Ross E. Byers

Harvest date influences fruit size and yield of 'York' and 'Golden Delicious' apple trees

Abstract A delay in apple harvest caused an increase of fruit diameter, weight, price, and crop value, but allowed for increased fruit drop of ‘York’/MM.111. Economic returns for ‘York’ and ‘Golden Delicious’ were increased approximately 16% by delaying harvest by 3 weeks. Crop load of ‘Golden Delicious’/MM.111 trees (from 50 to 120% crop load) did not affect growth rate of fruit in the critical 6.1 to 6.4 cm diameter category. AVG did not influence the rate of ‘Golden Delicious’ fruit growth, but fruit were more firm and had higher starch levels, which allowed for a harvest delay compared to those not treated. Non-treated samples of ‘Golden Delicious’ taken from the same trees in 1997 and 1998 were 32 days more “advanced” in equivalent fruit firmness, 19 days in starch, 11 days in soluble solids, and 21 days in fruit diameter in 1998, thus demonstrating that in some years the normal harvest date could be delayed to gain additional crop value. Sprays of AVG delayed Gala/M.27 fruit ripening which allowed for an increase in fruit size; however, three sprays of Accel at 10 to 20 mm fruit diameter did not cause a delay in maturity or increased fruit diameter.

Weathering and the field efficacy of pelletized rodenticide baits in orchards

Abstract Commercially available US rodenticide bait formulations were tested in the field and laboratory to examine their weather resistance and the influence of moisture on efficacy and acceptability to voles (Microtus spp.). Baits containing one of several anticoagulant compounds or zinc phosphide (Zn3P2) were mechanically broadcast in orchard plots. Precipitation (7·62 mm) fell within 48 hours after application. There was not a marked difference in control between the multiple-feeding anticoagulants and the single-feeding anticoagulants or zinc phosphide. Laboratory tests showed that moist pellets of three rodenticide formulations were as effective and acceptable to pine voles (M. pinetorum) as dry pellets. No direct relationship was found to show that wet weather or moisture resistance of the given rodenticide formulations tested affected field control or laboratory mortality. Toxicity and concentration of the active ingredient in formulations used were important to efficacy.

Growth of apple trees, nitrate mobility and pest populations following a corn versus fescue crop rotation

We compared conventional and alternative systems for the establishment of apple trees on a replicated, whole-orchard scale. The alternative system consisted of a K-31 fescue sod rotation followed by planting of trees directly into sod that had been kitted with herbicide. The conventional system consisted of a standard corn rotation, accompanied by application of fertilizer and nematicide. Orchard floor management in the three years following tree planting was based on the use of both pre-and post-emergence herbicides in the conventional system and only contact herbicide in the alternative system. The study documented tree growth, pest incidence, and nitrate mobility in the two systems. The alternative system compared favorably with the conventional system for the growth and establishment of four apple cultivars. Many advantages accompanied the killed sod system, including less subsurface leaching ofnitrate-N and lower costs (largely from decreased herbicide use). The alternative system provided an economical alternative to the problem of soil organic matter depletion in conventional orchard soils without requiring increased use of commercial fertilizers. Grower concerns regarding increased potential for vole damage and poor initial tree growth were unsubstantiated.

Effects of thinning time on yield, fruit size, and return bloom of 'York' and 'Golden delicious' apple trees

Abstract In 1994, heavily flowering ‘York’ apple trees (Malus Xdomestica Borkh.) selected for 80% or more of spurs flowering were hand thinned to a crop density (CD) of approximately 7 fruit/cm2 trunk cross-sectional area (FCSA) at bloom, petal fall, or up to 61 days after bloom. This thinning did not result in an adequate return bloom even for a partial crop in 1995. Heavily flowering ‘Golden Delicious’/M.26 trees were treated similarly in 1994 and responded with more flowering in 1995 than ‘York’/M.26 trees. In 1995, a different group of heavily flowering ‘York’/M.26 trees were hand thinned to a CD of 3 to 5 FCSA at bloom and at 7 day intervals up to 35 days AFB. Thinning at bloom or 7 days after full bloom (4.5 mmfruit diameter) resulted in much greater return bloom in 1996 than any other thinning. In 1995, ‘Golden Delicious’/M.26 trees were treated similarly to ‘York’/M.26 and responded similarly in 1996 with the greatest return bloom resulting from bloom thinning with somewhat less return bloom from thinning 7 or 14 days after full bloom and dramatically reduced return bloom.

Poor anchorage and growth of spur ‘Red Delicious’ apple trees with deep crown roots

Abstract Spur ‘Red Delicious’ apple Malus domestica (Bork.) trees on MM 111 and seedlings that had been blown over by high winds had greater depth to first root and had thinner trunks than adjacent undamaged trees.