ABSTRACT
Seashore paspalum (Paspalum vaginatum Swartz) is a warm-season perennial turfgrass commonly used for golf courses that are grown in saline environments or using saline water for irrigation. However, seashore paspalum is also grown in non-saline conditions due to its low fertilizer and water requirements (2). In Barbados, on a newly constructed golf course, seashore paspalum 'Sea Isle Supreme' sprigs were imported from Georgia (United States) and were planted over 2006 and 2007 on greens, tees, fairways, and rough. Golf greens were constructed following the United States Golf Association Green Section (Far Hills, NJ) putting green guidelines. Tees and fairways were constructed using native soil. Two years after the grow-in, the putting greens began to exhibit irregular chlorotic patches, followed by gradual thinning and decline of turfgrass stand density in those areas. Additionally, turfgrass roots sampled from those symptomatic patches appeared to be abbreviated compared to non-symptomatic areas of the greens. A survey was conducted in May 2013 to determine if plant-parasitic nematodes were present coinciding with the observed symptoms, which were similar to those described in a previous report (3). Consequently, two samples were collected from each green with a total of four greens sampled. Each sample consisted of 20 soil cores (15 cm depth × 1.2 cm in diameter) from either areas of the greens showing symptoms or from non-symptomatic areas. Nematodes were extracted from 100 cm3 soil samples using a modified centrifugal-sugar flotation technique (4). No plant parasitic nematodes were present in any of the samples from the non-symptomatic areas. Three genera of plant parasitic nematodes were found in all the samples from the symptomatic areas: Helicotylenchus. Mesocriconema, and Pratylenchus. Nematode populations of these genera averaged 30, 60, and 200 nematodes per 100 cm3, respectively. Populations of the genera Helicotylenchus and Mesocriconema were below the action threshold levels for seashore paspalum used by the University of Florida Nematode Assay Laboratory (1). Currently, no threshold exists for Pratylenchus for seashore paspalum. Conversely, the genera Helicotylenchus. Mesocriconema, and Pratylenchus were found associated with the irregular chlorotic patches but not with the non-symptomatic areas. To our knowledge, this is the first report of plant parasitic nematodes associated with seashore paspalum maintained as putting greens in Barbados. References: (1) W. T. Crow. Nematode management for golf courses in Florida. EDIS. Accessed 31 July 2013 from: http://edis.ifas.ufl.edu/in124 , 2001. (2) R. R. Duncan and R. N. Carrow. Seashore Paspalum: The Environmental Turfgrass. John Wiley & Sons, Inc., Hoboken, New Jersey, 2000. (3) A. C. Hixson and W. T. Crow. Plant Dis. 88:680, 2004. (4) W. R. Jenkins. Plant Dis. Rep. 48:692, 1964.
ABSTRACT
This study was conducted to determine the degradation rates in turfgrass soil over a 12-month period after a single field application of propoxur and to isolate microorganisms from the soil capable of degrading the insecticide. Soil samples were collected from a turfgrass experimental site near Fort Lauderdale, FL one week before the field application of propoxur, and over a 12-month period after the field application. Mineralization rates in surface (0-15 cm depth) and subsurface (15-30 cm depth) soil samples collected before the field application were low. Mineralization in surface and subsurface samples collected 1, 6 and 8 months after the field application was much higher than for corresponding samples collected before the field application. Mineralization in the subsurface samples collected 12 months after the field application had reverted back to the similar rate for the corresponding sample collected before field application. Half-life values (t1/2) for propoxur showed similar trends to the results of mineralization. After a single application of propoxur, degradation in turfgrass soil was enhanced. Such enhancement lasted less than 12 months for the subsurface, but more than 12 months for the surface. A strain of Arthrobacter sp. capable of degrading propoxur was isolated from the soil.
Subject(s)
Arthrobacter/metabolism , Propoxur/metabolism , Soil Microbiology , Arthrobacter/isolation & purification , Biodegradation, Environmental , Time FactorsABSTRACT
Thirty-seven warm-season bermudagrass (Cynodon spp.) accessions, two cool-season grasses (Lolium perenne and Festuca arundinacea), 'Transvala' digitgrass (Digitaria decumbens), and Sorghum bicolor were evaluated to determine host suitability and susceptibility to the sting nematode, B. longicaudatus, in a 140-day microcell bioassay. All seven of the evaluated commercial cultivars of Cynodon were suitable hosts for B. longicaudatus but varied in their tolerance to the nematode. 'Midiron,' 'Tifdwarf,' 'Tifgreen,' 'Tifgreen II,' 'Tifway II,' and 'Tufcote' were sensitive, with reductions in root weight of >24%, whereas 'Tifway' appeared to be relatively tolerant with only a 4% reduction in root dry weight. Twenty other Cynodon accessions showed decreases (P 11% root reductions. In addition to 'Tifway,' 10 other Cynodon accessions and L. perenne, F. arundinacea, D. decumbens, and S. bicolor appeared to be relatively more tolerant of B. longicaudatus than the other accessions evaluated.
ABSTRACT
Three nematicides were evaluated for control of Belonolaimus longicaudatus, Hoplolaimus galeatus, Criconemella spp., and Meloidogyne spp. in 'Tifgreen II' bermudagrass mowed at golf course fairway height (1.3 cm) in Fort Lauderdale, Florida. Bermudagrass plots were treated with fenamiphos (13.5 kg a.i./ha), oxamyl (13.5 kg a.i./ha), or 30% formaldehyde (6.4 liter a.i./ha). The plots treated with fenamiphos or formaldehyde were split 14 days later and one-half of each plot received two biweekly applications of formaldehyde. Forty-two days after the treatments were applied, the turfgrass vigor ratings and dry root weights in plots treated with fenamiphos were higher (P < 0.05) than the control, oxamyl, or formaldehyde treatments. The population levels of B. longicaudatus were suppressed (P < 0.05) in the fenamiphos, fenamiphos plus formaldehyde, and oxamyl treatments.
