Optimizing Metam Sodium Fumigation in Fine-Textured Soils

Transcription

1 Optimizing Metm Sodium Fumigtion in Fine-Textured Soils Neil C Gudmestd University Distinguished Professor & Endowed Chir of Potto Pthology Deprtment of Plnt Pthology North Dkot Stte University

2 Erly Dying Primry cuse of erly dying is Verticillium dhlie Primrily soil-orne, fungus survives s microscleroti in the soil nd on crop deris Microscleroti re relesed into the soil from potto deris rekdown fter 1.5 to 2 yers Vd cuses wilt of plnt y locking wter conducting tissues Proly the most importnt cuse of economic losses in potto industry in the U.S. tody (cost of control + direct losses)

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4 V. dhlie Potto Interction Microscleroti infect growing root tissue Must e in close proximity to roots, do not move within the soil Bulk of the root tissue elow the seedpiece Despite lower inoculum potentil t 4-8 depth, inoculum efficiency high (Courtesy of Alert, Food nd Rurl Development)

5 Vpm Tril-2011 & 2012 The ojective ws to study interction of soil temperture, injection depth, nd rte of metm sodium on Verticillium wilt control Vpm pplied t two temperture; 39F in 2011; 55F nd 39F in 2012 Vpm shnked in t nd t single 10 depth Vpm rtes; 0, 40, 50, 60, & 70 gl/ Dt included Vppg, weekly wilt redings, yield

6 Summry & Conclusions In most recent work, 60-70% Verticillium inoculum is in the top 4 of soil In most instnces, fumigtion t 39F significntly improved reduction Vppg, prticulrly t 0-4 Injection depth did not ffect Vppg reduction Metm sodium rte did not ffect Vppg reduction Fumigtion t 39F significntly improved mrketle yield compred to 55F Injection depth hd no effect on mrketle yield

7 Recommendtions Apply metm sodium when tempertures re <50F t 6 depth Very little evidence tht metm sodium rtes >40 gl/ provide greter reduction of Vert propgules A single injection depth of 10 provides equl or greter reduction of Vert propgules thn split pplictions Continue to monitor soil popultions; inoculum levels >40 Vppg (% reduction only fir) my require dditionl mngement tctics eyond metm sodium

8 Unresolved Questions All previous work on fumigtion for Verticillium wilt mngement done in lomy snd soils with medium texture nd OM <1.5% Questions sked y regionl potto growers: Cn I expect the sme results in my fine-textured silt lom soils? Wht impct does OM hve on metm sodium effectiveness? We repeted the forementioned studies in silt lom soil with 2.3% OM

9 2014

10 Vppg Effect of Injection Depth on Vppg Control 10 in 6 in +10 in c c c 0 0-4" 4-8" 0-8" Soil smpling depth

11 Vppg 80 Effect of Injection Timing/Temperture on Vppg F 38 F ns 60 ns 40 ns " 4-8" 0-8" Soil smpling depth

12 Vppg Reduction (%) 100 Effect of Injection Depth on Vppg Reduction By Depth in 6 in +10 in " 4-8" 0-8" Soil smpling depth

13 Vppg Reduction (%) 100 Effect of Soil Temp on Vppg Reduction By Depth F 38F ns " 4-8" 0-8" Soil smpling depth

14 Vppg Effect of Metm Sodium Rte on Vppg gl / 40 gl / 50 gl / 60 gl / 70 gl / " 4-8" 0-8" Soil smpling depth

15 RAUWPC Effects of Temperture nd Injection Depth on Verticillium Wilt Development- RAUWPC Control 10 in 6 in +10 in ns 0.10 c F Fumigtion Temperture d 38F

16 RAUWPC Effects of Temperture nd Metm Sodium Rte on Verticillium Wilt Development-RAUWPC Control 40 gl 50 gl 60 gl 70 gl ns ns 0.10 de F Fumigtion Temperture 38F

17 Mrketle Yield (cwt/) 500 Effect of Injection Temp on Mrketle Yield Control Erly-54 F Lte-38 F

18 RAUWPC RAUWPC Reltionship etween Reltive Are under the Wilt Progress Curve (RAUWPC) nd Verticillium propgules per grm (Vppg) soil post-fumigtion t 0-4 (A) nd 4-8 (B) r = P = A r = P = B Vppg (0-4 in) Vppg (4-8 in)

19 Totl yield (cwt/) Totl yield (cwt/) Reltionship etween Totl Yield (cwt/) nd Verticillium propgules per grm (Vppg) soil post-fumigtion t 0-4 (A) nd 4-8 (B) A B r = P = r = P < Vppg (0-4 in) Vppg (4-8 in)

20 Mrket Yield (cwt/) Reltionship etween Mrket Yield (cwt/) nd Verticillium propgules per grm (Vppg) soil post-fumigtion t 0-4 (A) nd 4-8 (B) A B r = P = r = P < Vppg (0-4 in) Vppg (4-8 in)

21 Summry The highest proportion of Verticillium dhlie inoculum is in the top 4 of soil. However, inoculum in 4-8 depth my e more efficient hs greter influence on wilt development nd totl/mrketle yield. Results of fumigtion trils in fine-texured/ higher OM soil differ somewht from those oserved in medium-textured/low OM soil.

22 Summry Shnk injection t two depths (6 & 10 ) my e needed in fine-textured soil nd in soils with >2% OM to optimize efficcy. Temperture hd less impct of fumignt efficcy in fine-textured/higher OM soil thn in low OM lomy snd. Interestingly, despite the field tril, yer of the study, nd soil type, we hve not oserved nd metm sodium rte response.

23 THANK YOU! QUESTIONS?