ABSTRACT
Eight commonly cultivated Ixora species or cultivars were tested for their suitability as hosts and their level of tolerance to Meloidogyne incognita race 1 and M. javanica in a greenhouse study. Twenty weeks postinoculation with 5,000 eggs per pot, M. incognita race 1 and M. javanica produced galls and formed egg masses on roots of all eight Ixora species or cultivars tested. However, only M. javanica-infected 'Petite Yellow' and 'Maui' had decreases (P = 0.05) in root wet weights, suggesting that the other cultivars were more tolerant to these root-knot nematode species. Differential host suitability to each Meloidogyne species was based on the relative number of galls, galls per gram root weight, egg masses, and second-stage juveniles produced per plant. 'Bonnie Lynn,' 'Maui,' and 'Petite Red' were good to excellent hosts for both Meloidogyne spp. Ixora coccinea was a good host for M. incognita race 1 but less suitable for M. javanica. 'Singapore' and 'Petite Yellow' were poor hosts for M. incognita race 1 but excellent hosts for M. javanica. 'Nora Grant' and I. casei 'Super King' were poor hosts for both species of root-knot nematodes.
ABSTRACT
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 = 0.05) in root dry weight relative to uninoculated plants of the same germplasm and (or) > 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
A survey was conducted between 1985 and 1989 of isolates of the Pasteuria penetrans group on phytoparasitic nematodes in bermudagrass (Cynodon spp.) turf in southern Florida. Six different isolates of the P. penetrans group were observed from five different species of phytoparasitic nematode hosts. Five of the bacterial isolates were different (P = 0.01) in sporangium diameter, endospore width, and ratio of sporangium diameter to endospore width. All locations surveyed had one or more isolates present, suggesting that the Pasteuria penetrans group is widespread in its distribution in southern Florida. Three survey sites had high densities of Belonolaimus longicaudatus, with more than 60% of the host population encumbered with a large-spored isolate of Pasteuria (mean sporangium diameter = 6.10 mum). One of these sites was monitored for 16 months during which the proportion of nematodes encumbered with this Pasteuria isolate remained constant. Soil infested with this isolate was not suppressive to Pasteuria-free populations of B. longicaudatus grown on bermudagrass for 6 months after controlled soil inoculation. However, the proportion of spore-encumbered and parasitized B. longicaudatus after 6 months was 73%, which was similar to the 74% level observed at the field site. The uhrastructure of mature sporangia of the large-spored isolates of Pasteuria from B. longicaudatus and Hoplolaimus galeatus is described and compared with ultrastructural descriptions of P. penetrans sensu strictu and P. thornei from the literature. These B. longicaudatus and H. galeatus isolates of Pasteuria appear to be distinct from the known species and may warrant new species status.
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.