Sorghum pest management

Transcription

1 Sorghum pest mngement

2 The suite of potentil pests Impct on the crop Helicoverp rmiger Sorghum midge Corn phid Rutherglen bug Sorghum hed cterpillr Yellow Pech moth Armyworm Estblishment pests Cutworm, FWW, crickets, blck field erwigs, cockroches Locusts Lrve feed on filling grin = Yield nd qulity Prevent seed set = Yield Honeydew contmintion = No impct on yield Adults nd nymphs feed on setting nd developing grin = Yield nd qulity Lrve feed on filling grin = Yield Lrve feed on filling grin = Yield Feed on vegettive plnts = no impct on yield Adults nd lrve feed on seed, seedlings = reduced plnt stnd or retrded seedling development In plgue yers = defolition, feeding on developing nd mturing grin = Yield nd growth.

3 The focus of the discussion Impct on the crop Helicoverp rmiger Sorghum midge Rutherglen bug Sorghum hed cterpillr Yellow Pech moth Corn phid Armyworm Estblishment pests Cutworm, FWW, crickets, blck field erwigs, cockroches Locusts Lrve feed on filling grin = Yield nd qulity Prevent seed set = Yield Adults nd nymphs feed on setting nd developing grin = Yield nd qulity Lrve feed on filling grin = Yield Lrve feed on filling grin = Yield Honeydew contmintion = No impct on yield Feed on vegettive plnts = no impct on yield Adults nd lrve feed on seed, seedlings = reduced plnt stnd or retrded seedling development In plgue yers = defolition, feeding on developing nd mturing grin = Yield nd growth.

4 Helicoverp rmiger corn erworm Only H. rmiger in sorghum no H. punctiger H. punctiger H. rmiger mjor driver of locl popultions = pest pressure Chickpes Control in chickpes, nd pupe busting ply role in mnging locl popultions Infesttion of vegettive sorghum control these popultions? Sorghum is sink for H. rmiger in the system Egg nd lrvl prsitism, predtion cn be significnt

5 Monitoring nd Mngement The bsics: 80% of eggs lid prior to flowering Uniform crop flowering = uniform lrvl ge Also impcts on sorghum midge mngement (wht influences uniformity of flowering, nd cn this be mnged?) Erly instrs feed on pollen, 4 th instr nd older feed on developing seed Egg density not good mesure of potentil lrvl density Prsitisim by Trichogrmm, predtion by Orius, cnnblism of erly instrs

6 Mnging Helicoverp in sorghum How do you monitor? Visul, bet heds, spin heds Wht do you record, nd why? Monitoring nd control decisions getting the timing right the contribution of beneficil insects thresholds control options nd considertions

7 Mking decisions to control Threshold Bsed on yield loss of 24 kg/h yield loss per lrv per m row. On line clcultor now vilble there is compenstion (pplies to midge too) = lrger seed beside seed tht doesn t fill Dmge post physiologicl mturity cnnot be compensted for. Influences on product choice Lrvl density nd ge Crop uniformity nd lrvl ge spred

8 Getting the best out of NPV NPV hs gretest efficcy ginst lrve up to 4 th instr (<13 mm) Low volume (<10 L/h + Optimol ) coverge remins n issue ingestion ctive Influence of cool wether on efficcy or speed of kill 12 degree threshold for lrvl ctivity/feeding) DIET CONSUMED (mg) FOOD CONSUMPTION (6-dy old) d 6.2 d 4.5 d Time to deth 20 C 25 C 30 C NPV Helthy

9 Getting the best out of NPV Acquisition is rpid (mx uptke within 1 hour) focus on chieving optiml coverge % NPV INFECTION EC ULV HOURS AFTER TREATMENT

10 NPV hs no impct on beneficils but timing importnt to preserve Microplitis (needs 3 dy dvntge to complete development) - Beneficil ctivity more importnt where single ppliction my not give high level of control - benefits for other crops in the system = Apply NPV 3 dys post flowering (50% of heds with brown nthers) % M. demolitor Prsitism y = x R 2 = % NPV Infection Yellow nthers Brown nthers Microplitis lrv inside helicoverp lrv But, better to go erly thn lte

11 Summry Crop uniformity mkes control decisions simpler re. timing nd product selection Sorghum potentilly sink for Helicoverp nd source of prsitoids in the system Lte crops, with lrve present pst mid Mrch, potentilly hrbour dipusing lrve pupe busting considertion.

12 Midge bsics Midge popultions driven by Johnson grss first genertion in this host Successive genertions in locl re successive plntings nd low MR vrieties 10 x increse in popultion ech genertion Midge Resistnce Physicl resistnce to plcement of egg in the floret Allowed incresed flexibility in terms of plnting time Where sprying still required SP use will impct on H. rmiger resistnce Extreme midge pressure will put strin on the resistnce

13 Multipest considertions (Lis Bird, NSW DPI) SP resistnce in Helicoverp rmiger incresed in 2011/12 seson Why? midge sprying in sorghum? sp use in chickpe?

14 Mngement nd control Threshold Bsed on midge numbers erly morning monitoring Incorportes compenstion, MR, insecticide residul On line clcultor vilble ( Sorghum midge prsitoids Contribute to overll popultion suppression not midge control. Eupelmus Sorhgum midge prsitoid Eupelmus Sorhgum midge prsitoid

15 Strtegy for mnging sorghum Control lternte hosts in spring i.e. Johnson grss Plnt erly (prior to mid November) Avoid high midge pressure Reduce likelihood of sprying Mintin efficcy of MR Mnge the crop for uniform flowering 3 week spred will result in midge from erly heds ttcking lte heds in the sme crop Highest possible MR for lter plntings Midge pressure increses s the seson progresses

16 Rutherglen bug Tril work to dte: Chrcterised dmge dry nd irrigted Provisionl threshold Need field vlidtion of provisionl threshold Insecticide evlution Anthesis Milky dough Soft dough Hrd dough Check for RGB Control wrrnted if >20-25 bugs/hed Control wrrnted if >30-50 bugs/hed No impct on yield or qulity post physiologicl mturity

17 Chrcterising dmge

18 No. Nysius nymphs/hed No. Adult Nysius /hed NSD NSD ADULTS c c bc c Unspryed Indoxcrb 200 Indoxcrb 400 Fipronil Dimethote Alph-cypermethrin 0 3 Unspryed 6 NYMPHS Indoxcrb 200 Dys After Tretment b bc b bc Indoxcrb 400 Fipronil Dys After Tretment b c c Dimethote Alph-cypermethrin b bc c d bc e

19 RGB in sorghum insecticide evlution impct on predtors (minly spiders) No. predtors/hed NSD PREDATORS Dys After Tretment b c b Unspryed Indoxcrb 200 Indoxcrb 400 Fipronil Dimethote Alph-cypermethrin b b b c

20 Dignosing cuses of yield loss in sorghum t the end of the seson Sterility? Midge? Rutherglen bug? Corn erworm? Mice? Birds? Discussion How often re you fced with this sort of sitution? And how do you go bout identifying wht hs hppened?

21 Look t the pttern of yield loss Sterility Lrge res of hed devoid of grin No evidence of shriveled grin in glumes Uniformity in where the poor seed set is in heds cross the field High tempertures during flowering Persistent rin during flowering Sorghum midge Grin fils to develop nothing in the glumes Squshed grin exudes pink fluid (midge pup) Empty pupl cses visible (>2wks post flowering) No grin or frss on the ground

22 Dignosing cuses of yield loss in sorghum Rutherglen bug Grin fils to develop nothing in the glumes (looks like midge dmge) Smll shrivelled grin tht fils to develop further Spotting on mturing grin (feeding punctures + fungi/bcteri) Dmge to the endosperm (developing seed) No grin or frss on the ground Corn erworm Preflowering dmge (grzing) Chewed nd prtly consumed grin Empty glumes but open Grin or frss on the ground nd in lef xils

23 Other sorghum pests Sorghum hed cterpillr No thresholds Beneficils likely to control smll infesttions (<10/m row) Webbing chrcteristic Monitor long with helicoverp Yellow pech moth Threshold ~ 0.4x helicoverp threshold No webbing Monitor long with helicoverp