T.G. Beckman, G.W. Krewer, and W.B. Sherman
G.W. Krewer, K.S. Delaplane, and P.A. Thomas
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).
James D. Dutcher, Gerard W. Krewer, and Benjamin G. Mullinix Jr.
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.
T.G. Beckman, W.R. Okie, G. Krewer, and W.B. Sherman
The purpose of this three-way cooperative project is to develop new fresh-market peach and nectarine varieties in the 400 to 650 chill hour range for the early season shipping market. Since 1990, >3000 seedlings have been evaluated, resulting in 48 selections. Additionally, several hundred selections from other programs have been evaluated. `Sunsplash', an attractive, early season, 400 chill hour nectarine, was released in 1993 as a result of this cooperative effort. A novel aspect of the program has been the use of non-melting flesh parents for the purpose of improving handling characteristics. Selections include both yellow- and white-flesh types, peaches and nectarines. Some may be adapted for use in other production areas and are available for testing under non-propagation agreement. Evaluation summaries of selections and standards will be presented.
Gerard W. Krewer, Thomas G. Beckman, Jose X. Chaparro, and Wayne B. Sherman
Gregory L. Reighard, Michael L. Parker, Gerard W. Krewer, Thomas G. Beckman, Bruce W. Wood, John Ed Smith, and Johnny Whiddon
W.R. Okie, T.G. Beckman, G.L. Reighard, W.C. Newall Jr., C.J. Graham, D.J. Werner, A.A Powell, and G. Krewer
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.