If you’re expecting plug plants for your strawberry crops, you’ve likely heard about the emerging threat of Neopestalotiopsis disease. For those unfamiliar, I recommend reading Dr. Phil Brannen’s article, “Dramatic Neopestalotiopsis Disease in Strawberry Tips and Plug Plant Production Nurseries“ from the University of Georgia Extension.
Recently, I’ve been in discussions with a few fruit growers who ordered plants from affected nurseries to explore our options. Some nurseries hit hard by this disease are unable to fulfill orders, while others are offering farmers options: accept the plants with no performance guarantees or receive a refund within a limited time. The real dilemma for fruit growers is that everything is prepared—except the plants. Refusing the potentially affected plants now could mean a very difficult task of finding healthy replacements at this late stage.
If you do accept the plants, Dr. Brannen suggests an aggressive spray program to combat the disease. While none of us like the idea of additional sprays, this might be the necessary course of action this year.
Moreover, I strongly recommend adopting a strategic approach to planting. If you’ve already planted bare-root plants, avoid placing plug plants adjacent to them. To our knowledge, bare-root plants are not affected by this issue. If we face a season conducive to disease, at least this strategy might help prevent the disease spread to healthy crops. Similarly, if you are planting multiple varieties, consider spacing them apart, as research shows that cultivars vary in their susceptibility to Neopestalotiopsis.
A few years ago, we tested 22 varieties for susceptibility to Neopestalotiopsis. Our findings revealed that Florida Brilliance, Florida Sensation, Camino Real, and Florida Radiance were among the most susceptible. Day-neutral cultivars Albion, San Andreas, and, to a lesser extent, Evie 2 also showed significant susceptibility. However, several short-day cultivars, including AC Valley Sunset, Darselect, Earliglow, Flavorfest, Galletta, Honeoye, Jewel, and Sonata, remained asymptomatic during our trials. You can find more details on this trial in the publication “Strawberry Cultivar Susceptibility to Neopestalotiopsis Leaf Spot in Indiana.”
Dr. Dan Egel, now retired from Purdue University, has also conducted fungicide trials for managing this disease. His research found that Captan 80 WDG®, Thiram SC®, Tilt®, and Switch 62.5 WG® provided significantly better control than other treatments. Interestingly, the disease levels in treatments with Abound® andPristine®were not different from the untreated control. So, do not use these fungicides. Organic options like Badge X2®, Serenade Opti®, and SilMatrix® performed better than Pristine® and Abound ® but were not as effective as Captan 80 WDG®, Thiram SC®, Tilt®, and Switch 62.5 WG®. For more information, refer to his article, “Evaluation of Fungicides for the Management of Neopestalotiopsis Leaf Spot 2021”.
Note that this article discusses the foliar portion of this disease. For example, the fungicides and cultivars discussed here are mentioned in relation to the foliar portion of the disease. There is also a dieback disease that may be caused by Neopestalotiopsis. Plants that show such symptoms should be sent to the PPDL on Purdue campus. More information about both phases of the disease can be found in the link below.
Dr. Dan Egel has provided a presentation titled ‘A Midwestern Perspective on a New Strawberry Disease Caused by Neopestalotiopsis spp.’ that summarizes these findings. We hope this information proves helpful during this challenging time.