Disease Management in Turf Nancy Bosold Penn State Cooperative Extension Berks County
Common Turfgrass Diseases Algae Anthracnose Brown Patch Dollar Spot Fairy Ring Gray Leaf Spot Leaf Spot Powdery Mildew Pythium Blight Pythium Root Rot Red Thread Rust Summer Decline Slime Mold Snow Mold many others
Abiotic Turfgrass Disease Non-living causes of disease Temperature Moisture Nutrient imbalance Compaction
Biotic Turfgrass Disease Living causes of turf disease Fungus Bacteria Nematodes Virus Protozoa
Disease Triangle Environment Pathogen Host
Disease Triangle Disease Disease Environment Time
Host The host must be susceptible
Pathogen Disease producing organism
Environment Weather Management Site conditions Damping off disease
Development over Time Leafspot and melting-out diseases
REGULATORY GENETIC CULTURAL IPM CHEMICAL PHYSICAL BIOLOGICAL
Genetic Disease resistant cultivars. When establishing new turf areas or renovating or overseeding, consider using disease resistant cultivars For more information: www.psu.edu turf fact sheets (Dr. Pete Landschoot Penn State) NTEP reports
Mowing practices Mowing height Mowing frequency Cultural remove no more than 1/3 of top growth scalping significantly reduces root mass Clipping removal? Change mowing direction Keep blades sharp
Clippings may spread disease
Cultural Irrigation. Light, frequent watering bad Deep, infrequent watering good The concentration of roots in the top inch or two of the soil makes turf more sensitive to stress Periodic watering restrictions may severely impact shallow rooted turfgrass Excessive watering... bad Early morning watering... good
Irrigation. Cultural Irrigation/Water Management The amount of water and the timing of its application can either prevent or contribute to disease development, especially leaf diseases. Most fungal pathogens require a minimum of 8 to 10 hours of free water on the leaf tissue to initiate the infection process.
Cultural Thatch, traffic, soil compaction issues. - Aerification
Cultural Fertility. Soil test may solve problems... ph, nutrient imbalances Nitrogen: amounts and time of application P roots, seed germination K root growth, hardiness Secondary elements and micronutrients
Brown patch severity in perennial ryegrass. NaN0 + P + K 3 NaN0 3 SCU + P + K SCU 0 20 40 60 80 100 Percent Disease Severity (Source: Fidanza et al., 1996)
Chemical Pesticides, in most cases, are the most popular and effective means to control pests. Class and mode of action of pesticides. Preventative / Curative. Use and over reliance may lead to problems.
Fungicide Issues and Concerns Disease misdiagnosis Fungicide application strategies Fungicide application technique Post-spray irrigation or rainfall Cultural practices Resistance to the pesticide
Preventative vs. Curative Use preventative applications on chronically damaging diseases such as, Pythium Blight, Brown Patch, Summer Patch, Gray Leaf Spot, and Anthracnose. Curative treatment requires careful scouting to identify diseases prior to extensive damage.
Residual Activity Systemic fungicide Moves inside the plant Contact fungicide Provides activity on the plant surface
Sprayer Calibration The purpose of calibration is to ensure that the sprayer is applying the proper amount of pesticide uniformly over a given area
Post-Application Irrigation or Rainfall Fungicides Contacts and localized penetrants: - rainfall or irrigation prior to the spray drying on the leaf will reduce disease control Systemic: - reduction of disease control can happen if excessive irrigation or rainfall occurs prior to absorption into the plant (Source: Couch, 1985)
Diagnosing Turfgrass Disease Signs Symptoms Plant host Environmental conditions Time of year
Sclerotia Signs
Symptoms Individual leaves Overall stand
Disease Mis-diagnosis Host (Turfgrass) Pathogen Environment
Dollar Spot ABG, B, KBG, PR, FF Spring, summer and fall Warm days (80 degrees), cool nights, heavy dew formation Poor fertility, slow growth, low N Frequent, light irrigation or high humidity Low or poorly drained areas
Dollar Spot
Dollar Spot Management Late spring N applications Slow release N Deep, infrequent irrigation in early morning TF is very resistant, or use resistant cultivars Curative fungicides effective Balanced fertility - 50% slow release N Alleviate compaction and thatch
Brown Patch PR, TF, B, KBG June-Sept. Warm, humid, moist conditions Daytime air temp. >85 degrees Night air temp. >65 degrees Relative humidity >95% for 8-10 hrs Worse on lush, succulent turf (High N) Leaf wetness for 8-10 hrs. Excess thatch
Brown patch
Brown Patch Management Remove excess water from turf (by mowing in the morning or dragging hose) Irrigate early in the day Avoid high N Remove excess thatch
Cultural Disease Management Plant regionally adapted/disease resistant cultivars Maintain mowing height in recommended range Balance N-P-K. Use mostly slow release N. Apply 75% of the N in the fall Irrigate deeply and infrequently
Cultural Disease Management Monitor soil ph and also soil P and K rates. Adjust ph to 6-7 range Alleviate compaction Reduce thatch Overseed/renovate chronically damaged sites
Principles Applied in IPM Develop reliable monitoring techniques Inspections of turf areas to monitor pest levels: time of year, weather conditions, turf species/cultivar, history of turfgrass cultural practices, history of previous pesticide appls. Maintain weather records: correlate with damage levels Disease diagnostics Use of computer assisted forecasting systems Keep records on results of actions taken