• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.106-111
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• 1987

The susceptibility of 8 chrysanthemum varieties to Apelenchoides ritzemabosi, Shuhonothikara and Sagakiku were resistant by 11.7% and 14.5% each infested leaf, Sinrokusiogio, Dangonanako and Sintoa were susceptible as above 50%, Gold wave and Tenju were modertae by 24 to 26%. Percentage of infested leaf was positively correlated with the number of epidermal hair but not with leaf area, leaf thickness, stomatal size, number of stomata and length of epidermal hair. In effect of watering method, Polyethylene film cover plot was lowest by 9.4%, next conventional watering plot by 50%, Conventional watering and spray plot was the highest by 62%. The infested leaf rate was closely related with a number of rainy days than the amount of rainfall. Effect of chemical soil treatment, Temik showed the lowest infested leaf rate by 5%. There was no significant difference between the chemicals except Temik, but these are markedly effective in compare to control.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.154-159
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• 2000

This study was carried out to elucidate the symptom of leaf injury to ozone and to determine varietal difference to ozone injury in rice and soybean plant. Ozone was produced by electrostatic discharge in oxygen and was monitored by UV absorption ozone analyzer. The rice leaves were spotted red and rolling leaf edge, discolored to reddish brown or yellowish white in response to ozone, and the leaves that were severely stressed were withered from the tip of leaf. The soybean ones were also discolored to lemon yellow, yellow or dark brown. The leaf injury in both rice and soybean was clearly appeared at the reverse side of leaf and in lower leaves. Milyang 23 and Nonganbyeo among rice cultivars tested were resistant to ozone, but Chucheongbyeo was resistant to it. The ratio of leaf injury was increased and chlorophyll content was decreased as the extension of ozone exposure from 2 to 8 hours in rice. Keunolkong and Danyeopkong among soybean cultivars tested showed resistant reaction to ozone, but Kwangankong and Muhankong were susceptible to it. It was observed that the soybean plants grown for 45 days after seeding were severely damaged by ozone than those of other growth stages.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.15-20
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• 2004

Leaf damage by apple leafminer, Lyonetia prunifoliella, was surveyed on Fuji apple orchards with seedling rootstock from 1992 to 2001 and with M.9 rootstock from 1999 to 2001. The damage was negligible in apple orchards with seedling rootstock as 0.15% in 1992 and 0.06% in 1993. However it sharply increased to more than 3.39% since 1994, reaching at peak damage of 6.28% to 7.78% in 1996 to 1998. Damages on apple orchards with M.9 rootstock from 1999 to 2001 were higher as 6.09% to 15.3%, compared with those with seedling rootstock in the same years. In seedling rootstock apple, the damage was highest on september but in M.9 rootstock apple, the difference was not significant. Leaf damage showed no differences between cultivars including 4 Korean cultivars and Fuji. These results may explain that increase of M.9 rootstock apple orchards is responsible for the recent outbreak of the leafminer in Korea.

• Korean journal of applied entomology
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• v.39 no.3
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• pp.141-147
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• 2000

This study was carried out to investigate the population changes of Liriomyza trijolii (Burgess) on chrysanthemum and its relationship to plant growth and damages. In spring culture of chrysanthemum, L. trifolii adults begun to be attracted by the yellow sticky trap from early May and maintained high population until the middle of July. Larval density increased gradually from late May and reached peak in early July. In autumn culture, the population density of adult was lower than that of spring culture but the number of adult was great in late September and the middle of October. This trend was similar to that of larval stage. Damaged leaves by larva could be found from 4 weeks after transplanting and its rate was low until 5 weeks but increased abruptly after 6 weeks and maintained 70% level until flowering stage in spring culture. Damaged leaves increased with plant growth in some varieties tested in this experiment.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.2
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• pp.109-116
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• 1979

This experiment was conducted to find out the effects on soybean plant exposed with various concentration and different fumigation periods of ammonia gas ($0.2mg/{\ell}$). The yield of soybean, nitrogen and, chlorophyll contents in leaves, and percentage of destroyed leaf area were investigated. The results were summarized as: 1. The soybean yield losses and percentage of destroyed leaf area were positively correlated with concentration of inflicting ammonia gas respectively. The yield losses was higher at noon exposure time than at night exposure time. 2. The soybean yield was negatively correlated with the percentage of destroyed leaf area. 3. The highest percentage of destroyed leaf area had at afternoon exposure time (14:00-15:00 o'clock) by $0.2mg/{\ell}$ ammonia gas fumigation, and the lowest one had at midnight exposure time (22:00-23:00 o'clock). 4. According to the increasing concentration of ammonia gas, the total and water soluble nitrogen contents in soybean leaves were increased, but the contents of chlorphyll b on decreasing rate. 5. The nitrogen contents in plant were higher in the afternoon exposure than in the morning, but the contents of chlorophyll were higher at night time exposure than at day time. 6. The highest decreasing of absorption spectra of chlorohpyll in chloroplast had at 10:00-11:00 o'clock on fumigation time and the lowest one had at 22:00-23:00 o'clock.

• Korean journal of applied entomology
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• v.35 no.4
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• pp.309-314
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• 1996

The American serpentine leafminer (ASL), Liriomyza trifolii (Burgess), was fist found from a vinyl house planting gerbera in Kwangju area on January 26, 1994. To learn its distribution and damage pattern on crop plants, a nationwide survey was carried out at 293 vinyl houses from 25 cities/counties in six provinces. Its damage was found at 22 vinyl houses in Kwangju and Chinju areas. The range of leaves damaged by the ASL was 5-100% on gerbera, 40-70% on chrysanthemum, 20% on cherry-tomato, and 5-20% on celery. Host crop plants included gerbera, chrysanthemum, celery, cherry-tomato, watermelon, and pumpkin.

• Korean journal of applied entomology
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• v.48 no.1
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• pp.81-86
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• 2009

Economic injury level and control thresholds for the management of beet army worm, Spodoptera exigua (Lepidoptera: Noctuidae) were evaluated on chinese cabbage of two different planting time. Two inoculation times were tested for each planting and the number of inoculated larva was 10, 20, 40, 80, respectively. Damages of leaves by first inoculation were 63.2% after eight days planting on 80 larva inoculation plot. By the second inoculation, those were below 50% after 20 days planting on the end of September. The linear relationships between population density and yield reduction were as following; Y = -10.62x + 867.9 ($R^2\;=\;0.643$) for 5 days and Y=-6.432x + 1074 ($R^2\;=\;0.720$) for 20 days. Based on these results the economic injury level was 5.4 larva for five days and 9.0 larva for 20 days per 20 chinese cabbage. The control thresholds calculated by 80% level of economic injury level were 4.3 and 7.2 larva, respectively.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.50-55
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• 2000

Occurrence, Injury aspects and control effect of some chemicals were investigated on tomato in plastic house from 1997 to 1998. Adults trapped by yellow sticky trap and sweeping net were increased from late May abruptly. Survey of population densities by yellow sticky trap was more clear than sweeping net. Damaged leaves were found out all the year round in continuous cropping fields and rate of damaged leaves was below 20% in early April and increased gradually up to 80% level after late May. Otherwise, damaged leaves were appeared from 6 weeks after transplanting in first growing field and then damaged leaves was 80% level in spring culture. In autumn culture, rate of damaged leaves was maintained 80% level from transplanting to harvesting date regardless of cultivation years. Number of adults was trapped from late May and peak was late June but mature larva was $6{\sim}8$ individuals in spring culture. In autumn culture, adult and larval densities was maintained high for 3 weeks after transplanting but begun to decrease from 4 weeks(early September). Chlorfenapyr EC, cyromazine WP and abamectin EC could suppress larval populations of Liriomyza trifolii effectively.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.157-162
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• 1981

The studies we re carried out to examine the effect of soil improvement agents, such as lime, wollastonite and phosphate, in reducing the damage caused by hydrogen fluoride gas to the vegetative growth of rice. The yield loss, damage rate of the plant leaves, the fluoride of the plants were measured. The results obtained are summarized as follows : 1. The best results were obtained a treatment of lime and wollastonite. 2. The rice yield was not significantly increased by the soil improvement agents. 3. The fluoride content of the plants was positively correlated with yield loss and damage rate during vegetative growth.

• Korean journal of applied entomology
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• v.24 no.3 s.64
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• pp.157-162
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• 1985

Leaf damage rate and actual damaged leaf area by the apple leaf miner (ALM), Phyllonorycter ringoniella(Matsumura), and its parasitism were investigated in 1982 and 1983 in apple orchards. Percent leaf damage was higher in the occasionally sprayed orchards than in the periodically sprayed orchards from May to August, but the trend was reversed after September. Seasonal changes of the leaf damage seemed to be different with the varieties of apple trees. A few species of Eulophidae and Holcothorax testaceipes R. of Encyrtidae were the predominant parasites of the ALM. Overall percent parasitism was highest in the 5th (overwintering) generation, and conspicuously decreased in the 3rd-4th generation (July-August) when insecticides were sprayed periodically. Actual damaged leaf area per mine of the ALM was apparently different with the generations; $0.67cm^2$ for the 1st, $0.8{\sim}0.9cm^2$ for the 2nd-4th on the first growth shoot, and $1.49cm^2$ for the overwintered generation on the second growth shoot. When ALM leaf damage rate was about $53{\sim}73%$, the decrease in the photosynthetic area to the damaged leaf was about $6{\sim}8%$.