T urf Disease By Season IDENTIFICATION Causes ses Of T - - PowerPoint PPT Presentation

IDENTIFICATION

T urf Disease By Season

Causes ses Of T urfgras grass Dis iseas ease e & I Introd

• duct

uctor

• ry

y Definiti finitions

• ns

The most important cause of an infectious abnormality on turf that either kills the plant or destroys it’s aesthetic value is a Path thogen.

• gen.

Most pathogens are parasites that obtain nutrients from a host. Obli ligat gate Parasit rasites s survive only on a live host or living tissue. Saprophyte

• phyte Parasit

rasites s survive only on dead organic matter. Organisms that are mostly obligate but can live under certain conditions as saprophytes are classified as Facul ulat ative ive Sap aprophytes. phytes. Organisms that live most of the time as saprophytes but that can,

• n occasion, become obligate are classified as Facula

ulative tive Oblig bligat ates. es.

The he D Diseas ease e T Triangle gle

In order for disease to occur three conditions are necessary (1) A susceptible host (2) An active pathogen (3) Favorable environment If any of the three conditions are missing, disease will not develop

Diseas ease e Progresses

• gresses In 4 Stag

ages

1. A disease pathogen enters the plant.

• 2. The pathogen inhibits it’s host without producing visible symptoms.
• 3. The interaction between pathogen & susceptible host.
• 4. Stage when pathogen reproduces for self-preservation.

Snow Mold

Snow Mold Early March

Snow Mold d affects all cool season turf grass species in areas where

there are extended periods of snow cover. In areas without prolonged snow cover Snow Mold damage is mostly cosmetic and will recover once the turf begins actively growing. Infection and disease progress is favored by cold (32 -36 degrees F) wet conditions. Extended periods of snow cover provide ideal conditions for establishment and spread. On taller mown turf, matted grass blades provide a similar insulating environment, but outbreaks normally are not severe without prolonged snow cover.

Snow Mold Recovery

FIRS RST T WEEK K OF MARC RCH 10 DAYS S LATE TER

Red Thread The New Spring Scourge

Red d Thread ad in recent years has become one of the most

troublesome late spring diseases affecting ryegrass & fine fescues in particular. Optimum weather conditions for development are air temperatures in the 68 to 75 degree ranges in conjunction with prolonged wet conditions and extended long dew periods. Symptoms initially appear as small (3 to 8”) circular patches of off- colored turf with a pinkish cast. Inspection of the leaf blade reveals red threads growing from the blade tip These threads are structures called scle leroti

• tia that enable the

fungus to survive in the turf and upper layers of soil. The disease may spread by water or mechanically transmitted from lawn by infected mower blades.

Cult ltural ural M Managem ement ent O Of R Red ed T Thr hrea ead

Normally maintaining adequate nutrient levels, especially nitrogen, would control the incidence and severity of the disease. However in recent years we have seen increasing pressure from red thread even on high maintenance properties with proper nutrient levels. Fertilize on a timely program to maintain proper nutrient levels Use a controlled release nitrogen source to avoid spikes and lulls. Do not irrigate late in the day which can leave the grass blade wet overnight. Disinfect mower blades with isopropyl alcohol and clean underside

• f mower deck whenever possible after cutting a highly infected

lawn.

Chemica cal l Control

• l F

For R Red T Thread

Due to the favorable weather conditions during mid spring when cool season turf is at it’s finest , a preventative red thread program is usually not employed. However in recent years the incidence and severity of a once easily controlled aesthetic disease has become a serious early season problem to many LCO’s. Recent research has shown excellent control using the Strobilurin chemical class that are labeled for residential turf such as Insignia (pyraclostrobin) Compass (trifloxystrobin) Headway (azoxystrobin + propiconazole) Other options include the DMI chemical class such as Banner Maxx (propiconazole) & Bayleton (triadimefon) As well as the Benzimidazole class containing only Clearys 3336 (thiophanate methyl) that is labeled for residential.

Necr croti

• tic

c R Ring ing S Spot

• t

Necr crot

• tic

ic Rin ing g Spot as well as Summer Patch have been for years

mistakenly classified as Fusarium Blight. Necrotic Ring Spot can occur midspring and again in early fall affecting established turf that is 2 to 5 years old and especially sod since Kentucky Bluegrass is one of the most susceptible species. The pathogen survives as dormant mycelium in infected turf and thatch and becomes active during cool wet periods in the spring. Symptoms begin as scattered light green patches 1 to 3 inches in diameter and then may grow to a foot or two turning dull tan to reddish brown. Larger patches may exhibit a frogs eye pattern with an apparently healthy green patch of grass that is partially or completely surrounded by a ring or crescent of dead turf. Diagnosis by leaf lesion is very difficult with NRS since they may not be present and if so not distinct.

Cult ltural ural C Control l O Of N Nec ecrotic tic R Ring Sp Spot

Maintain thatch levels with scheduled aeration programs built into your yearly contracts with fall being the optimum window. Excessive thatch will benefit with an aeration in both spring & fall. Irrigation schedules should be set up to encourage deep rooting. Water deeply and infrequently to promote a healthy root mass. Disease conditions increase as mowing heights decrease. Maintain 2 ½ to 3 inches through the growing season without cutting more than one third of grass blade with any one mowing. Always apply a high quality controlled release nitrogen source to inhibit surge growth that weakens root mass.

Che hemica cal l C Control l O Of N Nec ecrotic tic R Ring S Spo pot

Preventative fungicide applications for NRS are difficult without a previous history of disease prone turf Initial symptoms can be mistakenly

• verlooked in the spring due to favorable growing conditions that can

mask a shallow root system caused by the disease. Once stressful weather conditions appear the symptoms become much more evident. Curative controls include Headway (Azoxy+Propiconazole) Banner Maxx (Propiconazole) Note that the DMI chemical class at high rates can slow down plant growth resulting in slower recovery. Eagle (Myclobutanil) is one fungicide in the DMI class that claims minimal side effects on plant growth. Systemic fungicides used on NRS should be watered in before they dry so the material has a chance to get to the shallow root zone.

Dollar Spot

Dolla lar r S Spot on residential turf normally begins to appear

as weather conditions progress from late spring (cool and wet) to early to mid summer (hot and humid) conditions. It is not uncommon to have initial outbreaks occur in the same areas that experienced red thread pressure earlier due to the weakening of the plant. First stages begin as small spots of blighted turf that develop into circular straw colored areas 2 to 3 inches in diameter. When dew is present a white co-webby growth of mycelium may be seen in the affected areas. On residential cut turf these areas may be much larger and irregular and range from 6 to 12 feet in diameter. Upon close inspection an hourglass effect will be present towards the middle of the blade with thin brownish lesions at both ends

• f the hourglass.

Doll llar r S Spo pot P Progresse ressed d S Stage

Doll llar r S Spo pot

Mycelium

Path thogen

• gen Transp

anspor

• rte

ter

Cult ltural ural M Manageme ement nt Of D Doll llar Sp Spot

Maintaining adequate nutrient levels will generally check severe outbreaks of the disease. Studies have shown that the dollar spot pathogen is a very weak parasite that primarily attacks the older yellowing leaves of the plant as compared to the younger vigorously growing green leaves. Therefore by providing consistent nutrient levels using a high quality slow release nitrogen source young growth will be encouraged while minimizing the aged leaves that serve as a food base for the disease. Mow at the recommended height of 2 ½ to 3 inches frequently enough so that no more than 1/3 of the leave blade is removed at any one time. Avoid irrigating at any time that will leave the grass blade wet overnight encouraging transmission of fungal mycelium.

Che hemica cal l C Control l F For D Doll llar ar S Spo pot

Fungicide recommendations for Dollar Spot are similar to controls used on Red Thread with the exception of the Strobilurin class that are limited to suppression. Options include the DMI ( Dimethylation Inhibitors) class Banner Maxx (propiconazole) Bayleton (triadimefon) Benzimidizole class Clearys 3336 (thiophanate – methyl) Both chemical classes above are systemic fungicides. One contact fungicide in the Dithiocarbamate class is also recommended for Dollar Spot control. Dithane (manganese /zinc combination)

Fairy Ring

Fair iry y Rin ing g fortunately is not as common as some of the

previous discussed diseases so far but can become problematic and difficult to control when it does occur. In our area the disease is normally caused by decaying

• rganic matter in the soil from buried construction debris

such as tree trucks. Conditions promoting disease are these fungal pathogens in conjunction with moist warm weather however in some cases it can become active with cooler temperatures. Symptoms show as circular or semi – circular bands of darker than normal turf with areas within the band not as vigorous and possibly in decline Older rings will normally have dead grass on the outside bands with green turf in the middle. During rainy moist conditions a band of mushrooms may appear.

Cult ltural ural C Control l O Of F Fairy R Ring

Fairy Ring is virtually impossible to control through cultural management. Fortunately since the cause of the disease has been identified most local government ordinances prohibit the burial of construction debris. Fairy Rings are best managed by alleviating stress to reduce their prominence and disguise their appearance. Because Fairy Ring fungi create hydrophobic soil conditions deep watering in conjunction with aerification and wetting agents can reduce the extent of their development. Frequent mowing and the application of moderate amounts

• f nitrogen will help mask their appearance.

Che hemi mica cal l C Control l O Of F Fairy R Ring

In the past control through fumigation and soil drenches were almost always unsuccessful. However with the introduction of the strobilurin chemistry two products labeled for residential use have shown promise Headway (Heritage / azoxystrobin +Banner Maxx propiconazole) Insignia (pyraclostrobin)

Powdery Mildew

Powder dery y Mil ildew dew is basically an aesthetic disease that

normally has no damaging effect on turf. Close inspection of affected leaf blades reveal the presence of small pustules with masses of white spores that can under the right circumstances cover the entire leaf blade. The spores are the only means of dispersal and only the leaves are infected with no web-like mycelium produced. Powdery Mildew occurs most often on slow growing turf usually in shaded areas under cool cloudy conditions. Poor air circulation with high humidity favors development. Excess nitrogen may also encourage severity. Chemical control is not recommended however careful pruning of trees & shrubs to improve air circulation will limit development.

Slime Mold

Slim ime e Molds lds can occur on any species of turf but are

most common on taller cut lawns. Despite their threatening appearance Slim Molds are not infectious and result in nothing more than cosmetic annoyance. Outbreaks are normally brief (1 to2 weeks) and coincide with cool wet weather. Initial signs are colorful well defined patches ranging from white to gray to purplish/ black as it becomes dry and powdery Since no lasting harm to turf will occur chemical control is not necessary. Affected areas can be hosed with water if objectionable or raked to break up the mold especially during dry periods.

Brown Patch

Brow

• wn

n Patch h is a summer disease that becomes active during

hot humid periods when nighttime temperatures remain above 65 degrees with extended dew periods. Disease development is more severe under conditions of high nitrogen fertility. The Brown Patch pathogen is an excellent saprophyte and will remain in the soil causing the disease to appear annually once favorable conditions prevail. Initially Brown Patch may look very similar to drought causing

• verwatering which aggravates the disease.

Characteristic lesions (tan blotches with irregular dark brown margins) can be seen on individually infected blades as well as a white-gray mycelium web observed especially in the morning when due is present.

Brown wn P Patch ch L Les esio ions ns

Cult ltural ural C Control l O Of B Brown wn P Patch ch

Brown Patch severity can be limited in most cases with a sound fertility program that utilizes nitrogen in a stabilized form that delivers a consistent feed without surges and lulls. Do not apply nitrogen when the disease is active. Maintain mowing height at 2.5 to 3 inches. Do not irrigate in the late afternoon or at night leaving the grass blade wet overnight which helps pathogen transmittal via mycelium.

Che hemica cal l C Control l O Of B Brown wn P Patch ch

Since the pathogen is such an excellent saprophyte and lays dormant in the soil until conditions are favorable a preventative program can be utilized with reduced rates successfully in most cases. The strobilurin class shows excellent control Compass (trioxystrobin) 14 to 21 day residual Headway (azoxystrobin+propiconazole) 14 to 28 day residual Insignia (Pyraclostrobin) 14 to 28 day residual The DMI class also demonstrates good control Banner Maxx (propiconazole) 14 to 21 day residual Bayleton (triadimefon) 21 to 28 days Always remember to rotate chemical classes to avoid resistance.

Summer Patch

Summer r Patch ch first appears as small circular grayish green

patches ranging from a few inches up to a foot in diameter. With high temperatures the patches quickly change from light green to reddish brown & then finally to straw colored At this stage the most characteristic symptom is the “frogs eye” The pathogen when not active survives in the thatch layer &

• n infected roots, crowns, and rhizomes>

As temperatures increase above 70 degrees spores produce When air temperatures reach 75 to 90 degrees with humidity spores profuse & affected turf may die in 4 to 7 days. The disease is most serious during hot humid conditions when the turf is under drought stress. As the disease progresses, turf dies as the crown & root tissues are destroyed at the soil line & the dead foliage appears tan.

Su Summer er Patch ch

Su Summer er P Patch ch F Frogs E Eye

Cult ltura ural l C Control l O Of S Summer P Patch ch

Proper irrigation and thatch reduction is the key to managing this disease preventatively along with a sound fertility program High nitrogen levels in season will increase the severity. Healthy turf should be watered deep and infrequently to encourage deep root development, however once symptoms appear deep watering serves no purpose since infected turf has a shallow root system as a result of the disease. is needed at this stage is frequent light watering to keep the top inch of soil or thatch moist where the surviving roots exist. Infected turf may still wilt and die on days with temperatures

• ver

80 Degrees, however if the areas can be syringed during the hottest part of the day (normally 10am to 2pm) turf loss should be minimal.

Che hemica cal l C Control l O Of Su Summer er P Patch ch

As with Necrotic Ring Spot control can be difficult without an accurate history of disease prone areas Chemical control has not been completely effective in eradicating the disease, but it can reduce severity if used in conjunction with good turf management Timing of preventative applications is critical for effective control The first preventative should be made when soil temperatures remain above 65 degrees at a depth of 2 inches which is typically mid-May in the Northeast or about 2 to 3 weeks after crabgrass emerges. A 2nd application should be made

• ne month later

Headway (Axoystrobin+Propiconazole), Balyeton (T ridimefon) and Eagle (Myclobutanil) are recommended as preventatives Summer patch is difficult to control once symptoms have developed Cleary’s 3336 (Thiophanate-Methyl) has been reported to be the most effective curative to suppress further development

Pythium Blight

Pyt ythium ium Blight ight sometimes referred to as “ Cottony Blight “ or

“Grease Spot “ is one of the most destructive late season diseases that particularly infects ryegrasses in cool season turf. The pathogen can destroy turf in a matter of hours under the right conditions and is especially threatening to new seedlings where it is also referred to as “dampening off “ Symptoms initially appear as small irregular shaped patches ranging from 1 to 3 inches patches or sometimes in streaks that follow water drainage or mower patterns. Leaves first appear water soaked to greasy then turn tan to white The soil in the infected areas can also have a black greasy appearance thus the common name “ Grease Spot “ Conditions favorable for disease development are daytime temperatures of 85 to 95 degrees with overnight temps over 68 and extended high humidity along with poor drainage and air circulation.

Active ive Myc ycelium elium On Pyt ythium ium Blig ight ht

Cultura ltural l C Control l O Of Pythium hium Bli light ht

Improve soil drainage to avoid any standing water. A seasonal aerification program to relieve compaction and excessive thatch in established turf. Improve air circulation wherever possible with judicious pruning of constricting ornamentals and tree canopies. Avoid high levels of nitrogen that will cause lush blade growth. Modify irrigation so as not to leave the grass blade wet for extended periods especially at night. Rapid spread occurs when spores are moved by water or equipment when attempting to cut wet turf. Avoid high release nitrogen sources.

Che hemica ical l C Control l O Of Pythium hium Bli light ht

Chemical control of Pythium is extremely difficult because of how rapidly development occurs (within hours) under favorable conditions. Residential lawn care is very restricted to effective curative fungicides however the strobilurin chemical class can be effective if caught in time. Headway ( Azoxystrobin/Propiconazole) has good to excellent efficacy. One fungicide in the Dithiocarbamate class can also be effective at high rates labeled as Dithane or Manzate (manganese/zinc combination) Damping Off on new seedlings can be preventatively treated with Mefenoxam (Subdue Maxx)

Rust On KBG

Rust in infectio ection usually occurs in clusters on or after the

heat of summer on KBG and perennial rye in the northeast. Infection occurs over a range of temperatures (65 to 85 degrees) with extended dew periods present. Slow growing turf usually due to low fertility, drought stress from late summer, along with close cut mowing and restricted air circulation promote Rust. It can be especially troublesome on newly laid sod in the late summer and early fall that hasn’t fully rooted. The turf initially appears off color (an orange –yellow cast) Elongated reddish brown pustules enlarge in rows parallel to the leaf vein and rupture at which point the spores are easily rubbed

• ff on shoes, clothing, and equipment.

Cult ltural ural C Control l O Of R Rust

Sustain a judicious fertility program through late summer into early fall with a controlled nitrogen release product that will maintain moderate shoot growth. Avoid drought stress coming out of late summer and continue irrigation schedules to reduce extended periods that prolong wet grass blades especially over night. Mow frequently to remove infected leaf tips and retard spore formation and avoid close cutting. Improve air circulation wherever possible with judicious pruning on constricting trees and shrubs. Chemical control is rarely warranted and not recommended for incidental outbreaks of Rust.

Fungicide ide R Res esistan stance ce M Manageme ement nt

Fungicide resistance can be defined as an adjustment by a fungal population to the use of a particular fungicide or chemical class This adjustment results in reduced effectiveness. Only apply fungicides at labeled rates and spray intervals Applying at off labeled rates or decreasing the number of days between sprays will not only increase the likelihood of developing a resistant population IT’S AGAINST THE LAW. Systemic fungicides exhibit a high risk of developing resistance These materials act on a single site in the fungal cell and their mode of action is so specific that a simple natural mutation may

• ccur in the target fungus leading to resistant populations.

Alternate fungicides that have different modes of action as well as different chemistry (Chemical Classes)

Than anks ks for r yo your ur interest rest in Syn ynat atek ek!

Doug g Cherr rry

T echnical Lawn Care Sales Representative Metro NY & Northern NJ Markets Mobile: 845-490-2835 Email: dcherry@synateksolutions.com www.synateksolutions.com