A Review of Issues Pertaining to Transgenic Turfgrasses

Recombinant DNA technology is a rapidly growing field in plant and animal breeding. This technology involves the transfer of pieces of DNA, or genes, regardless of the organisms involved or how they are related. Transformation procedures in plants were first developed for important crop and model plant systems. Although turfgrass management and production is one of the fastest growing areas of agriculture, genetic transformation of turfgrasses lags behind that of many other important crop plants. Turfgrasses are becoming more important primarily because of their association with the ever-increasing urban population. The size of the turfgrass seed market is second only to that of hybrid seed corn (Lee, 1996). However, much less is known about the genetics and physiology of turfgrasses. Many are polyploid, perennial, and/or outcrossing. These characteristics make them more difficult to study than many other crop plants. Use of transgenic technology in turfgrasses will likely follow as interest and corporate motivations allow. Application of transgenic technology is virtually limitless. The past few years have seen a rapid increase in releases of transgenic plants. Between 1987 and 1997, 3330 permits and notifications were filed with the U.S. Dept. of Agriculture (USDA–APHIS, 1998) for release of genetically engineered organisms in the United States. Twenty-nine percent involved herbicide tolerance and 24% insect resistance. Compared with the major crop species, genetically engineered turfgrasses are uncommon. By Dec. 1998, 31 permits and notifications had been filed on creeping bentgrass (Agrostis stolonifera L.) and two notifications on Kentucky bluegrass (Poa pratensis L.) (USDA–APHIS, 1998). But as additional genes are identified and cloned, a myriad of traits will probably be introduced into the turfgrasses. The first applications of transformation in turfgrasses were the incorporation of glufosinate [N,N-bis (phosphomethyl)glycine] resistance into creeping bentgrass (Lee et al., 1996; Liu et al., 1998), allowing application of a very effective nonselective herbicide to control unwanted weeds or other turfgrasses. In the future, recombinant DNA technology may be used to introduce other traits, such as insect resistance, disease resistance, and improved environmental stress tolerance. Transformation technology may offer many economic and agronomic benefits that are difficult or impossible to achieve through traditional breeding techniques (Dale, 1993). Essential steps of recombinant DNA technology include identification of the gene of interest, its isolation (cloning), study of the gene’s function and regulation, and introduction of the gene and expression factors into cells (Marois et al., 1991). Finally, the traits must be evaluated in an agriculturally desirable genotype

Beneficial Arthropods Associated with Buffalograss

Beneficial arthropods collected from buffalograss, Buchloe dactyloides (Nuttall) Engelmann, evaluation plots and vegetatively established buffalograss lawns included predatory ants, spiders, ground beetles, rove beetles, big-eyed.bugs, and several species of hymenopterous parasitoids. Ants and spiders were the most abundant beneficial arthropods collected, representing 84% of the total beneficial arthropods captured. Pitfall traps collected \u3e2.5 times as many (16,094) beneficial arthropods as sod plug samples (6,054), demonstrating that pitfall traps are a more effective technique than sod plugs for capturing highly mobile surface-dwelling arthropods. Families of parasitoids captured on sticky traps during the 2-yr sampling period included Scelionidae, Encyrtidae, Mymaridae, and Trichogrammatidae. Mymarids and trichogrammatids were the most abundant parasitoid families, representing 76.8% of the total parasitoids collected. Total numbers of beneficial arthropods collected from sites maintained at higher and lower management levels were not significantly different, suggesting that beneficial arthropod abundance may not be adversely affected by the 2 management regimes applied in this study

Beneficial Arthropods Associated with Buffalograss

Beneficial arthropods collected from buffalograss, Buchloe dactyloides (Nuttall) Engelmann, evaluation plots and vegetatively established buffalograss lawns included predatory ants, spiders, ground beetles, rove beetles, big-eyed.bugs, and several species of hymenopterous parasitoids. Ants and spiders were the most abundant beneficial arthropods collected, representing 84% of the total beneficial arthropods captured. Pitfall traps collected \u3e2.5 times as many (16,094) beneficial arthropods as sod plug samples (6,054), demonstrating that pitfall traps are a more effective technique than sod plugs for capturing highly mobile surface-dwelling arthropods. Families of parasitoids captured on sticky traps during the 2-yr sampling period included Scelionidae, Encyrtidae, Mymaridae, and Trichogrammatidae. Mymarids and trichogrammatids were the most abundant parasitoid families, representing 76.8% of the total parasitoids collected. Total numbers of beneficial arthropods collected from sites maintained at higher and lower management levels were not significantly different, suggesting that beneficial arthropod abundance may not be adversely affected by the 2 management regimes applied in this study

G89-925 \u27Helminthosporium\u27 Leaf Spot and Melting Out Diseases of Turfgrass (Revised December 1995)

Symptoms and controls for Helminthosporium leaf spot and melting out are discussed. Leaf spot and melting out are two fungal diseases of turfgrass within the Helminthosporium leaf, crown and root disease complex. They are the most common and serious groups of cool season turfgrass diseases in North America

G89-925 \u27Helminthosporium\u27 Leaf Spot and Melting Out Diseases of Turfgrass (Revised December 1995)

Symptoms and controls for Helminthosporium leaf spot and melting out are discussed. Leaf spot and melting out are two fungal diseases of turfgrass within the Helminthosporium leaf, crown and root disease complex. They are the most common and serious groups of cool season turfgrass diseases in North America

G81-558 Tall Fescue Lawn Calendar (Revised April 2004)

This NebGuide on tall fescue lawns discusses the calendar dates of when to mow, fertilize, water, apply herbicides and pesticides, check for insects and diseases, remove thatch, and when to aerify and overseed

Influence of \u3ci\u3eRhopus nigroclavatus\u3c/i\u3e (Hymenoptera: Encyrtidae) on the Mealybugs \u3ci\u3eTridiscus sporoboli\u3c/i\u3e and \u3ci\u3eTrionymus\u3c/i\u3e sp. (Homoptera: Pseudococcidae)

This research investigated parasitism of the buffalograss mealybugs Tridiscus sporoboli (Cockerell) and Trionymus sp. by Rhopus nigroclavatus (Ashmead) through rearing and dissection studies, paired comparison tests, and a field survey. Rates of parasitism reported in this article reflect combined parasitism of the 2 mealybug species. In the rearing study, parasitism of adult female mealybugs by R. nigroclavatus was 48.6%, with an average emergence of 1.77 parasitoids per parasitized mealybug. A maximum of 7 R. nigroclavatus adults emerged from a single mealybug female. Mealybug dissections documented parasitism rates by R. nigroclavatus of 78.5, 67.5, and 4.3%, respectively, for adult females, 3rd and 4th (male pupae) instars, and 1st- and 2nd-instar mealybugs. Results revealed the preference of R. nigroclavatus for adult female mealybugs and later instars, and suggested a potential regulating effect of R. nigroclavatus on buffalograss mealybug populations. Paired comparison tests with and without R. nigroclavatus demonstrated the effectiveness of this parasitoid as a biological control agent for buffalograss mealybugs under greenhouse conditions. Significant differences were detected in the number of nonparasitized mealybugs between treatments containing only mealybugs and treatments containing both mealybugs and parasitoids. Sticky trap captures in the field suggested a functional relationship between the seasonal abundance of R. nigroclavatus and its mealybug hosts

Heritability Estimates of Turf-type Characteristics in Buffalograss

Buffalograss [Buchloë dactyloides (Nutt.) Engelm] is a drought-resistant, dioecious species, native to the Central Great Plains, which shows excellent potential as a low maintenance turfgrass. Although buffalograss can be propagated vegetatively, there is a need for seeded turf-type cultivars. To assist in developing seeded cultivars, heritabilities of turf characteristics were estimated. Heritabilities from maternal half-sib analyses ranged from h2 = 0.04 ± 0.03 for the 1988 uniformity rating to h2 = 0.62 ± 0.26 for the 1989 spring color rating. Heritability estimates calculated from offspring-parent regression were also variable and generally lower than maternal half-sib analysis. The results suggest that some turf characteristics are highly heritable and that growing conditions markedly affect heritability estimates

G85-742 Dollar Spot Disease of Turfgrass

This NebGuide describes the symptoms and disease cycle of dollar spot, and provides recommendations for controlling this turfgrass disease. Dollar spot of turfgrass is one of the most persistent diseases on golf courses in North America. All commonly grown turfgrasses in Nebraska may be attacked, but differences in susceptibility exist within cultivars of the various turf species. Presence of dollar spot in a well-managed lawn affects its aesthetic appearance and value, but usually does not threaten its survival. Lawns recover from dollar spot injury when conditions are favorable for vigorous, healthy growth