Disease Management in Turf. Nancy Bosold Penn State Cooperative Extension Berks County

Transcription

1 Disease Management in Turf Nancy Bosold Penn State Cooperative Extension Berks County

2 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

3 Abiotic Turfgrass Disease Non-living causes of disease Temperature Moisture Nutrient imbalance Compaction

4 Biotic Turfgrass Disease Living causes of turf disease Fungus Bacteria Nematodes Virus Protozoa

5 Disease Triangle Environment Pathogen Host

6 Disease Triangle Disease Disease Environment Time

7 Host The host must be susceptible

8 Pathogen Disease producing organism

9 Environment Weather Management Site conditions Damping off disease

10 Development over Time Leafspot and melting-out diseases

11 REGULATORY GENETIC CULTURAL IPM CHEMICAL PHYSICAL BIOLOGICAL

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13 Genetic Disease resistant cultivars. When establishing new turf areas or renovating or overseeding, consider using disease resistant cultivars For more information: turf fact sheets (Dr. Pete Landschoot Penn State) NTEP reports

14 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

15 Clippings may spread disease

16 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

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18 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.

19 Cultural Thatch, traffic, soil compaction issues. - Aerification

20 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

21 Brown patch severity in perennial ryegrass. NaN0 + P + K 3 NaN0 3 SCU + P + K SCU Percent Disease Severity (Source: Fidanza et al., 1996)

22 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.

23 Fungicide Issues and Concerns Disease misdiagnosis Fungicide application strategies Fungicide application technique Post-spray irrigation or rainfall Cultural practices Resistance to the pesticide

24 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.

25 Residual Activity Systemic fungicide Moves inside the plant Contact fungicide Provides activity on the plant surface

26 Sprayer Calibration The purpose of calibration is to ensure that the sprayer is applying the proper amount of pesticide uniformly over a given area

27 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)

28 Diagnosing Turfgrass Disease Signs Symptoms Plant host Environmental conditions Time of year

29 Sclerotia Signs

30 Symptoms Individual leaves Overall stand

31 Disease Mis-diagnosis Host (Turfgrass) Pathogen Environment

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34 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

35 Dollar Spot

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37 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

38 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

39 Brown patch

40 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

41 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

42 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

43 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