil) PRN+ Bacteria (log prnd gene copies g -1 soil) Soil Treatment Control 9.75 c 7.91 ab 8.19 b 5.13 b 6.68 b Fumigation 9.91 bc 7.65 b 8.55 ab 5.23 b 6.80 b Compost 10.2 ab 8.16 a 8.82 a 6.30 a 7.13 ab Mulch 10.0 bc 8.02 ab 8.43 ab 5.62 ab 6.93 ab Com+Mulch 10.3 a 8.15 a 8.88 a 6.10 a 7.34 a Irrigation Type Drip 9.97 7.88 b 8.52 5.53 6.85 b Microsprinkler 10.1 8.08 a 8.62 5.82 7.01 a Amendment <0.001 0.005 0.001 <0.001 0.002 Irrigation 0.078 0.035 0.364 0.102 0.020 Amendment x Irrigation 0.821 0.979 0.223 0.220 0.530
2015 Cherry experiment setup Summer 2014 (10 th year of previous experiment) Early spring 2015
2015 Cherry experiment setup Whole (row) plots: Fumigation or not Subplots: Pre-plant compost at 50 Mg ha -1 Sub-subplots: Historical treatments of mulch, P-fertigation, nothing Planted spring 2015 Soil sampling: 2014: May, August 2015: At-plant (late March), May, August, May, July, October 2016
Nematodes / L soil Nematodes / L soil Root lesion nematodes in soil May 2015 700 600 Pratylenchus penetrans Fumig * Non-fum 200 180 160 140 120 500 100 400 300 200 * * 80 60 40 100 20 0 May-15 Aug-15 May-16 0 No compost Compost Fumigation x Date interaction p < 0.001 Compost effect p = 0.02
Nematodes / g root Root lesion nematodes in roots 500 450 400 350 300 250 200 150 100 50 0 P. Penetrans in roots Compost No compost Fumig Non-Fumig Fumigation p = 0.008; Compost p = 0.04 Samples courtesy Paige Munro
Photosynthesis A n (umol cm -2 sec -1 ) Results tree growth Photosynthesis 12.5 12 11.5 11 10.5 10 Fumigated Non-fumigated Benefit of historical mulch to stem water potential and photosynthesis has not translated to tree growth (as of 2016) 9.5 9 Mulch Control
Lessons learned: Preplant incorporation/replant Compost immediately improves root zone soil organic matter, soil chemical properties, bulk density/aggregate stability and water relations Compost can suppress P. penetrans populations & improve replant success Other components of replant disease? Long-term prior use of mulch translates to: Enhanced soil organic matter through replant phase Improved plant water relations Tree growth?
Other options for replant mangement Brassica green manure biofumigant cover crops Nematode suppressive rotation cover crops: Marigolds Saia oats, forage pearl millet Brassica seed meals Anaerobic Soil Disinfestation Non-fumigant nematicides
Brassica green manure cover crops Canola/oilseed rape: Brassica napus, Brassica rapa, Indian/brown mustard: Brassica juncea forage radish: Raphanus sativus White mustard: Brassica hirta/sinapsis alba (e.g. Braco) Most crops also hosts for P. penetrans! Can be very effective for nematode and fungal pathogen control, but Must manage for high biomass production and chop & incorporate material
P. Penetrans / g root Brassica seed meals e.g. MustGrow TM Preplant 3 month 6 month 700 600 500 400 300 200 100 0 Control BnDE BnAT SaIG BjPG Mazzola et al. 2007. Phytopathology 97:454-460. Can also suppress Rhizoctonia, but may stimulate Pythium Suppression associated with enhanced Streptomyces populations Also rich source of N and organic matter
Anaerobic Soil Disinfestation Prepare soil, incorporate readily decomposable C source: Rice bran, fresh yard waste, green manure crops, poultry manure, molasses Fruit or veg processing waste? Dairy manure? Tarp (VIF)/irrigate, incubate 6 weeks Anaerobic decomposition leads to: O 2 conc < 1%; Eh < -200mV production of fatty acids, H 2 S, NH 3, etc. Great control of nematodes Good control of fungal pathogens Modest/mixed control of weeds Does not reduce natural suppressiveness like chemical fumigation may enhance it Beneficial shifts in microbial community? Photo: California Agriculture
Minor Use trials on Velum Prime Initiated 2015 Apple (2), Cherry (1), Raspberry (2) Treatments: Untreated Vydate (except cherry) Velum 250 g a.i./ha x 2 chemigated Velum 250 g a.i./ha x 2 broadcast Velum 500 g a.i./ha x 2 broadcast All treatments chased with 2.5 cm irrigation Continued in apple plots in 2016
Summary MUPP trials on Velum Prime Significant reductions relative to control: 500BC: 6/24 variable x site x time combinations 250BC: 5/24 250Chem: 2/24 Vydate: 4/24 Velum Prime shows potential - help is on the way But Delivery may be limiting efficacy under these application conditions What about incorporated/replant scenario? Next MUPP trial at Summerland stay tuned!