The art of powdery mildew control Technical Manual

Transcription

1 The art of powdery mildew control Technical Manual

2

3 TABLE OF CONTENTS INTRODUCTION Introduction Powdery Mildew Vivando s Features and Benefits Mode of Action Powdery Mildew Control Trial Results Australian Wine Institute Fermentation and Sensory Studies (AWRI) Application Guidelines Usage and Handling Mixing Application Compatibility Export of Treated Fruit or Wine Re-entry Period Withholding Period IPM Powdery mildew is caused by the fungal pathogen Erysiphe necator. It is the most persistent fungal problem of grapes in Australia and one of the most widespread fungal diseases of grapevines in the world. It is characterised by ash-grey to white powdery growth on green tissue of the vine. If uncontrolled it can cause serious crop losses and impair wine quality. Vivando is a highly effective fungicide for control of powdery mildew in grapes. Metrafenone, the active ingredient in Vivando is classified chemically as a benzophenone and is the first fungicide within this group to be developed. Vivando inhibits penetration of the plant cuticle in the early stages of powdery mildew development. Crop Registrations Crop Care - Vivando Fungicide 1

4 POWDERY MILDEW SYMPTOMS The upper and lower surfaces of young leaves, shoots or clusters are particularly susceptible to the disease. The chains of conidia that develop from the powdery mildew hyphae give the infected tissue the characteristic powdery or dusty appearance. Powdery mildew is often confused with downy mildew however downy mildew occurs only on the underside of the leaf while powdery mildew grows on both sides of the leaf surface. DAMAGE AND LOSS Powdery mildew infections around flowering and up to five weeks later pose the greatest risk of damage and loss. WEATHER CONDITIONS Powdery mildew is favoured by mild cloudy weather, humid conditions, low to moderate light and prefers temperatures of 22 o C to 28 o C. Powdery mildew is reduced on exposed leaf surfaces by air temperatures of 35 o C or greater and direct sunlight. MONITORING Early detection is important to reduce disease development. It is best to begin monitoring from budburst onwards at two week intervals. MANAGEMENT If powdery mildew was a problem the previous season it is most likely that high levels of overwintering buds and cleistothecia will be present in the vineyard. Early season control is the key to managing powdery mildew. A protective program beginning with application of sulphur for both powdery mildew and mite control is recommended. However fungicide sprays applied just before flowering and during the five weeks after are the most important as these protect the berries during the period when they are most susceptible to powdery mildew. Vivando is a new powdery mildew fungicide containing 500g/L of metrafenone in a suspension concentrate formulation. It offers grape growers a new and unique option for control of powdery mildew over this critical time period. Metrafenone is a member of the benzophenone fungicide group and represents the first commercial development from this novel group, U8. The mode of action of the benzophenone group is still under evaluation but it appears to be unique and shows no sign of any cross-resistance when tested on strains of powdery mildew that have developed tolerance to other fungicide groups. Metrafenone is locally systemic and also redistributes itself in the vapour phase. It has some post-infection activity but is best used on a protectant schedule. The compound is not active on the early stages of powdery mildew development, spore germination, germ tube elongation and the formation of appressorium all proceed normally in treated fungi but once the fungus penetrates the plant cuticle it is killed and does not grow on to form haustorium. When applied after cuticle penetration the product prevents the further development of secondary hyphae, mycelia and spores. The product is rainfast within one hour and shows excellent residual activity for up to 14 days after application due to a low rate of volatilisation. Vivando will provide grape growers with valuable alternative chemistry to rotate into their powdery mildew spray programs. VIVANDO S FEATURES AND BENEFITS FEATURES Unique fungicide group for Australian crops Vapour activity* Rainfast within one hour Long lasting effect (14 days after application) Water based formulation Re-entry allowed once spray is dry Storage and user safety Has no affect on wine fermentation IPM compatible BENEFITS An excellent tool for resistance management Extends the reach of spray coverage Does not need to be re-applied immediately after rain Maximise spray intervals No formulation solvents for better crop and beneficial insect safety Allows work to continue in vineyards Low toxicity to workers Use with confidence in wine grapes Can be used in IPM programs * Vivando s vapour activity extends the reach of the spray coverage and is especially useful for protecting the developing bunches. Long-lasting vapour release into bunch air space protects berries. Its local systemicity provides translaminar activity on leaves. 2 Crop Care - Vivando Fungicide

5 MODE OF ACTION Metrafenone affects organisation of the actin cytoskeleton and thereby disrupts multiple cellular processes: Appressoria formation (infection) Hyphal cell polarity (mycelial hyphal growth) Figures 4 and 5: Effect on Hyphal Cell Polarity Disruption of the actin cap disrupts mycelial growth which causes bifurcation and hyperbranching. Cellular import/export (mycelial growth and pathogenicity) Cell division and spore septation (sporulation) The following figures show these effects in detail. Figure 1: Antibody based actin staining Showing the difference between untreated and treated fungal hypahe. Note actin delocalisation at the hyphal cap. Terminal actin cap Actin delocalisation Bifurcation and hyperbranching Metrafenone - 4ppm Figures 7 and 8: Effect on Cellular Import / Export Metrafenone disturbs cellular export which results in impaired fungal cell wall growth. Metrafenone (4ppm) Antibody based Actin staining Figures 2 and 3: Disruption of Appressoria formation Appressoria are flattened hyphae from which the infection peg grows. Metrafenone disrupts the actin cap which results in non-functional appressoria formation. Metrafenone 4ppm Figures 8 and 9: Metrafenone may also cause swelling and bursting of hyphal tips. Bifurcated or multi-lobed non-functional appressoria Metrafenone - 4ppm Metrafenone - 4ppm Crop Care - Vivando Fungicide 3

6 MODE OF ACTION (Cont) Figures 10 and 11 : Effect on Cell Division and Spore Septation (sporulation) mycelium with functional spore chains All treatments applied at 1200L/ha except Vivando at 3x which was applied at 400L/ha. Fungicides applied twice at flowering. Graph 2: Severity of Bunch Powdery mildew control in Chardonnay grapes, SARDI, 2008/ UTC 4ppm Metrafenone: Disrupted spore septation Inset: Conidiospores containing several nuclei (arrows) % Severity of Powdery Mildew Vivando Vivando at 3x Vivando at 3x plus Du Wett Thiovit Topas Legend Prosper All treatments applied at 1200L/ha except Vivando at 3x which was applied at 400L/ha. Metrafenone causes inhibition of spore septation which results in irregularly septated or non-differentiated conidia. It can also cause complete inhibition of sporulation. POWDERY MILDEW CONTROL TRIAL RESULTS The results from extensive trials conducted in many grape growing regions show that Vivando provides equal or superior control of powdery mildew compared with standard control options while providing the added benefit of new chemistry for resistance management. Graph 1: Incidence of Bunch Powdery mildew control in Chardonnay grapes, SARDI, 2008/2009 % Incidence of Powdery Mildew UTC Vivando Vivando at 3x Vivando at 3x plus Du Wett Thiovit Topas Legend Fungicides applied twice at flowering. AUSTRALIAN WINE INSTITUTE FERMENTATION AND SENSORY STUDIES (AWRI) Crop Care contracted the AWRI to perform a fermentation and sensory study on Vivando. The study showed that there was no significant difference between the untreated control sample and the treated samples with respect to fermentation onset and the ability to complete fermentation. Vivando has no adverse effect on fermentation. The study also showed that Vivando had no effect on overall wine quality. APPLICATION GUIDELINES The best time to apply Vivando is from inflorescence development and from fruit set to early bunch closure (EL-31). Apply as part of a protectant spray program commencing when shoots are less than 10cm in length. DO NOT apply more than two consecutive applications of Vivando 7 to 10 days apart before changing to an alternative fungicide group for powdery mildew control (e.g. Cabrio Fungicide). DO NOT apply more than 4 applications of Vivando per crop. 0 Prosper 4 Crop Care - Vivando Fungicide

7 USE AND HANDLING MIXING To ensure thorough mixing, half-fill the spray tank with clean water and add the required amount of product. If required, add compatible products and agitate thoroughly, then add the remainder of the water. Agitate again before spraying commences. APPLICATION Apply using equipment calibrated to deliver dilute or low volume application using a medium spray droplet size. Good coverage is essential for best results. The addition of Du-Wett will assist coverage when low volume spray applications are made. COMPATIBILITY Vivando is a suspension concentrate formulation and displays good compatibility with most insecticides and fungicides. For further information on compatibility please contact your local Crop Care Australasia Pty Ltd representative. EXPORT OF TREATED FRUIT OR WINE Growers should note MRL s or import tolerances do not exist in all markets for fruit treated with Vivando. If you are growing fruit for export (either fresh, dried or for wine production) please check with your industry representative or the Australian Wine Research Institute for the latest information for the latest information on MRL s and import tolerances before using Vivando. RE-ENTRY PERIOD DO NOT allow entry into treated areas until the spray has dried. When prior entry is necessary, wear cotton overalls buttoned to the neck and wrist (or equivalent clothing) and chemical resistant gloves. Clothing must be laundered after each day s use. WITHHOLDING PERIOD The withholding period for Vivando in grapes is 5 weeks. IPM Vivando is safe to use in IPM programs. Powdery mildew affected crop Crop treated with Vivando CROP REGISTRATIONS CROP DISEASE RATE WHP CRITICAL COMMENTS Grapes Powdery mildew (Erysiphe necator) Dilute spray 20mL/100L Concentrate spray Refer to the product label. 5 Apply as part of a protectant spray program commencing when shoots are 10 cm in length. DO NOT apply more than two consecutive applications of VIVANDO 7 to 10 days apart before changing to an alternative fungicide group for powdery mildew control (e.g. Cabrio Fungicide). DO NOT apply more than four applications of VIVANDO per crop. Apply by dilute or concentrate spraying equipment. Apply the same amount of total product to the target crop whether applying this product by dilute or concentrate spraying methods. The addition of Du Wett will assist spray coverage on leaves and bunches especially if spray volumes are less than dilute. weeks PLACEHOLDER Crop Care - Vivando Fungicide 5

8 Du Wett is a registerd trademark of Elliot Chemicals. Prosper is a registered trademark of Bayer CropScience. Legend is a registered trademark of Dow. Vivando is a registered trademark of BASF. This publication is a guide only and no substitute for professional or expert advice. The product label should be consulted before use of any of the products referred to in this publication. Crop Care Australasia Pty Ltd shall not be liable for any results, loss, or damage whatsoever, whether consequential or otherwise through the use or application of products and/or materials referred to herein. Copyright Crop Care Australasia Pty Ltd ACN Crop Care Australasia PTY LTD. 15/16 Metroplex Ave Murarrie QLD 4172