Jay W. Pscheidt, Extension Plant Pathologist
Abound (azoxystrobin) is registered for hazelnuts and
is a FRAC group 11 fungicide. This material has
translaminar properties meaning that it moves into the
plant tissue but does not move with the transpiration
stream. Abound is best used as a protectant
material at 10 day intervals. Greenhouse trials
have shown that this product does not have after infection
Rates should be kept high at 12 fl oz/A as stated on the
label. We obtained 96% control during
the spring of 1998 using Abound at 15.4 fl oz/100 gal
water. However, control has averaged only 62% when rates were
dropped to 3 fl oz/100 gal water.
See also the prepackaged mixes QuiltXcel and QuadrisTop below.
Adament (tebuconazole plus trifloxystrobin)
Adament is a prepackaged mix of tebuconazole (FRAC group 3) and Gem (trifloxystrobin, group
products have worked well against EFB. Testing of rates below 3 fl
oz/100 gal water were always significant but averaged only 64% control.
Testing at 3 fl oz/100 gal water gave 38% control but then all materials
with either chemistry did not do well that year. The 3 fl oz/100 gal
water rate plus the surfactant Silwet did well the next year with 89%
control. Registered rates for Adament 50 WG are at 4 to 8 oz/A (plus a
surfactant). The only problem with using combination materials is that
you must switch to a different chemistry after 2 applications. The only
other chemistry to alternate with would be materials that contain
chlorothalonil such as Bravo or copper-based materials.
(chlorothalonil) and generics such as Echo
Bravo (chlorothalonil) is an excellent,
broad-spectrum fungicide registered on a wide variety of
crops. It is one of the longest residual fungicides on
the market today. Another useful characteristic is
redistribution during rain events. A small but important
portion of each application redistributes to other
possibly unprotected parts of the plant during
rainstorms. After approximately two weeks, depending on
weather events, much of the material is washed off and
reapplication is necessary for continued protection. Soil
microorganisms quickly decompose any material washed onto
the ground. Some people develop an allergic skin rash
upon repeated exposure to this chemical.
Bravo was one of the first fungicides we found to be
highly effective against EFB. I can still remember
walking through a trial in 1989 that everyone thought was
a failure. Many fungicides had been applied to several
replicate trees but primarily during the dormant
A lot of disease developed in the trees, which is why
no one thought much of it. I walked to each replicate
without knowing where each treatment was located and
picked out the best looking tree. In 6 out of 8
replicates I picked out the Bravo treatment. It turned
out that one of the spray applications was close to
budbreak. By the spring of 1990 we had an emergency
exemption for use of Bravo on hazelnuts and a full
special local needs registration (SLN or 24 C) in
There have been close to 50 field trials during the
1990's that included Bravo but each with a specific
and often different objective.
Objectives have included different numbers of
applications, rates, timings and application methods.
When all of this information was combined, both good and
bad results, the average level of control was only 65%.
If we only consider the labeled rate then the average
level of control is 83% (30 trials). To
understand why Bravo is considered a good product we must
evaluate the data more closely.
For example, if we consider only trials evaluating
various numbers of applications at labeled rates we get a
different picture. A single application at budbreak
resulted in an average of 51% control but only 7 out of
11 trials resulted in control that that was significantly
better than no application at all. If another application
was applied two weeks after the bud break spray then the
average control is 59%. With a total of 3, 4, and 5
applications (all starting at bud break and 2 weeks
apart) then the average level of control jumped to 77, 90
and 85%, respectively. In addition, all of these later
trials were significantly better than no applications at
all. The data suggest that a total of 4 applications is essential.
Rate trials with Bravo 720 have shown that as the rate
was reduced the level of control was reduced. The number
of significant trials also drops such that Bravo's
performance against EFB becomes similar to that observed
for the copper hydroxides.
A negative aspect of Bravo applications to hazelnuts
is the chance of increased summer sunburn. Spring
applications of Bravo have resulted in a noticeable
increase in sunburned leaves during August. Although this
does not affect yields it may increase the number of
leaves on the ground during harvest. The affect was only
observed on slow growing, non-vigorous trees. The
manufacturer suspected an interaction with other
pesticides, which we have not been able to duplicate.
Nevertheless, the label recommends that no other
pesticides, especially oils, be tank mixed with Bravo and
that Bravo applications not occur within one week of a
application of oil-based products.
Because of the volume of data and its effectiveness
against EFB, Bravo will be the standard by which we will
compare most other fungicides. There are other
formulations of chlorothalonil (such as Echo and Equus) which provide a similar level
of efficacy. Home labels such as Bnoide Fung-onil or Hi-Yield Vegetable, Flower, Fruit and Ornamental fungicide can also be found.
Cabrio (pyraclostrobin) has a label for EFB and has also been tested unter the
code name BAS 500. Cabrio, like Abound and Flint, is a strobilurin (group 11 fungicide) and has
translaminar properties meaning that it moves into the plant tissue but
does not move with the transpiration stream. Cabrio is best used as a
protectant similar to the way Bravo is used. We observed 91% control in 10
trials when it was used in this way.
In one greenhouse trial, Cabrio was shown to have significant activity
when applied 2 days after spores of EFB were applied to young hazelnut
seedlings. This activity, however, was gone after 3 days.
See also the prepackaged mixes Merivon and Pristine below.
Use of copper as a fungicide has a long history
starting with the use of Bordeaux mixtures during the
1880's. Further developments of copper-based fungicides were
aimed at improving the handling and safeness to plants
over copper sulfate and lime mixtures while trying to
maintain its retention properties. The closest result was
the development of copper hydroxide.
Several formulations have been evaluated for efficacy
against EFB. Interest in these materials occurred early
since they were already registered on hazelnuts for
control of bacterial blight. Control has varied from 53%
to 89% over the years. In general, trials with copper
hydroxide products have been inconsistent unlike those
with Bravo. In some years, applications of these
materials even at highest labeled rates have not provided
significant control of EFB over using no fungicide at
all. This is why Bravo has been favored over copper
hydroxide products for control EFB.
There have been 6 trials where both Bravo and copper
hydroxide were in the same test, applied at the same
timings, in the same location, during the same year. In
these tests, the average level of control obtained for
the copper hydroxide materials was 72% compared to an
average of 79% for Bravo 720. So, in those years where
copper hydroxide works against EFB it works about as well
In all of the tests with copper hydroxide it was used
with the addition of supreme oil, as recommended on the
label. Oil alone was evaluated (0.25%) but was not found to be
effective against EFB. Some labels of copper hydroxide
still carry the old and outdated recommendation to use
dormant applications for the control of EFB. Only spring
applications when shoots are actively growing will be
effective against EFB.
(tebuconazole) and generics
Elite (tebuconazole) is in the DMI family of
fungicides (FRAC group 3) and has both locally systemic and kickback activity.
This product was the next generation from Bayleton, Bayer's first DMI
Use of Elite alone in 13 different research trials has resulted in an
average of 84% control of EFB. When compared head to head with Bravo the
average control was 84% for Elite and 90% for Bravo. Higher rates are
more effective. An average of 87% control was gotten at the 4 oz/100 gal
water rate comparied with
78% control at 2 oz/100 gal water. When
used in a
combined program using Bravo first at bud break followed by multiple
applications of Elite, there was an average of 97% control.
Elite can be used right at bud break. Some DMI
fungicides, like Rubigan, need a little more green tissue exposed after
bud break to be effective. Other fungicides, like Elite or Orbit, are
effective when starting applications at bud break. The flowable
formulation of tebuconazole, Folicure, does not seem to be equally
effective with an average control of 72% and only significant in 2 out of
An emergency exemption (section 18) for use of Elite on hazelnuts for
the control of EFB was issued by EPA for the 2000 and 2001 growing
seasons. The emergency use expired on May 30th, 2001 and was denied
The generic Tebucon is registered for use on hazelnut. The
combination material Unicorn has both tebuconazole and sulfur. Sulfur alone has had variable results averaging
44% control but only significant in 1 out of 3 trials. Unicorn averaged 76% control in 3 trials. It might be
useful on the second application to also catch big bud mite crawlers.
Gem or Flint
The registration of Flint for use on nut crops during the
summer of 2002 was a pleasant surprise. Flint is a strobilurin or FRAC group 11
fungicide and has
translaminar properties meaning that it moves into the plant tissue but
does not move with the transpiration stream. Flint is best used as a
protectant similar to the way Bravo is used. We observed 87% control in 7
trials when it was used in this way. The average dropped in 2003-04
when it did not preform as well as other chemicals such as Bravo.
In one greenhouse trial, Flint was shown to have significant activity
when applied 2 days after spores of EFB were applied to young hazelnut
seedlings. This activity, however, was gone after 3 days. This is very
exciting as other members of the strobilurin group (Abound and Sovran) did
not have any kickback activity.
A flowable formulation called Gem was introduced to the marketplace
2006. Technically, Flint is no longer registered for use on hazelnuts.
A few combination products that contain trifloxystrobin are registered for control. The products include
Stratego (propiconazole plus trifloxystrobin) and Luna products. Stratego has both a FRAC group 3 and 11
fungicide and does very well against EFB. Luna Sensation also contains trifloxystrobin but in addition contains
fluopyram (FRAC group 7). Fluopyram did
not do well and was not
significatly different from trees that did not get treated with any fungicide. Based on this result we are not
recommending the use of Luna Sensation or any of the Luna products.
Merivon (pyraclostrobin plus fluxapyroxad)
Merivon has a label for EFB and contains both Cabrio (pyraclostrobin, FRAC group 11) and Xemium
(fluxapyroxad, FRAC group 7). Cabrio works very well alone against EFB. Xemium (also known as Sercadis) averaged
83% control in two trials. Unlike other combination fungicides (such as Pristine or Luna products) we do
recommend the use of
Merivon for EFB. Use of Merivon at 3.25 to 4 fl oz per 100 gal water resulted in an average of 93% control in 4
Pristine (pyraclostrobin plus boscalid)
Pristine has a label for EFB and contains Cabrio (pyraclostrobin, FRAC group 11) and Endura
(boscalid, FRAC group 7). Cabrio works
very well alone against EFB but Endura does not. Endura had an average of 13% control and
was not significatly different from trees that did not get treated with
any fungicide. Based on this result we are not recommending the use of
Pristine even though we have observed 93% control in 2 trials.
(propaconazole) and similar generics
The active ingredient propaconazole was orginially sold by a
wide variety of trade names depending on the market and
location of the sales. Orbit was the name used for the
tree fruit and nut markets. Tilt was traditionally for
agrinomic crops such as grass seed. Generic names include Bumper and Propi-Max.
The average level of control when using the product Banner was 91% (7
trials) while 10 trials with Orbit have resulted in 82% control. Two
trials looked at only 3 applications for the season which
resulted in 74% control. Greenhouse trials
have show that Orbit has a 2-3 day
kickback activity aganst EFB and is greater when used
at higher rates.
An attempt to get a section 18 in 1999
was not sucessful but was granted in 2003, 2004, 2005 and
2006. A regular section 3 registration was obtained in 2007.
Application of Tilt will result in what is called plant
regulation (PGR) effects. The young developing shoots produce smaller,
greener leaves and shorter internodes. This picture shows normal
shoots on the right and shoots treated with Tilt on the left.
Shoots seem to grow out of the
effect 2 weeks after the last application. From 1994 to 1996, we sprayed
the same young Ennis trees with various amounts of Orbit (2 to 16 oz/A)
to see if there were any adverse effects on
yield. The PGR effects were seen each year and the average leaf area was
reduced at 4 or more oz/A. However, trees sprayed for 3 consecutive
years with 10 oz Orbit/A or 2 years with 16 oz Orbit/A did not result in
significant difference in fresh nut weight, fresh kernel weight or dried
kernel weight when compared with trees that had never been sprayed.
Research during 2002-03 and 2003-04 has shown that whether Orbit is
used for a total of 4 applications or once at bud break or once 6 weeks
after bud break, the average shoot length at the end of the seasion is
same as on trees that had not been sprayed with any fungicide at all.
In 1995, a few mature Barcelona trees were sprayed in commercial
orchards to see how growers might react to this PGR effect. Grower
comments included, "If the whole orchard were sprayed with Orbit you
never notice the difference or think anything was wrong." and "Does not
represent a significant problem."
A few combination products that contain propiconazole are registered and
recommended for control. The products include QuiltXcel (propiconazole plus azoxystrobin) and Stratego
(propiconazole plus trifloxystrobin).
Procure (triflumizole) received an emergency section 18
registration in 2001 and 2002 and regular section 3 registration late
spring 2006 for use against EFB. Trials have tested Procure from 1.5 to
6 oz/100 gal water for an average of 78% control (17 trials).
Procure has the same mode of action (group 3) as Orbit, Elite or Rubigan.
We expect it to have similar curative or kickback properties, as do the
materials in this group. In one greenhouse trial, Procure was shown to
have significant activity when applied 2 to 3 days after spores of EFB
were applied to young hazelnut seedlings.
Procure has not shown a plant growth regulation (PGR) effect on
hazelnuts even though it is in the same chemical class as Orbit. Leaves
on Procure treated trees apear to have the same size and color as
QuadrisTop (azoxystrobin plus
Another mix of two effective products against EFB - Abound (azoxystrobin, FRAC group 11) and
difenconazole (FRAC group 3). Both FRAC groups have worked well against EFB. Testing of rates from 7 to 14 fl
oz/100 gal water averaged 91% control in 5 trials. The only problem with using combination materials is that you
must switch to a different chemistry after 2 applications. The only other chemistries to alternate with would be
materials that contain chlorothalonil (such as Bravo) or copper-based materials.
Quash (active ingredient metconazole) is registered for use against EFB. It is in the same chemical group as
Tilt, Procure and Rubigan (all FRAC group 3 materials). Tests for the last 4 years have found this material
effective only at the 4 oz rate. However, better control
(91% in 2 trials) was found when a surfactant was used. We used the surfactant Regulaid but suspect any surfactant will help boost efficacy of this material. This
product can only be used in two sequential sprays before you must switch to a different product in a different chemical group.
QuiltXcel is a prepackaged mix of Tilt
(propiconazole, FRAC group 3) and Abound (azoxystrobin, FRAC group 11). This
material was tested at 14
fl oz/100 gal water in 6 trials resulting in an average control of 91%. The label rate allows
use of 14 to 21 fl oz/A. As with any product that contains propiconazole
you will see a growth regulation effect of smaller deeper green leaves.
Hazelnuts begin to grow normally 2 weeks after the last application.
Stratego (propiconazole plus
Another prepackaged mix of two effective products against EFB - Tilt (propiconazole, FRAC group 3)
and Gem (trifloxystrobin, FRAC group 11). Both products have worked well against EFB.
This material was tested at 5 fl oz/100 gal water in 3 trials resulting in an average control of only 79% but
when tested at 7 fl oz/100 gal water it resulted in 93% control. The label rate allows use of 12 to 15.4 fl oz/A
so use the higher rate for better control.
As with any product that contains propiconazole you will see a growth regulation effect of smaller deeper
leaves. Hazelnuts begin to grow normally 2 weeks after the last application. If you use combination materials,
you must switch to a different chemistry after 2 applications. The only other chemistries to alternate with would
be materials that contain chlorothalonil (such as Bravo) or copper-based materials.
TopGuard (flutriafol, FRAC group 3) is one of the most systemic materials of all of FRAC group 3
products. It can move so well with the transpiration stream that it can accumulate at the leaf margins. When
combined with a surfactant this systemic activity can work too well and result in some phytotoxicity at the leaf
margin. Although registered at a rate of 7 to 14 fl oz/A, it is recommended to use the higher rate for best