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  • Author or Editor: R. Young x
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Ataenius spretulus (Haldeman) (Coleoptera: Scarabaeidae) is the most common grub in golf course fairways in Michigan. Ataenius spretulus grubs are 3- to 10-fold more abundant in golf course fairways (mowed at a height of 1.5 cm) than in the roughs (mowed at a height of 5.0 cm or higher). Predation and infection by Paenibacillus sp. were previously reported to be greater in the rough, and may partially explain outbreaks of A. spretulus grubs in golf course fairways. In addition to natural enemies, cultural practices of irrigation and mowing could also be important factors, especially if A. spretulus prefers to oviposit in the fairway over the rough. In this paper we examine the impact of soil moisture and mowing height on oviposition and habitat selection. In a greenhouse experiment where A. spretulus adults were given a choice of turf maintained at fairway or rough height, no ovipositional preference for one or the other was observed. In three different growth chamber experiments where adults were allowed to choose among fairway or rough turf plugs held in soil at different moisture levels, adults preferred turf plugs in soil at a volumetric moisture content of 13% to 26% over turf plugs in soil at 8% to 9% moisture for their habitat selection. We conclude from these greenhouse and growth chamber experiments that A. spretulus adults do not choose turf habitat based on mowing height, but may be influenced by soil moisture levels.

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A change in orchard culture caused a significant reduction in activity of pine voles (Microtus pinetorum Le Conte). Cultivations in May, July, and November were not as effective as 2 cultivations plus 2 residual herbicide treatments (July and November). A single cultivation in November caused a small but significant reduction in vole activity but the effect was short lived. A heavy annual residual herbicide treatment in July caused a small but significant reduction in vole activity. No cultural treatment resulted in adequate control by December of 3 consecutive years and toxic hand placed baits were required each year to reduce populations.

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Pine vole, Microtus pinetorum LeConte, activity in an apple orchard was reduced by cultivation of a 4 m-wide strip down the tree row. Bare-ground-culture using a single annual application of Simazine plus Amitrol (1964-71) or Paraquat (1972-73) herbicide for 10 years reduced pine vole activity.

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Triclopyr was applied once or twice in consecutive years to Virginia creeper [Parthenocissus quinquefolia (L.) Planch.] that was growing along the ground beneath the peach [Prunus persica (L.) Batsch.] tree canopy. All rate (0 to 1.1 kg·ha-1) and month combinations controlled Virginia creeper during the season of application. A single application of triclopyr at 1.1 kg·ha-1 was insufficient for control beyond 1 year. Satisfactory control of Virginia creeper was obtained with two applications of triclopyr at 1.1 kg·ha-1 made in either August or September. Chemical name used: [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr).

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The ability of various leaf removal treatments or shoot tipping to induce lateral shoot development on current-season stoolbed shoots of MM.106 EMLA and M.26 EMLA apple (Malus domestica Borkh.) rootstocks was investigated. Removal of the five uppermost immature leaves or shoot tipping after every 20 to 25 cm of terminal growth produced more lateral budbreak than occurred on nontreated shoots. Shoot tipping resulted in the highest number of branches (≥5 cm) and greatest total branch length. Only tipping consistently induced lateral budbreak higher than 30 cm up the shoot. Removal of the 10 uppermost leaves and tipping resulted in the shortest terminal shoots. MM.106 shoots had more lateral budbreak, branches, and total branch length than did M.26 shoots.

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Chilling sensitivity of ‘Fuerte’ and ‘Hass’ avocados (Persea americana Mill.) is a function of the stage of the climacteric. The least sensitive stage is postclimacteric where fruit can be kept at 2°C for 6 to 7 weeks. ‘Hass’ avocados on the climacteric rise and at the climacteric peak were most sensitive to chilling and showed injury after 19 days of treatment at 2°. Postclimacteric fruit could be transferred to 2° at 36 to 48 hours after the climacteric peak. The time preclimacteric fruit could be held at 2° varied during the picking season but could be as long as 30 days.

Open Access

One-year-old unbranched whips of `Empire' apple [Malus domestica Borkh.) on MM.111 and M.26 rootstocks were planted in November 1991 and March 1992 in an eastern Piedmont and western Mountain site of North Carolina. Trees were subjected to one of five branch-inducing treatments: (1) notching: removing a thin band of bark above each bud: (2) `knip boom': removing emerging apical leaves of the leader at regular intervals: (3) bending: tying whip to horizontal position, tying horizontally to opposite side four weeks after budbreak, and setting upright after another four weeks: (4) renewal: after a mid-season heading cut, tipping a weak lateral and setting upright to serve as a new leader: or (5) control: heading whip 30 inches above the graft union. After one year of growth, trees with M.26 rootstocks had more, slightly longer laterals man those with MM.111. Notching resulted in a much greater number of laterals than the control treatment, but increased branch length only in fall plantings. Bent trees had fewer and shorter laterals by mid-season than those of control trees. Although branch number and length did not differ from that of the control by the end of the season, bending resulted in shorter, asymmetric trees. Knipping and lateral renewal quickly led to the development of many laterals on current season growth, but were less effective later. Overall, planting date did not influence tree height, branch number, or branch length.

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Investigation of optimum conditions for extraction, titrimetric assay and activity of avocado (Persea americana Mill cvs. Fuerte, Hass) pectinmethylesterase (PME) showed maximum extraction was obtained from lyophilized mesocarp using 0.4 m NaCl. Best assay conditions required a substrate of 0.5% pectin in 0.1 m NaCl. The enzyme was released from the tissue by salt but not by nonionic detergents. The Arrhenius plot between 3 and 32°C was a straight line which indicates no involvement with membrane lipid. Incubation with air or ethylene did not affect the enzyme. PME activity declined rapidly as ripening was initiated and reached a minimum shortly before the peak in respiration and ethylene production.

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Available young hybrid trees of Eremocitrus glauca with ‘Valencia’ orange (Citrus sinensis (L.) Osbeck), Sicilian sour orange (C. aurantium L.), ‘Nagami’ kumquat (Fortunella margarita (Lour.) Swing.), and Koethen sweet orange (C. sinensis) were more cold hardy than the Citrus or kumquat parent in natural and controlled freezes. Eremocitrus may be a useful source of cold hardiness for breeding cold-hardy citrus hybrids.

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Zn content was higher in trunk bark (cambium to outer scrapings) than in the adjacent wood in healthy and blight-affected sweet orange (Citrus sinensis (L.) Osb.) and grapefruit (C. paradisi MacF.) trees. Zn levels were elevated in trunk bark and wood of blight-affected trees on rough lemon (C. limon (L.) Burnt, f.) rootstock, whereas affected seedling trees or trees on ‘Cleopatra’ mandarin (C. reticulata Blanco) rootstock that were tested had high Zn levels only in the bark. Bark Zn content was much higher above the bud union than below in blight affected trees on rough lemon or trifoliate (Poncirus trifoliata (L.) Raf.) rootstocks, but Zn content was high above the bud union in healthy trees only on rough lemon rootstock. The inner half of the bark, an area representative of the active secondary phloem, had much more Zn than the outer half of the bark or the most recently developed xylem. The outer half of the bark served as a barrier against outside contamination. Accumulation of Zn in wood occurred only when the phloem Zn was high.

Open Access