Just a reminder that we currently recommend applying effective fungicides every 10-14
days in the fall to manage Neopestalotiopsis (Picture 1) . In addition, I just want to note that we have seen very little Neopestalotiopsis compared to last year, and I hope it stays that way. Ultimately, we should still
treat this year as if the risk is high, as the potential losses far outweigh the cost
of additional sprays.
Picture 1. Neopestalotiopsis symptoms on strawberry plants
What’s up with Thiram?
First off, many growers are having issues finding Thiram SC, and it feels like it
is not going to become any easier to find. The EPA has been reviewing the registration
for Thiram since 2015 and has proposed the removal of all non-seed treatment uses,
including strawberry and peaches, since at least 2021. See the amended proposed interim
decision (PID) from April 2024 for an outline of the details and timeline: https://www.federalregister.gov/documents/2024/04/30/2024-09181/pesticide-registration-review-proposed-decisions-for-several-pesticides-notice-of-availability . The posting of that PID started a comment period that allowed stakeholder input
through July 2024, which is now closed. We have not heard any further updates since
then.
The reality is that until Neopestalotiopsis became an issue, this review wasn’t on our radar. It was occurring at the same time
as others we were talking about, like the review of Captan. The good thing is that
the comment period occurred after we had our worst year of Neopestalotiopsis across the entire country, meaning the EPA will have to fully consider the impact
this decision will have on strawberry production in the US alongside their findings
of risk of use. The reality of any pesticide review is that they are necessary to
ensure the safety of our communities and farms, which can only be accomplished if
we take continued looks at registered pesticides as technology and medical understanding
advances over time. This system does a great job of weighing potential risk with impacts
to food production. These checks and balances were evident with the Captan review,
where the initial PID was backed down heavily after comment periods as grower groups
and universities clearly communicated its importance in preventing increased pesticide.
Another reality is the actual production of pesticides like thiram. Many producers
are struggling to find thiram and what we have heard from some distributors is that
the production may have come to a standstill. The reality is that the production company
could have decided that the future of a product under review may not be a profitable
endeavor. We’ve seen this with many other products, such as those that contain chlorpyrifos,
where the main producers decided to go in other directions once the possibility of
a ban increased. The good thing is that if the EPA backs down from the current verbiage
of the PID on thiram, there is a large need for the product and generally someone
will try to fill that need. The reality here is that even if strawberry uses stay
on the label, the product will be hard to find in mean time since distribution has
dried up.
Without Thiram, what options do you have for the fall?
Thiram is our go-to product for fall management of Neopestalotiopsis . It is critical to spray plants immediately after they are planted to reduce disease
inoculum, and continued protection is necessary until we significantly cool down.
Below is a list of the products that have exhibited acceptable efficacy in reducing
Neopestalotiopsis (Table 1) . Without thiram we could only consider Inspire Super, Rhyme, Switch, and Tilt as
our full arsenal of labeled and effective products to cover fall and spring spray
schedules. See the end of the document for a suggested full season spray schedule
(Figure 1) . You may wonder why other states are recommending Inspire instead of Inspire Super,
but no label exists for Inspire in Arkansas currently. Old stock could still be used
if purchased when it was labeled.
Table 1 – Fungicides that are effective in suppressing Neopestalotiopsis in strawberry
Product Active Ingredient FRAC Use Rate Uses and Notes PHI (days)
Thiram
thiram
M03
2.5 qts
5 apps East of Mississippi River
0
Switch
cyprodinil +
9 + 12
11 - 14 oz
5 apps at 11 oz/acre rate
0
Rhyme
flutriafol
3
7 fl oz
4 apps max
0
Tilt
propiconazole
3
4 fl oz
3 apps max
0
Inspire Super
difenoconozole +
3 + 9
16 - 20 fl oz
4 apps max
0
We currently only recommend thiram for fall use to save some fungicides like Switch
or Inspire Super for the spring where they are vital for management of Anthracnose
fruit rot and grey mold. You may ask, “Why don’t we save Switch for the spring and
use Inspire Super in the fall?” The problem is that fungicide labels consider any
application of Inspire Super as one use of Switch due to their shared active ingredient,
cyprodinil. Spraying five, 11 oz applications of Switch in a season would fully use
up your allowable cyprodinil limits.
We also run into a few speed bumps when considering Rhyme or Tilt for fall use. First,
Rhyme can be harder to find than many of the other chemicals listed, and I have heard
from many small producers that it has been cost prohibitive for them. Second, Tilt,
and other propiconazole containing products, have been known to stunt strawberry plants.
Previous research indicates that significant stunting is evident above three applications,
which is why we don’t recommend the four applications allowed by the label. Some southeastern
states have recommended propiconazole usage in the fall for Neopestalotiopsis suppression,
however we don’t think that would be a good strategy in our growing region.
It can be very difficult in our region to get plant size and crown numbers necessary
for optimal yield prior to the dormancy period, especially considering variable plant
deliveries and how variable our climate can be. I’d highly recommend you take a look
at all of Amanda McWhirt’s research on these factors, where she has consistently demonstrated
how important it is to maximize time for growth before dormancy. Growers often even
leverage risks to maximize growth with extended row cover use to make up for lost
time, which really showcases how a fungicide that slows down plants may do more harm
than good. In fact, Guido Schnable at the University of Clemson looked at propiconazole
usage in the fall on strawberries in 2024/2025 and did observe numerically lower plant
size and yield, although no statistically significant impact was found at his location.
I believe the risk is much higher in our growing region compared to South Carolina.
We have a much shorter time from planting to dormancy and plants usually withstand
much cooler temperatures earlier in their transition into dormancy. Ultimately propiconazole
use in the fall may be worth it with heavy disease loads and normal planting times,
you should just expect some lower yields to lower the disease risk.
For more information on DMI (FRAC 3) usage in strawberry, consider the follow article
by Phil Brannen in the Small Fruit News. https://smallfruits.org/2025/09/dmi-fungicides-for-Neopestalotiopsis/
Recommendations for fall Neopestalotiopsis sprays if you don’t have Thiram
If you can’t find Thiram, your go-to product in the fall needs to be Rhyme. This product
is available from several sources online and I would highly recommend you weigh heavy
losses from Neopestalotiopsis against the price to buy it. In the 2024-2025 strawberry season, producers who put
out effective fungicides in the fall were the ones that saw the least amount of plant
loss from Neopestalotiopsis . If you still haven’t put out an effective product this fall, I highly recommend
you get something out ASAP. The priority needs to be spraying ASAP after planting,
then we usually recommend considering all the factors you can on when to continue
applications. In years when plants appear clean, as many do this year, and we are
relatively dry with a quick cool-down, I think 1-2 applications would get you to dormancy.
If you have pervasive leaf spot and/or have been hit by several rain events, you really
need applications out every 10-14 days, which would probably mean 3-4 applications
in the fall.
If you have to rely on Rhyme due to not having thiram, I would highly recommend mixing
it with captan for each application. Captan has shown some suppression of Neopestalotiopsis in some studies, which may mean effective resistance management when relying more
heavily on FRAC 3 fungicides. For smaller growers it’s possible you could get away
with using Captan as a replacement, especially this year where the risk appears be
lower. Captan has been shown to have some activity on Neopestalotiopsis , and I really think getting it out every 10-14 days in the fall will be better than
not spraying. I’ve talked with some growers who have none of the products listed above
as of late October and had not applied fungicides yet to their strawberries. I think
in this situation get out Captan ASAP if you have it and try to get your hands on
Rhyme in case this cool down doesn’t last.
Spraying around rain events
Not every situation has a perfect solution, and I think in the last week many growers
have grappled with several excessive rain events in a week. Many were 10-14 days from
their last spray and looking at 3 days of rain in their near future. The main factor
you need to consider is time since your last spray and the weather that occurred during
that interval. Neopestalotiopsis will readily sporulate and germinate in mild or warm temperatures when leaf wetness
and heavy rain events are abundant. If it has been 10 days since you sprayed and it
rained during that period, your plants are at a high risk of further infection of
Neopestalotiopsis if another rain event is in the near future. Even if a protectant fungicide like Thiram
may get washed away in 1-2 days, it is still worth applying before the rain event
to reduce the number of spores that will germinate during the extended periods of
leaf wetness in your near future. In most cases, spraying before the rain event will
be the correct decision if you can get 12 hours of time from application to any rain
event to ensure rain-fastness and activity of the fungicide.
When to terminate applications for the fall
Neopestalotiopsis is a disease that doesn’t necessarily need warm weather to occur, but in our experience
once it cools down the risk of continued development and furthered infection reduces
significantly. Once the high gets between 50-60°F with cold nights, I think we have
reached our last spray for the fall. We plan to make our last application in our trials
the first week of November unless we get a big warmup after this last week of October,
and I feel confident that it will be the same for many others in the state. Keep an
eye out for extended warm periods (highs between 70-80°F and warmer nights) and if
you are playing catch-up with diseased plants, I would extend sprays further into
the fall.
As always there are many nuances when making these decisions. Feel free to give me
a call or send me a text or email anytime to discuss your situation and we can try
to find a successful path forward.
Aaron Catoacato@uada.edu
West of the Mississippi River East of the Mississippi River
Figure 1. Example spray schedules for strawberry protection in the Mid-South
App # Fungicide FRAC Groups App # Fungicide FRAC Groups
Fall 1
Thiram
M03
Fall 1
Thiram
M03
Fall 2
Thiram
M03
Fall 2
Thiram
M03
Fall 3
Thiram
M03
Fall 3
Thiram
M03
Fall 4?
Thiram
M03
Fall 4?
Thiram
M03
Spring 1
Switch
12 + 9
Spring 1
Switch + Thiram
12 + 9 + M03
Spring 2
Captan + Elevate + Rhyme
M04 + 17 + 3
Spring 2
Captan + Elevate + Rhyme
M04 + 17 + 3
Spring 3
Switch + Captan
12 + 9 + M04
Spring 3
Switch + Thiram
12 + 9 + M03
Spring 4
Captan + Elevate + Rhyme
M04 + 17 + 3
Spring 4
Captan + Elevate + Tilt
M04 + 17 + 3
Spring 5
Luna Sensation + Thiram
7 + 11 + M03
Spring 5
Luna Sensation + Thiram
7 + 11 + M03
Spring 6
Switch + Captan
12 + 9 + M04
Spring 6
Switch + Thiram
12 + 9 + M03
Spring 7
Luna Sensation + Captan + Tilt
7 + 11 + M04 + 3
Spring 7
Luna Sensation + Captan + Tilt
7 + 11 + M04 + 3
Spring 8
Switch + Captan
12 + 9 + M04
Spring 8
Switch + Thiram
12 + 9 + M03
Spring 9
Luna Sensation + Captan + Rhyme
7 + 11 + M04 + 3
Spring 9
Luna Sensation + Thiram + Rhyme
7 + 11 + M03 + 3
Spring 10
Switch + Captan
12 + 9 + M04
Spring 10
Switch + Thiram
12 + 9 + M03
Spring 11
Cabrio + Captan + Tilt
11 + M04 + 3
Spring 11
Cabrio + Thiram + Tilt
11 + M03 + 3
Figure 1. Example spray schedules for strawberry protection in the Mid-South
