• Korean Journal of Environmental Agriculture
• /
• v.25 no.3
• /
• pp.276-283
• /
• 2006

To evaluate the effectiveness of the foliar spray of calcium on "Baekdo" peach fruit, we carried out experiments in the orchards. The sprays were applied with $CaCl_2\;(Ca:\;400mg.kg^{-1})\;and\;CaCl_2$ with adjuvants (amino acid, $2g.kg^{-1}$; phytic acid, $2ml.kg^{-1}$ and wood vinegar, $2ml.kg^{-1}$) for four times from June 12 through July 4 at weekly intervals. The fruits and leaves were evaluated for Ca content, firmness and incidence of Brown rot caused by Monilinia fructicola at harvest To evaluate fruit quality included Ca content, firmness natural decay during the storage, the fruits were stored at room temperature for 14 days. The Ca content in leaf and fruit flesh at harvest was significantly increased (P=0.05) in $CaCl_2$ + amino acid treatment among $CaCl_2$ treatments. However, there was not significant Ca content in fruit peel. The firmness of flesh increased significantly (P=0.05) in $CaCl_2$ + amino acid treatment. The natural decay (Rhizopus stolonifers) during storage at the room temperature for 14 days, the fruit treated with $CaCl_2$ + wood vinegar exhibited lowest (P=0.05) incidence. Also, the firmness of the fruit during storage was firmer with treated $CaCl_2$ than untreated fruit. In the treatments of $CaCl_2$ + phytic acid and $CaCl_2$ + amino acid, it was possible to reduce incidence of Brown rot caused by M. fructicola most effectively in the field. In addition, inoculation with M. fructicola in fruits was also the most effective treatment for inhibiting disease development in vitro. These results suggested that the foliar spray of $CaCl_2$ with adjuvants increased the content of Ca and firmness of the fruits positively. It also inhibited the natural decay and the Brown rot effectively.

• Korean Journal of Weed Science
• /
• v.3 no.2
• /
• pp.190-198
• /
• 1983

To examine the possibility of enhancing activity of foliar applied herbicides by spray methods and additives, field experiments were conducted to evaluate the effects of surfactant, spray volume, and additions of ammonium sulfate or potassium chloride to glyphosate on toxicity to Digitaria sanguinalis or Artemisia princeps. Glyphosate toxicity increased as spray volume was decreased from 120 1/10a to 40 and 80 1/10a. Additions of surfactant in the spray solution increased toxicity of glyphosate to D. sanguinalis and usually more pronounced effect was obtained at glyphosate 30.5g a.i./10a. Additions of 1 and 5% (w/v) ammonium sulfate to glyphosate increased toxicity to A. princeps at glyphosate 30.5 and 61.5g a.i./10a. 10% ammonium slufate, however, had no effect or were antagonistic. Additions of potassium chloride at 1,2 and 3% (w/v) were also very effective to increase herbicidal activity to A. princeps at glyphosate at 30.5 and 61.0g a.i/10a. These results suggest that the practices for enhancement of herbicidal activity by improvement of spray method and additions of ammonium sulfate or potassium chloride to glyphosate can be employed to use lower herbicide levels while giving the same degree of weed control in orchards and non-crop lands.

• Korean Journal of Weed Science
• /
• v.3 no.2
• /
• pp.208-222
• /
• 1983

To control ideally the weeds in orchards and systematize the utility of herbicides, the mixing effect of oxyfluorfen and paraquat was evaluated. Combinations of oxyfluorfen with paraquat were increased the control efficacies at any treatment without giving damage to fruit trees and appeared a synergism. The control effects were reduced from 80-90% to 40-60% as the time advanced. However, the relative synergistic index was higher at 60 days after treatment in preemergence treatment and at 90 days after treatment in early and late postemergence treatment, respectively. Also the index was relatively higher at lower dosage of both herbicides.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.11 no.2
• /
• pp.61-71
• /
• 2009

Most deciduous trees in temperate zone are dormant during the winter to overcome cold and dry environment. Dormancy of deciduous fruit trees is usually separated into a period of rest by physiological conditions and a period of quiescence by unfavorable environmental conditions. Inconsistent and fewer budburst in pear orchards has been reported recently in South Korea and Japan and the insufficient chilling due to warmer winters is suspected to play a role. An accurate prediction of the flowering time under the climate change scenarios may be critical to the planning of adaptation strategy for the pear industry in the future. However, existing methods for the prediction of budburst depend on the spring temperature, neglecting potential effects of warmer winters on the rest release and subsequent budburst. We adapted a dormancy clock model which uses daily temperature data to calculate the thermal time for simulating winter phenology of deciduous trees and tested the feasibility of this model in predicting budburst and flowering of Niitaka pear, one of the favorite cultivars in Korea. In order to derive the model parameter values suitable for Niitaka, the mean time for the rest release was estimated by observing budburst of field collected twigs in a controlled environment. The thermal time (in chill-days) was calculated and accumulated by a predefined temperature range from fall harvest until the chilling requirement (maximum accumulated chill-days in a negative number) is met. The chilling requirement is then offset by anti-chill days (in positive numbers) until the accumulated chill-days become null, which is assumed to be the budburst date. Calculations were repeated with arbitrary threshold temperatures from $4^{\circ}C$ to $10^{\circ}C$ (at an interval of 0.1), and a set of threshold temperature and chilling requirement was selected when the estimated budburst date coincides with the field observation. A heating requirement (in accumulation of anti-chill days since budburst) for flowering was also determined from an experiment based on historical observations. The dormancy clock model optimized with the selected parameter values was used to predict flowering of Niitaka pear grown in Suwon for the recent 9 years. The predicted dates for full bloom were within the range of the observed dates with 1.9 days of root mean square error.

• Korean Journal of Agricultural Science
• /
• v.1 no.1
• /
• pp.59-66
• /
• 1974

This paper describes how location influences on the development of dairy farming. It compares Chuncheon, which in the mountains, Daejeon, which is a transportation center and on flat ground, and Incheon, which is the gate to Seoul and an industrial city. The results analyzed are summarized as follows : 1. Incheon, due to her vast market, influenced strongly on the development of management. But shortage of roughage for feeds is the critical problem there. 2. Owing to the side job of raising chicks, which involves 92% of dairy farmers there, Chuncheon does not make smooth utilization of vast grass pasture. 3. In Daejeon's case, running orchards concurrently is the problem. 4. There exists no gap in wages between the region. The labor supply is most affluent in Incheon and there is competition with other forms of agriculture in the mountainous area. 5. The full-time employee tends to be skillful in accordance with his career. Family labor has been skillful, but the full-time employee is very fluid and shows varieties of skill. 6. Because of the obscurity of the distribution of labor with other jobs in Chuncheon and Daejeon, many unspecialized men serve. 7. The prices of milk are different in each region. The income of dairy farmers is strongly influenced by the low purchasing price of milk plants, and this is one of the important factors hindering the development of dairy farm ing in Chuncheon.

• Korean journal of applied entomology
• /
• v.50 no.3
• /
• pp.235-245
• /
• 2011

Temperature-related parameters of Panonychus citri (McGregor) (Acarina: Tetranychidae) development were estimated and a stage-structured matrix model was developed. The lower threshold temperatures were estimated as $8.4^{\circ}C$ for eggs, $9.9^{\circ}C$ for larvae, $9.2^{\circ}C$ for protonymphs, and $10.9^{\circ}C$ for deutonymphs. Thermal constants were 113.6, 29.1, 29.8, and 33.4 degree days for eggs, larvae, protonymphs, and deutonymphs, respectively. Non-linear development models were established for each stage of P. citri. In addition, temperature-dependent total fecundity, age-specific oviposition rate, and age-specific survival rate models were developed for the construction of an oviposition model. P. citri age was categorized into five stages to construct a matrix model: eggs, larvae, protonymphs, deutonymphs and adults. For the elements in the projection matrix, transition probabilities from an age class to the next age class or the probabilities of remaining in an age class were obtained from development rate function of each stage (age classes). Also, the fecundity coefficients of adult population were expressed as the products of adult longevity completion rate (1/longevity) by temperature-dependent total fecundity. To evaluate the predictability of the matrix model, model outputs were compared with actual field data in a cool early season and hot mid to late season in 2004. The model outputs closely matched the actual field patterns within 30 d after the model was run in both the early and mid to late seasons. Therefore, the developed matrix model can be used to estimate the population density of P. citri for a period of 30 d in citrus orchards.

• Korean journal of applied entomology
• /
• v.59 no.2
• /
• pp.153-163
• /
• 2020

This study was conducted to evaluate the fitness of Tetranychus kanzawai Kishida on different host plants: young and old leaves of the mandarin orange 'shiranuhi' ((Citrus unshiu × C. sinensis) × C. reticulata), Japanese violet (Viola japonica Langsd.) and kidney bean (Phaseolus vulgaris L.). The development and oviposition experiments were conducted at constant temperatures (20, 25 and 30℃) and a life table parameters were estimated. T. kanzawai could complete it's development on 'shiranuhi' young leaves, japanese violet and kidney bean, while all died during the immature period on 'shiranuhi' old leaves. The total developmental period of T. kanzawai feeding on 'shiranuhi' young leaves was 17.4, 13.4 and 10.2 days at each temperature, respectively, which was longer than 16.1, 9.5 and 7.0 days of kidney bean. The female longevity of T. kanzawai on young leaves of 'shiranuhi' were 19.1, 15.0 and 12.3 days at each temperature, respectively, and there was no significant difference from 22.1, 14.1 and 10.9 days investigated from kidney bean. The fecundity was 18.1, 23.9 and 17.8 eggs per female, which was less than them of japanese violet and kidney bean at each temperature, respectively. As a result of estimating the life table parameters based on the experimental data, intrinsic rate of increase (r_m) were significantly different from each other, and appeared in the following order: kidney (0.1542, 0.2563 and 0.3251), japanese violet (0.1087, 0.2007 and 0.2673) and 'shiranuhi' young leaves (0.0868, 0.1002 and 0.1217) at each temperature, respectively. Finally, the management strategy against T. kanzawai in citrus orchards was discussed based on the results.

• Journal of Korean Society of Forest Science
• /
• v.87 no.4
• /
• pp.549-556
• /
• 1998

To develop the effective methods of flowering stimulation, Hinoki cypress (Chamaecyparis obtusa Sieh. et Zuec.) grafts growing in a seed orchard and in a clone bank in Southern Breeding Station of Cheju were applied with gibberellin treatments, and predicted the seed production potential. In the seed orchard, $GA_{4/7}$ 1.5cc was injected into the stem of drafts and sprayed whale tree crown with $GA_3$ 300ppm and $GA_{4/7}$ 300ppm. Un the other hand, in the clonal archives, drafts were given intrusion of $GA_{4/7}$ 1.5cc into the excised and open inner part of bark wind $GA_3$ 20mg and sprayed with $GA_3$ 300ppm. Additionally, grafts growing in the seed orchard were treated with gibberellins at 3 different periods of time and 3 different treatments during the growing season. The results obtained here are summarized as follows : 1. All of the applications of Gilbberellin promoted female flower formation. Among these, the treatment of intrusion of $GA_{4/7}$ 1.5cc into the excised and open inner part of bark was racist effective, followed by the spraying of $GA_3$ 300ppm. Similarly, the applications of gibberellin promoted male flower formation. 2. Regarding the time of applications, treatment on August 15 was more effective than those of August 31 and September 11 in the stimulation of female flowers. On the contrary, there was no significant difference in the number of male flowers among 3 different time treatments. 3. It was supposed that the application of the intrusion of $GA_{4/7}$ 1.5cc into the excised and open inner part of bark on August 15 showing the best effect in female flower formation can produce 22.12kg seeds per ha. 4. Considerable significant difference existed among clones for both female and male flower formations. 5. Flower formation, especially female flower formation, seemed to be partially associated with the genetic potential of individual trees.

• Korean journal of applied entomology
• /
• v.24 no.4 s.65
• /
• pp.183-190
• /
• 1986

Identification of fruit sucking moths, their larval host plant, and degree of damages to fruits were investigated in $1982{\sim}'83$ at two orchards in Cheonnam province. In this study, 4 families 30 species were collected as fruit sucking moths and among them 10 species are newly recorded in Korea as fruit sucking moth: Catocala electa(B.), Spirama helicina(H.), Erebus ephesperis(H.), Parallelia stuposa(F.), Simplicia niphona(B.), Marumba gaschkewitschii(B. et G.), Agrius convolvuli(L.), Thyatira batis (L.), and Spilosoma niveum(M.). Larval host plants of fruit sucking moths in the vicinity of the fruit orchard include Cocculus trilobus D., Albizzia julibrissin D., Pterocarya rhoifolia S., Jaglans mandshurica M., Solanum melongena L., Brassia campestris S., Rubus idaeus C., Thalictrum aquilegifol L., and Rhus succedanea L. As the damage on different varieties of the main fruit trees, plum was orderly Santa Rosa>Beauty, Apple was Chook>Hong Og, Peach was Choseng Baeg Do>Hwang Do>Baeg Do, and Grape was Campbell Early>Neo Mascat>Golden Queen. Seasonal occurrence of main fruit sucking moth Spirama retorta(C.) showed peak 3 times in early-July, late-July, early-September. Oraesia emerginata(F.) showed peak 3 times in late-July, early-August, early- September and Lagoptera juno(D.) showed peak only in late-July and Adrias tyrannus amurensis(S.) showed peak only in mid-July. Fruit sucking moths were immigrated from p.m. 6 to a.m. 2, with peak in p.m. 10 to p.m. 12.

• Korean journal of applied entomology
• /
• v.54 no.3
• /
• pp.191-197
• /
• 2015

Fruit drop due to Eurytoma maslovskii infestations of Japanese apricot (Prunus mume) is a serious economic issue in most parts of Jeonnam Province, with the exception of the coastal areas such as Wando, Shinan, Yeosu, and Muan. The average incidence of fruit drop was 67% in 2013 and 33.3% in 2014. E. maslovskii larvae overwinter inside the pits of Japanese apricots. Larval survival rates decrease to less than 30% after a rainy summer season. The eggs are long oval of 0.68 mm, 0.29 mm and ivory white. Mature larva is of 6.56 mm, 3.18 mm. Free pupa are black, adult females and males of 6.97 mm, 4.90 mm lengths, respectively, while the ovipositor is 0.64 mm in length. Adult emergence occurs from early April to early May, when Japanese apricot fruits are from 4 mm to 17 mm in diameter. Adults persist for 13.5 d after emergence, and the sex ratio of females to males was found th be 45.9:54.1. Although up to four eggs may be oviposited per fruit, only one larva will ultimately survive, ans the larvae are cannibalistic. The period during which E. maslovskii is able to oviposit on Japanese apricots only lasts from mid- to late April (fruit diameter: 12~16 mm). When the diameter of the fruit is >16 mm, the pit of the Japanese apricot hardens and larvae have difficultly penetrating the stone. Therefore, the most effective method of controlling this pest is to spray orchards with a control agent 2~3 times, at 5 d intervals, beginning in mid- April.