Fraser Fir Seedlings Research Articles

Effects of Metalaxyl on Growth and Ectomycorrhizae of Fraser Fir Seedlings

Effects of Metalaxyl on Growth and Ectomycorrhizae of Fraser Fir Seedlings

RESPONSES OF NEOSEIULUS FALIACIS (ACARINA: PHYTOSEIIDAE) TO DIFFERENT PREY DENSITIES OF OLIGONYCHUS UNUNGUIS (ACARINA: TETRANYCHIDAE) AND TO DIFFERENT RELATIVE HUMIDITY REGIMES

AbstractThe effectiveness of the phytoseiid predator Neoseiulus fallacis in controlling population growth of the spruce spider mite, Oligonychus ununguis was examined in the laboratory. Development and fecundity of N. fallacis under various relative humidity levels were also studied. Under controlled conditions, N. fallacis significantly limited population growth of O. ununguis on Fraser fir seedlings. Survival, development, and fecundity of N. fallacis were similar for all relative humidity ranges tested, except at the lowest range (60–65%), in which none of the individuals survived to maturity.

EFFECTS OF CONSTANT TEMPERATURE, RELATIVE HUMIDITY, AND SIMULATED RAINFALL ON DEVELOPMENT AND SURVIVAL OF THE SPRUCE SPIDER MITE (OLIGONYCHUS UNUNGUIS)

AbstractExperiments were conducted on Fraser fir,Abies fraseri(Pursh) Poir, seedlings or cut terminals. Results indicate thatOligonychus ununguis(Jacobi) responds most favorably to temperatures approximating 26 °C and to relative humidity levels approaching 50 to 60%. Developmental time, time to 50% mortality, net reproductive rate, mean generation time, intrinsic rate of natural increase, finite rate of increase, and days for populations to double were computed for each temperature and relative humidity regime. Simulated rainfall severely limits population density on Fraser fir seedlings.

Dormancy in Abiesfraseri seedlings at the end of the first growth cycle

Two experiments were conducted to examine the effect of chilling duration and postchilling photoperiod on breaking dormancy in Fraser fir (Abiesfraseri (Pursh) Poir.) seedlings. Chilling durations were 0, 2, 4, 6, 8, 10, or 12 weeks at 4 °C. Five postchilling photoperiods were used: 9, 12, 15, and 18 h, or a9-h natural day plus a3-h night light break with incandescent light.Rest in Fraser fir seedlings is shallow at the end of the first growth cycle. Dormant containerized plants outplanted in the spring grew abnormally, and resumed normal growth only after experiencing a winter. Those chilled 2 or more weeks broke dormancy rapidly under controlled-environment conditions and grew well under photoperiods > 15 h. Shoot elongation increased with day length, but not linearly. One-year-old seedlings taken from an outdoor nursery in early October broke dormancy under 9-h days in a greenhouse only after 4 weeks of chilling. A night light break resulted in 100% budbreak, even in nonchilled plants. Time to budbreak decreased with increasing duration of chilling. Dry matter increased linearly with chilling duration and was greatest under long days. Less chilling was required for budbreak than for maximum shoot elongation or dry matter production. Four to 6 weeks of chilling was sufficient to overcome rest.

Fusarium Root Rot of Douglas-Fir and Fraser Fir Seedlings in Pennsylvania

Fusarium Root Rot of Douglas-Fir and Fraser Fir Seedlings in Pennsylvania