Based on conversations with Dr. Natalia Peres (UFL) and others today, I believe it is accurate to say that thiram will be in short supply this spring. This is based on correspondence to Dr. Peres from one of the major manufacturers of thiram, if not the only one. At a minimum, strawberry growers are currently struggling to find thiram products. I think it is fair to say that the manufacturer needed a decision by EPA to proceed with a product run, and none was forthcoming. That is my interpretation anyway. I am writing a blog post based on the information I have, as this will affect spray programs for strawberry growers as we head into spring. It is unclear at this time what the future production of Thiram will be, and EPA is still reviewing the use of the product.
Regarding the suppression of Neopestalotiopsis, Natalia and I specifically discussed captan. Although it has generally not been as efficacious in Florida trials compared to thiram, captan does offer efficacy. A trial from Indiana conducted by Egel and Guan (2022) actually showed that Captan 80WDG was as effective as Tilt, Thiram, and Switch in reducing leaf spots caused by Neopestalotiopsis. In this trial, Captan 80WDG decreased Neopestalotiopsis disease severity from 37.5% to 5.4%. Therefore, if thiram products are unavailable this spring, captan is a logical alternative to thiram in spray programs, even if its efficacy is not as consistently reliable as thiram. Additionally, captan is active against Botrytis and anthracnose diseases.
Where Neopestalotiopsis is active this spring, Switch and DMI fungicides (Rhyme, Tilt, and Inspire) also suppress Neopestalotiopsis and should be incorporated as part of the disease management program. Please contact your local county agent if you have questions or need additional guidance with any aspect of your strawberry integrated pest management program.
