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  • Author or Editor: G. W. Krewer x
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Abstract

Rooted twig cuttings of ‘Jefferson’ peach [Prunus persica (L.) Batsch] infected or noninfected with phony peach disease were divided into nonphony, medium phony, and severe phony based on symptoms and on Fastidious, gram-negative, xylemlimited bacteria (PPXLB) counts. During the dormant season, the rooted plants were subjected to cold treatments of -11.7°, -14.4°, -17.9°, -20.0°, and -21.6°C in cold chambers. Plants with higher PPXLB counts exhibited more cold injury than plants with lower counts.

Open Access

Abstract

Softwood cuttings taken from phony peach disease-infected and uninfected trees of ‘Jefferson’ peach [Prunus persica (L.) Batsch] produced 80% or more well-rooted cuttings with no significant difference (5% level) between phony and non-phony cuttings.

Open Access

Observations in controlled field experiments over 5 years indicated that imidacloprid, applied as a soil drench around the trunks of peach (Prunus persica), nectarine (P. persica var. nectarine) and japanese plum (P. salicinia) trees at planting and in the early spring and mid-summer for two subsequent seasons (0.7 g/tree a.i.), slowed the development of symptoms of phony peach disease (PPD) and plum leaf scald (PLS) (Xylella fastidiosa) in the trees. After 3.5 years, the percentage of peach trees showing PPD symptoms was 8.5% for the imidacloprid-treated trees compared to 34.3% for untreated trees. After 4.5 years, the percentage of peach trees showing PPD symptoms was 13.1% in the treated trees and 71.4% in the untreated trees. After 3.5 years, nectarine trees in untreated and treated plots showed PPD symptoms in 8.3% and 0.9% of the trees, respectively. After 4.5 years, PPD symptoms in nectarine were found in 32.3% of the untreated trees and 8.5% of the treated trees. Development of PLS disease in plum was also slowed by the trunk drench with imidacloprid in two japanese plum varieties. After 3.5 years, dieback was observed in 55% of the twigs of untreated and 23% of the twigs of treated trees of `Au Rosa' plum and 33% of the twigs of untreated and 12% of the twigs of treated trees of `Santa Rosa' plum.

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Bumblebees (Bombus spp.) are important pollinators of mostly self-sterile rabbiteye blueberry (Vaccinium ashei Reade). Annual bee colonies start from solitary overwintered queens who emerge in near-synchrony with rabbiteye blueberry bloom. Although colony populations may reach several hundred individuals by midsummer, in early spring most Bombus visiting rabbiteye blueberry are queens reared the previous season. Thus, practices that encourage production of queens in summer may increase populations of blueberry pollinators the next spring. In south Georgia, midsummer shortages of nectar-yielding plants may nutritionally limit queen production, and cultured bee forages may help overcome this deficiency. Candidate plants must not compete with the crop for pollinators, and they must be attractive to bees, easy to grow, vigorous, and non-invasive. In 3 years of trials, the following plants have shown promise as supplemental bumblebee forages in south Georgia: Althea (Hibiscus syriacus), abelia (Abelia ×grandifolia), vitex (Vitex agnuscastus), red clover (Trifolium pratense perenne), Mexican heather (Cuphea hyssopifolia), monkey grass (Liriope muscari), summer sweet (Clethra alnifolia), and giant sunflower (Helianthus giganteus).

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Abstract

Semihardwood peach [Prunus persica (L.) Batsch] cuttings were successfully rooted when the bases and tops were misted intermittently with water. Rooting was not affected by cultivar or type of cutting (basal vs. terminal). Closer proximity of the bases of the cuttings to the mist line and overhead misting improved rooting percentage.

Open Access

This paper describes the climatic and cropping conditions in the major peach [Prunus persica (L.) Batsch] producing areas in the southeastern United States in 1996. The peach and nectarine crop was the smallest since 1955 due to a series of unusually cold temperatures in February, March, and April. Crop set was not strictly a function of late blooming. No variety produced a full crop across the region. Many reputedly hardy peaches cropped poorly. The only peach or nectarine varieties that produced substantial crops in multiple locations were `La Premiere', `Ruston Red', and `Contender'. Cropping ability of some breeding selections shows that peach frost tolerance may be improved further.

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Abstract

Dormant cuttings of muscadine grape, Vitis rotundifolia Michx., rooted best early in the dormant season, although root quality was poor and the percentage rooting was low. Large-diameter cuttings rooted better than small-diameter cuttings. A high percentage of cuttings with aerial roots produced additional root growth. Medium heating was necessary for root formation. No significant rooting response was observed with indolebutyric acid (IBA), (2-chloroethyl) phosphonic acid (ethephon), precallousing, sucrose treatments, or with mallet cuttings.

Open Access

Abstract

Application of 960 ppm (2-chIoroethyl)methylbis(phenylmethoxy)silane (CGA-15281) substantially inhibited carbon transport into young fruit of peach [Prunus persica (L.) Batsch] 4 to 5 days before visual symptoms of senescence occurred. Carbon transport was unaffected 4.25 hours after treatment, but was greatly reduced after 24 hours. Reduced carbon transport continued through 144 hours following CGA-15281 application.

Open Access