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Sanjun Gu and Kirk Pomper

Feeding by Japanese beetles (JB) can damage grape leaves and result in a loss of vine leaf area, thus reducing both yield and fruit quality. The objectives of this study were to determine if there was a grape cultivar feeding preference by JBs and whether application of organic feeding deterrents to leaves would reduce damage by JBs. Eleven American and hybrid grape cultivars were evaluated in a choice feeding study in cages, where 15 JBs per vine were introduced for 48 hours. The number of leaves damaged by JBs varied by cultivar. `Chardonel' (43%) had fewer damaged leaves than `Seyval' (78%), `Edelweiss' (74%), `Norton' (63%), and `Vignoles' (63%). The leaf area lost by feeding varied by cultivar, with `Lacrosse' (15%) showing the least damage and `Seyval' the most (40%). In another JB choice feeding study with organic feeding deterrents, Surround (at label rate) and Neemix 4.5 [at high label rate (A) or doubled high label rate (B)] were compared to a water control with `Chardonel', `Traminette', and `Vignoles' grapes. Surround and Neemix 4.5 applied at level A reduced the number of damaged leaves compared to the control; however, Neemix 4.5 at level B showed similar damage to the control. Loss of leaf area due to feeding of JBs was greatest on vines treated with Neemix 4.5 at level B and least on those treated with Surround, although this loss of leaf area was not significantly different between the two Neemix 4.5 treatments. Vines treated with Surround had the least leaf area loss, followed by the control, Neemix 4.5 at level A, and Neemix 4.5 at level B.

Free access

Sanjun Gu and Kirk W. Pomper

Kentucky has a rich history in viticulture. The Kentucky Vineyard Society was founded in 1798 and Kentucky was the third largest grape and wine producer by 1860. During Prohibition, however, vines were either uprooted or left unattended, and the grape industry essentially disappeared in Kentucky. Since 1990, the grape and wine industry has shown a resurgence; however, there are limited educational opportunities in viticulture in Kentucky. Kentucky State University (KSU) emphasizes the development of alternative high-value crops for sustainable agriculture production. In 2000, a viticulture program was initiated at KSU to develop cultivar, vine management, and pest and disease control recommendations. Aware of the fact that grape growers in Kentucky are mostly new to grape culture, KSU has developed a viticulture website (http://www.pawpaw.kysu.edu/viticulture/index.htm) to disseminate viticulture information. The website provides information that includes setting up a new vineyard, managing a “mature” vineyard (Vitis, Kentucky weather and climate, site selection, cultivars, rootstocks, trellising, care of young vines, canopy management, irrigation and nutrition, pest, and disease management), grape growers' corner (questions and answers, buy and sale, resources), and selected links. A monthly viticulture calendar is also available. In the future, the site will be updated with research results in viticulture from KSU and other southeastern institutions, growers' feedback, and information on wine making. The viticulture website will aid in the promotion of the grape and wine industry in Kentucky and states with a similar climate, and benefit grape growers from this profitable and expanding market.

Open access

Tekan S. Rana and Sanjun Gu

North Carolina’s fresh strawberry has a $21.4 million economic value, which is primarily from short-day cultivars in the annual plasticulture system. Organic and off-season day-neutral strawberries have higher prices than the conventional, field-grown strawberries. There have been no published studies on suitable cultivars, transplanting dates, and additional winter protection methods for day-neutral strawberry production in high tunnels in North Carolina. The objective of this study was to examine the effect of low tunnels, planting dates, and cultivars on growth, yield, and season extension potential of day-neutral strawberries in high tunnels. Plugs of day-neutral cultivars Albion and San Andreas were either transplanted in raised beds covered with low tunnels (LT) or without low tunnels (control, NLT), inside high tunnels on the N.C. A&T State University Farm (Greensboro, NC) on two different planting dates, which were 1 Sept. (D1) and 29 Sept. (D2) of 2016, or 9 Sept. (D1) and 10 Oct. (D2) of 2017, respectively. A completely randomized design with split-split plots was used. LT did not significantly affect the total yield and plant phenology, but they promoted the first harvest by a week compared with NLT, which resulted in higher yield during the winter of both years. D1 promoted about 24 days of earlier harvest than D2. ‘Albion’ had an earlier bloom and harvest date (by 1 to 3 weeks and 2 to 3 weeks, respectively) than ‘San Andreas’. Strawberry yield was low in the fall season, but it started to increase from January, peaked in April, and decreased again in May. D1 increased the whole season’s marketable yield of ‘Albion’ (430.3 g/plant), compared with that of ‘San Andreas’ (330.9 g/plant). During the winter, ‘Albion’ had a higher yield than ‘San Andreas’. Our study indicates that LT inside HT might not significantly improve the plant growth, early harvest, or total yield. Planting dates had no consistent effect on yield. It was suggested that ‘Albion’ should be considered for high winter yields, and ‘San Andreas’ be a cultivar with high yields of the entire season in high tunnels.

Free access

Paul E. Read and Sanjun Gu

Free access

Sanjun Gu and Kirk W. Pomper

The Japanese beetle is a major insect pest of grapes in the eastern United States. An examination of Japanese beetle preference for currently grown grape cultivars would be useful to growers in developing pest control strategies with reduced chemical inputs. The objective of this study was to examine grape cultivar preference of Japanese beetles for commercially available grape cultivars in both cage choice and field experiments. Outdoor cage choice screening studies included 32 grape cultivars from various Vitis species and were conducted at the Kentucky State University Research Farm in Frankfort, KY. Feeding preference was determined by examining incidence of damage (percent of leaves damaged per vine) and leaf area loss, which was rated as 0 pt, 0%; 1 pt, 1% to 10%; 2 pt, 11% to 20%; 3 pt, 21% to 30%; 4 pt, 31% to 40%; 5 pt, 41% to 50%; 6 pt, 51% to 60%; and 7 pt, more than 60%, by leaf position from the first (shoot tip) to 10th leaves. Analysis of variance indicated that there were significant differences in Japanese beetle leaf damage for cultivar and leaf position main effects. Leaf damage by Japanese beetles varied by leaf position on the shoot, with the fourth through sixth leaves from the tip with the most severe damage. Generally, cultivars showing an incidence of damage greater than 70% were either European or French hybrid cultivars, and those with less than 70% incidence of damage were either American cultivars or American cultivars with a V. labrusca background. The grape cultivars Marquis, Reliance, Catawba, Concord Seedless, Concord, Edelweiss, and Einset showed promise as selections for growers interested in reduced chemical inputs for control of Japanese beetles.

Full access

Sanjun Gu, Wenjing Guan, and John E. Beck

High-tunnel strawberry (Fragaria ×ananassa) production for extended seasons has a great economic potential for small farmers. However, information on cultivars that are suitable for high tunnels is rather limited. In this study conducted in the 2014–15 season, strawberry plugs of eight June-bearing cultivars (Florida Radiance, Benicia, Camarosa, Camino Real, Chandler, Strawberry Festival, Sweet Charlie, and Winterstar) and two day-neutral cultivars (San Andreas and Albion) were evaluated for yield performance, fruit quality, and vegetative growth in organically managed high tunnels at two locations in North Carolina. Significant cultivar differences in whole-season yield were observed at Greensboro, NC; but not at Goldsboro, NC. The cultivar Florida Radiance had the highest marketable and total yields, followed by Winterstar and Chandler at Greensboro, whereas Benicia, Winterstar, and Chandler were the top producing cultivars at Goldsboro. Harvest of day-neutral cultivars San Andreas and Albion started in November. For June-bearing cultivars, Florida Radiance began to produce harvestable berries in late December, followed by Winterstar in early January. Peak harvest occurred in April for all cultivars. At the end of the season, ‘Albion’ had smaller canopy size than other cultivars. It also developed the fewest number of branch crowns and least aboveground biomass. Total soluble solid (TSS) content in April was lower than that observed early and late in the season for all cultivars, although Strawberry Festival exhibited a relatively stable TSS throughout the season. ‘Benicia’ produced the largest strawberries in the early season, but its fruit weight was remarkably reduced as the season progressed. Severe frost events occurred on 18 and 20 Feb. that caused an average of 61.5% and 32.2% open blossom damage at Greensboro and Goldsboro, respectively. The recommended cultivars based on this 1-year study are Florida Radiance, Benicia, and Camino Real for June-bearing cultivars, and Albion and San Andreas for day-neutral cultivars.

Full access

Julia Charlotte Robinson, Guochen Yang, Sanjun Gu, and Zhongge (Cindy) Lu

Black cohosh (Actaea racemosa L.), a medicinal herb commonly used in herbal supplements for the treatment of various ailments, is a perennial herb that grows naturally under shade conditions in temperate forest regions. This project studied the growth and rhizome yield of Black cohosh under shade conditions of 0%, 40%, 60%, and 80% in a high tunnel (9.1 m wide × 29.3 m long) on the North Carolina Agricultural and Technical University Farm. Seed rhizomes were planted in raised beds incorporated with 9070 kg/acre compost and preplant fertilizer on 29 May 2016. There was one row per bed, with in-row spacing at 45.7 cm, and one drip line per bed for irrigation. Fertigation was done weekly through the drip tapes with Multi-K 13–0–46 (27.2 kg N/acre) during the growing season. Beds were mulched after sprouting. Growth data of fully mature plants were collected on canopy width and length, total number of stems per plant, stem diameter, and length/height; and rhizome fresh and dry weight. Data were analyzed at the 0.05 level of significance. Plant canopy, stem diameter, and length/height were significantly greater in 40% shade (average, 504.7 × 472.6 mm, 3.7 mm, and 135.9 mm, respectively) than in other shade conditions, with the smallest sizes in 0% shade (average, 255.8 × 255.7 mm, 2.1 mm, and 95.4 mm, respectively). There were no significant differences between the 60% and 80% shade conditions in plant canopy, stem diameter, and length/height. However, the total number of stems per plant (4.9) in 0% shade was significantly more than those in other shade conditions, with the least of stems per plant (2.9) in 80% shade. Rhizome fresh and dry weight per plant were the greatest (164.6 and 48.1 g, respectively) in 40% shade, and the least (77.8 and 22.5 g, respectively) in 0% shade. The results indicate that optimum growing conditions for Black cohosh was in 40% shade with a Daily light integral (DLI) between 15 and 0 mol/m2/day, and a day- and nighttime temperature difference between 8.3 and 2.7 °C.

Open access

Gina Fernandez, Jeremy Pattison, Penelope Perkins-Veazie, James R. Ballington, Elizabeth Clevinger, Rocco Schiavone, Sanjun Gu, Jayesh Samtani, Edgar Vinson, Amanda McWhirt, and Jose Guillermo Chacón