Lower Branches Of Trees Research Articles

The effects of various pest control regimes on the community structure and population dynamics of selected natural enemies of Cacopsylla pyri in pear orchards

ABSTRACT The effects of three different pest control regimes in three pear orchards (two with integrated pest management regimes and one with an organic farming regime) on communities of arthropods were studied in a two-year experiment. Insects were collected in three stages by beating the lower branches of trees. The number of species and other taxa of natural enemies increased with the reduction in insecticide applications. A total of 2,492 individuals of 145 species and other taxa were found in the samples from the three pear orchards with different pest management practices. The most numerous groups were Araneae, with 44 species, and Coleoptera, with 42 species, followed by Hymenoptera, with 33 taxa, and Heteroptera, with 24 species. Of the total number of taxa, the share of entomophagous arthropods was, on average, 62.6%. The share of predaceous individuals was, on average, 63.7% of the total number of individuals. The number of dominant predaceous species decreased with an increase in the diversity of species and other taxa. A significant relationship was found between the number of C. pyri adults and the Shannon-Wiener index of diversity for the predaceous taxa. It was demonstrated that generalist predators and their diversity have an important influence on the regulation of pear psylla in the vegetative period.

Seasonal Population Patterns of a New Scale Pest, Acanthococcus lagerstroemiae Kuwana (Hemiptera: Sternorrhynca: Eriococcidae), of Crapemyrtles in Texas, Louisiana, and Arkansas.1

Abstract The crapemyrtle bark scale, Acanthococcus lagerstroemiae, is an invasive scale insect pest of crapemyrtles. Crawler populations were monitored using double-sided sticky tape on established crapemyrtle trees in Tyler (TX), Huntsville (TX), Dallas (TX), College Station (TX), Shreveport (LA), and Little Rock (AR) from 2015 - 2017 to determine crawler activity and determine if degree-day models could predict the first peak in crawler activity. Difference in crawler densities on upper and lower branches of trees was also determined by using double-sided sticky tapes. The first peak in crapemyrtle bark scale crawler activity was between March 26th and May 22nd across all locations and years, with multiple subsequent peaks per season frequently found, suggesting multiple generations. Using the average date (May 2nd) to predict the first peak crawler activity resulted in the lowest variance and was subsequently considered a better predictor compared to any degree-day model. There was no apparent difference in crawler activity between upper and lower branches of crapemyrtle trees across an entire season. This study provides the first set of population dynamics data for crapemyrtle bark scale in the U.S. and will help with future bark scale management decisions. Index words:, Crapemyrtle bark scale, invasive insect, population dynamics, Lagerstroemia spp Species used in this study: Crapemyrtle bark scale (Acanthococcus lagerstroemiae Kuwana); Crapemyrtle (Lagerstroemia spp.)

Nest Predation in Suburban and Rural Woodlots of Northern Ohio

The intensity of nest predation in small woodlots was compared across three regions in Ohio: (1) suburban Cuyahoga County, (2) semirural Lorain County and (3) rural Huron County. Artificial nests, each holding three Japanese quail eggs, were placed in seven Cuyahoga Co. woodlots, four Lorain Co. woodlots and four Huron Co. woodlots during July and August 1991. Half of the nests were placed on the ground, half were placed in the lower branches of trees. Eggs were removed from 257of 354 nests. Ground nests suffered significantly more predation than tree nests, indicating that mammals were the primary predators. No significant difference in egg removal was found among the three regions, and no significant dependence was found between woodlot size and rate of nest predation. The lack of a suburban/rural difference and the insignificance of the woodlot size/predation relationship do not corroborate previously published studies that used methodologies similar to ours. The deviant nature of our results may reflect the more extensive cropland in our rural study region that provides food resources to sustain large populations of mammalian nest predators.

Excess Calcium and Magnesium Associated with Lower Crown Mortality of Pin Oak

The ornamental value of pin oak trees is reduced when their descending lower branches die. In the upper Midwest, USA, premature dieback of lower branches is common among pin oak trees planted in soils that are calcareous within 1.5 m of the surface. Of 11 mineral nutrients, only Ca and Mg were more concentrated in the leaves of lower branches than in those found higher in the crown. The Ca concentrations of leaves of lower branches of trees showing dieback were much higher than those from trees without dieback. Small necrotic spots of apparently abiotic origin developed in early summer on either green or chlorotic leaves of lower branches and consistently formed before dieback occurred in the subsequent year. Excessive Mg was closely associated with this condition. Green pin oaks at dieback sites had actively absorbing roots within calcareous C horizons of otherwise acidic soils suggesting a source for absorption of the high concentrations of both Ca and Mg in the leaves. Methods of reducing Ca and Mg uptake are discussed.

Annotated List of Spiders (Araneae) from Apple Trees in Nova Scotia

Orchard spiders are important because of their predatory activities and their frequent abundance. They were recngnizcd as a group needing study at the time Pickett et al. (1946) began their long-term investigation of orchard fauna. The identities of the species involved, and their influence on populations of orchard pests, are the main factors to be considered.This paper presents a list of the species collected in the Annapolis Valley of Nova Scotia to date, together with brief comments of a general nature. Spiders have been collected in about 40 orchards since 1954. These orchards were subjected to a variety of cultural and pest control methods by the owners, but most were in sod cultivation, and under modified spray programs as described by Pickett and Patterson (1953). Collecting was done mainly by capping lower branches of trees over an inverted, open umbrella, hut specimens were also taken individually from crevices along tree trunks, and from trays under fumigated trees.

Field studies on the resting habits of flies in relation to chemical control.

Summary Musca domestica was the dominant species (97 per cent) observed in studies of fly resting habits in rural areas near Savannah, Georgia, 1950–1951. During the daytime hours only small percentages of the flies were observed resting on surfaces which are normally sprayed. In unscreened houses the greatest concentrations of flies during the day were found in the kitchens. Repeated all-night observations showed that flies remained in one place during the entire night. Screens were indicated to be more than 97 per cent effective in preventing flies from gaining entrance into homes. On unscreened premises approximately 90 per cent of the flies were found resting in the houses at night throughout the year. On screened premises in cooler temperatures flies were found resting at night in barns; with slightly warmer temperatures they began moving out to porches, and as minimum temperatures approached 70°F., most of the flies were found in the lower branches of trees and on shrubs. Residual spray applications for fly control on rural premises should include the treatment of porches, the lower portions of trees and shrubs adjacent to houses and animal shelters, barn interiors, and the ceilings and upper portions of the walls of unscreened dwellings. The high concentrations of flies at night in relatively small areas suggest the possibility of controlling flies economically by the selective application of space sprays at night.