Fungicide Tank-Mixes and Incompatibilities

Common Fungicides Used for Fruit Disease Management

Their Compatibilities and Incompatibilities 

·       Topsin M (thiophanate-methyl, FRAC 1)

o   Do not tank mix with highly alkaline materials such as Bordeaux or lime sulfur

o   Do not tank mix with copper

·       Inspire Super (difenoconazole + cyprodinil, FRAC 3 & 9)

o   Do not tank-mix with surfactants or foliar fertilizers

·       Rally (myclobutanil, FRAC 3)

o   Compatible with oil

o   Stable at a wide range of pH

·       Revus Top (mandipropamid + difenoconazole, FRAC 3 & 40)

o   Do not tank-mix with surfactants or foliar fertilizers

·       Topguard (flutriafol, FRAC 3)

o   Compatible with surfactants

·       Fontelis (penthiopyrad, FRAC 7)

o   Compatible with surfactants and oil

·       Pristine (pyraclostrobin + boscalid, FRAC 7 & 11)

o   Compatible with oil (except on pear)

o   Do not use Pristine + oil on pear

o   Do not use surfactants when applying by air (hops)

·       Scala (pyrimethanil, FRAC 9)

o   Not compatible with captan

·       Vangard (cyprodinil, FRAC 9)

o   Compatible with most tank additives

o   Adjust pH to 5.0 – 7.0 when tank-mixed with Rovral (stone fruit, small fruit)

·       Cabrio (pyraclostrobin, FRAC 11)

o   Compatible with most additives or adjuvants

·       Flint (trifloxystrobin, FRAC 11)

o   Compatible with most insecticides, fungicides, and foliar nutrients

·       Sovran (Kresoxim-methyl, FRAC 11)

o   Can be tank-mixed with most recommended insecticides, fungicides, plant growth regulators, adjuvants, or additives

 ·       Captan (FRAC M)

o   Do not mix with oil or within 4 days of an oil application

o   Do not mix with strongly alkaline materials (reduces fungicidal activity) such as   Bordeaux mixture or lime

o   Phytotoxic to apple when mixed with sulfur

·       Copper (FRAC M)

o   Not compatible with Topsin M

o   Do not apply under cool, slow-drying conditions

o   Do not tank-mix with phosphorus acids

o   Tank-mixing with mancozeb may cause phytotoxicity under wet or cool conditions. Spot check before use.

o   Many Bacillus products are incompatible with copper. Read label and use caution.

·       Dithane (mancozeb, FRAC M)

o   Compatible with most insecticides, fungicides, or growth regulators

·       Polyram (metiram, FRAC M)

o   Spray oils may be needed to achieve consistent control

·       Sulfur (FRAC M)

o   Do not mix with oil or use within 2 weeks of each other

o   Do not mix with Bt

o   Phytotoxic to apple when mixed with captan

o   Do not apply to sensitive crop cultivars

o   Do not use at temperatures above 80˚F

·       Syllit (dodine, FRAC M)

o   Do not mix with Bordeaux or lime

·       Ziram (FRAC M)

o   Compatible with most commonly used adjuvants

 

Above comments and compatibilities are per label recommendations, thus terminology and language may vary from one product to another.

Untangling the Web of Copper Fungicides

Fire blight season is approaching, and delayed dormant applications of copper fungicides are commonly recommended for management of various tree fruit diseases.  But there are so many...

Below is a summary of copper formulations, their characteristics, and their limitations. 

Copper Fungicides

·       Fixed Copper

o   Safer for plant tissue than “bluestone” copper (see below)

o   May be used throughout growing season, but may cause fruit russetting

o   Low solubility in water, lower risk for phytotoxicity

o   Release copper ions slowly (with water/rain), longer residual

o   Slow drying time (rainy conditions) increases solubility, ion release, and phytotoxicity

o   Acidic conditions/additives increase solubility, ion release, and phytotoxicity

§  Adjuvants, phosphorus acid fungicides, and mancozeb lower pH

o   Use high rates during dormancy for fire blight management (until ½” green)

o   Lower rates during growing season for management of other diseases, may add lime

o   Common forms of fixed copper fungicides

§  Basic copper sulfate – Cuprofix, Basicop, Phyton, Agristar

§  Copper Hydroxide – Kocide, Champ, Badge, NuCop, CuPro

§  Copper oxychloride sulfate – C-O-C-S

§  Cuprous oxide – Nordox, ChemCopp

·       Copper sulfate pentahydrate – bluestone

o   Dormant spray, only

o   CuSO₄.5H₂O

o   Highly soluble ions, phytotoxic

o   Often combined with lime to help tie up copper ions

o   No residual activity, rapid release of copper ions

o   Common brands of copper sulfate

§  Mastercop, Magna Bon, Aquavet, Delcup

  

Tree fruit diseases managed with copper fungicides:

•                 Fire blight (spray guide recommendations: dormant – label: silver tip to green tip)
•                  Apple scab (dormant to pink)
•               Bacterial canker (after harvest and late dormant)
•                Bacterial spot (dormant/budswell, pink, and petal fall)
•                Peach leaf curl (dormant)
•                Cherry leaf spot (after petal fall)
•                Black knot (dormant)

Copper is an antimicrobial; it is not selective.  Kills any exposed plant cells, bacteria, and fungi

Large numbers of copper ions (rapid release of ions) are phytotoxic to plant tissue, especially leaf tissue

Copper fungicides are not systemic and wash off with rain.  Fixed coppers have more residual activity due to slow release of copper ions.

Metallic copper equivalent is the amount of copper available for fungicidal activity (different from active ingredient).  Basic copper sulfate usually contains the highest metallic copper equivalent.

Copper can accumulate in soils, inhibit plant growth, and is toxic to microorganisms and earthworms

More on fire blight at http://nicolewarduk.blogspot.com/2013/04/fire-blight-infections-occur-during.html

 

Peach Canker & Oozing Sap

Oozing Sap Coming from Peach Canker?  It might be a Fungal Disease.

Perennial canker of peach is a fungal infection of fruiting twigs, scaffold limbs, or trunks (Fig 1 & 2).  The disease may also be referred to as Cytospora canker, Leucostoma canker, perennial canker, valsa canker, or peach canker.  A common symptom is oozing gum from canker sites, so symptoms may also be referred to as gummosis (Fig 1). 

The causal fungi, Leucostoma spp., are weak pathogens that infect stressed or wounded plants.  Infections cause cankers, or stem lesions, that enlarge every year, creating annual rings or target-like growths.  These cankers expand until limbs become girdled and die.  Cankers often ooze gummy sap (gummosis) that eventually hardens (Fig 1).

Figure 1 – Perennial canker of peach limb, advanced symptoms with oozing sap. (Photo Penn State)

 

Gummosis can also be caused by other plant injuries such as bacterial infection (bacterial canker of peach), boring or sucking insects, and mechanical damage.  It is important to properly diagnose the cause of gummosis before considering management options. 

The fungi that cause peach canker produce spores during spring.  Fungal spores ooze from cankers during cool rainy weather.  Consequently, disease is often more severe during rainy years. 

Figure 2 – Infection of peach twigs, early symptoms.  (Photo West Virginia University)

 

Prevention of peach canker begins with vigorous plants and proper orchard sanitation. 

·        Retain plant vigor.  Maintain soil moisture, fertilize according to soil tests, and mulch properly. 

·        Avoid plant wounds such as mower damage, sunscald, winter injury, and insect injury.

·        Make clean, sharp pruning cuts that heal quickly.  Avoid jagged cuts.

·        Prune peach trees during late winter, preferably during late-February or March.

·        Prune during dry weather, only.  Fungal spores spread during wet conditions.

·        Maintain a clean orchard by pruning dead and damaged wood.  Remove cuttings from the orchard; bury, burn, or move them at least 100 yards from peach plantings.

·        Some peach cultivars are less susceptible to peach canker than others.  Use resistant or tolerant trees when possible.

 

If peach canker becomes a problem in the orchard, a strict sanitation should be implemented.  There are no fungicide treatments available for management of peach canker. 

·        Remove diseased twigs and limbs, making clean cuts at least 6 inches below cankers.  Remove diseased cuttings from the orchard.

·        Infected trunks may require “surgery.”  Using a knife or chisel, remove bark at least one inch around each disease lesion.  There is no need to cut into hardwood.  Do not paint affected area with wound dressing, paint, or oil. 

·        Prune during dry weather, only.

·        Disinfest pruners and tools between cuts using a commercial sanitizer, 10% bleach, or 10% Lysol® concentrated disinfectant.

·        Apply fungicides to open pruning wounds as a preventative.  Captan, iprodione (Rovral), and thiophanate-methyl (Topsin M) may be applied after pruning (delayed dormant phase), after petal fall, and after shuck split to prevent new infections. 

 

Sanitation and increased plant vigor are the primary disease management options for peach canker.  Growers should be aware of potential risks for infection and prevent disease outbreaks by following the guidelines above.  Once trees become infected, the pathogen can spread through orchards in just a few years.  Fungicides do not cure peach canker, and cultural practices are the primary means for disease management.