In late May or early June, I (or my research associate) will call potato producers around the state to announce our program. I will also call Doug Werner of then Division of Agriculture asking him to spread the word in the farm community.
Any producers who want to participate in the program only need to give us a call to invite us to their farms.
I then will schedule the dates for disease survey and sample collections. After reaching agreement on the date of visit, producers will provide us a map of seed lots with information on cultivars, generations, etc. On the designated date, we will call before leaving the lab to tell the producer that we are on our way. Once there, we will first call upon the producers at their home or office. The producers will then lead us to the potato field. Before entering the fields, all workers will put on protective gear to prevent cross contamination. Workers trained in disease survey and sampling protocol, will be given specific instructions on the kind and number of samples to collect. Any plants showing signs of abnormality will be collected separately. These samples will be examined in the lab and processed for identification. On potatoes, the number of samples to be collected is based on generations. The lower generation will be subject to more intensive sampling and testing. Samples collected will be stored in proper condition in the field and labs to prevent degradation and deterioration.
After returning to the lab, workers will immediately process the samples for the ELISA test. Sap expressed from the samples (leaflets, stems) will be loaded on the 96-well sample plates coated previously with designated antisera. Each well contain a sample. Following a specific protocol of incubation with conjugates and substrates with thorough washing and drying in between results of samples can be read. If the specific pathogen is present in a sample, the sample well will be a bright yellow color as in the positive control. When the specific pathogen is absent, the well remains clear as in a negative control. The turn around time from sample collection to reading the test results usually takes three days.
At the end of the third day, I will call the producer and give him/her a report of the test results. If there is any inconsistency in test results, we will carry out a re-test. If necessary, another sampling trip will be conducted. We often visit a seed lot in question two to three times until we pin point the problem. Producers take the test results and incorporate them into their management. Through the years, many farms have been able to eradicate diseases from their seed lots and farms by using the information wisely.
For plant phytoplasma such as potato witches broom and aster yellow, molecular techniques provide the best means of identification when symptoms are absent. Soils and roots collected from the root zones will be prepared for nematode extraction. Identification of nematodes will be made by morphological examination and DNA studies. Results of these studies will also be reported to producers in a timely manner.
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At the end of the season, report of test results will be prepared for each farm. Then, the report will be sent to individual participating producers. The test results are kept strictly confidential in my lab. However, the producer can decide if he/she wants to share the results with others.
The general trend on the health of the potato crop in Alaska will be included in my activity report for this project.