Sakura 2013 review and Sclerotinia MIG crop updates Rick Horbury – Technical Advisor north

SAKURA pre-emergent herbicide:  Registered for use in wheat (not durum wheat) and triticale at 118 g/ha.  Registered for control or annual ryegrass, barley grass, silver grass, annual phalaris, and toad rush.  Registered for suppression of brome grass (great brome only) and wild oats.  Sakura is a Group K herbicide containing the active ingredient pyroxasulfone.  Sakura can be applied up to 3 days before incorporation.  Sakura provides prolonged residual soil activity under good soil moisture conditions.  Sakura works primarily through root uptake. Sakura ® is a Registered Trademark of Kumiai Chemical Industries Co. Limited http: Sakura at a glance:

SAKURA - the positives in a patchy start: Sakura applied prior to dry sowing generally performed well. i.e. pre 7 th May 2013 seeding. Sakura applied from late May onward activated in July with the germinating weeds providing good control. i.e. Mukinbudin Sakura activated after July rainfall and controlled later emerging grass weeds, even where some of the early weeds had escaped. Sakura + trifluralin mixtures worked well under a drying top soil (“The Grey Zone”) th May. http:

Understanding stubble & soil binding of pre-emergent herbicides used for ryegrass control in winter crops Today’s presenter is: Dale Shaner, USDA (retired) GRDC Webinar 13/12/13 Release of herbicide from surface residue with rainfall: Trifluralin and prosulfocarb are not washed from residue surface with rainfall. Metolachlor, dimethenamid and pyroxasulfone can be washed from surface residue.

The impacts of stubble without following rain are an issue for ALL pre-emergent herbicides Use high water rates if the stubble cover is likely to be problematic Prostrate stubble Standing stubble/ furrow concentration Pasture - compacted

SAKURA: Importance of rainfall after sowing Dry soil – awaiting activation Dry top soil, moist below Sakura – effective application video Moist soil and incorporated http: Actively growing weeds but inactive herbicide = reduced performance

The impacts of stubble without following rain are an issue for ALL pre-emergent herbicides Use higher water rates if the stubble cover is likely to be problematic Prostrate stubbleStanding stubble/ furrow concentration Pasture - compacted

2013 Key factors influencing performance: Seed bank (high density), especially coming out of pasture in Stock pulverising stubble and pushing weed seeds into soil profile. Following a germination event 2-10 days after spray application & seeding. “The Grey Zone” Stubble (not washing through) in time to be active in the soil where weeds are germinating. Insufficient rainfall within 7-10 days after application to facilitate movement of Sakura into the weed seed zone ( top 2.5 to 3 cm). http: Sakura needs to be “Present for the Germination event”

SAKURA: GETTING THE BEST POSSIBLE RESULTS The checklist: Use Sakura in rotation with other chemical and non-chemical control options Mix Sakura in the tank first (pour slowly) and ensure it is fully dispersed before adding other products Maintain good agitation before and during spraying. Apply Sakura at full label rates Apply Sakura evenly to uncultivated soil that isn’t too ridged or cloddy Cultivation before Sakura application (including “tickle”) will bury weed seeds, or stimulate increased emergence. Use high water rates if the stubble cover is likely to be problematic Stubble cover or other plant residues of greater than 50% can reduce the effectiveness of Sakura. Pulverised pasture stubble ‘blanketing’ the paddock or only partially burned windrows will be more problematic than crop stubble, even if it’s prostrate. Ensure emerged weeds are controlled by an effective knockdown herbicide before planting the crop Sakura needs to be present when weeds germinate for most effective uptake Sakura works well for dry seeding, but control will be compromised if Sakura is applied onto moist soil without follow-up rain. For application after a weed germination event with minimal rain forecast, tank-mixing with trifluralin may improve control. Incorporate Sakura by sowing (IBS) using either knife points and press wheels or narrow points and harrows within 3 days of application http:

Subline in Arial bold, 18pt Practice Integrated Weed Management to extend the life of all chemistry

Things we know about sclerotinia in canola What do we face? Canada typically flower for 4-5 weeks, Australia depending on variety. All canola varieties are susceptible and bigger healthier canopies can increase the risk. Liquid N fertiliser applications during flowering may increase severity of the disease (increasing canopy bulk). Main stem infections cause greater yield loss than lateral ones. The disease: Sclerotes survive for long periods in the soil (~6 years). When the soil temperature is ~15°C and soil becomes saturated apothecia will emerge in 7-10 days and will keep emerging while conditions are favourable (high humidity). A single sclerote can produce up to 15 apothecia. Optimal temperature for lesion development is 20-25°C with primary infection generally from petals but secondary infection can occur from contact with infected leaves or stems. Sclerotinia needs hours of continual leaf wetness to infect.

Assessment of flowering stages Flowering stages should be assessed on the main stem: 10% = 10 flowers open 20% = flowers open 30% = 20 or more flowers open 40% = 30 or more flowers open 50% = All flowers are open or have opened, crop is at its most intense yellow (full flower) 60% = Flowering intensity is beginning to decline http: or Think twice – Sclerotinia”

Prosaro control of sclerotinia in canola Average % yield increase over untreated (100% = 1.90 t/ha) 18% average yield increase (350 kg) over untreated across 25 commercial trials. http: or “Think twice – Sclerotinia” Economic return at ~$500 tonne

Spray timings – spray to the conditions Prosaro yield response in the Midwest 13WE02: Control of Sclerotinia in Hyola 404RR, Narngulu, WA Application (25/7) = 30% flower Location Narngulu VarietyHyola 404RR Flowering length6-8 weeks Yield t/ha response 320 kg/ha $ ROI Key messages: Apothecia found on 25 th July 30% spray resulted in 27% yield response 2 spray strategy starting at 30% ~3 weeks apart may have provided improved yield Protection period ~3 weeks Apothecia Treatment 03/10/2013 % Incidence t/ha % untreated Costs $/ha % Oil gross $/ha ROI $/ha % Sclerotes by weight Untreated53 a $ Prosaro 375 mL/ha14 b $ $712.97$ Prosaro 450 mL/ha7 b $ $764.70$ http: or “Think twice – Sclerotinia” Prosaro significantly reduced disease severity and incidence to maintain yield potential.

Fungicides: Getting the best results for sclerotinia in canola The checklist: Single spray: If opting for a single spray don’t apply too early. The best timing is generally ~20-30% flowering dependent on conditions. Later application at 30-50% timings can be beneficial in longer seasons. Other considerations: Air / soil temperature and rainfall are as important as flowering stage. Increased water rates are recommended – 100 L/ha is good. When plants are fast growing the window of protection will be shorter i.e. at 20% compared to 40% flowering. Multiple Sprays: Longer flowering varieties may require 2 applications under high disease pressure. Spray timings should consider favorable conditions for disease development not just crop stage. Future developments: Bayer CropScience continues to evaluate new chemistry for sclerotinia control. http: or “Think twice – Sclerotinia”