Eastern Filbert Blight

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Helping farmers find, destroy, and manage EFB


Fungicides

Jay W. Pscheidt, Extension Plant Pathologist

Abound
Adament
Bordeaux
Bravo
Cabrio
Copper Hydroxides
Elite
Gem (Flint)
Orbit / Tilt
Procure
Quash
QuiltXcel
Rubigan

Abound

Abound is registered for hazelnuts and is a group 11 fungicide also known as a strobilurin. These materials have translaminar properties meaning that they move into the plant tissue but do not move with the transpiration stream. Abound is best used as a protectant material similar to way Bravo is used. Unlike Bravo, Abound should be used at 10 day intervals. Greenhouse trials have shown that this product does not have after infection activity.

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.

Adament

Adament is a prepackaged mix of Elite (tebuconazole, group 3) and Gem (trifloxystrobin, group 11). Both products have worked well alone in the past. 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.

Bordeaux 

Bordeaux is a mixture of copper sulfate plus hydrated lime. It is recommended to use as a 6-6-100 which means 6 lb copper sulfate plus 6 lb hydrated lime per 100 gallons of water. Bordeaux mixture's ability to weather spring rains and adhere to plants is a valuable characteristic. However, if not mixed properly it has the tendency to clog sprayer lines and nozzles. It must be made just before spraying as in will loose efficacy when left in the sprayer for extended periods of time. It also has the tendency to burn young hazelnut foliage.

Most of the EFB control information on Bordeaux comes from Dr. Ron Cameron's work with mature, infected trees prior to the 1990's.

At that time they were not aware that ascospores of the fungus infected through young developing shoots. The average number of applications was 2.7 but only an average of 1.5 applications were applied during the spring to protect young shoots. Out of 6 trials, the average level of EFB control was 71%.

Most all of the other data in this report was conducted since 1989 using young, healthy trees. These healthy trees were inter-planted within heavily diseased orchards during the dormant season, sprayed with fungicide during the spring growth period, then tended until the following year when they were evaluated for EFB cankers. These trees were never used again for testing as a new set of trees was used each year. Using this technique there has only been one field evaluation of bordeaux, applied 4 times for an average level of 74% control.

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Bravo (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 season.

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 1996.

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) 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.

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Cabrio (pyraclostrobin)

Cabrio 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 89% control in 5 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.

Pristine also contains pyraclostrobin but in addition contains Endura (boscalid). Endura did not do well with an average 17% 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.

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Copper Hydroxides

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 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 as Bravo.

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.

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Elite (tebuconazole) and generics

Elite (tebuconazole) is in the DMI family of fungicides (group 3) and has both locally systemic and kickback activity. This product was the next generation from Bayleton, Bayer's first DMI product. It is label on grapes and stone fruits as well as several other crops under the Folicure label.

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 unlike Rubigan. 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 3 trials.

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 for 2002.

The generics Tebucon and Tebuzol are registered for use on hazelnut. The combination material Unicorn has both tebuconizole and sulfur. Although Unicorn was effective we are not quite sure if sulfur alone will work on EFB. It might be useful on the second application to also catch bug bud mite crawlers.

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Gem or Flint (trifloxystrobin)

The registration of Flint for use on nut crops during the summer of 2002 was a pleasant surprise. Flint is a strobilurin or 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 in 2006. Technically, Flint is no longer registered for use on hazelnuts.

Luna Sensation also contains trifloxystrobin but in addition contains fluopyram. 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.

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Orbit or Tilt (propaconazole) and similar generics

The active ingredient propaconazole is sold by a wide variety of trade names depending on the market and location of the sales. Orbit is 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 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.

Orbit PGR EffectApplication of Orbit will result in what is called plant growth 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 Orbit 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 a 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 the 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 would 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 QuiltEcel and Stratego.

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Procure

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 other 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 nontreated trees.

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Quash

Quash (active ingredient metconazole) is a new fungicide registered for use against EFB. Although it is new chemistry, it is in the same chemical group as Orbit, Tilt, Procure and Rubigan (all 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.

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QuiltXcel

QuiltXcel is a prepackaged mix of Orbit (propiconazole, group 3) and Abound (azoxystrobin, group 11). This material was tested during the 07-08 season at 3 rates from 10.5 to 17.5 fl oz/100 gal water. The average control was 99%. 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.

Rubigan

During the early 1990's we knew at least one of the DMI fungicides would be needed for effective management of EFB. To pursue a successful registration we needed an effective material with a good toxicology package and manufacturer support. Dow Elanco seemed most interested and with early efficacy data we focused on obtaining a registration for Rubigan. The first emergency exemption was issued in the spring of 1994 but we are still awaiting a section 3 registration. 

Over the years we have found that although Rubigan has 2-3 day kickback activity against EFB it was not a material to use exclusively. 

The overall average from all of our trials was 39% control. When compared one to one with Bravo under the same conditions Rubigan averaged 46% control while Bravo averaged 88% control out of 8 trials. Use of this material is restricted to a combined program first utilizing protectants like Bravo then systemic products such as Rubigan. This stratagy has resulted in an average 99% control in 12 trials.

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Management Pages
Scout
Replace Pollinizers
Apply Fungicides
Summary Tables
Abound
Adament
Bordeaux
Bravo
Cabrio
Copper Hydroxides
Elite
Gem (Flint)
Orbit/Tilt
Procure
Quash
QuiltXcel
Rubigan
Remove Cankers
Plant Resistant Cultivars
Destroy Escaped Seedlings
Burning Rules
Where to Focus 
Your Resources

Begin fungicide applications at budbreak.
Begin fungicide applications at budbreak

Photo by Ken Johnson, 1990.
 

In some years, applications of Bravo in the spring for EFB control have resulted in increased susceptibility of the leaves to summer sunburn. Vigorously growing trees do not seem to be as susceptible.
Leaves can become susceptible to sunburn after spraying Bravo
Photo by Jay W. Pscheidt, 1990.

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