Fire Blight Infections Occur During Bloom

Fire Blight Infections Occur During Bloom

Risk for fire blight infections are high this weekend.  Apple are in bloom throughout most of the commonwealth, and Friday’s rain created ideal conditions for infection.

Initial infections from the fire blight bacterium occur during bloom.  The pathogen is carried to blossoms through rain or insects.  With sufficient moisture, the bacterium moves down into blossoms and infects natural openings of flower parts.  Thus, it is critical to protect apple blossoms from infections throughout bloom, especially when weather is warm and rainy.  Predictive weather models are available (http://wwwagwx.ca.uky.edu/plant_disease.html) for evaluating risk for infection.

Applications of bactericides (streptomycin or oxytetracycline) begin as the first blossoms open and continue until petal fall.  When weather conditions are conducive for infection, sprays should be repeated every 4 to 5 days.  Even when risk is low, a minimum of 2 applications is necessary to protect blossoms. 

 

Fig 1 – Blighting of shoots, also called shepherd’s crook, is the most recognized symptom of fire blight on apple.

 

More on Fire Blight

Fire blight can be a devastating bacterial disease of apple, crabapple, pear, and flowering pear, but disease epidemics are often sporadic.  In fact, optimal conditions must be met for severe disease to occur.  Our current conditions are an indication that fire blight may be severe this spring.

Erwinia amylovora infects trees through flowers.  However, large numbers of bacterial cells must be present during flowering in order for the disease to develop into an epidemic.  The fire blight pathogen favors rain and temperatures above 60˚F.  Under these conditions, bacterial cells multiply quickly.  Thus, if conditions are favorable during flowering, infection can be severe.

Predictive systems are available for growers.  University of Kentucky’s Cougarblight model evaluates the potential for infection by analyzing temperature and leaf wetness data from the previous four days in order to estimate potential risk for infection.  Trees must be in bloom for this predictor to be effective.  Cougarblight is an excellent decision-making tool for growers and can be accessed at http://wwwagwx.ca.uky.edu/plant_disease.html .

Most growers are familiar with shoot blight, the most obvious fire blight symptom in which infected shoots die quickly, causing branch tips to form a distinct crook (photo 1).  Shoot blight, however, does not result from infection of blossoms.  Direct penetration of bacteria into green shoots or the upper leaves of young shoots after bloom typically causes shoot blight symptoms.

Fig 2 – Initial infection by the fire blight pathogen occurs through blossoms.  Notice bacterial ooze coming from the pedicel.

 

Initial fire blight infections occur through flowers.  We call this symptom blossom blight.  Petal browning is the first sign of petal blight, but many growers do not notice it.  Browning of pedicels (stems that attach flowers to stems) follows.  Often, droplets of bacterial ooze can be seen coming from pedicels (photo 2).  Bacteria quickly travel down the spur and into the twig.  Cankers that form around the spur-attachment site girdle branches, and then branch parts above the canker also die (photo 3). 

 

Fig 3 – Bacteria can spread through flowers and spurs into twigs.  Resulting cankers can girdle entire limbs and branches.

Fire blight control measures include anti-bacterial pesticides applied during bloom.  Applications made after bloom are ineffective.  When fire blight risk is high (warm temperatures combined with rain) during bloom or if fire blight was a problem last year, the following spray schedule should be followed:

1.       Apply fixed copper at silver tip.  Homeowners should not skip this step, as it is their only tool available to combat fire blight.  Do not use copper fungicides after bud break.

2.       Apply streptomycin beginning at pink stage, repeating every 4-5 days, through petal fall.  At least 2 applications are required, but up to 4 sprays may be applied, depending on rain and temperature conditions.  Ideally, bactericides should be applied just before rains.  Pay extra attention to susceptible varieties (i.e. Gala, Jonathan, and Rome).  Utilize Cougarblight or MARYBLIGHT predictive systems for assistance.  Mycoshield (oxytetracycline) is also available for management of fire blight but is not as effective as streptomycin.  Neither product is recommended for homeowner use.

Various cultural practices may be implemented to aid in disease management.  Combine these practices with bactericide sprays above for best control.

1.       Select disease resistant or disease tolerant varieties.  Liberty, Pricilla, SirPrize, Enterprise, Gold Rush, and Sundance are recommendations from ID-21.

2.       Prune last year’s cankers and dead wood before bud break.  Burn, bury, or completely remove prunings from the orchard to eliminate the possibility of bacterial cells being carried back to healthy tissue.  Monitor predictive systems.  Know your risk.  Cool temperatures or no rainfall will result in low disease incidence.

3.       Remove flower/fruit spurs immediately after symptoms develop so bacteria cannot continue infection into branches.  Dip tools in 10% bleach, 10% Lysol concentrate, or pure rubbing alcohol after each cut to keep from spreading bacteria.

4.       Do not prune limbs or branches during the growing season.  Trees natural defenses wall off infection sites and stop disease spread.  Remove these branches during the dormant season, instead, when threat of disease spread is lowest.  Removal of all infected wood is critical to prevent spread of inoculum.

 

More information on fire blight can be found in PPFS-FR-T-12 and PPFS-FR-T-7. 

Spray recommendations for commercial growers ID-92 and homeowners ID-21 are also available online.

Fire Blight Season is Approaching – Preventative Copper is Recommended

As apple flowering-season approaches, growers should begin thinking about management of fire blight.  This bacterial disease can cause severe damage on apples, pears, and related ornamental plants during warm, rainy spring weather.

 

There is no single method that will provide consistent and reliable control. Management of fire blight requires an integrated approach that relies primarily on cultural practices and is supported by the judicious use of bactericides.



Fig 1 – Blossom blight phase of fire blight in which bacteria infect blossoms during bloom.

Disease Development: The fire blight bacterium overwinters primarily in cankered or diseased branches and trunks. During spring, bacteria-laden ooze is exuded from canker margins. Splashing rain and insects carry the pathogen to blossoms (Fig 1), and bees further spread the pathogen as they pollinate.

 

If weather is warm and rainy, populations of the causal bacterium (Erwinia amylovora) double every few hours, and more than a million bacterial cells can colonize a single floral stigma. Rain or dew then washes the bacteria into openings at the base of blossoms. Resulting symptoms are called blossom blight.  Infections can spread from blossoms to supporting spurs and branches, causing cankers that eventually kill entire branches (Fig 2).

 

Even if there is no blossom infection, shoot infections may occur. Bacterial cells infect externally through shoot tips, as young, succulent tissue is susceptible during periods of rapid growth. This phase of fire blight is called shoot blight or shepherd’s crook.  

 

Fig 2 – Flower and shoot infections can spread to branches, causing cankers that eventually kill entire limbs.  The fire blight bacterium overwinters in cankers and dead wood.

 

Bactericides:  During bud swell (late dormancy), an application of copper fungicide (e.g. Kocide or other fixed copper) should be applied, especially if fire blight was severe last year.  This copper application should reduce amounts of bacterium present on the surfaces of branches and spurs, reducing risk for disease development.  Do not apply copper after ¼ inch green leaf stage, as can be phytotoxic (cause foliar burn). 

 

During bloom, beginning at the first sign of open blossoms, a bactericide such as streptomycin (e.g. Agri-strep) should be applied at 4- to 5-day intervals through petal fall.  A minimum of two applications is recommended.  Another type of bactericide, oxytetracycline (e.g. Mycoshield) may be substituted, but it is not as effective as streptomycin.  Oxytetracycline may be mixed with streptomycin bactericides to help reduce the risk for resistance development.  Disease risk assessment sites (see below) may be used to improve timing and efficacy of bactericide applications.  Note:  Home orchards are usually not sprayed with antibiotics, so the preventative copper spray is critical.

 

After bloom, certain weather conditions can increase risk for shoot infections.  This shoot blight phase can be severe during rapid shoot development, especially under warm, rainy conditions.  The growth regulator prohexadione calcium (e.g. Apogee) reduces terminal growth, reducing succulent tissue that is most susceptible to infection.

 

Pruning: Growers should remove all damaged, dead, or diseased wood from trees during dormancy, before bacteria become active this spring.  This will help eliminate large amounts of infective inoculum.    

 

Disease Risk Assessment & Weather Models: Plant disease prediction models utilize weather data to analyze disease risk. The University of Kentucky maintains weather stations and incorporates this data into disease risk predictions models. Models can be found at http://wwwagwx.ca.uky.edu/plant_disease.html

  

More information:  See also our newest fact sheet Fire Blight http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-FR-T-12.pdf

Midwest Tree Fruit Spray Guide http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/MW_tree_fruit_spray_guide_ID-92_(2013)[1].pdf

Disease and Insect Control Programs for Homegrown Fruit in Kentucky http://www.ca.uky.edu/agc/pubs/id/id21/id21.pdf

Apple Rots Common This Time of Year: Bitter Rot is the Most Prevalent

As apple harvent gets into full swing, many growers and backyard orchardists are encountering a variety of fruit rots.  Some of these rots are initiated by insect entry wounds or hail, and others are caused by fungal pathogens.

The most common of the fungal fruit rots is bitter rot.  

Initial infections begin as early as bloom and continue until about one month after petal fall.  Early symptoms are small, slightly sunken lesions that eventually develop concentric rings (bulls eye pattern).  Under moist conditions, spores turn a distinct salmon color.  Cutting into infected fruit reveals a V-shaped internal rot.

The fungus overwinters in mummified fruit, crevices in bark, and dead wood such as fire blight damaged tissue.  Removal of mummified fruit, cankers, and dead wood helps reduce inoculum for the following season.  Diseased fruit should be discarded immediately.  Fungicides are only effective with good sanitation, so these cultural practices are a necessary step in disease prevention and control.

Current recommendations indicate fungicide applications soon after petal fall (no later than first cover) and continue until harvest.  Fungicides  captan, mancozeb (dithane, manzate, penncozeb), polyram, and ziram are recommended on 10-14 day schedules.  Note:   Symptoms do not always occur immediately after infection, and it is sometimes late in the season before symptoms appear.  However, fruit should be protected in the early stages of development.

 

Some cultivars are more resistant or tolerant of bitter rot disease than others.  Cultivar susceptibility table available at http://www.caf.wvu.edu/kearneysville/tables/bitterrotsus.html .

More information at http://nicolewarduk.blogspot.com/2012/04/homeowner-apple-spray-schedule-low.html ,  http://www.uky.edu/Ag/IPM/appleipm/appleipm/frot.php , and http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-FR-T-2.pdf

Homeowner Apple Spray Schedule - Low Impact

Home gardeners who are overwhelmed by spray schedules may be interested in this quick publication.  Note, this is a low-impact schedule, so high disease pressure will warrant revision.  Contact your UK county Extension agent or refer to other UK publications for more detailed information http://www.ca.uky.edu/agc/pubs/id/id21/id21.pdf and http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-MISC-7.pdf 

Sample Simplified Home Apple Low-Spray Schedule

Compiled by Beth Wilson, Pulaski County Horticulture Agent, and

Dr. John Strang, University of Kentucky Extension Fruit Specialist

2011

For pictures of growth stages, see pages 18 and 19 in ID-21.

Recommendations based on ID-21. For organic options refer to ID-21.

Dormant (before buds swell)

Ø Fixed copper – fire blight control

Ø Dormant oil – only if you have scale insect problems

Ø These two sprays may be combined if fixed copper is used.

Green tip to half-inch green

Ø Fixed copper (if you did not spray as a dormant spray) – fire blight control

Ø Dormant oil if not used earlier – for mites and aphids

Ø Mancozeb* + Immunox (myclobutanil)  fungicides for control of apple scab and rust

Ø Fixed copper, dormant oil, Mancozeb and immunox can be combined in one spray.

Ø No insecticide needed at this point

Just before blooms open

Ø Mancozeb + Immunox – you will be on a 10 to 14 day spray schedule with this. Immunox is systemic and won’t wash off.

Ø Mancozeb must be re-applied if a significant rain (more than one inch occurs)

Ø Mancozeb has a 77 day pre-harvest interval (PHI), so you MUST stop spraying with this at least 77 days before you expect the apples to be harvested.

Ø Plus Malathion insecticide

Bloom

Ø Mancozeb – for cedar apple rust and scab control

Ø No insecticides

Ø Streptomycin – Fire blight control (every 4 days for a total of no more than 4 sprays for maximum control)

After petals fall

Ø Mancozeb + Immunox

Ø Malathion – for insect control

Ø Mix all of these in the same spray tank

Every 2 weeks after

Ø Use mancozeb as long as you can per the 77 day PHI, mix with malathion or permethrin (rotate these 2)

Ø Orchard spray – use this after mancozeb can no longer be safely used.

Ø Orchard spray contains captan (fungicide) and malathion usually, no need to mix in additional insecticide.  Add Topsin M (thiophanate-methyl), another fungicide for powdery mildew and improved sooty blotch and flyspeck control

Ø Check label for PHI and abide by this

*May substitute Captan for Mancozeb throughout this spray schedule

Freeze Damage and Fruit Diseases: Should You Abandon Your Spray Program?

Should you maintain your fungicide program after fruit loss?

After two nights of freezing temperatures (April 10-11, 2012), many apple growers reported some level of crop loss.  Susceptibility to freeze damage results from an early season when apple bloom began as early as mid-March in some areas.  I saw few late-varieties still in bloom earlier this week, but for the most part, apple flowering was complete when cold weather set in.

According to weather reports, temperatures did not get low enough to impart severe crop damage.  However, some growers have already reported losses.  I have been receiving questions regarding fungicide spray schedules for complete and moderate-loss orchards.  Below are a few disease facts to consider before abandoning your fungicide program.

 Apple

·         Fire blight bacterium was not active during the last few weeks due to dry weather.  Now, this cool dry weather continues to suppress the pathogen. 

o   Warm wet weather can reinvigorate the bacterium and raise risk of infection.

§  Dead blossoms cannot become infected.

§  Secondary (rat tail) blossoms can become infected.  These blossoms usually develop later, so monitor bloom.  If risk is high during secondary bloom, apply streptomycin.  Remember, check CougarBlight (see below) for risk assessment in your area. 

§  Shoot/twig blight phase of the fire blight disease can occur after bloom.  Young tender growth is most susceptible. 

·        Twigs and tissue damaged by freeze, hail, etc.  can become infected, especially when temperatures are warm and rainy. 

·         Twigs and shoots are can become infected even when there is not fruit.

·         Consider the level of risk by monitoring CougarBlight. 

o   Copper is a good choice if fruit load is minimal; streptomycin is recommended for fruit-bearing apple. 

o   If orchards have a history of twig blight, Apogee provides excellent control of twig blight.

§  Chances of a 50-75% crop are high, even though some growers fear the worst.  Evaluate crop losses (and non-losses) as soon as possible.  There is a possibility of at least a moderate fruit load this year.  Consider yield when adjusting spray schedules.  Good yields should receive regular spray regimes.

§  Ideally, plant pathologists prefer that growers maintain a sufficient fungicide program, even after complete fruit loss.  However, economics influence growers’ actions, and many growers opt for a reduced-pesticide regime.  Consider the following and assess your particular situation.

·         In the case of complete fruit loss, fire blight disease management can continue with copper sprays, alone. 

·         If yield potential is moderate to high, growers should follow their regular spray program as closely as possible.  This is a decision that should be based on individual situations.   

·         Bactericides should be applied during bloom or during spans of succulent tender growth if fire blight risk is high.  When conditions are wet and temperatures are above 60˚F, fire blight can infect.  

·         Orchards with a history of fire blight should be sprayed on a regular schedule, regardless of fruit load. 

·         Highly susceptible varieties (i.e. Fugi, Gala) require a regular spray schedule, regardless of fruit load.

·         If risk is low, consider that early copper and/or streptomycin sprays should have reduced inoculum, thus far.  However, proceed with caution.

·         Scab will be active, regardless of fruit load.

o   Continue to protect trees from scab.

§  Do not abandon your scab-management spray program.  However, a low-input programs may be considered – again, from an economic standpoint, not a plant pathology standpoint. 

·         Captan is a lower cost alternative that may be considered.

·         Fungicides may be applied at wider intervals if weather is not conducive for disease.

§  A low-input fungicide program this year will probably result in higher-than-normal disease pressure next year.  Be prepared to follow a strict spray schedule in 2013.

·         Growers should consider potential yield when evaluating low-input spray programs.  This is a decision that should be based on individual situations.

Peach

o   Even in the event of fruit loss, disease management, at some level, is required.  Protection of this season's foliage will positively influence next year’s fruit.

§  Monitor foliar and twig disease outbreaks carefully.

§  A low-input, lower cost spray program can include captan + sulfur. Growers should consider orchard history and weather conditions before selecting a low-input disease management program.

§  Alternatively, wider spray intervals may be suitable if weather is not conducive for disease.

Grape

o   Good disease management programs in the past, as well as during dormant and pre-bloom fungicide applications this season, should reduce fungal inoculum. 

§  Healthy vineyards that suffered complete fruit loss should not have severe disease problems. 

§  Vineyards with high to moderate fruit loss may opt for cheaper fungicides or wider spray intervals.  See above comments for apple and peach.

§  Monitor downy mildew infections in all vineyards.  Those with complete or moderate fruit loss may opt to treat downy mildew outbreaks instead of maintaining a preventative program.  As discussed above, this is not recommended, but economics may influence growers’ decisions. 

All growers should be utilizing UK’s Cougarblight predictive system for fire blight risk in apple.

It is extremely easy to use, as growers should first click on http://wwwagwx.ca.uky.edu/plant_disease.html. Next, click “Fire Blight” on the left side of the screen. Choose the weather station that is closest to the orchard by clicking the arrow under “Station” in the center of the screen. There are a few options below, such as the history of fire blight in the orchard. Finally, click “Submit Choices.” The next screen will describe the risk of infection in the orchard.

Freezing Temperatures Can Be Devastating to Fruit Blossoms

I pasted a chart of killing temperatures for tree fruit.  For more information, see UK publication "Midwest Tree Fruit Spray Guide" ID-92 or click on the chart below.

What You May Not Know about Fire Blight

Fire blight can be a devastating bacterial disease of apple, crabapple, pear, and flowering pear, but disease epidemics are often sporadic.  In fact, optimal conditions must be met for severe disease to occur.  Our current conditions are an indication that fire blight may be severe this spring.

Erwinia amylovora infects trees through flowers.  However, large numbers of bacterial cells must be present during flowering in order for the disease to develop into an epidemic.  The fire blight pathogen favors rain and temperatures above 60˚F.  Under these conditions, bacterial cells multiply quickly.  Thus, if conditions are favorable during flowering, infection can be severe.

Predictive systems are available for growers.  University of Kentucky’s Cougarblight model evaluates the potential for infection by analyzing temperature and leaf wetness data from the previous four days in order to estimate potential risk for infection.  Trees must be in bloom for this predictor to be effective.  Cougarblight is an excellent decision-making tool for growers and can be accessed at http://wwwagwx.ca.uky.edu/plant_disease.html .

Most growers are familiar with shoot blight, the most obvious fire blight symptom in which infected shoots die quickly, causing branch tips to form a distinct crook (photo).  Shoot blight, however, does not result from infection of blossoms.  Direct penetration of bacteria into green shoots or the upper leaves of young shoots after bloom typically causes shoot blight symptoms.

Blighting of shoots, also called shepherd's crook, is the most recognized symptom of fire blight on apple.

Initial fire blight infections occur through flowers.  We call this symptom blossom blight.  Petal browning is the first sign of petal blight, but many growers do not notice it.  Browning of pedicels (stems that attach flowers to stems) follows.  Often, droplets of bacterial ooze can be seen coming from pedicels (photo).  Bacteria quickly travel down the spur and into the twig.  Cankers that form around the spur-attachment site girdle branches, and then branch parts above the canker also die (photo). 

Initial infection by the fire blight pathogen occurs through blossoms.  Notice bacterial ooze come from the pedicel.

Bacteria can spread through flowers and spurs into twigs.  Resulting cankers can girdle entire limbs and branches.

Fire blight control measures include anti-bacterial pesticides applied during bloom.  Applications made after bloom are ineffective.  When fire blight risk is high (warm temperatures combined with rain) during bloom or if fire blight was a problem last year, the following spray schedule should be followed:

1.       Apply fixed copper at silver tip.  Homeowners should not skip this step, as it is their only tool available to combat fire blight.  Do not use copper fungicides after bud break.

2.       Apply streptomycin beginning at pink stage, repeating every 4-5 days, through petal fall.  At least 2 applications are required, but up to 4 sprays may be applied, depending on rain and temperature conditions.  Pay extra attention to susceptible varieties (i.e. Gala, Jonathan, and Rome).  Utilize Cougarblight or MARYBLIGHT predictive systems for assistance.  Mycoshield (oxytetracycline) is also available for management of fire blight but is not as effective as streptomycin.  Neither product is recommended for homeowner use.

Various cultural practices may be implemented to aid in disease management.  Combine these practices with bactericide sprays above for best control.

1.       Select disease resistant or disease tolerant varieties.  Liberty, Pricilla, SirPrize, Enterprise, Gold Rush, and Sundance are recommendations from ID-21.

2.       Prune last year’s cankers and dead wood before bud break.  Burn, bury, or completely remove prunings from the orchard to eliminate the possibility of bacterial cells being carried back to healthy tissue.  Monitor predictive systems.  Know your risk.  Cool temperatures or no rainfall will result in low disease incidence.

3.       Remove flower/fruit spurs immediately after symptoms develop so bacteria cannot continue infection into branches.  Dip tools in 10% bleach, 10% Lysol concentrate, or pure rubbing alcohol after each cut to keep from spreading bacteria.

4.       Do not prune limbs or branches during the growing season.  Trees natural defenses wall off infection sites and stop disease spread.  Remove these branches during the dormant season, instead, when threat of disease spread is lowest.  Removal of all infected wood is critical to prevent spread of inoculum.

More information on fire blight can be found in PPA-34 and PPFS-FR-T-7. 

Spray recommendations for commercial growers ID-92 and homeowners ID-21 are also available online.

Cedar Rusts Threaten Apple

Thanks to this beautiful weather, cedar rust galls are developing.  As galls swell, they produce spores that threaten apple (and sometimes crabapple and hawthorn).

 Images of swelling galls were taken from cedar in Lexington on Monday March 19.  Warmer temperatures in western KY allowed even earlier gall development.

These galls indicate that rust pathogens are releasing, or are preparing to release, infective spores.  Growers should protect trees with fungicides that are proven to be effective against rusts (listed below).  Once diseases symptoms develop on apple, it is often too late for control. 

Here in Kentucky, 3 types of cedar rusts affect apple: 

1.       Cedar-apple rust produces large brown galls on cedar and other species of Juniperus.  Soon after a rain, galls produce slimy yellow or orange “horns” that are made up of infective spores (basidiospores).  These spores immediately infect apple.  Upon infection, the disease causes yellowish leaf spots with red rings (called halos).  Leaf yellowing and leaf drop follow.  Infected fruit develop large spots near the calyx end.  These fruit are often stunted and may drop prematurely. 

Gall beginning to form "horns."

"Horns" contain infective spores in a gelatinous material. 
This is an old photo, but we can expect to see this fully-developed stage soon in central KY.
Never wait until this stage to start a spray program on apple.

2.       Cedar-quince rust produces orange swellings on twigs.  Spores produced in these slimy lesions affect apple fruit, but not leaves.  Infection of blooms and young fruit occurs early in the season, but symptoms do not develop until fruit mature.  Diseased fruit are puckered and have spongy lesions at the calyx end.

Sometimes growers must look closely to recognize rusts, so scouting is important.

3.       Cedar-hawthorn rust forms galls similar to those of cedar-apple rust, only smaller.  Spores produced from short “horns” infect apple, crabapple, and hawthorn.  Leaf spots on apple appear similar to those caused by apple cedar rust, and can cause defoliation.  Fruit infection is not common.

Often, many rust types occur on the same tree.

Fungicides should be used as protectants to prevent rust pathogens from infecting.  After symptoms develop on apple, it is often too late for control. 

Commercial and homeowner fungicide recommendations are listed below.

Commercial Fungicides for  Management of Rust on Apple
Bayleton	Triadimefon
Dithane	Mancozeb
Indar	Fenbuconazole
Inspire Super	Difenoconazole
Pristine	Boscalid + pyraclostrobin
Procure	triflumizole
Rally	Myclobutanil
Sovran	Kresoxim-methyl
Topsin-M	Thiophanate-methyl
Homeowner Fungicides for  Management of Rust on Apple
Dithane	Mancozeb
Immunox Multi-purpose	Myclobutanil
Mancozeb	Mancozeb

More details for management of cedar rusts can be found in Kentucky Pest News or PPA-23 (http://www.ca.uky.edu/agc/pubs/ppa/ppa23/ppa23.pdf ).