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  • Author or Editor: W.A. Dozier x
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Abstract

Ethephon, (2-çhloroethyl)phosphonic acid, was applied at rates of 125 ppm and higher to young apple trees in 3 greenhouse experiments. Leaf expansion and total number of leaves were reduced by ethephon; the effective concentration became lower as the growing season progressed. Leaf area on the primary shoot was reduced by 1,000 and 4,000 ppm ethephon, but was increased on the lateral branches by 4,000 ppm. Total leaf area was suppressed only by the 1,000 ppm treatment. Leaf necrosis occurred at 625 ppm and higher concentrations in 1 experiment. Lateral bud scales abscised and a proliferation of cells under the leaf scar occurred on trees treated with 7,500 and 10,000 ppm ethephon. Many lateral buds abscised on the lower two-thirds of trees treated with 10,000 ppm. Leaf abscission was induced by ethephon, and the higher concentrations caused earlier and more rapid leaf drop. The oldest leaves abscised first, and most leaves became somewhat chlorotic prior to abscission. Leaves apparently had to be of a certain physiological age before they could be induced to abscise.

Open Access

Abstract

Sprays of (2-chloroethyl)phosphonic acid (ethephon) were applied to young apple trees in 2 greenhouse experiments. Ethephon suppressed terminal growth, internode length, and elongation of the pre-treatment stem. Ethephon applied at 4,000 ppm, 64 days after bud break resulted in abscission of some shoot apices. Lateral branching was induced by ethephon, but it was not dependent on abscission of the shoot apex. Whereas dry weight of the lateral branches was increased at 4,000 ppm, total stem dry weight was decreased by ethephon.

Open Access

Abstract

Concentrations up to 4000 ppm of (2-chloroethyl)phosphonic acid (ethephon) did not affect the net photosynthesis (Pn) of leaves on greenhouse grown apple trees. Leaf respiration was increased by 4000 ppm ethephon, but not by lower concn. Pn rates did not differ between cvs., but respiration of ‘Golden Delicious’ leaves was greater than that of ‘York’ leaves.

Open Access

Abstract

The color and shape of ‘Delicious’ apples were improved with a combination treatment of (2-chlorethyl)phosphonic acid + α-(2,4,5-trichlorophenoxy)propionic acid (ethephon/fenoprop) and gibberellin A4A7 plus N-(phenylmethyl) 1H-purin-6-amine (GA4,7/BA). All ethephon/fenoprop treatments improved red color development. The length/diameter (L/D) ratio of fruit treated with GA4,7/BA, GA4,7/BA plus ethephon/2,4,5-TP, and GA4,7/BA plus ethephon/2,4,5-TP plus daminozide was greater than untreated fruit. The L/D ratio of fruit treated with GA4,7/BA plus daminozide did not differ from those not treated. The length, diameter, and weight of fruit treated with daminozide alone was less than for untreated fruit. Diameter of fruit treated with GA4,7/BA + daminozide or daminozide + GA4,7/BA + ethephon/fenoprop was less than for untreated fruit.

Open Access

Latron AG-98 (formerly named Triton AG-98) was applied to 8-year-old `Surecrop' peach trees on Lovell rootstock at 0%, 2%, 4%, and 6% (v/v) on 13 Mar. 1990 and 1992 and 28 Mar. 1991. Our objective was to determine the effect Latron AG-98 had on percentage of blossoms removed, fruit set, total fruit count and yield, and marketable fruit weight. The percentage of blossoms removed increased with increasing rates of Latron AG-98. The 4% and 6% rates removed the greatest percentage of blooms in all 3 years. The number of fruit per 50 cm of shoot length, number of fruit removed by hand-thinning, percent fruit set, total fruit number, and total fruit yield decreased with increasing rates of Latron AG-98 in 1990 and 1992 but not in 1991. The marketable fruit weight increased with increasing rates of Latron AG-98 in 1990 and 1992 but not in 1991. Latron AG-98 was not effective in 1991 because of a 2-day delay in application. Latron AG-98 was effective in removing blossoms from `Surecrop' peach at all three rates. However, the 4% and 6% rates reduced the yields below a commercially acceptable level. The 2% rate of Latron AG-98 could be useful as a tool to reduce the labor required to hand-thin peaches.

Free access

Own-rooted four-year-old kiwifruit plants (Actinidia deliciosa) protected by a Reese clip-on styrofoam insulation trunk wrap, or microsprinkler irrigation, sustained less freeze injury than unprotected plants under field conditions at temperatures as low as -17.8C. Trunk splitting occurred on the plants but no injury was detected on canes, buds, or shoots in the canopy of the plants. Unprotected plants had more trunk splitting and at greater heights than protected plants. New canes developed from suckers of cold-injured plants and developed a filled canopy the following season.

Free access

Abstract

Naphthaleneacetic acid ethyl ester (NAA-ethyl ester) sprays applied to the base of apple (Malus domestica Borkh.) nursery stock for sprout control suppressed sprout development. Rates of 0.25, 0.50, and 1% resulted in significantly less sprout development than the 0.125% rate. Sprout length was suppressed only by the second applications of the 0.25, 0.50, and 1% rates. A second application of the 0.50 and 1% rates killed the existing sprouts at time of application. Trees treated with 1% NAA-ethyl ester were shorter and smaller in diameter. The 0.25 and 0.50% rates were equally as effective in sprout control as the 1% rate, without adversely affecting tree height and diameter.

Open Access

`Chandler' strawberry plants were grown in a nutrient flow hydroponic systems with six solution N treatments (35, 70, 140, 210, 280, 350 ppm). Plant architecture was influenced by solution N levels with 350 ppm producing small dark green leaves with short petioles while 35 ppm produced light green leaves with large leaf blades and long petioles. Other treatments were intermediate but similar to the 35 ppm with darker green foliage. The 210 ppm treatment produced the most runners per plant while the 350 ppm treatment produced the least. The 210 ppm treatment produced the most crowns per plant while the 35 ppm treatment produced the least. The highest seasonal fruit yield and largest berry size was produced in the 70 ppm treatment with the 350 treatment having the lowest yield and smallest berry size.

Free access

Rooted rabbiteye blueberry cuttings were transplanted to 15 cm pots containing either builders sand or 80% sand 20 peatmoss v/v (1% OH). Five different herbicides were applied at the high and low recommended rates. Terbacil at 1.4 or 2.9 kg/ha a.i. caused a 72% mortality while 1.8 or 3.6 kg/ha a.i. application of norflurazon caused a 53% mortality. Root volume, weight, top weight, and leaf chlorophyll concentrations were reduced by terbacil treatment. Oryzalin at 2.7 kg/ha a.i. or norflurazon at 3.6 kg/ha a.i. reduced root and top weight and chlorophyll. Napropamide at 2.2 kg/ha a.i. reduced top weight and chlorophyll. Two good choices for young plants appear to be simazine at 1.8 kg/ha a.i. and napropamide.

Free access

A number of strawberry cultivars and breeding line selections have been tested in the annual plasticulture system. The only two cultivars currently recommended based on cultural and economic performance ate 'Chandler' and 'Oso Grande'. Plant type (fresh dug, plug, etc.) and nursery source have also been evaluated. Fresh dug plants with leaves intact generally perform better than those with leaves removed. Rooted runner tips in cell packs (plug plants) look very promising and outperform fresh dug plants in most situations. Plastic mulch treatments included clear (CLR), black (BLK), laminated white on black (W/B), laminated black on white (B/W), IRT-76 (IRT), AL-OR brown (ALOR), and a bare ground (BG) check. In the first season the highest yields for 'Chandler' were obtained on IRT, followed by CLR, ALOR, B/W, BLK, W/B, and BG. The highest yields for 'Selva' were on CLR followed by BLK, ALOR, IRT, B/W, W/B, and BG. In the second season the highest yields for 'Chandler' were on W/B followed by BLK. ALOR, IRT, B/W, CLR, and BG. In the case of 'Selva' ALOR was the top performing treatment followed by IRT, W/B, BLK, B/W, BG, and CLR.

Free access