Mummy Berry of Blueberry in the Pacific Northwest. Dalphy OC Harteveld and Tobin L Peever Department of Plant Pathology Washington State University

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1 Mummy Berry of Blueberry in the Pacific Northwest Dalphy OC Harteveld and Tobin L Peever Department of Plant Pathology Washington State University

2 Flower Strikes

3 Flower Strikes

4 Shoot Strikes

5 Dissemination of Spores (conidia)

6 Fruit Symptoms

7 Fruit Symptoms

8 Overwintering

9 Apothecia

10 Ascospore Release N Sanoamuang and RE Gaunt HR Dillard Philip Wharton, MSU

11 Problem Mummy berry causes annual losses to the blueberry industry in US-PNW, fruit yield loss up to 70% in individual affected fields Current control is inconsistent and timing of fungicide applications not based on fungal biology Limited information on epidemiology of mummy berry in PNW most research has been performed in eastern North America

12 Ascospores infect emerging leaf and flower tissues Monilinia vaccinii-corymbosi Annemiek Schilder, MSU

13 Timing of Apothecia in Different Locations * Georgia North Carolina Maryland Washington Oregon British Columbia March * Scherm (2001), Milholland (1977), Batra (1983), Bristow (1979), Pscheidt (2011), Teasdale (2009)

14 Timing of Apothecia in Same Location Corvallis, Oregon 15 Mar 20 Mar 25 Mar 30 Mar 3 Apr 8 Apr Data from Jay Pscheidt, OSU

15 From Mummy to Apothecia Chilling Requirement Maturation Dormancy Germination Sporulation Environmental factors

16 Mummy Germination and Apothecial Development Chilling requirement Hours Location NC 1 <700 GA 2 Environmental factors Relative humidity 4 Air temperature 5,6,7 Soil moisture 7 Light 7,8 ~700 WA 3 1 Milholland (1977), 2 Scherm (2001), 3 Bristow (1979), 4 Ramsdell (1973), 5 Scherm (2000), 6 Wharton (2004), 7 Milholland (1974), 8 Florence (2016)

17 Blueberry Susceptibility Young, emerging tissue from flower and leaf buds 1 Need to time the application of fungicides with leaf bud development 2 Host resistance likely related to phenology of the cultivar 3,4,5 1 Milholland (1974), 2 Ramsdell (1973,1974), 3 Lehman & Oudemans (1997), 4 Pepin (1969), 5 Ehlenfeldt (1996)

18 Research Objectives Determine timing of primary inoculum (ascospore) release in PNW Determine the environmental factors that influence apothecial development and longevity Determine differences in timing of bud break and susceptibility of blueberry cultivars grown in PNW Develop a prediction model for ascospore release

19 Infection risk Pathogen

20 Materials and Methods Field experiments during 2015 and 2016 production seasons Monitoring of apothecial absence/presence at: - one field in Whatcom County, WA - one field in Skagit County, WA - one field in Benton County, OR* Burkard spore traps to capture ascospores in WA *Jay Pscheidt, OSU

21 Timing of Apothecia Presence/Absence Duration of ascospore release Eastern USA = days, mean ~16 days. Lehman (1997, 2000), Sanderson (1992), Ramsdell (1974, 1975)

22 Infection risk

23 Environmental Factors Daily average or daily total of : WSU AgWeathernet Air temperature Relative humidity Leaf wetness Soil temperature Precipitation Solar radiation In-field weather stations (HOBO data loggers) Air temperature Relative humidity Leaf wetness Soil temperature Soil moisture Source:

24 Regression Analyses Significant environmental factors (P<0.05) affecting apothecia absence/presence Time frame Soil T Air T RH LW Precip Solar Soil M + 30 day prior ** ** ** ** * + 30 day post ** * * ** * * P < 0.05 ** P < 0.005

25 Environmental Factors Daily averages for environmental factors one month before, during, and one month after apothecial presence Factor Before During After Soil Temperature ( F) Soil Moisture (m 3 /m 3 ) Air Temperature ( F) Solar Radiation (MJ/m 2 ) Leaf Wetness (U)

26 Environmental Factors WSU AgWeatherNet data could be used instead of in-field weather stations BUT soil moisture data are not collected by AgWeatherNet

27 Infection risk

28 Susceptible Stages of the Host Tight bud Bud swell Bud burst Tight cluster Early pink bud Tight bud Bud swell Early green tip Late green tip Shoot expansion Lehman (1997), Ehlenfeldt (1996), Hildebrand (1991) Source: Michigan State University Extension

29 Timing of Susceptibility Whatcom and Skagit Counties 4 common WA cultivars (Bluecrop, Duke, Liberty, Draper) 3 fields of each cultivar per county Marked 6 shoots on 6 plants per field Weekly monitoring of development, taking photographs Determined stages from photographs

30 Susceptible Flower Buds during Ascospore Release Percentage susceptible tissue (%) Mar 10-Mar 17-Mar 24-Mar 31-Mar 7-Apr Whatcom Bluecrop Whatcom Draper Whatcom Duke Whatcom Liberty Skagit Bluecrop Skagit Draper Skagit Duke Skagit Liberty Mar 13-Mar 20-Mar 27-Mar 3-Apr

31 Susceptible Leaf Buds during Ascospore Release Percentage susceptible tissue (%) Whatcom Bluecrop Whatcom Draper Whatcom Duke Whatcom Liberty 80 Skagit Bluecrop Skagit Draper 70 Skagit Duke Skagit Liberty Mar 10-Mar 17-Mar 24-Mar 31-Mar 7-Apr Mar 13-Mar 20-Mar 27-Mar 3-Apr

32 Susceptible Buds during Ascospore Release Susceptible flower flower tissue tissue Susceptible leaf tissue AUSTC AUSTC = Area Under Susceptible Tissue Curve

33 Research Outcomes Initiation Experiencing and longevity relatively of long primary periods inoculum of ascospore release release and period up to the 37 days plants between may need early protection March and mid-april Multiple Timing and environmental duration of factors fungicide associated applications with require apothecia monitoring development of environmental were identified; factors soil moisture, using WSU soil temperature, AgWeathernet solar radiation, and/or air temperature in-field weather and leaf sensors wetness to determine risk for apothecia development Flowers may play a more important role than leaf buds Both flower and leaf bud development need to be monitored closely

34 Infection risk

35 Prediction Model Development Binary response variable: apothecial presence (1)/absence (0) Environmental factors 7 predictors Data Period: one month before, during and one month after apothecia were present, total of days Data random split into a training (70%) and test (30%) dataset, 500x Four different model building algorithms

36 Prediction Accuracy of Models 0.8 Accuracy 0.7 Number of predictors GLM MARS Neural Nets Random Forest

37 Prediction of Ascospore Release Environmental factors Range Average Soil Temperature( F) Soil Moisture (vol%) Solar Radiation (MJ/m 2 ) Susceptible Host Stages Flower bud Bud break Tight cluster Leaf bud >1/4 inch green

38 Estimating risk in your blueberry field History of mummy berry in field or neighboring fields? Early or late maturing cultivar? Monitor bud development in early spring Susceptible floral tissue versus leaf tissue? Check in-field weather station or AgWeatherNet for daily values of soil temperature and moisture and solar radiation

39 Spore Release Prediction - App

40 Mummy Berry Updates

41 Acknowledgements Washington Blueberry Commission Washington State Commission for Pesticide Registration Northwest Agricultural Research Foundation Washington blueberry growers Tobin L. Peever, Olga Kozhar, Dave Dutton Washington State University Small Fruit Pathology Jay W. Pscheidt - Oregon State University Michael R. Grant - University of Washington WSU Mount Vernon NWREC

42 Thank you! Questions?!