Scheduling copper applications and management of greasy spot and alternaria brown spot

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Yates 1 1 University of Florida, IFAS, Citrus Research and Education

1 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

2 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

3 Diseases Effectively Managed with Copper Foliar fungal diseases Melanose Greasy Spot Alternaria brown spot Citrus scab Black spot Non-systemic bacterial diseases Citrus canker

4 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

5 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

edu) or own weather data Incorporates data on copper residue degradation Incorporates fruit

6 How the scheduler operates Incorporates rainfall data from FAWN (Florida Automated Weather Network- 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

7 What s New? Lay out Select weather option and scion first Metric units

8 Select Bloom

9 Every 21- day Schedule Have insufficient coverage for 6 days About perfect timing for third spray

10 By Forecasts of Scheduler Moved first spray up 8 days Did not move third spray

11 What s New? Mobile version Under tools

12 Location, Bloom, Spray Date 1 2 3

13 Cultivar and Results Gives results in table format

14 Copper Residue Summer Average copper/surface area ( g/cm 2 ) Valencia Total daily rainfall (mm) 0.0 Jun Jul Aug Sep Oct Nov 0 Date

15 Copper Residue Summer Average copper/surface area ( g/cm 2 ) Grapefruit Total daily rainfall (mm) 0.0 Jun Jul Aug Sep Oct Nov 0 Date

16 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

17 GREASY SPOT

18 Greasy Spot Disease Cycle Mycosphaerella citri

19 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

20 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

21 Formulations and Products Rates Tested on Grapefruit Treatment Metallic Cu (%) Rate (lbs/acre) Metallic Cu/acre Nu-Cop 50 HB Nu-Cop 20 HB Nu-Cop 20 HB Nu-Cop 20 HB Basic HB Basic HB

22 Formulations and Products Rates Cont. Treatment Metallic Cu (%) Rate (lbs/acre) Metallic Cu/acre IQV 40 DF IQV 40 DF IQV 40 DF Untreated Control (UTC)

23 Greasy Spot Control on Leaves (lb/acre) 1.8 a b bc bcd bcd cde de de e e e e

24 Rind Blotch Control on Fruit (lb/acre) a ab ab abc bc bcd bcd bcd cde de ef f

25 % Marketable Fruit (lb/acre) a ab abc abc abc bc bc bc bc c c c 75 70

26 ALTERNARIA BROWN SPOT

27 Alternaria Brown Spot Disease Cycle Caused by Alternaria alternata

28 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

29 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

30 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

31 Strobilurin Resistance In Florida Alternaria alternata isolates recovered in field survey ( ) 36% 64% Resistant Sensitive N = 318

32 Number of isolates according to cultivar Resistant Sensitive No. Isolates Dancy Lee Minneola Murcott Orlando Sunburst Cultivar

33 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

34 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

35 Efficacy on Minneola a a ab b b Disease Rating b b c c % Marketability 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

36 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)

37 Efficacy on Murcott with Strobilurin Resistance 4.0 a a Disease Rating b b c c d % Marketability b bc cd d Untreated Control Program 2 Program 6 Program 3 Treatments Program 4 Program Program 5 Program 3 Program 4 Program 6 Treatments Program 2 e Untreated Control

38 Looking for Tangerine Groves Sampling for strobilurin resistance Want to sample all groves with or without problems Contact Megan Dewdney CREC ph

39 Questions?

Fungal foliar disease management

Fungal foliar disease management Megan M. Dewdney Associate Professor of Plant Pathology and Extension Specialist University of Florida, IFAS Citrus Research and Education Center POSTBLOOM FRUIT DROP Postbloom