U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Commodity Protection and Quality Research: Parlier, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Research Units
                        San Joaquin Valley Agricultural Sciences Center
                                    Crop Diseases, Pests and Genetics Research
                                    Water Management Research
                                    National Arid Land Plant Genetic RepositorySearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Parlier, California San Joaquin Valley Agricultural Sciences Center Commodity Protection and Quality Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Research Project: Integrate Pre- and Postharvest Approaches to Enhance Fresh Fruit Quality and Control Postharvest Diseases Location:
                                Commodity Protection and Quality Research Title:   Author  item
                                            KIM, Y - Pace International, Llc - Usaitem
                                            KWAK, J - Pace International, Llc - Usaitem
                                            AGUILAR, C - Washington State Universityitem
                                            Xiao, Chang-Lin
  Submitted to: Plant Disease
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 2/4/2016
                                    Publication  Date: 6/8/2016
                                    Citation: Kim, Y.K., Kwak, J.H., Aguilar, C.G., Xiao, C. 2016. First report of black rot on apple fruit caused by Diplodia seriata in Washington State. Plant Disease. 100:1499. doi: 10.1094/PDIS-12-15-1463-PDN.Interpretive Summary: In July 2014, a fruit rot disease was observed on Fuji apple fruit in commercial orchards in Mattawa, WA. Fruit rot symptoms appeared to originate mainly from infections at either the calyx-end (floral parts) of the fruit or wounds on the fruit skin associated with insect injuries. Diseased fruit exhibited light-to-dark brown lesions without centric rings. At the advanced stage, the entire fruit was completely rotten, sponge to firm, and light brown. A fungus was isolated from the decayed fruit and identified as Diplodia seriata De Not., which is the cause of black rot of apple, based on the morphological characters and DNA fingerprinting. On apple fruit inoculated with the fungus, the fungus is able to cause rots similar to those observed in the field. Black rot has been reported in other apple growing regions including the eastern United States, where black rot was first reported; however, it has not been reported in Washington State, where more than 60% of US apples are produced. This is the first report of the occurrence of black rot on apple caused by D. seriata in Washington State.
                                Technical Abstract: In July 2014, decayed ‘Fuji’ apple fruit (Malus × domestica Borkh.) were observed and sampled from commercial orchards in Mattawa (Grant County) in Washington State. Fruit rot symptoms appeared to originate mainly from infections at either the calyx-end (floral parts) of the fruit or wounds on the fruit skin associated with insect injuries. Diseased fruit exhibited light-to-dark brown lesions without centric rings. At the advanced stage, the entire fruit was completely rotten, sponge to firm, and light brown. The growers reported that this disease was also observed on other cultivars in the vicinity of Mattawa, including Aurora Golden Gala (20-25% loss) in 2013 and Pink Lady (1-2% loss) in 2014. To isolate the causal agent, small fragments of fruit flesh from decayed fruit were excised from the margin of lesions and placed on potato dextrose agar (PDA) acidified with 0.1% lactic acid. The plates were incubated at 20°C for 7 days and sub-cultured on PDA to obtain pure cultures. The cultures were initially white with dense aerial mycelium and gradually became dark gray to olive green from the center. Conidia were aseptate, cylindric, rounded at both ends and brown to dark brown at maturity, and 10 to 16 × 21 to 26 μm (n = 50) in size. The fungus was identified as Diplodia seriata De Not. based on the description of its anamorphic stage (Phillips et al. 2007; Sutton 2014). The identities of five representative isolates were further confirmed by analysis of nucleotide sequences of the internal transcribed spacer (ITS) regions amplified using the primers ITS1/ITS4. A MegaBLAST search in GenBank showed that the sequences of all five isolates had 99% homology (E-value = 0.0) to a D. seriata sequence (Accession No. AY259094). A representative isolate was tested for pathogenicity on apple fruit. Organic ‘Fuji’ apple fruit were surface-disinfected in 0.6% sodium hypochlorite solution for 5 min, rinsed twice with deionized water, and air-dried. Each fruit was wounded with a sterilized finish-nail head (3 mm in depth and 4 mm in diameter) and inoculated by placing a 4-mm-diameter mycelial plug from the leading edge of a 4-day-old PDA culture on the wound. Control fruit were treated with PDA plugs without the fungus. There were four 10-fruit replicates for each treatment, and fruit were placed in plastic crispers and stored at 4°C for 4 weeks. The experiments were conducted twice. Black rot symptoms developed on all inoculated fruit, while no decays appeared on the control fruit. Koch’s postulates were fulfilled by re-isolating the fungus from the decayed fruit. Black rot has been reported in other apple growing regions including the eastern United States, where black rot was first reported; however, it has not been reported in Washington State, where more than 60% of US apples are produced. To the best of our knowledge, this is the first report of the occurrence of black rot of apple caused by D. seriata in Washington State.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov