Research & Development Field Report – 8th Edition

GENERAL OBSERVATIONS

• The drought which was present across much of the Eastern half of the country in early summer gave way to beneficial rainfall. However, with the exception of areas that have received rainfall from tropical systems, significantly drier and/or droughty conditions have returned in September for much of the Southeast, Mid-Atlantic, and the Ohio River Valley.
• As of late August, drought conditions were sustained in the Southern plain states, Texas, and the Mountain West; Southern California has remained under non-drought conditions.

WEEDS

• Late-season summer weed control
  • Broadleaf and grassy weeds still present are likely very mature and difficult to control at this growth stage. Furthermore, environmental conditions may not facilitate optimal herbicide activity.
  • If herbicide applications are still warranted, consider applying the maximum labeled rate and adding an adjuvant such as a nonionic surfactant.
  • Before making applications ensure adequate soil moisture for herbicide activity.
• Poa, Poa, Poa
  • Herbicide programs for Poa control in bermudagrass and Zoysiagrass should include a combination of PRE and POST herbicides applied multiple times. The days of a single application timing to effectively control Poa season-long are behind us.
  • Early POST emergent timings when Poa is small lends itself to better overall control over beginning applications later in the season when the Poa has matured and tillered out.
  • When targeting Poa that may have herbicide resistance consider applying two modes of action (ie. Katana^® Turf Herbicide (Group 2) and simazine (Group 5).
  • Research has shown Katana herbicide can provide season-long Poa control >90% when mixed with simazine and any PRE herbicide (e.g., indaziflam, prodiamine, and pronamide) and applied twice in fall and winter.
  • Katana and Bensumec™ 4LF Pre-Emergent Grass & Weed Herbicide can be used in a similar manner on ultradwarf bermudagrass putting greens.
  • Initial application should be made at an early-POST timing (October-December) with the follow-up application 2 months later. Application intervals are shorter for bermuda putting greens.
• Winter annual broadleaf control
  • Most herbicide programs for Poa control also provide winter annual broadleaf control.
  • In areas without Poa control, winter weeds such as chickweeds, henbit, purple deadnettle, speedwells, lawn burweed, and wild garlic can become problematic in managed turfgrasses.
  • It is best to control these weeds in the fall at an early-POST timing to limit their competition against the turfgrass during the winter and spring.
  • Make herbicide applications prior to cooler winter temperatures and PRE herbicides can be tank-mixed for more residual control.
  • SpeedZone^® EW Broadleaf Herbicide for Turf and TZone™ SE Broadleaf Herbicide for Tough Weeds herbicides are good options for winter annual weed control in cool- and warm-season turfgrasses.

DISEASES

• Spring dead spot
  • Kabuto^® Fungicide SC is the premium fungicide for control of spring dead spot.
    • >95% control is achieved with a single application of 3.2 fl. oz./1,000 sq. ft.
      • Application must be applied when 2” soil temperature is between 55-65°F
      • Immediate post-application irrigation (>1/8”) is critical.
    • >95% control is achieved with two applications 1.0-1.6 fl. oz./1,000 sq. ft.
      • First application when 2” soil temperature is below 70°F.
      • Second application ~21 days after treatment (before 2” soil temp is < 60°F).
      • Immediate post-application irrigation (>1/8”) is critical.
    • PBI-Gordon has a Fungicide Assurance Program with Kabuto for Spring Dead Spot that may be accessed by following this link:https://www.pbigordonturf.com/wp-content/uploads/2018/12/Kabuto_Fungicide_Assurance_Program_2024.pdf
• Large patch
  • Pedigree Fungicide SC (3.2 fl. oz./ 1,000 sq. ft.)
    • Addition of a nonionic surfactant aids in disease control.
  • Tekken^® Broad Spectrum Fungicide (3.0 fl. oz./1,000 sq. ft.)
    • Two applications in the fall when conditions are favorable for disease development 30 days apart.
    • Initial application is typically made prior to a major rain event, after which conditions are favorable for disease development.
    • Fall apps typically lead to less large patch damage in the spring. Additional apps in the spring may be warranted as well.
• Bermudagrass/Zoysiagrass Greens (Shoulder Season) Program
  • Pythium Blight/Root Rot/Root Dysfunction
    • Applied as part of a preventive fungicide program as the growth slows down allowing diseases to affect the grasses and the recovery during this period is significantly less.
      • Segway^® Fungicide SC (0.45 fl. oz./1,000 sq. ft.) 14-day interval.
      • Union^® Fungicide SC (2.9 fl. oz./1,000 sq. ft.) 14-day interval.
• Dollar Spot
  • As part of a preventive fungicide program, ensure that applications are made prior to disease development as the ability of these grasses to recover during this period is significantly less.
    • Kabuto (0.5 fl. oz./ 1,000 sq. ft.) 14-day interval.
    • Tekken (3.0 fl. oz./1,000 sq. ft.) 14 to 21-day interval.
• Brown Patch
  • • Tekken (3.0 fl. oz./1,000 sq. ft.) 14 to 28-day interval.
    • Union (2.9-5.75 fl. oz./1,000 sq. ft.) 14 to 28-day interval.
    • Pedigree (2.2 to 3.2 fl. oz./1,000 sq. ft.) 14 to 21-day interval.
• Gray Leaf Spot (Bermudagrass and overseeded ryegrass)
  • • Union (2.9-5.75 fl. oz./1,000 sq. ft.) 14-day interval.
    • Tekken (3.0 fl. oz./1,000 sq. ft.) 14-day interval.

INSECTS

• Curative white grub control: Late Summer/Early Fall
  • Curative treatments are an effective control strategy when damaging grub populations are present. If preventive treatments were not applied, site inspections or knowledge of past infections can help determine if an application is needed.
  • Curative applications when grubs are smaller will give better results. Control will be more difficult once grubs have reached the 3rd larval stage.
  • Broadcast applications for curative control are usually unnecessary because grub infestations are often localized to only part of the turfgrass area.
  • Chemical Control Options
    • Clothianidin – Neonicotinoid
    • Trichlorfon – Organophosphate
    • Carbaryl – Carbamate

FORMULATION CHEMISTRY

• Fall Reseeding: The summer heat typically takes its toll on turf health with the months of September and October; ideal months to reseed those vacant spots in turf. Even though most herbicides have reseeding intervals on the label, there can still be variability of the active ingredient residue on soil that can impact germination rates. Photodegradation and aqueous photodegradation may shorten this interval. Below normal fall temperatures with cloudy days could extend this reseeding interval. When planning your reseed strategy, allow sufficient time that could take into account this variability. Ultimately, you want to enhance the germination rate of your turf seed so reflect on the environmental conditions prior to reseeding.
• Fall Fertilizer Tank Applications: Deciding to use liquid fertilizer as opposed to traditional granular applications is an option. However, any residual herbicide in the spray tank can impact seed germination. Utilize commercial spray tank cleaners and don’t forget the hoses and spray nozzles. If mixing with micronutrients or iron products, conduct a jar test first for compatibility. The extreme pH differences between these products can result in precipitation clogging the lines and spray head. The jar test will determine if these products need to be applied separately or can coexist in a single application.