Botryosphaeria, Phomopsis and Anthracnose Management in Walnuts

Transcription

1 Botryosphaeria, Phomopsis and Anthracnose Management in Walnuts Yong Luo 1, Dan Felts 1, Dani Lightle 2, Roger Duncan 3, & Joseph Connell 4 1 Dept. of Plant Pathology, University of California Davis/ Kearney Agricultural Research & Extension Center; UC Cooperative Extension, 2 Glenn & Butte Counties, Orland; 3 Stanislaus County, Modesto 4 Butte County, Oroville. 49 th Quad-County Walnut Institute, 5 Feb 2019

2 Bot and Phomopsis canker and blight of walnut: Infection of walnut fruit & killing of spurs Development of blight and canker The causes of the disease Contributing factors Best disease management

3 Walnut Blight Bot latent infection

4 1 --- Disease Progress --- Infection of intact fruit in the orchard All the species of Botryosphaeria and Phomopsis Fruit Fruit 2 3 Peduncle Walnut leaves are not infected by Bot Infect Spurs/shoots

5 Progress of infection by Botryosphaeria in the orchard Pycnidia

6 Symptoms in the orchard Blighted nuts (late August, September, & October) Moldy nuts at harvest

7 Blighted fruit and spurs Symptoms in the orchard buds dead!

8 Symptoms in the orchard buds dead!

9 Other Symptoms in the orchard Branch cankers canker Trunk cankers (in young trees) J. Hasey pith

10 The Causes: Fungal species Walnut Pistachio Almond Botryosphaeria dothidea + Neofusicoccum parvum + Neofusicoccum mediterraneum + Diplodia mutila + Neofusicoccum nonquaesitum + Neofusicoccum vitifusiforme + Diplodia seriata + Dothiorella iberica + Lasiodiplodia citricola + Neoscytalidium dimitiatum (=Hendersonula toruloidea) branch wilt pathogen +

11 The Causes Fungal species Walnut Pistachio Almond Botryosphaeria dothidea + Neofusicoccum parvum + Neofusicoccum mediterraneum + Diplodia mutila + Neofusicoccum nonquaesitum + Neofusicoccum vitifusiforme + Diplodia seriata + Dothiorella iberica + Lasiodiplodia citricola + Neoscytalidium dimitiatum (=Hendersonula toruloidea) branch wilt pathogen Diaporthe rhusicola (Phomopsis) + Diaporthe neitheicola (Phomopsis) + +

12 The Causes: Summary of Botryosphaeriaceae in nut crops California Fungal species Walnut Pistachio Almond Botryosphaeria dothidea Neofusicoccum parvum Neofusicoccum mediterraneum Diplodia mutila Neofusicoccum nonquaesitum Neofusicoccum vitifusiforme Diplodia seriata Dothiorella iberica Lasiodiplodia citricola Neoscytalidium dimitiatum (=Hendersonula toruloidea) Diaporthe rhusicola (Phomopsis) Diaporthe neitheicola (Phomopsis)

13 Water-splashed inoculum in pycnidia pycnidia conidia oozing pycnidia water splashed or insect spread pycnidia

14 Inoculum in pseudothecia Ascospores: airborne-spread pseudothecia

15 Contributing factors: walnut scale Walnut scale Botryosphaeria canker

16 Effect of walnut scales on infection of walnut by Botryosphaeriaceae (cv. Vina) Inoculation without wounding 60-75% more shoots were infected when scales were present

17 Contributing factors: Irrigation Sprinkler irrigation wetting the tree canopy High-angle irrigation systems

18 High risk for Bot disease to srart early in this orchard D. Lightle 2018

19 Contributing factors: Pruning wounds D. Lightle 2018 Susceptible for 4 months!

20 pith pith Pith in the center of walnut shoots and Botryosphaeria infections pith

21 Effect of shoot age on infection of pruning wounds to infection by Bot 16 Pruning on 9 & 10 February 2015 Average canker length (cm) b b a a 0 1 year 2 year 3 year 4 year Age of inoculated shoots

22 Accumulated dead wood on the tree

23 Contributing factors: nut and shoot wounds Sunburn Hail Damage Downy Spot Leaf Scars Microstroma juglandis

24 Contributing factors: Brown Apical Necrosis Walnut blight

25 Contributing factors: Branch wilt: (Neoscytalidium dimitiatum)

26 Contributing factors: branch wilt 40% Bot 20% Phomopsis 40% Blighted (no fungus) Phomopsis Branch wilt Botryosphaeria Botryosphaeria Botryosphaeria Botryosphaeria Phomopsis

27 Contributing factors: frost damage About 50% of the frost damaged shoots/spurs developed pycnidia in a year.

28 Disease management Sanitation: Pruning dead wood is very important

29 What is wrong in this orchard? Too much inoculum is present on the trees

30 What is wrong with this photo? 1 2 Too much inoculum is left in or brought back in the orchard

31 Huller debris 90% infected Botryosphaeria. 40% Phomopsis.. 30% Botryosphaeria + Phomopsis. 20% No fungus.10% No pathogen Compost: 0% pathogens Botryosphaeria....0% Phomopsis..0% Botryosphaeria + Phomopsis 0%

32 Which orchard is more at risk? Winter pruning - February Fall pruning -November D. Lightle 2018

33 Brush Disposal Recommendations Infestation level Chip? Remove? Fungicide program? None Yes No Not needed Light (1-20%) No Yes 1 spray Moderate (20-50%) No Yes 1+ sprays Heavy (> 50%) Yes No Full program Chipping brush reduces inoculum by two-thirds (66%)

34 Fungicide Active ingredient (FRAC #) Efficacy Quash metaconazole (3) ++++ Merivon fluxopyroxad + pyraclostrobin (7/11) ++++ Pristine boscalid + pyraclostrobin (7/11) ++++ K-Phite polyphosphite (33) ++++ Luna Experience Luna Sensation Fungicide efficacy: fluopyram + tebuconazole (7/3) ++++ fluopyram + trifloxystrobin (7/11) = excellent and consistent ipm.ucanr.edu/pdf/pmg/fungicideefficacytiming.pdf

35 Timing sprays Option 1: Late June/ early July (1x) Option 2: Standard calendar sprays (3x) mid-may, mid-june, mid-july (PCAs and Growers favorable) Option 3: Leaf wetness model (weather dependent)

36 Using the Leaf Wetness Model Rain: April 22-23: 0.6 Infection event: At least ¼ inch rain At least 50 ºF

37 Anthracnose (Marssonina juglandis) Initial infections in the spring after rains

38 Severe anthracnose leaf blade necrotic lesions

39 Salt burn symptoms

40 Severe anthracnose leaf petiole necrotic lesions

41

42 Inoculum of the pathogen Marssonina juglandis Acervulli = spore fruiting structures of anthracnose t =

43 Severe defoliation

44 Airborne phase (Gnomonia leptostyla) perithecia with ascospores

45 Initial Anthracnose lesions on fruit

46 Anthracnose of walnut fruit * Acervullus = spore producing structure

47 Walnut blight bacterial disease

48 secondary cycle Gnomonia

49 Anthracnose of black walnut Necrotic lesions on leaves and fruit

50 Paradox Black walnut

51 Anthracnose Foliar Disease Ratings (by Bill Coates, FA, San Benito Co.) 1= NO DISEASE, 5 = SEVERE DISEASE Most susceptible RATING # OF OBS Serr Payne Hartley Chandler Pedro Howard Tulare Least susceptible Serr, Payne > Hartley, Chandler > Howard > Tulare

52 Precipitation from March to September and anthracnose incidence (San Benito Co.; ) Rainfall from March to September inches (133 mm) 0.4 inches (10.6 mm) 2.6 inches (66 mm) 1.4 inches (34 mm) 1.4 inches (36 mm) 3.4 inches (85 mm). 5.1 inches 129 mm) A n t h r a c n o s e %* 0% 0% 0% 41% 85.7% 27%

53 Anthracnose Fungicide Trial (Hollister; Serr, recorded July 5, 2012) Control Leaves c (Not registered) Syllit b Inspire Super Pristine Quilt Xcel Luna Experience ab ab a a Leaves with lesions (%)

54 Anthracnose Efficacy Trial (Serr, 2017) Indar a Spray dates: 24 April; 12 May; 2 June Luna Experience a Merivon a Luna Experience + Movento a Luna Experience + Serenade/Movento ab Luna Experience + Serenade ab Pyraziflumid 3.4 fl oz bc Pyraziflumid 5 fl oz Badge + Manzate ProStick c d Control e Leaves with lesions (%)

55 Fungicide efficacy against Anthracnose Fungicide Active ingredient (FRAC #) Efficacy Copper mancozeb (Manzate/Dithane) Carbamate (EBDC) 2 (M3) ++++ Luna Experience fluopyram + tebuconazole (7/3) ++++ Merivon fluxopyroxad + pyraclostrobin (7/11) ++++ Pristine boscalid + pyraclostrobin (7/11) ++++ Ph-D chitin synthesis inhibitor (19) ++++ Quadris Top Difenoconazole (3)+azoxystrobin (11) ++++ Quash metaconazole (3) ++++ Quilt Excel Propiconazole (3)+azoxystrobin (11) ++++ TIMING: 1 st spray: 3 rd week in April (1/2 first leaves size); 2 nd spray: 1 st 2 nd week in May; and 3 rd spray: 4 th week in May

56 Thank you for your attention A We also thank: California Walnut Board, UC Farm Advisors, PCAs, & BASF, Syngenta, Bayer, DuPont, Nishino, Valent, FMC, et al. and a multitude of walnut growers

57 Interaction of Botryosphaeria (Neofusicoccum med.) and Phomopsis Length of necrosis (cm) a c b a a 2 0 N. mediterraneum D. rushicola Dr Nm (after 4 days) Nm Dr (after 4 days) Nm Dr Neof. Phom. Phom.+Neof. Neof.+Phom. Both

58 Effect of temperature on growth of Phomopsis, Neofusicoccum, and Lasiodiplodia species Phomopsis 72 F 81 F Lasiodiplodia F Neofusicoccum Radial growth (mm) Degrees Celsius