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Abstract

Naphthaleneacetic acid (NAA) and 1-naphthyl N-methyl carbamate (carbaryl) applied separately in both dilute and concentrated sprays significantly increased fruit size; however, when butanedioic mono-2,2-dimethylhydrazide (daminozide) was added, fruit size remained about the same as on unsprayed check trees. Crop load was not significantly affected by any of these treatments. Dilute and concentrated sprays of carbaryl produced more return bloom than did NAA. The most effective treatments were combinations of NAA and carbaryl, either dilute or concentrated. Combining first-cover pesticides [azinphosmethyl (guthion) and cis-N-(trichloromethyl)thio)-4-cy-clonexane-l,2-dicarboximide (captan)] with NAA, and captan with carbaryl, produced satisfactory thinning.

Open Access

Abstract

Three years’ investigations of ethephon sprays for thinning of ‘Redskin’ and ‘Redhaven’ cvs. are summarized. In screening, thinning without foliage injury was achieved up to about 3 weeks after full bloom at concn up to 300 ppm. Field experiments tended to confirm screening results. Within timing used, satisfactory thinning was accomplished most often during blossoming. Foliage injury generally increased as application was delayed and as concn increased. Fruit size at harvest was increased more by blossom treatments than later application. Fruit abscission occurred quickly after spraying. Ethephon is most promising as a peach thinning chemical, but time-dosage curves within acceptable injury Emits are not yet established.

Open Access
Authors: and

The game-show format, used recurrently in an undergraduate-level, introductory plant propagation course, fostered a friendly, competitive incentive for students to master facts and concepts critical to understanding processes in plant physiology. Because student teams, rather than individuals, served as the contestants in each game, and because game points were never translated into grade points, participants and observers learned from and enjoyed the exercises without anxiety. Propagation-specific clues and questions were prepared for “Wheel of Fortune,” “Win, Lose, or Draw,” and other games. These were followed up at the end of each semester with several play-off rounds of a plant propagation variant of “Jeopardy!”, which served as an excellent means of course synthesis and review of key concepts. The format allowed for liberal use of humor as an effective pedagogical tool and resulted in the hands-on contributions of former students in construction of new game quizzes and puzzles for subsequent semesters.

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Abstract

Sevin was used in thinning sprays in dilute—1x—and concentrate form—ranging from 3X to 33X —over a 4-year period on mature ‘Rome Beauty’ apple trees. Although treatments were not the same in each year, all sprays applied significantly thinned in 3 out of 4 years. There was some evidence that concentrate sprays thinned less than dilute sprays, but usually not significantly so. When using 33X concentrates, significant thinning was achieved in 1 year when Sevin was used at full strength—33 lb./100 gal. Approximately the same degree of thinning was obtained when the rate was reduced by one-half. Adding pesticides commonly used in petal-fall sprays to Sevin—all concentrated to the same extent—did not alter significantly the thinning obtained with Sevin alone.

Results on ‘Jonathan’ apples in a 1-year experiment revealed significant thinning with NAD and Sevin in a dilute spray, as well as Sevin at 3X and 6X concentrates. In a 1-year experiment on ‘Golden Delicious’, NAA thinned significantly as a dilute spray, and at 3X and 6X concentrates. The dilute spray was more effective.

Open Access

The only method for large scale production of pure hybrid seed in Zinnia elegans involves the use of male sterile individuals. The male sterile trait, however, is a three gene recessive which at best produces only 50% male sterile progeny from seed. Since no method of clonal propagation is available, seed-produced female lines require labor intensive field roguing to insure removal of all normal flowered individuals. Clonal micropropagation was investigated as a means of mass producing male steriles for use as female lines. Sterilization procedures were developed for seed and axillary bud explants. Shoot proliferation media containing various levels of BAP, 2ip, and kinetin were screened using in vitro germinated seedling explants of the inbred line `Orange Starlight'. Microshoots demonstrated a high rooting percentage after 2 weeks on basal medium without growth regulators. Plantlets were easily acclimated in 1 to 2 weeks in a high humidity environment. In vitro derived plants of identified male sterile plants were phenotypically evaluated as to their suitability for use in field production.

Free access

The only method for large scale production of pure hybrid seed in Zinnia elegans involves the use of male sterile individuals. The male sterile trait, however, is a three gene recessive which at best produces only 50% male sterile progeny from seed. Since no method of clonal propagation is available, seed-produced female lines require labor intensive field roguing to insure removal of all normal flowered individuals. Clonal micropropagation was investigated as a means of mass producing male steriles for use as female lines. Sterilization procedures were developed for seed and axillary bud explants. Shoot proliferation media containing various levels of BAP, 2ip, and kinetin were screened using in vitro germinated seedling explants of the inbred line `Orange Starlight'. Microshoots demonstrated a high rooting percentage after 2 weeks on basal medium without growth regulators. Plantlets were easily acclimated in 1 to 2 weeks in a high humidity environment. In vitro derived plants of identified male sterile plants were phenotypically evaluated as to their suitability for use in field production.

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Use of a liquid media during micropropagation has promoted improved proliferation and rooting response in several species. In this experiment, a double phase system (a combination of liquid and agar solidified medium) was applied to three cultivars of miniature roses (Rosa chinensis var. minima) to determine the effects on shoot quality and subsequent ex-vitro rooting. Applications of liquid media to the surface of agar solidified media were made at 0, 2, and 4 weeks. Evaluation via computerized image analysis after eight weeks of proliferation revealed equal or greater values for shoot length, area and weighted density (equivalent to fresh weight) for cultures receiving overlay, regardless of timing, compared to the solid media control. Additionally, application of a liquid overlay improved rooting response by up to 20% over the control and resulted in a tendency for a greater number of roots of greater length and area than the treatment without liquid media overlay.

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