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  • Author or Editor: Elden J. Stang x
  • Journal of the American Society for Horticultural Science x
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Abstract

‘Earliglow’ strawberry (Fragaria × ananassa Duch.) plants were covered with 60% shade cloth in Wisconsin and Ohio during each of the following developmental phases: 1) check, no shade; 2) the runnering period after plant establishment; 3) flower initiation period in Fall 1983; 4) early growing season (from mulch-off until first flowering); 5) the fruiting period, 1984; and 6) constant shade. ‘Earliglow’ has a photosynthetic light response curve typical of a C, plant. Leaf dry weight per plant was decreased at both locations by constant shading during the fruiting period, just prior to plant sampling. Crown dry weight was reduced by constant shading. Leaf nutrient element contents of K, Ca, Mg, B, and Fe varied by location, but were not appreciably affected by shading treatments. Shading during the active runnering period resulted in increased total yield the following spring by 12% in Wisconsin and 17% in Ohio. In Wisconsin, increased total yield was the result of increased number of fruit in midseason harvests. Berry size was increased for constant shading or shading during fruiting, but yield was offset by lower fruit numbers. Usable fruit in Ohio on plants shaded during runnering was increased by 20% compared to the unshaded control. Constant shade resulted in an 18% and 46% reduction in total yield in Wisconsin and Ohio, respectively. Shading during the fruiting period resulted in yield reductions in both Ohio (13%) and Wisconsin (27%). Yield reductions were also noted in Ohio when shading occurred during early spring (21%), just prior to fruiting, or during flower formation (24%) the previous fall. Shading during the spring growth and fruiting period delayed fruit maturity and peak harvest 5 to 7 days.

Open Access

Abstract

Pollination and pollen tube growth were evaluated in two years as potential factors suppressing cranberry (Vaccinium macrocarpon Ait.) fruit set. Supplementing insect pollination with hand pollination increased fruit set from ≈30% to ≈38% in both years. The number of flowers per unit area was an important contributor to fruit set variation in one year. Cranberry uprights exhibited a temporal decline in fruit set when flowers were pollinated sequentially; the first flowers to open had a higher probability of fruit development than flowers opening later. Examination of stigmas indicated flowers receiving low amounts of pollen (<10 tetrads), or pollen that fails to germinate, are more likely to abort. An inadequate number of pollen tubes and lack of subsequent fertilization provides a partial explanation of fruit abortion in cranberry. Cranberry fruit set under existing field conditions appears to be limited, in part by insufficient pollination and pollen tube growth, with the latter apparently the result of intraplant competition for resources. Providing supplemental hand pollination increased cranberry yields in both years, 48% over natural insect pollination when the number of flowering uprights per unit area was high (≈3000/m2). A significant amount of yield variation was explained by the number of flowering uprights per unit area in both years.

Open Access

Abstract

A computer simulation was developed to analyze the economic feasibility of over-tree misting based on the interrelationships of daily temperature, bud development and corresponding effects of low temperature on apple (Malus domestica Borkh.) and peach (Prunus persica (L.) Batsch) flower bud kill in Ohio. Utilizing historical temperature data from 1940 through 1972, a revised model for estimating rest and bud development was constructed and the probability and extent of bud kill was simulated. Model validity was tested utilizing 1973-1976 temperature data. Using the 1940 to 1976 period, it was evident that the risk of substantial losses in revenue was reduced when over-tree misting was employed in all Ohio locations. Potential economic returns of the over-tree misting technology were greater for peaches than apples. Need for this risk reduction varies geographically in Ohio for apples and to a lesser extent for peaches.

Open Access

Cranberry (Vaccinium macrocarpon Ait. cv. Searles) vegetative tissue was analyzed at various stages of development to determine carbohydrate levels under field and greenhouse conditions and to identify the carbohydrates. Except during dormancy, cranberry uprights in the field had the highest concentration of carbohydrates (soluble and starch) at early blossom, when the lower flowers were at anthesis. As early flowers developed into fruit and upper flowers were at or just beyond anthesis, uprights had lower carbohydrate concentrations. As fruit growth slowed, soluble carbohydrate levels increased and were highest at dormancy. Upright shoot tissue produced the previous year and trailing woody stems followed the same trend as the current season's growth but had consistently lower soluble carbohydrate levels at each growth stage. Starch levels were low in current growth and did not change appreciably with fruit development. Starch was primarily stored and subsequently depleted in the previous season's upright growth and trailing woody stems. Tissue from the greenhouse was generally higher in carbohydrates than was field-grown tissue. Fruit developed from 53% of the flowers under greenhouse conditions, compared to 38% in the field. Insufficient carbohydrate levels may be responsible for the low fruit set observed in the field. Sucrose, glucose, fructose, raffinose, and stachyose were present in cranberry vegetative tissue.

Free access

Abstract

Spring overtree misting using greenhouse mist nozzles was tested for effects on bloom delay, incidence of disease, European red mite populations, fruit size, maturity, fruit russeting and tree survival of ‘Golden Delicious’ apple (Malus domestica Borkh.) on Mailing 9 rootstock. Bloom delay of 9 and 8 days was observed in misted trees in 1975 and 1976, respectively, Apple scab was controlled with standard fungicide spray programs, but fireblight was severe in 1975 on misted trees. European red mite (Panonychus ulmi Koch.) egg hatch was delayed on misted trees but post treatment populations were not affected. Phytotoxicity occurred on calyx and foliar tissue in misted trees in 1975. Fruit set and yield were reduced in misted trees in both years. Fruit size in misted treatments in 1975 was reduced through late July, but was comparable at harvest. In 1976, misted fruit size was reduced. Fruit color, soluble solids and firmness tests indicated maturity was delayed by mist. Fruit russeting in spring misted treatments was reduced. Substantial tree losses occurred in misted treatments in 1975.

Open Access