No abstract

A 2-yr study was conducted to document the inßuence of selected buffalograss, Buchloë dactyloides (Nuttall) Engelmann, management practices (three mowing heights and Þve nitrogen levels) on the seasonal abundance of the western chinch bug, Blissus occiduus Barber (Heteroptera: Lygaeidae), and its beneÞcial arthropods. Vacuum, pitfall, and sticky traps samples were collected every 14 d from the middle of May through October from western chinch bug-resistant (ÔPrestigeÕ) and-susceptible (Ô378Õ) buffalograss management plots. In total, 27,374 and 108,908 western chinch bugs were collected in vacuum and pitfall traps, respectively. More than 78% of all western chinch bugs were collected from the highly susceptible buffalograss 378. SigniÞcantly more bigeyed bugs (Geocoridae: Geocoris spp.) were collected from the 378 buffalograsss management plots than the Prestige plots. In contrast, buffalograss cultivar had little inßuence on the abundance of other beneÞcial arthropods collected. Statistically, western chinch bugs were least abundant at the lowest mowing height (2.5 cm) and increased in abundance with increasing fertility. Numerically, however, differences among management levels on western chinch bug abundance were minimal. Numerous beneÞcial arthropods were collected from buffalograss management plots, including spiders, predatory ants, ground beetles (Carabidae), rove beetles (Staphylinidae), bigeyed bugs, and several species of hymenopterous parasitoids. In general, beneÞcial arthropods were essentially unaffected by either mowing height or nitrogen level. Scelionid wasps represented 66.3% of the total parasitoids collected. The total number of scelionid wasps collected among the three mowing heights and Þve nitrogen levels were approximately equal.

No abstract

Willow (Salix L.) species have good qualities for becoming a biomass crop for production of biofuels. They grow on marginal soils, produce high yields of wood in a short period of time, and are easily propagated. Salix is one of the few genera that may be cryopreserved as dormant winter buds (DBs) instead of using tissue culture techniques. The objective of our study was to evaluate selected factors that affect cryotolerance of nine Salix germplasm accessions in the USDA-ARS National Plant Germplasm System collection. One-year-old branches harvested in January over 3 yr were cut into either 6-to 7-or 10-cm segments containing at least two DBs. Segments were treated with a slow-cooling procedure and stored in vapor-phase liquid N (LNV). Control segments were stored at −5 °C until planting. The LNV-exposed and the −5 °C-stored nodal segments were warmed and directly planted in a cold greenhouse. Six weeks later, the material was evaluated for shoot and root development. Segments that developed a shoot were considered viable. Average viability varied among years (0-35.1%) even for the same accession, species (4.2-51.4%), and segment length. Dormant buds on 10-cm segments had higher average viability (82.2%) than did DBs on 6-to 7-cm segments (43.9%), suggesting higher suitability for cryopreservation. In the material studied, Salix DB viability was correlated with branch diameter, DB density, and the ability to develop shoots and roots prior to cryopreservation.

No abstract