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Laurie E. Trenholm, Darin W. Lickfeldt, and William T. Crow

This research was conducted to determine if application of 1,3-dichloropropene (1,3-D) could reduce turfgrass water requirements in soil infested with sting nematodes (Belonolaimus longicaudatus Rau). The effects of 1,3-D and fenamiphos were evaluated on quality and persistence of `Tifway 419' bermudagrass (Cynodon dactylon × C. transvaalensis Burtt-Davy) subjected to drought or deficit irrigation. The research consisted of two greenhouse studies in 2002 and 2003 where irrigation was either withheld or applied in deficit quantities, and one field study in 2003 where irrigation was withheld. In general, 1,3-D-treated turf maintained up to 40% higher quality during drought than other treatments and had up to 27% less leaf wilting. As drought severity increased, 1,3-D treatments had better spectral reflectance values, indicating better physiological functioning under stress. Results of this research suggest that application of 1,3-D in sting nematode-infested soils may increase bermudagrass drought survival.

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S.K. Braman, R.R. Duncan, and M.C. Engelke

Turfgrass selections including 21 paspalums (Paspalum vaginatum Swartz) and 12 zoysiagrasses (Zoysia sp.) were compared with susceptible `KY31' tall fescue (Festuca arundinacea Schreb.) and more resistant common bermudagrass (Cynodon dactylon Pers.) and common centipedegrass [Eremochloa ophiuroides (Munro.) Hack] for potential resistance to fall armyworm [Spodoptera frugiperda (J.E. Smith)], an occasionally serious pest of managed turf. Turfgrass and pasture grasses annually suffer sporadic damage by this pest, often severe in the Gulf Coast states. Resistant grasses offer an alternative management tool for the fall armyworm, reducing the need for pesticide use. Laboratory evaluations assessed the degree of antibiosis and nonpreference present among more than 30 turfgrass genotypes to first and third instar fall armyworms, respectively. Zoysiagrasses exhibiting high levels of antibiosis included `Cavalier', `Emerald', DALZ8501, DALZ8508, `Royal', and `Palisades'. Paspalum selections demonstrating reduced larval or pupal weights or prolonged development times of fall armyworm included 561-79, Temple-2, PI-509021, and PI-509022.

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Julia Whitworth

The usefulness of cover crops for weed management in strawberries were evaluated. Wheat (Triticum aestevum L.), rye (Secale cereale L.), and crimson clover (Trifolium incarnatum L.) were grown in individual pots then killed by tillage or herbicide and followed in the same pots by plantings of bermuda grass [Cynodon dactylon (L.) Pers.], yellow nutsedge (Cyperus esculentus L.), crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.], or strawberries (Fragaria ×ananassa `Cardinal'). Rye and wheat tilled into the medium generally increased the growth of strawberries and decreased the growth of bermuda grass. Rye and wheat residues appeared to suppress growth of weeds and strawberries when the residues remained on the medium surface. Crimson clover had little affect on the growth of weeds or strawberries. Yellow nutsedge and crabgrass were not significantly affected by cover crop residues.

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C. Scott, R.K. Nishimoto, and C.S. Tang

Cyperus kyllingia and Cyperus brevifolius are problematic turfgrass weeds in Hawaii. Both are closely related weed species with similar morphology and growth characteristics. C. kyllingia appears to be a more successful weed with regards to interference than C. brevifolius. Greenhouse experiments were conducted to compare the levels of interference exerted by C. kyllingia and C. brevifolius upon Cynodon dactylon turfgrass. C. kyllingia reduced the growth of C. dactylon by about 50 %, while C. brevifolius did not significantly reduce C. dactylon growth. These results correspond with the chemical profiles of C. kyllingia and C. brevifolius. Analysis has shown that C. kyllingia contains two sesquiterpenes which have been identified as potentially allelopathic components of Cyperus rotundus. C. brevifolius contains waxes and the two sesquiterpenes found in C. kyllingia are absent. This suggests that allelopathy may be the mechanism responsible for the different levels of interference exhibited by C. kyllingia and C. brevifolius, and these species may provide an important model for the study of allelopathy.

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Jeff A. Anderson

One method of plant freeze protection involves the application of compounds that promote freeze avoidance or tolerance. FreezePruf, a commercially available product recently marketed to improve both freeze avoidance and tolerance, contains polyethylene glycol, potassium silicate, glycerol, silicone polyether surfactant, and a bicyclic oxazolidine antidessicant. The goal of the present study was to evaluate the protection level provided by FreezePruf using laboratory-based methods involving plants and plant parts from species capable and incapable of low-temperature acclimation. FreezePruf did not lower the freezing temperature of pepper (Capsicum annuum) seedlings, celosia (Celosia argentea) seedlings, detached tomato (Solanum lycopersicum) leaves, or postharvest tomato fruit. Spray application of the putative cryoprotectant did not increase the freeze tolerance of bermudagrass (Cynodon dactylon) crowns or stolons. It is possible that a greater level of protection could be achieved with other species or different experimental protocols.

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Edward W. Bush, James N. McCrimmon, and Allen D. Owings

Four warm-season grass species [common carpetgrass (Axonopus affinis Chase), common bermudagrass (Cynodon dactylon [L.] Pers.), St. Augustinegrass (Stenophrum secondatum Walt. Kuntze.), and zoysiagrass (Zoysia japonica Steud.)] were established in containers filled with an Olivia silt loam soil for 12 weeks. Grasses were maintained weekly at 5 cm prior to the start of the experiment. Water stress treatments consisted of a control (field capacity), waterlogged, and flooded treatments. Waterlogging and flood treatments were imposed for a period of 90 days. The effects of water stress was dependent on grass species. Bermudagrass vegetative growth and turf quality were significantly reduced when flooded. Carpetgrass, St. Augustingrass, and zoysiagrass quality and vegetative growth were also reduced by flooding. St. Augustinegrass and zoysiagrass root dry weight was significantly decreased. Zoysiagrass plants did not survive 90 days of flooding. Leaf tissue analysis for common carpetgrass, common bermudagrass, St. Augustinegrass, and zoysiagrass indicated that plants subjected to waterlogging and flooding had significantly elevated Zn concentrations.

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M.A. Czarnota

Glyphosate traditionally has been used by growers and landscapers as a nonselective herbicide; however, selective uses do exist. The use of glyphosate to control weeds in dormant and actively growing bermudagrass (Cynodon dactylon) is an example of selective weed control. Several ornamentals, including conifer species, have been known to exhibit good tolerance to over-the-top applications of glyphosate. Unfortunately, little published information exists on rates of glyphosate that may be used on specific ornamental species. The objective of this research was to determine the tolerance levels of three juniper species [‘Blue Pacific’ shore juniper (Juniperus conferta), ‘Blue Star’ juniper (Juniperus squamata), and ‘Parsoni’ juniper (Juniperus davurica)] to various rates of glyphosate. Research conducted in 2004 and 2005 indicated that injury to three juniper species did not exceed 23% with glyphosate rates up to 2.5 lb/acre.

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W.G. Foshee, W.D. Goff, K.M. Tilt, J.D. Williams, J.S. Bannon, and J.B. Witt

Organic mulches (leaves, pine nuggets, pine straw, grass clippings, and chipped limbs) were applied at depths of 10, 20, or 30 cm in a 3 × 3-m area around young pecan [Carya illinoinensis (Wangenh.) K. Koch] trees. These treatments were compared to an unmulched herbicide treatment and a common bermudagrass [Cynodon dactylon (L.) Pers.] sod. Trunk cross-sectional areas (TCSAs) of the mulched trees were larger than those of trees in the sod or unmulched plots and increased linearly as mulch depth increased. All mulches influenced TCSA similarly. Mean TCSA for mulched trees increased 14-fold compared to an increase of 8-fold for the unmulched trees and the sod in this 3-year study. Thus, common yard-waste mulches can be used effectively to increase growth of young pecan trees.

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M.L. Elliott

Eight demethylation inhibiting (DMI) fungicides were applied at two rates to `Tifgreen' bermudagrass [Cynodon dactylon (L.) Pers. ×x C. transvaalensis Burtt-Davy] to determine if DMI fungicides would produce a plant growth regulation effect on healthy bermudagrass. After three applications at 28- to 30-day intervals, compared to the control, both rates of cyproconazole, bromuconazole, propiconazole and triadimefon and the high rate of myclobutanil significantly decreased turfgrass quality on at least one evaluation date in each year of the study. The low rate of myclobutanil and both rates of tebuconazole and fenbuconazole did not adversely effect turfgrass quality in either year. For both rates of fenarimol, there was only one date during both years of the study when the turfgrass quality was significantly lower than the control. These results demonstrate the wide range of physiological activity the DMI fungicides can have on bermudagrass.

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R.L. Green, J.B. Beard, and M.J. Oprisko

Root hairs contributed variously to total root length, ranging from a low of 1% for `Emerald' zoysiagrass (Zoysia japonica Steud. x Z. tenuifolia Willd. ex Trin) and 5% for `Georgia Common' centipedegrass [Eremochloa ophiuroides (Munro.) Hack], to a high of 95% and 89% for `Texturf 10' and `FB 119' bermudagrasses [Cynodon dactylon (L.) Pers.], respectively. Genotypes ranking highest for root lengths with root hairs also ranked highest for root lengths without root hairs and for number of main roots per plant. In terms of root lengths with root hairs, first-order lateral roots contributed more to total root length than root lengths of either main roots or second-order lateral roots for all nine genotypes. Number and length of root hairs arising from either main or lateral roots were not significantly affected by their relative distance from the cap of the main root. `Texturf 10' and `FB 119' bermudagrasses ranked highest for root and root-hair extent.