SOUTHERN SEPTEMBER 2018 CANOLA SECTION 7 INSECT CONTROL INTEGRATED PEST MANAGEMENT | INCIDENCE OF INSECT PESTS IN CANOLA | EARTH MITES | LUCERNE FLEA | SLUGS | DIAMONDBACK MOTH | APHIDS | RUTHERGLEN BUGS | HELICOVERPA PUNCTIGERA (NATIVE BUDWORM) | SNAILS | SOIL PESTS Table of Contents SECTION 7 CANOLA - Insect control Feedback December 2015 SECTION 7 Insect control Insects that can pose a problem in canola include blue oat mites (Penthaleus spp.), Stay informed redlegged earth mites (Halotydeus destructor), Bryobia mites (Bryobia spp.), Balaustium Stay informed mites (Balaustium medicagoense), cutworms, diamondback moth (DBM, Plutella about invertebrate xylostella), aphids, slugs, snails, earwigs, millipedes, slaters, lucerne flea (Sminthurus pest threats viridis) and Rutherglen bugs (RGB, Nysius vinitor). throughout the winter Viruses can also occur in canola, carried by aphids that suck sap from leaves, growing season transferring the virus and causing yield loss and sometimes plant death. Protection by subscribing to against early aphid infestation in seedling canola may reduce the incidence of viruses in SARDI’s PestFacts the crop. South Australia and ® cesar’s PestFacts Gaucho (imidacloprid) is the only seed dressing registered for control of aphids in south eastern. canola. Sowing canola into standing cereal stubble may help to reduce aphid numbers and hence virus infection (Figure 1). 1 Subscribers to PestFacts also benefit from special access to cesar’s extensive Insect Gallery, which can be used to improve identification skills of pest and beneficial insects. More i information SARDI: PestFacts South Australia cesar: PestNotes cesar: PestFacts south eastern GRDC Update Papers: Viral diseases in canola and winter pulses Figure 1: Sowing canola into standing cereal stubble may help to reduce aphid numbers and GRDC Update Papers: hence virus infection. (Photo: Penny Heuston) Emerging insect pests GRDC: ‘Serial pests’ wrap up—lessons from 2014 and 2015 and some research updates CropPro: Canola 1 L Serafin, J Holland, R Bambach, D McCaffery (2005) Canola: northern NSW planting guide. NSW Department of Primary Industries, http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0016/148300/canola- northern-NSW-planting-guide.pdf Know more. Grow more. 1 Table of Contents SECTION 7 CANOLA - Insect control Feedback December 2015 More 7.1 Integrated pest management i information Pests are best managed by using an integrated pest management (IPM) approach. IPM Workshops: Careful planning prior to sowing, followed by regular monitoring of crops after sowing, Decision making for will ensure that potential problems are identified and, if necessary, treated early. insect management in The IPM approach uses a range of management tactics to keep pest numbers below grain crops the level where they cause economic damage. It focuses on natural regulation of pests, IPM Workshops: ‘Best particularly by encouraging natural enemies, and on using broad-spectrum chemicals Bet’ IPM strategy only as a last resort. IPM relies on monitoring the crop regularly, having pests and beneficial insects correctly identified and making strategic control decisions according NIPI: I SPY, Insects of to established damage thresholds. 2 southern Australian broadacre farming systems identification 7.1.1 Key IPM considerations for canola manual Integrated pest management is a year-round approach to pest management and includes ‘off-season’ operations and planning as well as crop management: DEDJTR: Pest insects • Monitor regularly and record numbers of pests and beneficials. Review checking and mites data for population trends. Research paper: Insect • Tolerate early damage. Canola can compensate for early damage by setting new pests buds and pods to replace those damaged by pests. Excessive early damage may cesar: PestFacts south- reduce yield. eastern • Use aphid-selective products (e.g. pirimicarb) to preserve the beneficial insects, potentially reducing the need for follow-up applications. • Biopesticides used in vegetative canola prior to flowering will preserve beneficials. • Nuclear polyhedrosis virus (NPV) is effective against Helicoverpa larvae <7 mm long. • Bacillus thuringiensis (Bt) is effective against DBM and Helicoverpa (<7 mm long). • Consider the use of spray oils where aphid populations are low to moderate (repeat applications required). • Where pests invade from adjacent fields, consider spraying only borders and not the whole field. • Control some pests (e.g. lucerne flea or mites) in preceding pasture or broadleaf crops. • Seed dressings may be the most effective control for some soil insects, as well as the least disruptive to natural enemies. • Consider cultural control or biological control methods (Table 1). 3 2 K Hertel, K Roberts, P Bowden (2013) Insect and mite control in field crops. NSW DPI Management Guide. NSW Department of Primary Industries, http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/284576/ Insect-and-mite-control-in-field-crops-2013.pdf 3 IPM guidelines—Canola. National Invertebrate Pest Initiative, http://ipmguidelinesforgrains.com.au/crops/ canola/ Know more. Grow more. 2 Table of Contents SECTION 7 CANOLA - Insect control Feedback December 2015 Table 1: Summary of ‘Best Bet’ IPM strategies 4 Summer–autumn Winter Spring Aphids, particularly green peach aphid (GPA) Assess virus risk. Monitor crops for aphid Monitor trends in aphid and beneficial populations over colonisation from late winter time. High risk where: when daily temperatures start • summer rainfall creates a to rise. High risk where: Brassica green bridge • aphid populations rapidly increasing during early • warm conditions favour early High risk where: flowering–bud formation aphid buildup and timing of • mild winter • forecast is for warm and dry conditions to continue flights • GPA present on vegetative • low or no beneficial activity plants If high risk: • broad-spectrum insecticides (e.g. synthetic • forecast is for warm and • use an insecticide seed pyrethroids (SPs)/organophosphates (OPs) have been dry conditions that favour treatment to manage virus used to control DBM or native budworm) aphid development spread (e.g. Beet western Use thresholds to guide spray decisions, considering crop yellows virus) by GPA • no beneficial activity (predation or parasitism) stage (% flowering) and moisture stress. NSW, SA, WA • manage Brassica weeds and thresholds: 10–50% of plants infested. volunteers (ideally area wide) 3–4 weeks before sowing If spraying: • sow early to promote early • use soft products (pirimicarb) to retain beneficials flowering in spring before • consider border sprays to prevent/delay buildup aphids peak • rotate insecticide groups to reduce selection for resistance in GPA Rutherglen bug (RGB) Remove summer–autumn weeds Increased risk where: Monitor crops from flowering to windrowing–harvest. (especially fleabane, wireweed, and • abundant weed hosts cape weed) in and around fields overwinter allowing build- High risk where: 3–4 weeks before sowing. Monitor up of local populations • hot, dry conditions in spring and early summer force crops for RGB and other pests RGB to move from weed hosts during establishment. • moisture stressed plants (limited compensation potential) High risk if: • long-distance migration into cropping areas • warm conditions in late summer–autumn Use economic thresholds to guide spray decisions, • nearby weeds (in or near crop) considering moisture stress. drying off If spraying, monitor for reinvasion and the need for repeat If spraying: sprays. Large numbers of RGB at harvest may pose a live- • border-spray infested areas of insect contamination risk. crop and nearby host weeds NSW threshold: 10 adults or 20 nymphs per plant (podfill– • monitor for reinvasion and the harvest) need for repeat application Diamondback moth (DBM) Manage Brassica weeds and Monitor crops for moths and Monitor crop with a sweep-net for larvae until maturity. volunteers (ideally area wide) 3–4 larvae from midwinter. weeks before sowing. High risk where: High risk where: • warm and dry conditions favour rapid population High risk where: development • DBM population present in • high summer rainfall creates a • low beneficial activity and/or DBM parasitism (note: mid–late winter green bridge of Brassica hosts this can also happen if SPs/OPs are used) • warm temperatures in (e.g. wild radish, volunteer • moisture-stressed plants canola) mid–late winter • warm summer–autumn • seasonal forecast is for a Use thresholds to guide spray decisions, considering crop conditions favour early DBM warm/dry spring stage and moisture stress. If spraying: buildup • avoid SPs/OPs, which destroy beneficial insects (may If high risk: flare pests) and increase resistance selection in DBM • consider a Bt spray to • consider Bt to control small larvae delay population buildup. Best results where most • consider emamectin or spinetoram to control larger larvae are small and larvae beneficial activity and/ • rotate insecticide groups across seasons or DBM parasitism (e.g. • ensure good spray penetration into the canopy Diadegma sp.) is detected. • monitor after spraying to determine need for repeat application SA threshold: Mid–late flowering: 20 larvae per 10 sweeps Pod maturation: 50 larvae per 10 sweeps 4 ‘Best Bet’ IPM strategy. IPM Workshops, http://ipmworkshops.com.au/wp-content/uploads/BestBet_ Canola2014.pdf Know more. Grow more. 3 Table of Contents SECTION 7 CANOLA - Insect control Feedback December 2015 Summer–autumn Winter Spring Helicoverpa punctigera