The information below was compiled by Guido Schnabel (Clemson University), Bill Cline (North Carolina State University), and Phil Brannen (University of Georgia) to give an improved recipe of sorts for Neopestalotiopsis management with fungicides after planting this fall. It does not address spring applications — growers will need to incorporate remaining applications of fungicides at that time.

Whether or not Neopestalotiopsis will substantially harm your strawberries this season depends on many things – including the cultivar, sanitation practices, initial inoculum levels, weather conditions, the fungicides you apply, and application timing. This article focuses on chemical management options after planting – including thiram, fludioxonil (a component of Switch, Alterity, Miravis Prime), and the DMI fungicides propiconazole, difenoconazole, and flutriafol. There are a few issues that need to be discussed, but let’s not get into the possible cancellation of thiram. That is another story. Here are some key points to consider:

Spray fungicides every 10-14 days even when conditions are dry, and when conditions are wet, your spray program should be tightened to include a fungicide application every 7-10 days.
We only have 4 applications of Switch (or any of the labeled generics such as Alterity) if applied at the full rate of 15 fl oz. If you use the lower rate (11 fl oz) you may use it five times. We will need most, if not all, of those applications in spring/early summer for fruit rot prevention. And no, you cannot legally use four more applications of Miravis Prime after having exhausted the Switch label restrictions.
Thiram solo applications should be the backbone of your spray program to keep inoculum levels low. It is a good Neopestalotiopsis and Botrytis material.
Ahead of an infection event (12 hrs of rain at >70F), spray a mixture of Thiram with something else. Use a DMI, but note that some (including propiconazole and difenoconazole) can act as plant growth regulators (PGR), especially on young plants. That is why nurserymen rarely use propiconazole when growing plugs or bare-root plants from tips. Also, excessive applications of propiconazole and difenoconazole on bigger plants have been shown to stunt plants and cause reduced yields. We still need to investigate how much (if any) one or two applications of these DMIs will stunt plants when applied in the fall or whether there are differences in cultivar susceptibility. We do know that Rhyme (flutriafol) does not have this negative effect, but it is also the least effective of the three DMIs.

For the first 4 weeks after planting, we do not recommend you use a DMI fungicide (especially propiconazole and difenoconazole) for fear of PGR effects. Use Rhyme with Thiram if you must use a DMI during this time. During late fall, be aggressive before high disease-pressure situations by using Thiram PLUS Inspire OR Thiram PLUS Tilt tank mixtures because we need to kill the spores before plants are wet. High disease pressure will occur when it rains for over 12 hours at temperatures (>70F). Don’t use this mixture twice in a row. Use the Thiram PLUS Rhyme mixture instead if you need consecutive applications. Until we have more crop safety data, this may be a good strategy to minimize the PGR risk but maximize protection of your plants against Neopestalotiopsis.

During low infection conditions (temp <60F plus rain), use a less aggressive approach and apply Thiram only.

Fall application recommendations:

First four weeks after planting and before low-disease-pressure situations:

Thiram SC at 2 to 2.5 qts per acre

or

Thiram SC at 2.5 qts PLUS Rhyme at 7 fl oz (if you must apply a mixture during early plant establishment)

Before high-disease-pressure situations

Thiram SC at 2.5 qts PLUS Tilt OR Inspire at labeled rates

followed by (if high-pressure situation persists)

Thiram SC at 2.5 qts PLUS Rhyme at 7 fl oz

Followed by (if high-pressure situation persists)

Thiram SC at 2.5 qts PLUS Switch at 11 fl oz