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  • Author or Editor: Wilbur Reil x
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Two management systems were initiated in a 10 year old Juglans regia cv. Hartley orchard planted 8 m. × 8 m. in 1977. Annual dormant selective pruning was practiced for the next 8 years on all trees within one treatment (pruning) compared to dormant severe pruning on alternate temporary trees with no pruning on adjacent permanent trees (thinning). Temporary trees were removed in the thinning treatment in 1985.

Yield, trunk cross sectional area, pruning weight and nut quality factors were evaluated each year from the 5 replicate, completely randomized trial.

Yield and nut quality factors did not differ between the two treatments during the 15 years.

In 1990 the pruned trial was again pruned causing a 20% drop in production (p=.06). With no additional pruning yield returned to slightly above the thinned treatment in 1991.

This trial demonstrates that Hartley walnut trees (terminal bearing habit) continue to produce satisfactory crops under crowded canopy management but a tree thinning program offers other advantages which also should be considered.

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Three selections from different bud sources of Bartlett pear were planted in a split block experiment grafted to five rootstocks in 1971. In 1992 and 1993, significant yield and yield efficiency differences occurred between the three selections. The highest yielding selection produced 51 and 40% greater weight then the lowest. The lowest yielding selection also had smaller fruit and lower soluble solids.

Differences of 37 and 52% occurred between the highest and lowest yielding rootstocks. There were also significant differences in trunk cross sectional area, yield efficiency. fruit pressure and soluble solids between rootstocks.

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Nursery grown and budded one year old .8 cm `Nonpareil' almond trees were placed bareroot in sealed containers at 2°C and subjected to concentrations of 0, 1, 3, 5% CO2, 0, 0.5, 1, 2 μl·l-1 C2 H2, or combinations of both gases. All trials were conducted under 100% R. H. and constant air flow. Trees were removed after 10 or 20 weeks and then grown in 19 1. containers for approximately 12 weeks before grading.

Growth was the same for all concentrations of CO2 after 10 weeks but caused a 20 and 32% decrease in shoot growth at 3 and 5% concentrations after 20 weeks. C2H4 caused 34, 34 and 89% decrease after 10 weeks and 78, 83 and 100% decrease of shoot growth after 20 weeks. Root growth was also seriously decreased.

C2H4 caused no growth decrease after 10 weeks when 3 or 5% CO2 was present. After 20 weeks CO2 only partially offset the detrimental effect of C2H4.

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Orchard hedgerow production systems have been used successfully in fruit and nut crops in California for decades to enhance yield, particularly in the early years of production. English walnuts (Juglans regia) are compatible with hedgerow techniques under prime soil conditions but are thought to require deep well drained soil to be commercially productive. Combining the production techniques of micro-irrigation, close spacing, minimal pruning and frequent fertilization in almonds has improved yield substantially on soils exhibiting a shallow, course textured topsoil underlain with a dense clay layer. Paradox hybrid rootstock (J. regia × J. hindsii) has shown greater tolerance to root lesion nematodes and heavier textured or poorly drained soils than Northern California Black (J. hindsii). Fourteen years of evaluation (1986-99) using `Chandler' and `Howard' Ctvs English walnuts in a replicated field trial on marginal soil has shown that 1) yields of 6700 kg·ha-1 (inshell) are attainable under these substandard soil conditions 2) Paradox hybrid rootstock out-yields Northern California Black by 30% on both cultivars tested, 3) kernels of high commercial quality for can be produced for both cultivars and 4) slip plow soil modifications may not improve tree growth, yield or crop quality in drip irrigated walnut hedgerow plantings.

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Prune (Prunus domestica) producers have an increased incentive to produce larger fruit. Potassium is thought to be critical in prune production and the fruit utilize large amounts of K. Growers have been fertilizing heavily with K to maximize fruit size. We conducted a survey of 16 `French' prune orchards in 1998 and 1999 growing seasons. Low (≈1.0% mid-July) leaf K concentration is associated with leaf chlorosis, early leaf drop and shoot dieback, with symptoms pronounced in the upper canopy, particularly with heavy cropping. The survey orchards were chosen to represent a range of leaf K within and among orchards, and among counties. At harvest, fruit drying ratio, dry yield per tree, and dried fruit size were determined in order to develop relationships between fruit quality and yield, and leaf K over the growing season. To date we have determined the following: 1) spring (May 1998 and April–May 1999) leaf K concentration is correlated with mid-summer (mid-July 1998) and early summer (late June 1999) leaf K concentration, respectively; 2) mid-April to mid-May leaf K concentration is being maintained by growers due to thinning and fertilizing, and to light cropping in 1998, at adequate to above adequate levels (2%) that increase through the growing season; 3) no beneficial relationship between fruit size, drying ratio or dry yield has been found with spring or summer (June or mid-July) leaf K concentration above 2%, either when evaluating all surveyed orchards together or as individual orchards.

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Third-generation navel orangeworm (Amyelois transitella) damage to almond (Prunus dulcis Mill.) kernels is a serious problem in the California almond industry. An early harvest is one means of reducing losses and increasing crop quality. A successful early harvest was accomplished 2 to 3 weeks before the normal harvest date, with no perceptible effect on kernel quality. Percent hullsplit was correlated with nut removal, providing a field guide to acceptable maturity. Within defined limits, yield, drying rate, and hullability of early harvested almonds were acceptable.

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