Treesearch

Disease-free larvae of Neodiprion sertifer (Geoffroy) treated with its nucleopolyhedrosis virus in the field and under laboratory conditions showed a high correlation between virus accumulation and body weight. Simple linear regression models were found to fit viral accumulation versus body weight under either circumstance.

Samples of a gypsy moth nucleopolyhedrosis virus product, Gypchek®, were taken each day during a 100-day production run and monitored for the presence of pathogenic bacteria and fungi. The standard plate count/g of product was 5.97 ± 1.51 x 108 over the 100-day period, while the sporulating bacteria count was 3.81 ± 1.21 x 106/g. We did not detect obligate anaerobic or fecal coliform bacteria in any of the samples. Bacillus cereus, Staphylococcus epidermidis, B. licheniformis, Streptococcus faecalis, Serratia liquefaciens, and Aspergillus niger were the most frequently isolated microorganis...

An artificially-induced epizootic was created in European pine sawfly (N. sertifer) populations at density levels of 5, 7, and 10 colonies per tree when plots were treated with 3.5 x 108 polyhedral inclusion bodies (PIB) per 0.04 ha. The progress of the epizootic was followed daily. The onset of mortality was at 13 days posttreatment, with a peak mortality period between 14 and 16 days across all density situations. During this period, ca. 70% of the total larval mortality was recorded. Of all the larval instars that died, the 4th experienced the greatest percentage of virus-induced...

Deer browsing and interference from forest weeds, particularly hayscented fem (Dennstaedtia punctilobula (Michx.) Moore), New York fern (Thelypteris noveboracensis L.), and short husk grass (Brachyelytrnm erectum Schreb.), influence the establishment of Allegheny hardwood reproduction. We determined the independent interference by deer and weeds after a seed cut and a removal cut in a two-cut shelterwood sequence. Weeds, particularly the ferns, caused significant interference with germination, survival, and growth of desirable species following both cuttings. Deer browsing had no direct...

Study quantitatively describes the woody plant component that developed in an uneven-aged loblolly/shortleaf pine stand following hardwood eradication. Comparisons are made with four other stands managed at various intensity levels.

The extent of beech bark disease was examined on permanent inventory plots in western Massachusetts and on Bartlett Experimental Forest in New Hampshire. The amount of disease-caused defect was correlated with a reduction in the proportion of beech in a stand. Sites on lower slopes and with greater abundance of hemlock contained more defective beech.

Changes to an extant model of forest growth and transition that allow an evaluation of the consequences of beech bark disease are outlined. Required are a function to scale beech growth for the effects of beech bark disease, a function to predict beech mortality from beech bark disease, and a function that predicts root-sprout regeneration of beech.

The twice-stabbed lady beetle Chilocorus stigma (Say), was studied in two infestations of beech scale, Cryptococccus fagisuga Lind., to elucidate predator biology and to determine the predator's effect on scale populations. C. stigma is univoltine in north-central regions of New York and its seasonal occurrence is well synchronized with that of C. fagisuga. The predator was most abundant in dense scale populations and exhibited a numerical response at hiqh scale densities. The effectiveness of C. stigma was limited by the propensity of adults to disperse following eclosion, its apparent...

The fungal flora of Cryptococcus fagisuga colonies on Fagus sylvatica bark included the entomogenous species Verticillium lecanii wherever infestation was or had been very heavy. This fungus seemed to accelerate insect mortality in vitro. Cladosporium cladosporioides was present at all stages of insect colony development and, with other fungi, caused blackening of the wax secretion.

Some crustose lichens that colonize the stems of beech trees favor infestation by C. fagisuga, while others do not favor infestation. A predominance of species unsuited for infestation appears to be a reason why trees growing on some sites in Nova Scotia are remarkably free of beech bark disease.