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  • Author or Editor: R. E. Young x
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Abstract

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.

Open Access

Abstract

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
Authors: and

Abstract

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.

Open Access
Authors: and

Abstract

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.

Open Access
Authors: and

Abstract

Hand placement of 2-Diphenylacetyl-1,3-indandone (Diphacinone, DPN) and [(chloro-4-phenyl)-1-phenyl-1] acetyl-2-dioxo-1-3-indane (Chlorophacinone, CPN) baits applied in 2 applications at ca 30 day intervals at 11.2 kg/ha (10 lbs/A) each were effective in the control of pine voles (Microtus pinetorum LeConte) in apple orchards. In a cultural experiment designed to control pine voles, one Diphacinone preparation gave near 100% control with one application in plots previously cultivated and treated with residual herbicide in July and November.

Open Access
Authors: and

Abstract

Fruit growth of avocado (Persea americana Mill.) fruit measured by the increase in length, diameter, and volume was initially rapid, but later slowed to a linear growth. Linear extrapolation to zero from growth rate in the descending portion gave a definite point indicating that physiological maturity had occurred. In many cases, this physiological maturity date correlated well with horticultural maturity date determined by taste-panel analysis.

Open Access
Authors: and

Abstract

Avocado fruit (Persea americana Mill. ‘Fuerte’) were stored in air with or without C2H4 treatment (100 ppm) at 6°, 9°, 12°, 14°, 16°, 20°, 24°, 27°, 30°, and 34°C. During the storage period, respiration was measured by an automated continuous gas flow system. Fruit stored in air for more than 20 days at 6° developed chilling injury as indicated by gray discoloration of the mesocarp tissue. At high temperatures (30°, 34°), avocado fruit ripened abnormally, showed considerable surface pitting, and had poor flavor. When fruit were stored with 100 ppm C2H4, tissue discoloration was severe below 12°, which implied that chilling sensitivity of avocado fruit increased with C2H4 treatment. Fruit, whether stored with C2H4 or not, showed breaking points around the same temperature region on an Arrhenius plot, suggesting possible involvement of other mechanisms in addition to phase changes of membrane lipid components.

Open Access
Authors: and

Abstract

Treatment with calcium (0.1 M CaSO4, 0.1 M CaCl2) depressed respiration of avocado fruits during preclimacteric and climacteric phases. Na2SO4 was ineffective. Calcium not only inhibited respiration but delayed the onset of the climacteric and depressed the peak of ethylene production at the climacteric rise. Determinations of endogenous Ca confirmed that higher levels were positively correlated to delay in ripening and negatively correlated to peak of CO2 and ethylene production. It is inferred that this difference in Ca level is one of the factors causing lack of uniformity in ripening.

Open Access

Abstract

An expert decision support system for agricultural management called CALEX is currently being developed. The program runs on any IBM compatible personal computer with 256K or more of memory and either two floppy disk drives or a hard disk and one floppy disk drive.

Open Access

Though high electrical conductivity (EC) levels are commonly held to be the primary limiting factor for using spent mushroom compost (SMC) as a growing substrate, EC can be reduced by leaching. This allowed SMC to be successfully used for growing plants. Leaching reduced EC of the substrate solution from as high of 30 dS·m-1 (mmhos·cm-1) to 2 to 3 dS·m-1, a level acceptable for growing plants. The initial EC and container capacity determined the number of leachings and total volume of water required to lower EC of SMC substrates to acceptable levels. As the concentration of SMC was increased, a higher number of leachings or larger volume of water were required to adequately reduce EC levels. In trials spanning 2.5 years, SMC was effectively used as a substrate in the production of marigold (Tagetes patula) `Yellow Girl'. Benefits to plant growth from SMC incorporation included a slow release of nutrients as the SMC decomposed and a good air-filled pore space/water-holding capacity when amended with a commercial nursery mix. From these trials, it is recommended that SMC be incorporated at rates of 25% to 50%. It is not recommended that SMC be used in concentrations over 50% because the EC may be too difficult to manage and the high levels of air-filled pore space of SMC. Though season may affect the initial EC level of SMC, such variation is minimized by leaching while differences in plant response are more likely to be attributed to environmental conditions. No differences in plant growth were observed among SMC sources.

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