Non-fumigant options for replant disease/nematode management

Transcription

1 Non-fumigant options for replant disease/nematode management OSU Replant Discussion March 17, 2017 Tom Forge

2 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

3 Migratory endoparasites Root-lesion nematodes Pratylenchus species Ubiquitous chronic pests of horticultural crops

4 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

5 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

6 Ongoing question: Does soil organic matter/soil health management lead to PPN suppression?

7 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 Compost 50 Mg ha Mulch - ~5 cm fir bark mulch 5. Compost + Mulch Irrigation whole-plots: Microsprinkler vs- drip

8 TCSA (cm2) Early tree growth Fumig Control Mulch Amend A+M ab b ab a Ph.D. Thesis work of Tristan Watson

9 P. Penetrans / 100 ml soil P. penetrans populations a ab Fumig Control Mulch Amend A+M 100 ab --a 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 a Fumigation 1082 ab 463 a 1238 ab 1501 a ab Compost 315 b 131 bc 555 b 779 ab ab Mulch 236 b 100 bc 407 b 468 b ab Compost + Mulch 108 b 56 c 281 b 403 b b Irrigation Drip b b Microsprinkler a a Soil Treatment <0.001 < Irrigation Soil Treatment x Irrigation

10 Rhizosphere microbiology Tristan Watson et al 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 b b Microsprinkler a a Amendment < < Irrigation Amendment x Irrigation

11 2015 Cherry experiment setup Summer 2014 (10 th year of previous experiment) Early spring 2015

12 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

13 Nematodes / L soil Nematodes / L soil Root lesion nematodes in soil May Pratylenchus penetrans Fumig * Non-fum * * May-15 Aug-15 May-16 0 No compost Compost Fumigation x Date interaction p < Compost effect p = 0.02

14 Nematodes / g root Root lesion nematodes in roots P. Penetrans in roots Compost No compost Fumig Non-Fumig Fumigation p = 0.008; Compost p = 0.04 Samples courtesy Paige Munro

15 Photosynthesis A n (umol cm -2 sec -1 ) Results tree growth Photosynthesis Fumigated Non-fumigated Benefit of historical mulch to stem water potential and photosynthesis has not translated to tree growth (as of 2016) Mulch Control

16 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?

17 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

18 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

19 P. Penetrans / g root Brassica seed meals e.g. MustGrow TM Preplant 3 month 6 month Control BnDE BnAT SaIG BjPG Mazzola et al Phytopathology 97: Can also suppress Rhizoctonia, but may stimulate Pythium Suppression associated with enhanced Streptomyces populations Also rich source of N and organic matter

20 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

21 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

22 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!