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White Grubs
Above: More than a dozen different species of white grubs damage turf in the southern U.S. Most grubs feed primarily on grass roots, causing a reduction in water and nutrient uptake by plants.
cies is occurring in many areas where masked
A shift in white grub spe- chafers
(Cy-
clocephala spp.) overlap with Japanese beetles. For reasons not fully understood, urban neighborhoods that previously hosted 80-100 percent Japanese beetle populations are now predominately populated with
Dallisgrass: A Troublesome Weed
In 2004, the Southern Weed Science
Society survey named dallisgrass as one of the 10 most troublesome turf- grass weeds in 10 of 11 states in the southern U.S. Dallisgrass is a rhizomatous pe-
rennial warm-season grass that has long been used as a forage or roadside grass, but its ability to adapt to a wide range of environmental factors may have led to its success and spread as a turfgrass weed. Until recently, chemi- cal control of dallisgrass was neither efficient, nor cost effective. Typical programs included multiple applica- tions of monosodium methanearson- ate (MSMA), which can be damaging to warm-season turfgrasses, or appli- cations of glyphosate, which can be even more harmful to desirable turf- grass species. Experiments were conducted at Meadowbrook Country Club in Lubbock for the post-
masked chafers. Selective natu- ral control with milky spore disease and other beneficial pathogens may be part of the explanation for the shift. Masked chafers are not af-
fected by milky spore disease. Several chemical control op- tions exist for the control of white grubs in turfgrass, how-
ever, most of these insecticides provide inconsistent control of masked chafer grubs. Field experiments were conducted at the Texas Tech Turfgrass Research Farm in Lubbock to examine the effect of several insecticides for the control of masked chafer grubs. Treatments were sprayed in
mid-May and consisted of chlo- rantraniliprole
(Acelepyrn)
(8 or 16 fl oz/A), halofenozide (Mach 2) (4 qt/A), imidaclo- prid (Merit) (8.6 oz/A), and clothianidin (Arena) (6.4 or 12.8 oz/A). Chlorantraniliprole
treat-
ments exhibited 100-percent control regardless of appli- cation
rate 20 weeks after
treatment. Control with ha- lofenozide and imidacloprid treatments ranged from 88- to-91 percent. Clothianidin at 6.4 oz/A exhibited 88 per- cent control, while the higher rate (12.8 oz/A) provided complete control.
Spring Dead Spot Efficacy of fungicides for the
control of SDS and other root- infecting fungi may be limited by fungicide penetration into the soil profile. Therefore, cul- tivation practices aimed at re- ducing the thatch layer may also increase fungicide infiltration. Experiments were conducted over the past few years at Hill- crest Country Club in Lubbock, Texas to evaluate the effect of cultural practices on fungicide efficacy for the control of SDS disease in bermudagrass. Cultural treatments were con-
Above: The squares that are showing up in the picture illustrate the high level of control of dallisgrass in response to applications of Celsius plus Revolver (foramsulfuron.)
inset: A research trial at the Quaker Research Farm at Texas Tech University examinines the establishment of buffalograss and bermudagrass from seed with different mulching media (no mulch, wheat straw, gin trash, or hydro-mulch).
emergence control of dalliesgrass in bermudagrass turf. Treatments consisted of com- binations of dicamba + iodosulfuron + thiencarbazone (Celsius) (0.08 oz/1000 ft2) and foramsulfuron (Revolver) (0.4 fl oz/1000 ft2) applied in late August or early September. A se- quential application was made following dallisgrass re-growth approximately 4-to-5 weeks later. Dallisgrass emergence the following spring was severely reduced (< 5% regrowth) with no bermudagrass damage.
20 LC DBM
ducted prior to fungicide appli- cation and consisted of no culti- vation, verticutting, hollow-tine aerification, or aerification + verticutting. Fungicide treat- ments were applied in mid-Au- gust and consisted of fenarimol (Rubigan) at 6 fl oz/1000 ft2 or tebuconazole (Torque) at 0.6 fl oz/1000 ft2. Sequential applica- tions were made 30 days after initial treatment. Verticutting did not increase
the efficacy of either fungicide. Aerification and aerification + verticutting in combination with fenarimol (Rubigan) and tebuconazole (Torque) reduced SDS pressure 44-to-50 percent and 80-to-87 percent, respec- tively, compared to the applica- tion of fungicides alone.
Above: Spring dead spot (SDS) is considered to be the most devastating
bermudagrass
disease to turf
temperatures
low enough during the winter induce dormancy.
infect
the transition zone and southern U.S. where
throughout drop
to