Progress 07/01/10 to 06/30/12
Outputs
OUTPUTS: A resistance monitoring assay was developed that can be used to identify resistance to chemical classes within 3 days of inoculation. The assay is conducted with a 24 well plate filled with specially selected media (see reference) amended with fungicide-specific discriminatory doses of fungicides of different chemical classes. The selection of the media was done based on the mode of action of the fungicide. Some fungicides had to be tested on minimum medium, others on complete medium such as PDA or MEA. Each sample consisted of 10 subsamples. Visual observation of mycelial growth from the 24-well plates are entered into a web application together with information about the origin of the sample and spray history of the orchard. After three days, mycelium growth is assessed visually based on a rating of a dash, single plus, double plus, and triple plus for no growth, minor growth, up to 50 percent growth and more than 5o percent growth, respectively. Sensitive isolates revealed no growth, whereas resistant isolates will grow on the amended medium. The single, double, triple pluses indicate the degree of resistance; low, medium and high. In combination with the web application developed for this project (SCN-2007962), this assay provides a powerful tool for location-specific resistance monitoring. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Peach growers, county agents, and specialists PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The resistance monitoring assay is a new tool to assess fungicide resistance to several different classes. Previous assays included the use of the detection of single point mutations with expensive PCR machines or a microscope to assess germtube growth or germination of spores. Our new method is affordable and can be used effectively for location-specific resistance profiling. In fact, we have trained undergraduates with no biological background to produce the kits within a day. We developed specific media and concentration combinations that distinguish reliably sensitive from resistant isolates. We believe that this method in combination with the web application we developed (SCN-2007962) will be useful for years to come for effective resistance monitoring and provide growers with extremely valueable information to control brown rot of peach. The kit was also successfully used by trained county agents who now have a much greater appreciation and knowledge base in this area. Agents from South Carolina for example have requested the kits for the last two years so they can serve their clientele better. With more than 150 location specific profiles, we now have a very good idea about the fungicide resistance status in South Carolina and are able to design statewide anti resistance management strategies. The information obtaine from this grant was used to educate growers at state and regional meetings and to modify and improve the Regional Pest Management Guide for peaches.
Publications
- Hu, M. J., C. X. Luo, A. Grabke, and G. Schnabel 2011. Selection of a suitable medium to determine sensitivity of Monilinia fructicola mycelium to SDHI fungicides. J. Phytopathol. 159:616-620.
|
Progress 07/01/10 to 06/30/11
Outputs
OUTPUTS: We started developing a web application based on PHP and SQL background database. Visual observations from the 24-well plate or the lipbalm assays are entered into the web application together with information about the origin of the sample and spray history of the orchard (Fig. 2). The web application validates that all required information is entered and requests a final review of the data entered. Then a resistance factor (RF) is separately calculated for each chemical class (see details below). The location-specific portion of the final report is created by assembling pre-drafted resistance management recommendations for each fungicide and corresponding resistance category (no, low, moderate, and high). Upon completion of the location-specific portion, the final report is generated, displayed, and automatically e-mailed for review to the specialist in real time. The user of the web application can save the report in pdf format and instantly share it with the producer by e-mail attachment. To our knowledge, this is the first web application of its kind. The web application prototype for monitoring resistance in M. fructicola is currently located at www.peachdoc.com under Profile. The user will be asked to enter information in regard to the sample origin, nature of the sample (fruit rot or blossom blight), and same-year spray history of the orchard from which the sample was taken. Similar to the original data recording sheet that county agents and specialists had been using before, users can enter - (dash), + (plus), ++ (double plus), and +++ (triple plus) indicating no growth, less than 20% growth, up to 50% growth, and more than 50% growth, respectively, on disks/wells amended with a specific discriminatory dose of each fungicide. Any unusual observations can be entered as text directly next to each sample or into a separate text box. The program will accept a minimum of 8 and a maximum of 10 samples per location.After the data is entered by the user and processed by the web application, a report is prepared containing (i) a summary of the data entered, (ii) the calculated RF factor for each chemical class, (iii) the resistance category for each chemical class, and (iv) the corresponding disease control recommendation. The latter (iv) consists of an introduction indicating general guidelines for brown rot management, profile-specific recommendations, and finishing statements containing general considerations and a disclaimer. The disease control recommendations are managed and updated by the peach disease extension specialist in charge of the state in which participating producers reside. PARTICIPANTS: Computer Science students Karan Singh and Rohit Bath are developing the web application TARGET AUDIENCES: Target audience are commercial peach growers in the Southeastern United States. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Below is an example of the location-specific portion of the final report. In this hypothetical case, resistance to propiconazole was detected. Units are kept in the United States customary system to maintain authenticity: "The RF value for propiconazole indicates high resistance to DMI fungicides: Due to the absence of effective alternatives, DMI fungicides should still be used for preharvest brown rot control. In contrast to the benzimidazoles, however, DMI fungicides still work well against DMI-resistant populations if the rate is increased. Use Elite 45DF, Indar 2F, Indar 75WSP, or their generics at double the normal rate (highest allowable label rate). For Elite that would be 8 oz/acre, for Indar 2F it would be 12 fl oz/acre, and for Indar 75WSP it would be 4 oz/acre (rates are state specific for Indar products; check to confirm that this rate is legal in your state). Do not use DMI fungicides more than once per season if possible (not during bloom and again if possible, only once during the pre-harvest season). The RF value for thiophanate-methyl indicates no resistance to MBC fungicides: Use a benzimidazole product (i.e. thiophanate-methyl) such as Topsin-M 70W or -WSB or Thiophanate Methyl 85WDG in combination with another material (such as captan) once a year either during bloom sprays or three weeks before harvest. Incorporating benzimidazoles into your disease management program, which are effective in the absence of resistance, will maximize the efficacy and longevity of the other chemistries you are using. Remember to always tank-mix thiophanate-methyl with a fungicide having a different mechanism of action, such as captan. The RF value for azoxystrobin indicates no resistance to QoI fungicides: Use Pristine 38WG or Abound during the preharvest season as recommended in the most current Southeastern Peach, Nectarine, and Plum Pest Management and Culture Guide. Use the high dose. Do not use respiration inhibitor fungicides (Pristine or Abound) more than once per season if possible (not during bloom and again if possible, only once during the pre-harvest season)." A web application devoted to the resistance monitoring program is being developed in an effort to accelerate communication transfer and thus further improve the service to producers. Web applications are extremely useful due to the ubiquity of web browsers and the ability to update and maintain web applications without distributing and installing software on potentially thousands of client computers. The ability to update information for a web application also increases the utility of such programs, and in the case of resistance management, new fungicides or resistance conditions on the ground would require immediate changes to the recommendations. A web program gives maximum flexibility in restoring the integrity of the program when changes occur.
Publications
- No publications reported this period
|