Roots Of Apple Trees Research Articles

A RAPID METHOD OF DETERMINING THE DEPTH IN SANDY SOILS AT WHICH MECHANICAL IMPEDANCE WILL PREVENT GROWTH OF APPLE TREE ROOTS

The sound produced when soil is tapped with the handle of a pointing trowel depends upon the degree of compaction. Provided a suitable trowel is used, a distinct ringing sound is produced by the trowel blade if soil is compact enough to prevent growth of apple roots. The method is relatively unaffected by soil moisture within the range of 4 to 30 centibars in soil that contains more than 60% sand.

Pine Vole Reproduction in Relation to Food Habits and Body Fat

Pine Vole Reproduction in Relation to Food Habits and Body Fat

NOTES ON THE BIOLOGY OFPRIONUS LATICOLLIS(COLEOPTERA: CERAMBYCIDAE)

AbstractThe broad-necked root borer,Prionus laticollis(Drury), causes economic damage to apple orchards in the eastern United States by boring in the roots of apple trees. The insect has a 3- to 4-year life cycle. Eggs are deposited in the soil or on the soil surface in mid-summer, and larvae tunnel through the bark and may excavate the interior wood of living, weakened, or dead apple tree roots. Larvae leave the roots to pupate in the soil and have been found up to a depth of 84 cm below the soil surface. Prepupae occur in the soil during May and June and pupae in June and July. Adults live approximately 1 week after emergence and mate several times. A tachinid fly, several potential pathogenic microorganisms, larvae biting one another, and freezing temperatures were observed to be mortality factors.

Effects of Cytokinins in Xylem Sap From Apple Trees on Apple Shoot Growth

SummarySap sucked from the branches or exuding from the roots of apple trees showed similar cytokinin-like activity. Most of this activity was due to a butanol-soluble component which had the properties of zeatin riboside. This component promoted the growth of isolated apple shoots.

Mycoplasmas in apple trees infected with the proliferation disease

A mycoplasma-like microorganism was identified on electron micrographs of ultrathin sections of roots and abnormal underground sprouts growing from roots of young apple trees artificially infected with the proliferation disease. Specimens taken in November, contained mycoplasmas at various stages of reproduction in sieve tubes of the host. Mycoplasma-like bodies occurred especially in abnormal underground sprouts, and rarely also in lateral roots.

Effects of aeration and mineral supply on growth and mineral content of shoots and roots of apple trees (var. 'Golden Delicious' on M.IX).

One- or 2-year-old Golden Delicious apple trees on M.IX were grown either in a clay loam (in 60-1 containers) or in nutrient solution and the effects were studied of several aeration regimes. With the soil-grown trees these comprised flooding to various soil depths and for different times. With the trees grown in nutrient solution the aeration regimes compared were nutrient solution without aeration, tap water with or without aeration, and aerated nutrient solution (control). Shoot growth was depressed by high water tables, and that of trees receiving non-aerated nutrient solution or tap water (whether aerated or not) ceased after about 2 weeks. The root growth of trees receiving non-aerated nutrient solution or tap water was similarly depressed, but, by contrast, aerated tap water enhanced root growth. Details are given of treatment effects on the Ca, K, N and soluble sugar contents of the young and old leaves and of the young roots. The uptake of all mineral elements was similarly affected by lack of aeration, suggesting that the relationship between low Ca content and increased bitter pit incidence is not associated with differential absorption but rather with differential Ca distribution. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Seasonal Changes in the Diameter of Secondarily Thickened Roots of Fruit Trees in Relation to Growth of Other Parts of the Tree

SummaryThe diameters of apple and cherry tree roots, between 1·5 ft. and 6·0 ft. from the base of the tree trunk, were measured with a microscope through glass observation panels at intervals during 4 years. The rate of root thickening was low in June and was most rapid from mid-July to mid-September, whereas rapid trunk thickening occurred in June and continued until September. The period of maximum root thickening coincided with a second peak in the production of new white extension roots when the intensity of shoot growth was decreasing.Some root thickening was detected one week after bud burst but many roots showed no thickening until July or August. At this distance from the trunk there was no progression of thickening along the root from the proximal to the distal end.

Observation of Root Feeding by the Nematode Trichodorus viruliferus Hooper

OBSERVATION through the glass panels of an underground root observation laboratory1 and subsequent sampling for detailed study have shown a high proportion of the white growing tips of extending apple tree roots to be attacked by the ectoparasitic nematode Trichodorus viruliferus Hooper. Colonies of 10 to more than 100 individuals congregated 1–3 mm behind the apical meristem of suitable roots (about 1 mm in diameter), rasping the epidermis and hypodermis with their stylets and causing a superficial but characteristic browning. Severely damaged portions of the root often swelled and occasionally their surface split. Root extension usually ceased after 5–15 days of feeding, although the meristem itself was not the focus of attack. Once growth had ceased most of the nematodes dispersed within 1 or 2 days. The damage to the root tip was essentially the same as that associated with the ‘stubby root’ symptom in many herbaceous hosts, which has been ascribed to other species of this genus in the United States2. In extending apple roots, however, it was not accompanied by the characteristic branching and stopping of secondary and tertiary roots.

STUDIES OF CANADIAN THELEPHORACEAE: VIII. CORTICIUM GALACTINUM (FR.) BURT

During the course of an investigation into the decays of white pine in certain regions of Ontario it was found that the fungus, Corticium galactinum (Fr.) Burt, was important as an organism destroying considerable woody material in the roots and butts of living trees. Because of the increasing interest in this species, the early history and the literature concerning the pathogenicity on roots of apple-trees as well as other hardwood and coniferous species has been reviewed. A revised description, based on the study of a portion of the type specimen from the Fries herbarium and a comparison with specimens from apple and coniferous species, is presented. The taxonomy and relationships of C. galactinum are discussed. Detailed comparison is made with C. odoratum (Fr.) B. & G. and a description of that species is included. Cultural studies show that C. galactinum is heterothallic and of the tetrapolar type of interfertility and may possess multiple allelomorphs at the loci responsible for heterothallism002E