Scheduling copper applications and management of greasy spot and alternaria brown spot M. Dewdney 1, C. Fraisse 2, T. Zortea 2, J. Yates 1 1 University of Florida, IFAS, Citrus Research and Education Center, Lake Alfred 2 University of Florida, IFAS, Agricultural and Biological Engineering, Gainesville
Purpose of the Scheduler To improve timing of copper sprays over the calendar-based spray schedule of applications every 21 days To warn when residue levels are lower than expected To avoid unnecessary copper sprays To reduce management costs To reduce the environmental impact of copper applications
Diseases Effectively Managed with Copper Foliar fungal diseases Melanose Greasy Spot Alternaria brown spot Citrus scab Black spot Non-systemic bacterial diseases Citrus canker
Copper Facts Copper residue is significantly reduced by rain washing Copper does not move once dried Copper residue is cracked by fruit growth As the fruit grows, copper must be reapplied to continually cover the fruit as it becomes larger
Proper Application of Copper Use label rate recommended for a disease Be cautious in hot weather (> 94 F; 34C) Phytotoxicity can occur more easily in hot weather Potential for phytotoxicity can be reduced with greater water volume per acre Complex tank mixes, oil applications, and nutritional materials contribute to phytotoxicity Aerial applications not likely to get adequate penetration of canopy for control, best method is with an air blast sprayer
How the scheduler operates Incorporates rainfall data from FAWN (Florida Automated Weather Network-www.fawn.ifas.ufl.edu) or own weather data Incorporates data on copper residue degradation Incorporates fruit growth size This program may not be suitable for other citrus production regions due to varying climatic conditions and fruit growth habits The blue specks are copper residue
What s New? Lay out Select weather option and scion first Metric units
Select Bloom
Every 21- day Schedule Have insufficient coverage for 6 days About perfect timing for third spray
By Forecasts of Scheduler Moved first spray up 8 days Did not move third spray
What s New? Mobile version www.agroclimate.org/mobile Under tools
Location, Bloom, Spray Date 1 2 3
Cultivar and Results Gives results in table format
Copper Residue Summer 2011 2.0 120 Average copper/surface area ( g/cm 2 ) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Valencia 100 80 60 40 20 Total daily rainfall (mm) 0.0 Jun Jul Aug Sep Oct Nov 0 Date
Copper Residue Summer 2011 2.0 120 Average copper/surface area ( g/cm 2 ) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Grapefruit 100 80 60 40 20 Total daily rainfall (mm) 0.0 Jun Jul Aug Sep Oct Nov 0 Date
Future Plans Incorporate additional fruit growth data Two seasons collected Data collection resumed this year Potential Features Allow data to be stored on a server to avoid inputting the information every time Send alerts, as requested Login service
GREASY SPOT
Greasy Spot Disease Cycle Mycosphaerella citri
Greasy Spot Control Control products Copper - All formulations Strobilurin fungicides (Abound, Gem, Headline, Quadris Top and Pristine) Only once a year for greasy spot Mar Apr May Jun Jul Aug Sept Oct Valencia Oranges Grapefruit
Further Products Fungicides effective for greasy spot Enable good substitute for copper if concerned with stippling Petroleum oil Less consistent control on fruit than copper Can be mixed with all other fungicides
Formulations and Products Rates Tested on Grapefruit Treatment Metallic Cu (%) Rate (lbs/acre) Metallic Cu/acre 30 2.0 0.66 30 2.5 0.75 Nu-Cop 50 HB 50 2.0 1.00 Nu-Cop 20 HB 20 1.25 0.25 Nu-Cop 20 HB 20 1.875 0.375 Nu-Cop 20 HB 20 2.5 0.50 Basic HB 53 4 2.12 Basic HB 53 8 4.24
Formulations and Products Rates Cont. Treatment Metallic Cu (%) Rate (lbs/acre) Metallic Cu/acre IQV 40 DF 40 1.5 0.60 IQV 40 DF 40 2.0 0.80 IQV 40 DF 40 2.5 1.00 Untreated Control (UTC) -- -- --
Greasy Spot Control on Leaves (lb/acre) 1.8 a 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 b bc bcd bcd cde de de e e e e
Rind Blotch Control on Fruit (lb/acre) 0.6 0.5 0.4 a ab ab abc bc bcd bcd bcd cde de 0.3 0.2 0.1 0 ef f
% Marketable Fruit (lb/acre) 95 90 a ab 85 80 abc abc abc bc bc bc bc c c c 75 70
ALTERNARIA BROWN SPOT
Alternaria Brown Spot Disease Cycle Caused by Alternaria alternata
Alternaria Brown Spot Control Common control products Copper - All formulations Strobilurin fungicides (Abound, Gem, Headline, Quadris Top and Pristine) If severity high, useful for early sprays but also when hot Mar Apr May Jun Jul Aug Sept Oct Tangerines
Cultural Controls Ferbam Start with clean trees Increase air drainage in grove when planting Avoid excessive growth promotion Too much nitrogen Overwatering Severe hedging High vigour rootstocks
Fungicide Resistance Where the target population is no longer sensitive enough to a fungicide for sufficient control Occurs in response to the repeated use of a fungicide or related fungicides Field resistance Often becomes apparent with sudden total failure of control
Strobilurin Resistance In Florida Alternaria alternata isolates recovered in field survey (2010-2011) 36% 64% Resistant Sensitive N = 318
Number of isolates according to cultivar 160 140 120 Resistant Sensitive No. Isolates 100 80 60 40 20 0 Dancy Lee Minneola Murcott Orlando Sunburst Cultivar
Alternate Modes of Action? Currently registered Copper Ferbam Newer products released 2010 Quadris Top and Pristine Mixtures of strobilurins and novel modes of action Shown to be efficacious in two years of trials on Alternaria Brown Spot Two years of data on Melanose and Greasy Spot Rind blotch also effective
Programs with Pristine in 2010 Program April 20 May 21 June 16 July 7 Program 1 Boscalid (6.5 oz/acre) + Kocide 3000 (2.5 lb/acre) (3.5 lb/acre) Boscalid (6.5 oz/acre) + Kocide 3000 (2.5 lb/acre) (3.5 lb/acre) Program 2 Boscalid (6.5 oz/acre) (3.5 lb/acre) Boscalid (6.5 oz/acre) (3.5 lb/acre) Program 3 BAS703 (5.48 oz/acre) + Nonionic surfactant (1 pint/acre) (3.5 lb/acre) Bas 703 (5.48 oz/acre) + Nonionic surfactant (1 pint/acre) (3.5 lb/acre) Program 4 Pristine (18.5 oz/acre) (3.5 lb/acre) Pristine (18.5 oz/acre) (3.5 lb/acre) Program 5 Untreated control Untreated control Untreated control Untreated control
Efficacy on Minneola 2.0 1.8 1.6 a 100 90 80 a ab b b Disease Rating 1.4 1.2 1.0 0.8 0.6 0.4 0.2 b b c c % Marketability 70 60 50 40 30 20 10 c 0.0 Untreated control Program 1 Program 2 Program 3 Treatments Program 4 0 Program 4 Program 3 Program 2 Program 1 Treatments Untreated Control
Programs with Quadris Top, 2010 Date April 1 May 4 June 2 June 14 July 9 Aug. 9 Program 1 Program 2 Untreated control Headline (12 fl oz) Untreated control (3.5 lb) Untreated control Headline (12 fl oz) Untreated control (3.5 lb) Untreated control (3.5 lb) Untreated control Headline (12 fl oz) + 2% 435 Oil Program 3 Quadris Top (12 fl oz) (3.5 lb) Quadris Top (12 fl oz) (3.5 lb) (3.5 lb) Quadris Top (12 fl oz) + 2% 435 Oil Program 4 Quadris Top (15.4 fl oz) (3.5 lb) Quadris Top (15.4 fl oz) (3.5 lb) (3.5 lb) Quadris Top (15.4 fl oz) + 2% 435 Oil Program 5 Quadris Top (15.4 fl oz) SA 123 (6 pints) Quadris Top (15.4 fl oz) SA 123 (6 pints) SA 123 (6 pints) Quadris Top (15.4 fl oz) + 2% 435 Oil Program 6 SA 123 (6 pints) (3.5 lb) SA 123 (6 pints) (3.5 lb) (3.5 lb) SA 123 (6 pints)
Efficacy on Murcott with Strobilurin Resistance 4.0 a 3.5 70 60 a Disease Rating 3.0 2.5 2.0 1.5 1.0 b b c c d % Marketability 50 40 30 20 b bc cd d 0.5 0.0 Untreated Control Program 2 Program 6 Program 3 Treatments Program 4 Program 5 10 0 Program 5 Program 3 Program 4 Program 6 Treatments Program 2 e Untreated Control
Looking for Tangerine Groves Sampling for strobilurin resistance Want to sample all groves with or without problems Contact Megan Dewdney CREC ph. 863-956-1151
Questions?