Fight the Mite! Post-harvest Control of Eriophyid Mites in Garlic

This project was be implemented on four commercial garlic seed farms, each of which provided a complete picture of their mite management strategies through self reporting of conditions in both drying and storage environments. The farms we partnered with are geographically diverse, located from eastern NY through VT, and use different cultural practices for drying and storage. Each site will be treated as a replication when doing a analysis of the four farms, and we will also allow each farm to be analyzed independently by creating five replications of the treatment and control at each farm in which bulbs (5) will be samples and cloves (25 or more)  are sub-samples. This robust experimental design should provide us adequate information to develop solid recommendations on predatory mite release for dry bulb mite control. 

The protocol is designed to test the hypothesis that Stratiolaelaps predatory mites can be deployed in storage to significantly reduce A. tuplipae levels. 

Protocol: 

Update: We were not able to secure the dataloggers needed for this step, and are instead relying on self-reporting.

At harvest: researchers will visit each farm and install an Onset temperature and relative humidity sensor/datalogger in the drying facility. Censors will be protected from direct sunlight and located as close as practical (example: on the bench with garlic in a drying tunnel) to the garlic. Data will be collected from harvest through movement to storage. 

In storage: Researchers visit each site when the farmers are ready to move garlic from the drying area into the storage area. They will note any cleaning steps that growers take at this point, including removal of roots, dirt, and stems, and will set up the experiment deploying predatory mites within the storage area:

1. We used a Randomized Complete Block Design, whereby randomly assigned garlic will be assigned to an untreated control of garlic alone (with no predatory mites) or an experimental treatment of garlic and predatory mites at a rate equivalent to 1 liter per 1000 square feet.
2. Treatments were applied by placing 50 bulbs, all of uniform size and not showing obvious physical damage, into organza bags (www.uline.com/BL_5517/Organza-Bags).
3. Five control bags and five experimental bags, each containing 5 bulbs, were stored at each of the five farms, distributed throughout the commercial storage area.  
4. Variety selection: Three of the farms used Porcelain varieties (German white or Music), and one used a Rocambole (Killarney Red), which was believed to be more susceptible than the Porcelain varieties.
5. Experimental bulbs were mailed to PI for final assessment protocol:
   1. Assess all bulbs from each treatment and record and separate any which have deteriorated due to unrelated post-harvest diseases, such as penicillium or botrytis
   2. Each remaining bulb is assessed using the following protocol:
      1. Separate all cloves, peel, and rate individual cloves by bulb for both fusarium level and bulb-mite damage level
         1. Fusarium rating is by % of clove covered in lesions
         2. Bulb mite damage rating is completed using a pictorial benchmark on a scale of 1-5
         3. One clove per bulb is randomly selected for A. tuipae counting at 40X magnification. 

Analysis: Each of the 4 sites will be analyzed using a paired t-test to examine effectiveness of the experimental treatment. At each site,  each bag is a separate replication, and the 5 individual bulbs are samples while cloves are subsamples. Data from the five sites will be analyzed using an Analysis of Variance after an assessment of data by the Cornell Statistical Consulting Unit to ensure data are correctly transformed. The second analysis will give us a sense of which environmental conditions are most conducive to A. tulipae control using Stratiolaelaps.