Monday, December 17, 2012

How Much Does a Vegetable Garden Cost/Save?

OSU Master Gardener(TM): How Much Does a Vegetable Garden Cost/Save?

Great article from Gail Langellotto, coordinator of the OSU Master Gardener Program, who describes the monetary value of home vegetable gardens.  Click on the link above to read Gail's full story.  Here is a portion of the article:


"For each garden, I looked at the difference between yield and cost (difference = yield - cost). I adjusted the value of the difference to its 2012 value, using an online Consumer Price Index inflation calculator. I then divided this adjusted difference by the size of the garden, to arrive at the value per square foot of garden area.

Source Location Size (Square Feet) Cost Yield Difference Difference, Adjusted to 2012 Value Value/Square Foot
Stephens et al. 1980 #1 Tallahassee, Florida 1,400 $70 $384 $314 $874.14 $0.62
Stephens et al. 1980 #2 Jacksonville, Florida 638 $83.00 $416.00 $333.00 $927.03 $1.45
Stall 1979 Homestead, Florida 600 $333.65 $495.70 $162.05 $512.02 $0.85
Doiron 2009 Scarborough, Maine 10,890 $282.00 $2431.00 $2149.00 $2297.80 $0.21
Roth 2008 Oregon 878 $318.43 $606.97 $288.54 $307.42 $0.35
Cleveland et al. 1985 #1 Tucson, Arizona 833 $45.00 $154.00 $109.00 $232.38 $0.28
Cleveland et al. 1985 #2 Tucson, Arizona 627.5 $56.00 $178.00 $122.00 $260.09 $0.41
Utzinger and Connolly Harrison 1978 Columbus, OH 150.7 $46.00 $90.00 $44.00 $154.80 $0.41


Altogether, the gardens had an AVERAGE VALUE OF $0.65 / square foot of garden area, and a MEDIAN VALUE OF $0.52 / square foot of garden area.


For a modest-sized garden, 200 square feet in size, that's a return of $104 in the first year. For larger gardens, 500-700 square feet in size, that's a return of $260-$364 in year one, alone!

In at least 5 out of the 8 observations (all but Cleveland et al. 1985, and maybe Utzinger and Connolly Harrison 1978), the costs incurred included what was needed to establish a garden, and not simply to maintain a garden. These costs are sure to decrease in subsequent years, as the cost of maintaining a garden is substantially less than start up costs.


Thus, even in the first year after establishment, the net economic benefits of vegetable gardening are positive - and these economic benefits are sure to increase in years two, three and beyond.

The consistent 'winners' in these papers included:

  • salad greens
  • tomatoes
  • beets
  • broccoli
  • potatoes
  • strawberries





These were the fruits and vegetables that yielded the most, in terms of dollars saved by not having to purchase these items. However, to truly get the best value from your vegetable garden, it is important to plant what your family likes to eat."

Monday, September 17, 2012

Boxwood Blight - Memorable Tips for Easy Identification


This weekend, the local Lexington newspaper, the Herald Leader, published a story on boxwood and boxwood blight.  Thus, I anticipate an influx of suspect samples and concerns.  Also, as weather becomes cooler and more rain is upon us, it is possible that the disease may appear in Kentucky this fall.  Below is a refresher on this devastating disease:

Boxwood blight (Cylindrocladium buxicola) was reported in southern Ohio this spring, but has yet to be found in Kentucky.  Nursery growers in the northern counties are especially concerned about movement of the disease across state lines. 


Figure 1 & 2.  Boxwood blight is most easily recognized by leaf drop.  Photos by Kelly Ivors, NC State.

 

Symptoms of boxwood blight are different from some of the most commonly observed boxwood problems.  For example, stem blight and drought damage result in foliage turning bright bronze or straw-colored while remaining intact.  Boxwood blight, in contrast, results in rapid defoliation of plants (Figure 1& 2).  Another distinguishing symptom of boxwood blight is brown stem lesions that are easily recognized after leaf drop (Fig 3).  Earliest symptoms include leaf spots, but these spots often go unnoticed unless a persistent scouting program is in place (Figure 4).  Roots are not affected.
Figure 3.  Brown stem lesions, a distinguishing characteristic of boxwood blight, are often noticed after leaf drop.  Photo permission by Kelly Ivors, NC State.
 

Avoid unhealthy plants at all costs.  Homeowners should examine plants carefully before purchase, avoiding plants with leaf or stem lesions or an unhealthy appearance.  Growers should carefully inspect incoming plants and liners before introducing them into production areas. 
Cultural practices can help prevent conditions that are conducive for the fungal pathogen.  Space plants for air circulation and rapid drying of foliage.  Overhead irrigation should be avoided.  Fungicides are not available for management of boxwood blight.  Infected plants must be destroyed by burning or burying.
Figure 4.  Leaf spots, the earliest symptoms of boxwood blight, can be detected by scouting.  Photo permission by Kelly Ivors, NC State.
 
Report suspected cases of boxwood blight immediately to your local Extension agent or specialist or to the UK Plant Disease Diagnostic Lab. 
Figure 5.  Comparison of boxwood blight to Volutella stem blight and Macrophoma blight.
 

Tuesday, September 11, 2012

Chrysanthemum Dieback – Rhizoctonia is Likely the Culprit


Dense canopies and frequent overhead irrigation of fall mums create ideal conditions for many plant pathogens, especially web blight and stem rot.  In greenhouses, plants grow under tight spacing and high humidity.  Furthermore, plant compactness creates microclimates within canopies.  These extreme conditions are conducive for growth of the web blight and stem rot pathogen, Rhizoctonia solani.  Unfortunately, some of these diseased plants make their way into retail centers and our front porches.

Figure 1– Stems and crowns infected by Rhizoctonia solani result in dieback in the upper canopy.  Photo by NC State.
 

Symptoms:  Stem or leaf dieback is often the first recognizable symptom.  This dieback is caused by infections of stems at the base of shoots and branches or by infection of roots and lower stems (Figure 1).  Opening up the canopy will often reveal stem lesions and/or webs or strands of fungal tissue (mycelia) (Figure 2).  Infected leaves appear water-soaked or necrotic, often becoming matted together with the web-like mycelia.

Figure 2– Under wet conditions, Rhizoctonia may spread to upper plant parts, inducing web blight symptoms.
 

Disease Management:  Both cultural practices and fungicides are required for proper disease management.  Keep foliage dry by avoiding overhead watering, by increasing air circulation (wider spacing, increased sunlight), and by practicing strict sanitation (remove diseased tissue and clean up fallen leaves).  Homeowners may use propiconazole (Green Light Systemic Fungicide), mancozeb (Mancozeb or Dithane), or captan (captan) fungicides.  See the Homeowner’s Guide to Fungicides.  Commercial growers and landscape professionals may take advantage of a wider array of fungicides, such as the active ingredients azoxystrobin, fludioxonil, iprodione, PCNB, pyraclostrobin, thiophanate-methyl, trifloxystrobin, and triflumizole.  Refer to the following publications for specific trade names:  Fungicides for Management of Diseases in Commercial Greenhouse Ornamentals and Fungicides for Management of Landscape Woody Ornamental Diseases.  Consult labels for specific information.

Wednesday, August 29, 2012

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 .

Monday, August 27, 2012

Blueberry Mosaic Virus Detected in Kentucky


Blueberry mosaic virus was confirmed in a blueberry orchard in central Kentucky this summer.  This is the first report of blueberry mosaic in the state.  The virus has not previously been found in southern states, but it has been reported in Michigan, Indiana, New Jersey, New York, Oregon, Washington, and British Columbia. 

Formerly considered a “disorder,” blueberry mosaic has only recently been classified as a virus.  Not much else is known about it.  Highbush cultivars ‘Bluecrop,’ ‘Pioneer,’  ‘Concord,’  ‘Earlibule,’ and ‘Jersey’ are among the susceptible cultivars.  Virus symptoms have not been reported in rabbiteye blueberry.  Limited research has been conducted thus far, but it is under evaluation by a team of researchers at the USDA-ARS Marucci Center in New Jersey.
 

Symptoms

Foliar symptoms include mottling and mosaic-patterned characteristics on leaves.  Patterns range from mild to brilliant with yellow, orange, and/or red colorations (see photos).  Mosaic symptoms are not always produced each year, and environmental conditions may affect symptom development.  It is possible that during cool seasons, symptoms are more pronounced.  Thus, under ideal conditions, symptoms may appear suddenly, and it may appear that spread is rapid.

Infected plants often result in reduced fruit load.  Yield losses of 15% have been reported on ‘Bluecrop’ in Michigan.  Fruit on infected plants have been shown to ripen later than noninfected fruit, and fruit quality is low.
 

Spread

The vector (carrier) of the virus is not known.  Researchers report that blueberry mosaic is not transmissible by mechanical means (i.e. pruners).  However, the virus is graft transmitted.  Because virus particles are systemic (dispersed throughout the vascular system), once infected, all plant parts are infected, even when symptoms are absent.  Thus, cuttings should never be taken from a virus-infected plant.

As mentioned above, the vector of blueberry mosaic virus is not known.  Therefore, growers are encouraged to destroy infected plants until it is clear on how the virus spreads.  Whether an insect vector is involved is yet to be determined.

Current research indicates that the virus is slow-spreading (if at all) under field conditions.  However, in Michigan, spread is rapid. So far, the reason is unknown.
 

Treatment

There is no cure for plant viruses, including blueberry mosaic.  Growers should remove infected plants and destroy them by burning or burying.  Remove all roots within soil, as well.  Scout orchards, especially nearby plants, several times during the growing season.  Contact a local extension agent if a plant appears suspicious.

Most importantly, purchase plants from a reputable grower.  Visit nurseries before plant purchase and ask to inspect parent plants.  Furthermore, a virus-free certification is always worth the extra cost. 

 
 

Fungicide-Resistant Downy Mildew Detected in Kentucky Vineyard


This summer, a grape grower in central Kentucky reported persistent downy mildew in his vineyard.  He noted that regular applications of Abound and Pristine fungicides failed to manage the disease.  After laboratory analysis, the pathogen was deemed completely resistant to the two fungicides at the lowest recommended rates and 85% resistant at the highest recommended rates. 

 
What is fungicide resistance?

In the simplest terms, pathogens become resistant to fungicides when the chemical no longer manages disease symptoms.  However, even the most effective fungicides fail to completely eradicate a pathogen population.  There are always a few fungal spores or other fungal inoculum that survive the pesticide application.  Those survivors may be the result of ineffective spray coverage, but individual pathogens may have a trait that provides some type of resistance to the fungicide.  Think back to high school biology when we learned the theory of “survival of the fittest.”  Unfortunately, a single survivor can multiply into thousands of individuals while passing that resistance gene onto its offspring, much the way our parents passed on eye color to us. 

 

How did resistance develop?

Consider that it is highly unlikely that a fungal population will incur resistance to more than one chemical type, at least over the short term.  As a fungal population can become resistant to a single chemical, growers should rotate sprays with a different chemical group.  These chemical rotations can become confusing, and many growers do not fully understand the concept of chemical groups. 

 Chemical groups are classified by biochemical mode of action, not necessarily by active ingredient.  For example, within the strobilurin group of fungicides, active ingredients include azoxystrobin, pyraclostrobin, trifloxystrobin, and kresoxim-methyl, all of which are quinone-outside inhibitors.  Because information on biochemical modes of action can be confusing for growers, the Fungicide Resistance Action Committee (FRAC) developed numeric codes that represent these chemical groups.  Strobilurins are classified as FRAC group 11.  These codes appear on the top right side of all pesticide labels.  Thus, growers may simply refer to the coded chemical group number on labels as opposed to depending upon complex information such as mode of action.

Considering that all fungicides within the same group have the same mode of action, it is clear that if a grower fails to properly rotate fungicide groups, fungicide resistance risk is high.  Additionally, fungicide labels indicate the maximum number of applications allowed per growing season.  A maximum of four applications of strobilurins are allowed per growing season.  The grower mentioned above used Abound and Pristine fungicides consistently over a two-year period, exceeding the maximum number of applications and failing to rotate with a different chemical group.  This rapidly induced the development of a resistant population of the downy mildew pathogen.
 

Abound fungicide is classified as a FRAC Group 11 fungicide.  The chemical group code appears on the top right corner of fungicide labels.
 
How does a grower know if a resistant population developed?
Pathogen populations do not begin as 100% resistant.  In fact, resistance develops gradually.  Thus, growers should be aware of efficacy and disease control.  If a product(s) begins to become less effective over time, he should contact his local Extension agent immediately. 
 
What next?
If resistant pathogen populations develop within a vineyard, growers should immediately stop using the fungicide in question and all others in the same FRAC group.  With the assistance with an Extension agent or specialist, growers should identify other fungicides that will effectively manage disease.  In the aforementioned case, the grower stopped using strobilurin fungicides and substituted a phosphorous acid fungicide (ProPhyt, Rampart, etc.) for management of downy mildew.  If strobilurins are used for management of other diseases, tank-mix with another product (within a different FRAC group) that provides downy mildew control.
 
More Information
Fungicide resistance can appear complicated, so growers should not hesitate to seek assistance in development of a spray program.  Contact University of Kentucky Cooperative Extension agents or specialists for assistance. 

Tuesday, July 24, 2012

White Pine Decline versus White Pine Root Decline: What's the Difference?


Decline of White Pine

Decline is common among white pine in Kentucky.  Two distinct diseases with similar names are often confused, but they are distinctly different.  Note that white pine decline is an abiotic malady that leads to slow decline, while white pine root decline is a fungal disease that causes sudden plant death.  More details follow:

White Pine Decline

Symptoms

White pine decline causes needle s to yellow and drop prematurely, causing a noticeable thinning of the canopy (Fig 1).  Other symptoms include unusually shorter needles; needle tips may become brown.  Bark of individual branches may become shriveled and needles on those branches become wilted or limp (Fig 2).
Figure 1.  White pine decline, an abiotic malady, is caused by environmental conditions.  Symptoms include thinning needles and reduced plant vigor.

Cause

White pine decline is not caused by a pathogen.  Symptoms are induced by environmental conditions such as

·         high soil pH

·         high soil clay content

·         restricted root-growth

·         compacted soil

·         mechanical disturbances that cause root injury  
Figure 2.  Wrinkled bark is common on trees suffering from white pine decline.  Needles above damaged bark become wilted and drop.


Disease Management

The best way to manage white pine decline is through prevention. Select sites with the following characteristics:

  • acidic soil (pH of 5.5 and not above 6.5)
  • sandy or loamy rather than clay soils
  • large area for root development

·         loose soil free from soil compaction

·         sufficient soil moisture (regular irrigation and mulch)

·         vigorous plants (control insect pests and fertilize trees regularly)

Once decline begins, it may be difficult to reverse.  However, the following practices may be implemented.

·         lower soil pH by applying granular sulfur according to soil test results

·         aerate soil by vertical mulching or other means

·         fertilize and water to eliminate stress



White Pine Root Decline

Symptoms

Trees may be infected for several years without showing symptoms.  However, once symptom development begins, homeowners often notice delayed bud break and reduced candle elongation in spring.  Mature foliage then fades, droops, and turns brown rapidly (Fig 3-4).  Conversely, nearby trees may appear healthy; mortality appears quite random with a few trees dying each year. Resin flow (pitch) is visible at the tree base and is associated with a dark brown girdling canker under the bark (Fig 5).  The trunk may be flattened on the affected side.
Figure 3.  White pine root decline, a fungal disease, causes rapid wilting of white pine. 

Cause

White pine root decline, is caused by the fungus, Leptographium procerum that infects inner bark and sapwood of roots and lower trunks of white pine.  Although the disease is most serious on white pine, the fungus also can infect Scots and Austrian pines.  Losses within an infected planting range from 20 to 50%.
Figure 4.  Rapid wilting is often followed by rapid browning (needles intact) when trees are suffering from white pine root decline.


Trees planted on wet sites are more susceptible to infection, although other stresses may also cause trees to become susceptible to the disease.  Once infection occurs, the fungus may be spread from tree to tree by contaminated insects as they move from diseased trees to healthy trees nearby.  Galleries of insects such as the pine root collar weevil may be found in cankers and provide a place for the fungus to sporulate.  Weevils and other bark-infesting insects may serve as vectors for this disease.
Figure 5.  Pitch is often associated with trunk cankers caused by white pine root decline.


Disease Management

Cultural practices help reduce disease spread by insect vectors. No fungicide is available for disease management.

·         avoid  wet sites

·         do not replant eastern white pine among stumps of recently killed trees

·         remove and destroy infected trees including stumps,

·         collect samples for diagnosis by removing tissue from the canker face (bark removed) and shipping in a plastic bag.
 

Revision of original by John Hartman.

Monday, June 18, 2012

Black Rot Common on Grape


Black rot is the most common disease of grape in Kentucky.  If left unprotected, vineyards can suffer high economic losses. 

Infection occurs early in the season, usually before bloom, at temperatures as low as 50˚F.  Early symptoms develop as spots on leaves 1 to 2 weeks after infection (Fig 1).  Tan spots with darker margins often contain black fruiting structures (pycnidia) in centers (Fig.2).  Spores (conidia) from these structures cause secondary infections throughout the season.  As leaves mature, they become resistant, but newly developing leaves can become infected anytime during the season.
Fig 1.  Leaf lesions have light tan centers and darker brown margins.

Fruit infections occur early in the spring, as well.  Grapes are susceptible from flowering until 3 to 4 weeks after bloom.  Early fruit symptoms appear as light brown spots (Fig. 3).  Soon, entire berries turn dark brown and shrivel (Fig 4).  These raisin-like fruit develop black fruiting structures (pycnidia) that overwinter on the “mummies.” 

Fig 2.  Fruiting structures (pycnidia) produce spores that cause secondary infections.  They can be seen with a magnifying glass, and often with the naked eye.

Both cultural practices and fungicides are critical for control of black rot.  Fruit mummies must be removed from vineyards to eliminate sources of overwintering inoculum.  Beginning at pre-bloom, a rigid fungicide regime must be employed.  Strobilurin fungicides (Abound, Pristine, Flint) provide excellent control, but risk for fungicide resistance is high.  Rotate with triazole/SI fungicides (Bayleton, Elite, Rally) and protectant fungicides (Mancozeb, Ziram).

Fig 3.  Fruit infections begin as light brown spots.  Note:  bird’s eye rot (anthracnose) infections on fruit have dark reddish margins with light gray centers.

Commercial growers should refer to the Midwest Small Fruit and Grape spray guide for fungicide and schedule details, while homeowners can use fungicides listed in ID-21 and PPFS-misc-7.  These and other publications can be found at http://www.ca.uky.edu/agcollege/plantpathology/extension/pubs.html#Smallfruit
Fig 4.  Soon after infection, grapes with black rot disease turn dark and shrivel into hard, black mummies.  Fruiting bodies (pycnidia) that develop are the primary source of overwintering for this fungus.

Sunday, June 10, 2012

Fire Blight Damage on Flowering Pear

Homeowners continue to question me concerning management of fire blight in flowering pear, crabapple, cotoneaster, hawthorn, and pyracantha.  Shepherd’s crooks and spur dieback occurred in March or April, as pathogenic bacteria infected flowers or young shoots.  Often, homeowners do not notice damage until later in the season, and inquiries continue for weeks after damage occurred.

There is no management option during this time of year, as the fire blight bacterium is not currently active.  Hot summer temperatures suppress bacterial growth, and plants are able to compartmentalize and wall off spread.  Thus, visible symptoms are the result of early infections. 

Current recommendations indicate that pruning of blighted twigs and cankered branches should be delayed until winter when risk of disease spread is lowest.  Under certain circumstances, homeowners or commercial landscape contractors may choose to prune infected branches during the growing season.  Only young, vigorous trees should be considered, and care should be taken to prevent bacterial spread.  Always avoid working with wet plants.  Cut branches at least 6 to 8 inches below cankers, disinfesting pruners between each cut (10% Lysol disinfectant, 10% bleach, or rubbing alcohol).  Ideally, winter pruning is recommended. 


Disease management includes both cultural practices and preventative bactericides.  Because the fire blight bacterium overwinters in cankered branches, removal of diseased plant tissue before bud break (mid to late winter) is critical.  Copper applied as buds swell (late dormancy or silver tip) reduces build-up of bacterial cells, especially during warm rainy spring seasons.  Streptomycin applications are only recommended for fruiting apple and are not labeled for use in the landscape. 

See earlier posts for more information on the biology of the fire blight bacterium and for management in orchards.

Friday, May 25, 2012

Win the Battle Against Powdery Mildew


Powdery mildew is one of the most easily recognizable diseases of landscape and garden plants.  While most fungal pathogens are favored by wet weather, powdery mildew pathogens favor high humidity but not wet conditions.  Shady areas, areas with poor air circulation, and low areas that trap damp air are ideal environments for disease development.
Powdery fungal growth is an easily recognizable symptom of powdery mildew disease.

A wide range of plants are susceptible to powdery mildew:  annuals, perennials, shrubs, ornamental and fruit trees, small fruit, and vegetables.  While symptoms appear similar on most plants, powdery mildew fungi are usually host-specific.  For example, powdery mildew of dogwood cannot infect pumpkins or cucurbits, and powdery mildew of cantaloupe will not infect phlox or rose. 
Typical symptoms of powdery mildew include dusty fungal growth on surfaces of leaves and on young succulent plant tissue (Photo 1 & 2).  Powdery mildew may occur as isolated blotches or cover entire leaves, stems, buds, or flowers.  Early infections can lead to leaf stunting, curling, or other deformation (Photo 2).  Infected fruit may become disfigured or fall prematurely (Photo 3).  In the fall, small fruiting structures that resemble pepper flakes may be visible to the naked eye (Photo 4 & 5).  These structures contain overwintering spores that serve as inoculum for the following year.
Infection of young growth may result in stunted or deformed tissue.
Management of powdery mildew begins with prevention.  Plants should be properly spaced and thinned for improved air circulation and more rapid leaf drying.  Resistant cultivars are available for crabapple, dogwood, phlox, zinnia, cucurbits, and several other plants and are an excellent means of disease prevention.
Fruit infections ultimately lead to yield loss.
Fungicides usually are not warranted when cultural practices are implemented.  Early season infection, however, may require one or more applications of effective fungicides.  Homeowners have a wide range of fungicides available.  However, they should carefully read labels to confirm that the selected fungicide may be used legally on select plants or that the fungicide is suitable for edible plants.

Fungicides effective against powdery mildew include:
·         Chlorothalonil – broad spectrum protectant; ornamentals, some fruit and many vegetables

o   Bonide Fungonil concentrate or Fungonil RTU

o   Ortho MAX Garden Disease Control

o   Sevin Daconil

·         Myclobuanil – systemic; ornamentals, most fruit and vegetables

o   Spectracide Immunox (only Immunox Multi-purpose Fungicide Concentrate is labeled for use on fruit and vegetables)

·         Propiconazole – systemic; ornamentals, some fruit

o   Bonide Fungonil RTS (different from other Fungonil products, which contain chlorothalonil)

o   Bonide Infuse

o   Fertilome Liquid Systemic

·         Tebuconazole – systemic; ornamentals only

o   Bayer Advanced Disease Control

o   Bonide Rx Systemic

·         Triflorine – systemic; ornamentals only

o   Ortho Rose Pride Disease Control


Late in the growing season, powdery mildew fungi produce small, black overwintering structures that can serve as inoculum the following year.

Sunday, May 20, 2012

Black Root Rot

Black Root Rot affects a wide range of ornamentals.
Black root rot results in the decay of root systems; however, the most obvious symptoms are observed on above-ground portions of the plant. Foliar symptoms include yellowing, wilting, and necrosis (death) of foliage. Above-ground foliar symptoms are the result of root decay; as a result, the reduced root system is unable to take up sufficient water and nutrients to support foliage and stems. There is no cure for black root rot.

Learn more about black root rot from our latest fact sheet
http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-OR-W-3.pdf

Other disease-related fact sheets are available at http://www.ca.uky.edu/agcollege/plantpathology/extension/pubs.html#OrnamentalWoody