Source: OREGON STATE UNIVERSITY submitted to
SUSCEPTIBILITY OF DECIDUOUS BAREROOT NURSERY TREES TO PSEUDOMONAS SYRINGAE AND PHYTOPHTHORA SYRINGAE
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
TERMINATED
Funding Source
USDA COOPERATIVE AGREEMENT
Reporting Frequency
Annual
Accession No.
0407491
Grant No.
(N/A)
Project No.
5358-12210-003-02S
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Sep 25, 2003
Project End Date
Sep 24, 2007
Grant Year
(N/A)
Project Director
SCAGEL C F
Recipient Organization
OREGON STATE UNIVERSITY
(N/A)
CORVALLIS,OR 97331
Performing Department
HORTICULTURE
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
25%
Applied
75%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
10221101020100%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
2110 - Ornamental trees and shrubs;

Field Of Science
1020 - Physiology;
Goals / Objectives
Determine whether soil N and fall urea and/or defoliant treatments predispose deciduous nursery stock to either disease. Determine the stage of dormancy development in relation to the susceptibility of deciduous nursery stock to the infection of either disease. Determine the effectiveness of several biocontrol agents and proprietary chemicals developed by the collaborators in reducing the incidence of postharvest diseases of bare-root nursery plants, and enhancing the growth of bare-rooted deciduous nursery stock during plant establishment.
Project Methods
The effects of soil and fall urea and defoliant treatments of predisposition of nursery plants to Pseudomonas syringae and Phytophthora syringae will be evaluated with bareroot OHF97 pear plants grown in an N-free medium and given fertilizer containing different concentrations of nitrogen (N). The effect of plant dormancy development on the susceptibility of nursery plants to Pseudomonas syringae and Phytophthora syringae will be evaluated using bareroot OHF97 pear plants grown in an N-free medium and supplied with fertilizer. The effectiveness of several biocontrol agents and chemicals on the incidence of postharvest diseases of bareroot nursery plants and plant growth during establishment will be evaluated using OHF97 pear plants. Documents SCA with Oregon State Univ. Formerly 5358-12210-002-05S (3/2006).

Progress 09/25/03 to 09/24/07

Outputs
Progress Report Objectives (from AD-416) Determine whether soil N and fall urea and/or defoliant treatments predispose deciduous nursery stock to either disease. Determine the stage of dormancy development in relation to the susceptibility of deciduous nursery stock to the infection of either disease. Determine the effectiveness of several biocontrol agents and proprietary chemicals developed by the collaborators in reducing the incidence of postharvest diseases of bare-root nursery plants, and enhancing the growth of bare- rooted deciduous nursery stock during plant establishment. Approach (from AD-416) The effects of soil and fall urea and defoliant treatments of predisposition of nursery plants to Pseudomonas syringae and Phytophthora syringae will be evaluated with bareroot OHF97 pear plants grown in an N- free medium and given fertilizer containing different concentrations of nitrogen (N). The effect of plant dormancy development on the susceptibility of nursery plants to Pseudomonas syringae and Phytophthora syringae will be evaluated using bareroot OHF97 pear plants grown in an N- free medium and supplied with fertilizer. The effectiveness of several biocontrol agents and chemicals on the incidence of postharvest diseases of bareroot nursery plants and plant growth during establishment will be evaluated using OHF97 pear plants. Documents SCA with Oregon State Univ. Formerly 5358-12210-002-05S (3/2006). Significant Activities that Support Special Target Populations This report serves to document research conducted under a specific cooperative agreement between ARS and Oregon State University. Additional details of research can be found in the report for the parent project 5358-12210-003-00D, Influence of Root Growth, Development, and Function on Horticultural Crop Productivity and Quality. Dr. Les Fuchigami and collaborators conducted the following research towards the agreements objectives: The results of the studies of this cooperative agreement are reported below: 1. Plants treated with 3% urea and 1% CuEDTA had stem and root N concentrations similar to the naturally defoliated plants. 2. A high concentration of urea (3%) was phytotoxic to the leaves but not the stems of treated plants. The inoculation of P. syringe directly on stems treated with urea and/or CuEDTA showed no sign of disease. In contrast, inoculation P. syringae on artificial wounds made on the stems resulted in disease development. We concluded that wounding of the stem tissue is important for P. syringae infection. 3. Inoculation of wounded stems in October showed smaller lesions than those inoculated in November, regardless of the foliar application treatment. The environmental conditions in October were drier and warmer than in November. The cold, wet conditions of November favored P. syringae development because P. syringae is highly active in cold, wet conditions. The warm, dry conditions in October were favorable for wound healing, which may be a factor in preventing P. syringae infection. 4. Plants inoculated with P. syringae on fresh wounds were susceptible to infection. Treatment with P. syringae after wound healing prevented the formation of the disease and confirmed our findings that the wounding of stem tissues was important for disease infection. 5. Either Aliette (6g/l) or PhytoFOS (1%) was effective in controlling the disease when applied one week before inoculation on wounded stem tissues. The mixture of either Aliette or PhytoFOS with urea and CuEDTA treatments was effective in controlling the disease during October and November. The results of these studies showed that the application of urea and CuEDTA in early fall (October) before the cold wet season can be of benefit to growers since the pathogen is less active in warm, dry environments and plants are better able to heal any wounds caused by defoliation or chemical treatments. In contrast, applications made during the cold, wet season (November) favors the development of P. syringae and slows the healing of the leaf scars and any damage caused by the defoliation treatment. The addition of either Aliette or PhytoFOS to the urea and CuEDTA treatments can enhance the protection of plants from infection during harvesting, cold storage and establishment of plants in the landscape. ADODR Statement: The ADODR met with the cooperating PI and project personnel several times during the year and discussed results through phone calls and email. Results were reported in annual reports and informal meetings with growers. Final results will be published in peer- review publications.

Impacts
(N/A)

Publications


    Progress 10/01/05 to 09/30/06

    Outputs
    Progress Report 4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Oregon State University. Additional details of research can be found in the report for the parent project 5358-12210-003-00D, Influence of Root Growth, Development, and Function on Horticultural Crop Productivity and Quality. Dr. Les Fuchigami and collaborators conducted the following research towards the agreement: OBJECTIVES: 1. Determine whether fall urea/defoliant (U/D) treatments and nitrogen levels predisposes deciduous nursery stock to Phytophthora syringae; 2. Determine whether wound influences Phytophthora syringae infection. SUMMARY: 1. Pyrus communis L. plants were uniformly fertigated with the same concentration of 200 ppm N during the growing season. Then treatment UD (foliar urea +copper chelate defoliant) and control (water) were applied in October and November. There is no significant difference in N level between control and treated plants in October. However, the UD treated plants showed significantly higher nitrogen level than control in November. 2. Lesions were not found on stems when inoculation was made on the unwounded stems compared to the wounded stems. Therefore, wounding was necessary for Phytophthora infection. 3. There was no relationship between N levels and disease severity (stem lesions). 4. Disease severity in November was greater than October treatment.

    Impacts
    (N/A)

    Publications


      Progress 10/01/04 to 09/30/05

      Outputs
      4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Oregon State University. Additional details of research can be found in the report for the parent project 5358-12210-002-00D Factors influencing Root Development, Physiology, and Productivity of Horticultural Crops. OBJECTIVES: 1. Determine whether fall urea/defoliant (U/D) treatments predisposes deciduous nursery stock to Phytophthora syringae; 2. Determine if biocontrol agents and proprietary chemicals can control Phytophtora syringae in bare-root deciduous plants and plant tissues stored under cold storage conditions; 3. Determine the efficacy and longevity of PhytoFOS activity in controlling P. syringae under natural condition; 4. Determine whether plant growth stage influences Phytophthora syringae infection; 5. Determine whether wound age influences Phytophthora syringae infection. SUMMARY: 1. Pyrus communis L. plants treated with foliar urea and copper chelate defoliant produced greater disease severity (stem lesions) caused by Phytophthora syringae when applied in November than the water control plants. In contrast application made in October had no effect on disease severity. 2. Application of Phytophos either alone or as a mixture with the above chemicals significantly reduced the disease severity. 3. The disease severity increased when the inoculated plants were exposed to either cold refrigerated storage or under cold natural conditions in contrast to warm laboratory or greenhouse environments. 4. The growth status (e.g. dormant vs nondormant) of Pyrus communis plants had no effect on disease expression indicating that dormancy is not a prerequisite to disease infection. 5. Application of Phytophos prior to natural defoliation and harvest prevented the infection by Phytophthora syringae under cold storage and natural conditions for at least 8 weeks of storage conditions. 6. The age of wounding had a significant effect on Phytophthora infection. Plants inoculated two weeks after wounding did not result in disease infection by Phytophthora syringae.

      Impacts
      (N/A)

      Publications


        Progress 10/01/03 to 09/30/04

        Outputs
        4. What were the most significant accomplishments this past year? This report serves to document research conducted under a specific cooperative agreement between ARS and Oregon State University. Additional details of research can be found in the report for the parent project 5358-12210-002-00D Factors Influencing Root Development, Physiology, and Productivity of Horticultural Crops. L. Fuchigami and colleagues are evaluating factors that influence susceptibility of nursery stock to Pseudomonas syringae and Phytophthora syringae. 1. Determine whether fall urea/defoliant treatment predisposes deciduous nursery stock to Phytophthora syringae 2. Determine the best application time for using urea and Cu-EDTA to prevent and control Phytophthora syringae. 3. Determine the best application time for using Aliette to prevent and control Phytophthora syringae. 4. Determine whether the degree of plant dormancy influences infection by Phytophthora syringae. Experiment 1: (Objective 1, 2) A single spray of either urea (3%) + Cu-EDTA (1%) (U/D treatment) or water was applied to plants on either Oct 13 or Nov 13 2003. On November 20, 2003, three leaves from each plant were selected and hand defoliated. Hand defoliated trees were also wounded using a 4 mm diameter cork borer. Inoculum with the V8 agar + pathogen was applied to the leaf scars and wound, on the either the same day and/or 2 weeks after hand defoliation and wounding. Results: The pathogen caused extended lesions when inoculated to either fresh (inoculated at the day of defoliation or wounding) leaf scar or wound. In contrast, there were no extended lesions when inoculated on either leaf scar or wounds two weeks after hand defoliation or wounding. The data suggests that healing (waiting two weeks after leaf removal and wounding) prevented pathogen infection. On inoculated stems, the late U/D treatment showed larger lesions compared with the early U/D treatment and control. However, the relationship between the time of U/D treatment and lesion size was not clear on the leaf scar treatment. Experiment 2: (Objective 3, 4) Effect of urea, Cu-EDTA, and Aliette on P syringae infection Plants were sprayed with one of the following treatments: 1. urea (3%) (U), Cu-EDTA (1%) (Cu), Aliette (6g/l) (A); 2. urea (3%) +Cu-EDTA (1%) (U/D); 3. urea (3%) + Aliette (6g/l) (UA); 4. Cu-EDTA (1%) + Aliette (6g/l) (CuA), urea (3%) +Cu-EDTA (1%) + Aliette (6g/l) (UCuA); and 5. water (control) in either early October (October 5, 2003) or late November (November 13, 2003). Inoculation was made 1 week after chemical application. Plants were wounded at three sites. Two sites were inoculated with pathogen and one site was inoculated with V8 agar (control). Results: The pathogen caused the largest lesions in all November treatments. In October treated plants, lesion size was similar among all treatments. However, in the November treatments, plants treated with either U, Cu, or U/Cu showed larger lesions than the control. This data suggests urea and copper treatments can promote disease infection if the chemical is applied in November. In contrast, if urea and copper is applied during October, the incidence of disease infection by Phytophthora syringae is reduced significantly. Increased infection caused during the November treatment maybe due to the cold wet conditions that favor the growth of Phytophthora syringae. The extent of infection was reduced by applying Aliette (6g/l) 1 week before inoculation in all treatment combinations. Experiment 3: (Objective 4) Stage of plant growth and Phytophthora syringae infection Plants were divided into two sets. One set was kept in the lathhouse (LH) until the end of the experiment and the other set was moved to a heated greenhouse (GH, 16h/8h light/dark) one week before starting the experiment and kept in the greenhouse until the end of experiment. Each of five plants was inoculated at two week interval from October 7, 2003 to December 9, 2003. Result: Plants in the greenhouse showed smaller lesion sizes than the plants in the lathhouse over the experimental period. The lesion sizes on the plants in the lathhouse increased with later treatment dates, suggesting that the cause of the disease progression was not due to the dormancy status of the plants, but due to differences in the environment.

        Impacts
        (N/A)

        Publications