In turfgrass systems, nematicides are a valuable tool for managing plant-parasitic nematode populations, but few studies have examined nematicide effects on non-target nematodes. The study evaluated effects of turfgrass nematicide formulations of abamectin (Divanem SC), fluopyram (Indemnify), furfural (MultiGuard Protect EC), and fluensulfone (Nimitz Pro G) on non-target nematode populations in bermudagrass (Cynodon spp.). Nematicides were applied at labeled rates every four weeks as a summer treatment program from Samples were collected before the initial treatment and 2 d, 14 d, 56 d, and 238 d after the final treatment in both years for nematode community analysis. Data from each nematicide treatment were compared to the untreated at each sample date using analysis of covariance with initial population counts serving as the covariate. Abamectin had moderate impact and fluopyram had substantial impact on the nontarget nematodes. Furfural and fluensulfone had minimal impact on non-target nematodes. The results of this study suggest nematicides can impact non-target nematode densities in bermudagrass.

The genus Chionanthus, known as fringetrees, is a member of the olive family (Oleaceae). Chionanthus virginicus is an understory tree or shrub with a wide range in forests of the eastern United States and is used as an ornamental tree that is known to be free of insects and disease in the wild. The species is tolerant of a wide range of environmental conditions, and there is interest in developing new cultivars with improved horticultural traits, such as tree form or upright growth habit and superior flowering display that are widely adapted. To identify genepools in the native range of C. virginicus for use in breeding programs, the genetic diversity and population structure were assessed for 274 individuals from 12 locations in four states (Florida, Maryland, North Carolina, and Texas) using 26 simple sequence repeats (SSRs). An average of 12.54 alleles/locus were detected, allelic richness averaged 2.80. Genetic differentiation was 0.11, indicating moderate differentiation among subpopulations. Despite the high genetic diversity and low population differentiation, Bayesian clustering analysis identified six genetic groups that match the geographic distribution of collection sites. Analysis of molecular variance indicated that most (82%) of the variation is explained within individuals, and 11% and 7% of the variation is due to differences among individuals within populations and among populations. Analysis of isolation by distance across all samples showed a weak positive relationship between geographic distance and genetic distance. The C. virginicus samples analyzed in this study indicate there is sufficient diversity for germplasm collection for use in breeding programs. Given the relatively moderate genetic differentiation, there are not likely to be unique islands of genetic diversity that may be missed when gathering parental materials for a breeding program

In turfgrass systems, nematicides are a valuable tool for managing plant-parasitic nematode populations, but few studies have examined non-target nematicide effects on arthropods. Our study evaluated effects of turfgrass nematicide formulations of abamectin (Divanem SC), fluopyram (Indemnify), furfural (MultiGuard Protect EC), and fluensulfone (Nimitz Pro G) on arthropod populations in bermudagrass (Cynodon spp.; Poaceae). A randomized block design was used with 5 replications of the 4 nematicide treatments and an untreated control. Plots were 6 m 2 with 0.6 m untreated borders between adjacent plots. Data were collected from 1.5 m 2 subplots located in the center of the treatment plots. Nematicides were applied at labeled rates every 4 wk as a summer treatment program from 7 Jun to

Meloidogyne enterolobii is a virulent species of root-knot nematode that threatens watermelon (Citrullus lanatus) production in the southeast United States. There are no known sources of root-knot nematode resistance in cultivated C. lanatus. Specific genotypes of a wild watermelon relative, C. amarus, are resistant against Meloidogyne incognitaM. incognita, but the genetics that underly this resistance are still unknown and it is not clear that this same resistance will be effective against M. enterolobii. To identify and characterize new sources of resistance to M. enterolobii, we screened 108 diverse C. amarus lines alongside a susceptible C. lanatus cultivar (‘Charleston Gray’) for resistance against M. enterolobii. Different C. amarus genotypes ranged from resistant to susceptible for the three resistance phenotypes measured; mean percent root system galled ranged 10 - 73%, mean egg mass counts ranged 0.3 - 64.5, and mean eggs per gram of root ranged 326 - 146,160. We used each of these three resistance phenotypes combined with whole-genome resequencing data to conduct a genome wide association scan that identified significant associations between M. enterolobii resistance and 11 SNPs (single nucleotide polymorphisms) within the C. amarus genome. Interestingly, SNPs associated with reduced galling and egg masses were located within a single quantitative trait locus (QTL) on Chromosome Ca03, while reductions in nematode eggs per gram of root were associated with separate QTL on chromosomes Ca04 and Ca08. The results of this study suggest multiple genes are involved with M. enterolobii resistance in C. amarus and the SNPs identified will assist with efforts to breed for M. enterolobii resistance in watermelon.