cankers, and ascospores (sexual spores) Efficacy of Fungicide Treatments for Control of may cause new N. malicorticis infections Anthracnose Canker in Young Cider Apple in the spring (Powell et al., 1970; Rahe, 1997a). Canker progression is slow or Trees in Western Washington ceases in the winter, is more rapid in the spring, and by early summer, cankers 1 2 1 are fully developed (Creemers, 2014; Whitney J. Garton , Mark Mazzola , Travis R. Alexander , Davidson and Byther, 1992). Although and Carol A. Miles1,3 N. malicorticis is the primary pathogen that induces anthracnose canker, addi- tional species, including Phlyctema vaga- ADDITIONAL INDEX WORDS. Malus ·domestica, Neofabraea species, zinc, copper bunda (synonym Neofabraea alba)and sulfate, captan, thiophanate-methyl, pyraclostrobin plus boscalid Neofabraea kienholzii have also been SUMMARY. Anthracnose canker, caused by Neofabraea malicorticis, threatens the implicated as the cause of this disease sustainability of cider apple (Malus ·domestica) production in the maritime climate (Zang et al., 2011). of western Washington. In the short-term, the disease reduces overall orchard Populations of N. malicorticis productivity and in the long-term it reduces an orchard’s economic life span. The have been reported throughout North disease is difficult to manage using cultural practices, and information on fungicide America, Africa (Zimbabwe), Oceania efficacy is limited and contradictory. To address this situation, a 2-year study was (Australia and New Zealand), and conducted to evaluate efficacy of zinc (4.49 lb/acre), basic copper sulfate (2.49 lb/ acre), captan (2.94 lb/acre), thiophanate-methyl (0.69 lb/acre), pyraclostrobin Europe (European and Mediterra- plus boscalid (0.38 lb/acre), and combinations of these fungicides to manage nean Plant Protection Organization, anthracnose canker infection in young cider apple trees cultivated in a maritime 2017), with disease severity observed climate. Trees used in the first year of the study (2016) were found to be infected by to be highest in the maritime PNW. anthracnose canker on receipt, so the first year was a measure of disease control and Environmental conditions of the mar- the second year (2017) was a measure of disease prevention. In 2016, when itime PNW favor growth and spore fungicide treatments were applied every 3 weeks from March through October, dissemination of N. malicorticis year- none of the treatments evaluated inhibited the development of new infections or the round (Hortova et al., 2014; Kienholz, expansion of existing cankers (77% increase in canker size on average for all 1939; Miller, 1932; Senula, 1985; treatments). In 2017, when fungicide treatments were applied every 3 weeks from February through April, two to three new cankers were observed 3 weeks after final Spotts and Peters, 1982). The temper- treatment application for all treatments. Results from this study demonstrate that ature in northwest Washington, for the current fungicides recommended for control of anthracnose canker are not example, is 14 C on average during reliably effective in the orchard environment of northwest Washington. Future the growing season (April–October) studies should assess the fungicides evaluated in this study applied in rotation with and 6 C during the dormant season additional systemic fungicides. (November–March) (Washington State University, 2017). Relative humidity nthracnose canker, caused by newly planted cider apple trees west of is 73% to 82% on average during Neofabraea malicorticis, in- the Cascade Mountains in the U.S. the growing season and 82% to 91% Aduces tree cankers that can kill Pacific Northwest (PNW) (Garton during the dormant season, while et al., 2018a; Rahe, 1997a). N. mali- 76 mm precipitation occurs on average Received for publication 2 Oct. 2018. Accepted for corticis can infect intact bark tissue, during the growing season and 101 mm publication 7 Nov. 2018. and most infections occur through occurs during the dormant season. Solar Published online 4 February 2019. the lenticels (Cordley, 1900; Kienholz, radiation in the area also tends to be Funding and support for this project is gratefully 1939). Acervuli (asexual fruiting bodies) moderate, with 506 MJÁm–2 during acknowledged from Washington State University Extension, Washington State Commission on Pesti- form on mature cankers in midsummer the growing season on average, and cide Registration, Northwest Cider Association, to late-autumn, producing conidia 157 MJÁm–2 during the dormant season. Northwest Agricultural Research Foundation, and (asexual spores) that cause new N. mali- Cider apple growers in western Washington State Project WN00427–Acc. No. 1000194. corticis infections (Creemers, 2014) in Washington use several measures to The mention of a trademark, proprietary product, or autumn and winter during mild, moist control anthracnose canker, includ- company does not constitute a guarantee or warranty weather (Davidson and Byther, 1992; ing excising cankers from infected of the product by the USDA-ARS and does not imply its approval to the exclusion of other products or Rahe, 2010). Apothecia (sexual fruiting wood and applying fungicides before companies that also may be suitable. bodies) may develop on overwintering autumn rains (Pscheidt and Ocamb, 1Department of Horticulture, Washington State Uni- versity Northwestern Washington Research and Ex- tension Center, 16650 State Route 546, Mount Units Vernon, WA 98273 To convert U.S. to SI, To convert SI to U.S., 2U.S. Department of Agriculture-Agricultural Re- multiply by U.S. unit SI unit multiply by search Service, Physiology and Pathology of Tree Fruits Research Laboratory, 1104 N. Western Ave- 0.3048 ft m 3.2808 nue, Wenatchee, WA 98801 3.7854 gal L 0.2642
3 25.4 inch(es) mm 0.0394 Corresponding author. E-mail: [email protected]. 6.4516 inch2 cm2 0.1550 This is an open access article distributed under the CC 0.0418 langley(s) MJÁm–2 23.9006 BY-NC-ND license (https://creativecommons.org/ 1.1209 lb/acre kgÁha–1 0.8922 licenses/by-nc-nd/4.0/). 1.6093 mile(s) km 0.6214 https://doi.org/10.21273/HORTTECH04201-18 ( F – 32) O 1.8 F C( C · 1.8) + 32
• February 2019 29(1) 35 RESEARCH REPORTS
2017). Zinc [Fungicide Resistance was to better understand the efficacy for 4 h at a rate of 0.5 gal/h from early Action Committee (FRAC) code of current fungicides recommended June to early September (Moulton M03], captan (FRAC code M04), for control of anthracnose canker, et al., 2010). In 2017, irrigation was and copper-based products (FRAC specifically, zinc, basic copper sulfate, not applied, as there was adequate pre- code M01) are the common fungicides captan, thiophanate-methyl, and pyr- cipitation throughout the study period, applied in PNW cider apple orchards. aclostrobin plus boscalid, on cider whichendedinMay. However, Garton et al. (2018b) found apple trees in the maritime PNW. FUNGICIDE TREATMENTS. In new N. malicorticis infections of sus- 2016, trees were planted in the or- ceptible hosts to occur after applying Materials and methods chard in March, and a control treat- many of these common fungicide treat- ORCHARD SITE. This study was ment (no fungicide) plus four ments on cider apple trees in northwest conducted in 2016 and 2017 in fungicide treatments were applied: Washington. Further, in commercial a cider apple research orchard at 4.49 lb/acre zinc (Ziram 76 DF; orchards, these fungicide treatments Washington State University (WSU) United Phosphorus, King of Prussia, have not provided significant disease Northwestern Washington Research PA), 0.38 lb/acre pyraclostrobin control, as orchards continue to be and Extension Center (NWREC), in plus boscalid (Pristine; BASF Corp., abandoned or torn out within 4 years Mount Vernon, WA. Weather data Research Triangle Park, NC), 0.69 of symptom appearance (Garton et al., (mean air temperature, relative hu- lb/acre thiophanate-methyl (Topsin 2018a; Rahe, 1997a). midity, total precipitation, and solar M, United Phosphorus), and 2.49 Research on fungicide efficacy radiation) were recorded every 5 s and lb/acre basic copper sulfate (Bonide for control of anthracnose canker on summarized every 15 min by a weather Copper; W. Neudorff, Emmerthal, apple trees in general is limited and station located 0.4 miles from the Germany). Treatments were first ap- contradictory. In an orchard study in orchard (WSU, 2017). Plots were plied on 18 Mar. and were repeated western Washington, Byther (1986) established in a randomized complete every 3 weeks until 21 Oct. (13 found a 50% reduction in the number block design with five assigned single- applications in total). Application of of new canker infections to develop tree replicates per fungicide treatment. zinc was ended in September (11 on trees when zinc and basic copper Both years, experimental treatments applications in total) due to the treat- sulfate were applied in mid-October were applied to newly planted trees that ment inducing symptoms of phyto- and again in mid-February. In an in were sourced from commercial nurser- toxicity (premature leaf drop and leaf vitro study in British Columbia, Can- ies. In 2016, trees used in the study burn). Although this number of ap- ada, Rahe (1997a) found captan to were ‘Tompkins King’ on ‘Malling- plications of the same fungicide is not be moderately toxic to N. malicorti- Merton 106’ (MM.106) that were a recommended practice, the aim of cis, whereas copper-based fungicides budded at a local nursery in Aug. this test was to discern if these chem- were nontoxic to the fungus. Rahe 2014, received at WSU NWREC in istries had any activity against the (1997b) also investigated efficacy of early Nov. 2015, and were established pathogen in an orchard setting thiophanate-methyl (FRAC code 1) in pots in a screen house to minimize throughout the summer. In 2017, and thiram (FRAC code M3) for potential for N. malicorticis infection trees were moved outside the screen control of anthracnose canker on from the orchard before onset of the house in treatment groups, fungicide trees in British Columbia and found experiment; however, trees were found applications were performed, and af- the fungicides to be ineffective when to have early anthracnose canker in- ter the restricted entry interval for applied biweekly from mid-August fectiononreceipt.In2017,‘Ash- each fungicide treatment passed, the through late October. Research in mead’s Kernel’ on ‘Geneva 11’ were trees were planted into the orchard. A central Washington has tested fungi- sourced from a commercial nursery control treatment (no fungicide) plus cide efficacy to control four Neofab- outside of the PNW for this study. eight fungicide treatments were ap- raea species (N. alba, N. malicorticis, Trees were nursery-budded in Aug. plied: 4.49 lb/acre zinc (Ziram 76 N. perennans, and N. kienholzii) that 2015 and received at WSU NWREC DF), 0.38 lb/acre pyraclostrobin plus cause bull’s-eye rot on pome fruit the end of Nov. 2016. On receipt, trees boscalid (Pristine), 0.69 lb/acre thi- (Rosaceae), and found thiabendazole were inspected visually and found to be ophanate-methyl (Topsin M), 2.94 (FRAC code 1), thiophanate-methyl, clean of anthracnose cankers. Trees lb/acre captan (Captan 80 WDG; pyrimethanil (FRAC code 9), and wereestablishedinpotsinascreen Arysta LifeScience North America pyraclostrobin plus boscalid (FRAC house to prevent N. malicorticis in- Corp., Cary, NC); 4.49 lb/acre zinc + codes 11 and 7, respectively) to con- fection from the orchard before onset 0.69 lb/acre thiophanate-methyl, trol all Neofabraea species, whereas of the experiment. Trees were planted 4.49 lb/acre zinc + 0.38 lb/acre zinc did not provide effective control into different orchard blocks each year; pyraclostrobin plus boscalid, 2.94 of N. malicorticis but copper sulfate in 2016, spacing was 10 ft in-row and lb/acre captan + 0.69 lb/acre thio- did (Spotts et al., 2009). Creemers 13 ft between rows, and in 2017, phanate-methyl, and 2.94 lb/acre (2014) recommended the use of spacing was 3 ft in-row and 13 ft captan + 0.38 lb/acre pyraclostrobin chemistries such as quinone outside between rows. Both years, trees were plus boscalid. Treatments were first inhibitors (FRAC code 11) for con- staked (bamboo in 2016 and metal in applied on 17 Feb. and were repeated trolling anthracnose canker, but 2017) for support, and managed pur- every 3 weeks until 21 Apr. (four Aguilar et al. (2018) reported such suant to the principles of a tall spindle applications in total), and treatments chemistries as ineffective in control- orchard system. Drip irrigation tape was with two fungicides were alternated ling diseases incited by Neofabraea placed directly on the soil surface, and in in the order in which they were listed. species. The objective of this study 2016, irrigation was applied twice a week Treatment application in 2017
36 • February 2019 29(1) continued until trees in all treatments present throughout the excision zone. new cankers and tissue streaking were showed symptoms of infection. Both The amount of exposed cambium compared using Student’s t test at years, fungicide treatments plus sur- tissue that exhibited dark brown a 5% level of significance. factant (R-11 Spreader Activator; streaking was then visually rated on Wilbur-Ellis Co., Aurora, CO) were a scale of 0 to 5 as follows: 0 = no Results applied to the entire tree in each streaking, 1 = 1% to 20% streaking, CLIMATE. Daily mean air temper- treatment group, using a hand-pump 2 = 21% to 40% streaking, 3 = 41% ature in 2016 was 10.6 C from sprayer equipped with a cone nozzle to 60% streaking, 4 = 61% to 80% March through April, and 15.0 C (SureSpray; Chapin International, streaking, and 5 = more than 81% from May through October (Fig. 1). Batavia, NY) until runoff. Applications streaking. Symptomatic tissue was In 2017, daily mean air temperature in the orchard were made with a plastic collected from the treated cankers of was 7.5 C from February through screen (6 · 6 ft) placed between trees all five trees per treatment, for path- April (Fig. 2). Daily mean relative at the time of application to prevent ogen isolation and identification. Tis- humidity was similar both years, 78% chemical drift between trees. sue was surface sterilized in 0.5% in 2016 and 80% in 2017 (Figs. 1–2). CANKER SIZE. In 2016, three sodium hypochlorite and rinsed with Mean precipitation in 2016 was anthracnose cankers were randomly sterile distilled water, then small sec- 2.5 mm March through April and selected per tree for measurement tions were plated onto potato dextrose 1.9 mm from May through October, throughout the experiment to com- agar [PDA (Difco; Becton, Dickinson whereas in 2017, mean precipitation pare fungicide treatment effects. The and Co., Sparks, MD)] amended with was 3.2 mm February through April length and width of each canker were chloramphenicol (Sigma-Aldrich Co., (Figs. 1–2). measured pretreatment and 2 months St. Louis, MO). Plates were incubated CANKER SIZE. In 2016, average after the initial treatment application. at 68 to 72 F, and cultures were canker size was 0.24 cm2 pretreat- Thereafter, canker length and width transferred to fresh PDA weekly. ment and there was no significant were measured once every month DATA ANALYSIS. The assump- difference in initial size of cankers until 16 Sept. for the zinc treatment tions of normality and homogeneity before treatment application [P = and 11 Nov. for all other treatments. of variances were assessed in all cases 0.88 (Fig. 3)]. Canker size signifi- Canker size was calculated for each using the Shapiro-Wilk test (W > cantly increased over time (P < date using an equation for an ellipse 0.80) and the Levene test (a = 0.0001), but did not differ among [PI function (Microsoft Excel 2013; 0.05), respectively. Size of the canker, fungicide treatments over time (P = Microsoft, Redmond, WA)], and size total number of new cankers to de- 0.72). Two months after the initial was averaged for the three canker velop on each tree, and disease sever- application, canker size increased by subsamples per treatment replicate. ity data were subjected to repeated 25% on average for all treatments Canker size was not measured in measures analysis, time modeled as compared with the pretreatment size, 2017, as newly formed cankers had a factor, block as a random effect, and reaching an average canker size of 0.3 poorly defined margins that pre- multiple comparison test within each cm2 for all treatments. By the end of vented an accurate assessment of size. date performed using Tukey’s hon- the experiment, 8 months after the C ANKER NUMBER AND estly significant difference at a 5% level initial application of all treatments, INCIDENCE. In 2016, the total num- of significance in JMP (version 12.0 canker size had increased 77% on ber of cankers present on each tree for Windows; SAS Institute, Cary, average for all treatments compared was recorded before treatment appli- NC). For tissue streaking rating, an with the pretreatment size, reaching cation, and every 3 weeks after the ordinal logistic model was used. an average canker size of 0.45 cm2.At initial treatment application until 11 Treatment means for the number of the end of the study, the average size Nov., which was 3 weeks after the final treatment application. In 2017, trees were visually inspected for can- kers and incidence (present or absent) was recorded before fungicide appli- cation and every 3 weeks thereafter until 12 May, which was 3 weeks after the final application. DISEASE SYMPTOM SEVERITY. On 14 Feb. 2017, which was 4 to 7 months after final fungicide applica- tion, disease severity was rated visu- ally on cankers treated in 2016. Following Rahe (2010), healthy tis- sue beyond the perceived margin of infection was removed, as the path- ogen may reside in this tissue. Fol- lowing Garton et al. (2018b), the Fig. 1. Mean daily air temperature, relative humidity (RH), and precipitation at resulting excisions were 1 mm to Washington State University Northwestern Washington Research and Extension 3 mm beyond the original canker Center in Mount Vernon, WA, during the 2016 study of fungicide efficacy in margins, but cambium tissue was controlling apple anthracnose canker; (1.8 · C) D 32 = F, 1 mm = 0.0394 inch.
• February 2019 29(1) 37 RESEARCH REPORTS
plus boscalid, and captan plus thi- ophanate-methyl; cankers were first observed in these three treatments 9 weeks after the initial application (Ta- ble 2). The total number of cankers observed on 12 May, 3 weeks after the final treatment application, ranged from one to three per tree and did not differ among treatments [P = 0.88 (Table 1)]. DISEASE SYMPTOM SEVERITY. In 2017, dark brown streaks indicative of the disease were observed in the cambium tissue below the treated cankers 4 to 7 months after the final application of all treatments. Disease severity was moderate (20% to 40%) Fig. 2. Mean daily air temperature, relative humidity (RH), and precipitation at for all treatments, and there was no Washington State University Northwestern Washington Research and Extension significant treatment difference [P = Center in Mount Vernon, WA, during the 2017 study of fungicide efficacy in · D 0.65 (Table 1)]. N. malicorticis was preventing apple anthracnose canker infection; (1.8 C) 32 = F, 1 mm = not successfully isolated from symp- 0.0394 inch. tomatic cambium tissue; however, symptom morphology aligned with descriptions of N. malicorticis by Byther (1986) and Rahe (2010). Discussion Average air temperature, relative humidity, and precipitation were fa- vorable for the dissemination and de- velopment of N. malicorticis both years. This finding is similar to Garton et al. (2018b) at the same location, and aligns with previous reports that indicate mild temperatures ranging from 0 to 22 C in combination with a moist environment are favorable for disease development by N. malicorti- cis (Cordley, 1900; Hortova et al., 2014; Kienholz, 1939; Spotts and Peters, 1982). In the maritime PNW, zinc, cap- tan, and copper-based fungicides have been recommended for control Fig. 3. Effect of fungicide treatments on canker size incited by Neofabraea malicorticis on ‘Tompkins King’ cider apple trees in 2016. Fungicide treatments of anthracnose canker in orchards were applied every 3 weeks until 21 Oct., but the zinc treatment was ended in (Pscheidt and Ocamb, 2017); how- September due to plant toxicity issues. Canker size increased significantly over ever, none of these fungicide treatments time (P < 0.0001), but there were no significant differences in canker size among prevented infections by N. malicorticis treatments (P < 0.72), based on repeated measures analysis followed by Tukey’s in this study when applications were honestly significant difference test at a 5% level of significance; 1 cm2 = 0.1550 made every 3 weeks from February inch2. Pre-trt = pretreatment. through October. Although captan in combination with the systemic fungi- cide pyraclostrobin plus boscalid was of cankers on trees treated with basic there was no significant difference expected to provide a good level of copper sulfate, zinc, and pyraclostro- due to treatment [P = 0.50 (Table control, this was not the case in this bin plus boscalid were numerically 1)]. In 2017, no cankers were ob- study. Better control was provided smallerthancankerstreatedwiththio- served (‘‘no’’ incidence rating) on when zinc was alternated with pyraclos- phanate-methyl and the untreated can- any of the trees in the study before trobin plus boscalid, or when captan kers (controls), but not significantly. treatment application. Cankers were was alternated with thiophanate- NUMBER OF CANKERS. In 2016, observed (‘‘yes’’ incidence rating) 3 methyl, or when thiophanate-methyl 3 weeks after the final treatment ap- weeks after the initial application in was applied alone (although this is not plication, there were two to three new all treatments except thiophanate- recommended due to potential for cre- cankers per tree in all treatments, and methyl, zinc plus pyraclostrobin ating pathogen resistance). Efficacy of
38 • February 2019 29(1) Table 1. The number of new cankers observed 11 Nov. 2016 on ‘Tompkins trees. Until recently, most fungicide King’ apple trees and 12 May 2017 on ‘Ashmead’s Kernel’ apple trees (3 weeks assays against N. malicorticis have after final treatment application both years), and disease severity under the been carried out only in vitro or for canker on ‘Ashmead’s Kernel’ apple trees as rated 14 Feb. 2017 (4 to 7 months the control of bull’s-eye rot on apple after the final treatment application). fruit. In the current study, no fungi- Disease severity cides showed consistent efficacy at New cankers (no.) (1–5 scale)z controlling N. malicorticis infections Active ingredient(s) 2016 2017 2017 on apple trees. As each fungicide Zinc 3y 12showed only modest efficacy toward Pyraclostrobin + boscalid 3 2 2 either limiting canker expansion and/ Thiophanate-methyl 2 2 2 or preventing the development of Basic copper sulfate 2 —x 2 new infections, further work should Captan — 2 — use an in vitro bioassay to examine Zinc + thiophanate-methyl — 3 — pathogen sensitivity/resistance to the Zinc + pyraclostrobin + boscalid — 2 — fungicides evaluated. Neofabraea spe- Captan + thiophanate-methyl — 1 — cies appear to exhibit sensitivity to Captan + pyraclostrobin + boscalid — 2 — individual fungicides and may develop Control (nontreated) 3 3 2 resistance to particular active ingredients P 0.50 0.88 0.65 or modes of action, which have already been detected in certain populations of zDisease severity rated on a scale of 0 to 5, where 0 = no discoloration beyond margin, 1 = 1% to 20% discoloration beyond margin, 2 = 21% to 40% discoloration beyond margin, 3 = 41% to 60% discoloration beyond margin, 4 = Neofabraea species (Spotts et al., 2009; 61% to 80% discoloration beyond margin, and 5 = more than 81% discoloration beyond margin. Weber and Palm, 2010). Furthermore, yTreatment means for the number of new cankers and disease severity were compared using Student’s t test at a 5% level of significance. additional fungicides, or combining or xThe (—) symbol indicates treatment was not included. alternating fungicides with different modes of action, should be tested, as Table 2. Canker incidence pretreatment (pre-trt) and 3 to 12 weeks after initial none of the fungicides included in fungicide treatment application to ‘Ashmead’s Kernel’ apple trees in 2017 to test this study showed high efficacy. prevention of anthracnose canker; (Y) cankers present, (N) cankers not present. Under the climate conditions in Canker incidencez the maritime PNW, a year-round 17 Feb. 9 Mar. 30 Mar. 20 Apr. 12 May disease management program may Treatment (Pre-trt) (week 3) (week 6) (week 9) (week 12) be required for successful manage- Zinc N Y Y Y Y ment of Neofabraea species. This Pyraclostrobin + boscalid N Y Y Y Y study also demonstrated that cider Thiophanate-methyl N N N Y Y apple trees produced commercially Captan N Y Y Y Y in the region can be infected by Zinc + thiophanate-methyl N Y Y Y Y anthracnose canker in the nursery; Zinc + pyraclostrobin + boscalid N N N Y Y thus, a commercial source from out- Captan + thiophanate-methyl N N N Y Y side the region may be needed to Captan + pyraclostrobin + boscalid N Y Y Y Y avoid introducing infection into Control (nontreated) N Y Y Y Y a new orchard. With the challenges zEach data point represents the mean canker incidence of five replicates. faced in attempting to manage an- thracnose canker using the currently available fungicides, cultivar and zinc or captan as a preventive treatment plus boscalid did not prevent the de- rootstock susceptibility and resistance against anthracnose canker may be fur- velopment of new infections on cider or tolerance to anthracnose canker ther enhanced if it is alternated with apple bark. It is possible that pathogen also should be evaluated. a systemic fungicide that has proven resistance occurred due to repeated effective against Neofabraea species, such applications of single fungicide chem- as thiabendazole or pyrimethanil (Spotts istries in 2016. However, it is unlikely Literature cited et al., 2009); however, the efficacies of this affected 2017 results, as the two Aguilar, C., M. Mazzola, and C. Xiao. these combinations need to be evaluated. studies were carried out in different 2018. Control of bull’s-eye rot of apple Systemic fungicides, such as pyr- orchard blocks, each year the treat- caused by Neofabraea perennans and aclostrobin plus boscalid and thio- ments were applied to only five single- Neofabraea kienholzii usingpre-andpost- phanate-methyl, can penetrate plant tree replicates within the orchard (an harvest fungicides. Plant Dis. 102:905–910. tissues and redistribute to nontreated entire block of trees did not receive an Byther, R.S. 1986. Apple anthracnose. tissue through the vascular system individual treatment), and different Western Cascade Tree Fruit Nwsl. p. 6–8. (Hewitt, 1998). In a previous study, chemistries were used each year. pyraclostrobin plus boscalid was ef- Cordley, A.B. 1900. Apple tree anthrac- fective at controlling bull’s-eye rot Conclusion nose: A new fungus disease. Oregon Agr. on apple fruit caused by all species This is the first orchard study Expt. Sta. Bul. 60:1–8. of Neofabraea (Spotts et al., 2009). that tested the efficacy of currently Creemers, P. 2014. Anthracnose canker In the current study, however, re- available fungicides for the control of and perennial cankers, p. 51–53. In: T. peated application of pyraclostrobin N. malicorticis infections on apple Sutton, H. Aldwinckle, A. Agnello, and J.
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Walgenbach (eds.). 2014. Compendium Kienholz, J.R. 1939. Comparative study Senula, A. 1985. Untersuchugen zur of apple and pear diseases. 2nd ed. APS of the apple anthracnose and perennial morphology und physiologie von Cryp- Press, St. Paul, MN. canker fungi. J. Agr. Res. 59:635–665. tosporiopsis malicorticis (Cordl). Nannf. und Phyctaena vagabundha Desm. Arch. Davidson, R. and R.S. Byther. 1992. Ap- Miller, E.V. 1932. Some physiological Phytopathol. Pflanzenschutz 21:273–286. ple anthracnose: Bulls-eye rot. Wash- studies of Gleosporium perennans and ington State Univ. Ext. Bul. 0940. Neofabraea malicorticis. J. Agr. Res. Spotts, R.A. and B.B. Peters. 1982. The 45:65–77. effect of relative humidity on spore ger- European and Mediterranean Plant Pro- mination of pear decay fungi and d’Anjou tection Organization. 2017. Neofabraea Moulton, G.A., C.A. Miles, J. King, and pear decay. Acta Hort. 124:75–78. malicorticis distribution. 27 Mar. 2017. A. Zimmerman. 2010. Hard cider pro-
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