• Journal of Sericultural and Entomological Science
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• v.32 no.2
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• pp.89-93
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• 1990

Mulberry, damaged by a late frost on April 27, received a foliar spray of 0.5% Urea or Jambi(a foliar fertilizer). The sprays were applied once every 3 days from May 16 for 12 days. The results were : 1. Approximately 70 auxillary buds per tree sprouted after the frost. The difference between the lowest and highest number of buds was 3 to fold. 2. For the 25 days beginning May 18, shoot length increased 5.4 fold, leaf number 2.1 fold, and shoot weight 9.6 fold. 3. Yield from latent buds was about 5% of total yield. 4. Length of new shoots decreased 26% due to frost. Urea spray and Jambi increased shoot length 10% and 1%, respectively, compared to control. 5. Leaf number decreased by 5.2 due to frost. Urea spray and Jambi increased leaf number 18% and 5%, respectively, compared to control. 6. Weight of new shoot was decrease 43% by frost. Urea and Jambi spray increased shoot weight 7% and 6%, respectively, compared to control. 7. Net leaf yield decreased 47% due to frost. Urea spray and Jambi increased left yield 7% and 5%, respectively, compared to control. 8. Yield in an undamaged plot was 1,587kg, damaged 932kg, 1,070kg in urea spray, and 1,033kg/10a in Jambi spray. Yield of frost damaged plots was 59% of undamaged. Foliar spray increased this to 68% of undamaged. 9. Yield increased 3.5% daily by with postponement of harvest. Yield of four days postponement was expected 73% of undamaged. Urea spray with 4 days postponement expected to be increased this to 82% of undamaged.

• Journal of Bio-Environment Control
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• v.20 no.1
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• pp.45-49
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• 2011

This research was carried out to investigate frost damage of mulberry tree (Morus alba) according to topographic characteristics in Buan province. The first bud-break, leafing, blooming and harvest date of mulberry tree in 2010 were two, four, fourteen and eight days later than those in 2009, respectively. These results were that daily mean temperature during March and April in 2010 were lower than those in 2009 by $2.3^{\circ}C$ and $2.4^{\circ}C$. Frost damage of orchards at flat-bottomed valley, flat near hill and lake, and plain were 50.0%,12.0%, and 4.2%, respectively. Also, frost damage of branch of below 15 mm in diameter was serious than that of branch over 16 mm, but orchard at flat-bottomed valley was high as the range of 46.2~54.0%. These results in 2010 were caused by occurrence of below zero temperatures in leafing stage. Since then, many shoots came out at accessary bud on proximal and the top part of the branches. Therefore, frost damage of mulberry tree in Buan province in 2010 was caused by occurrence of below zero temperatures on April and topographic characteristics of orchard.

• Journal of the Korean Geographical Society
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• v.43 no.6
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• pp.824-842
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• 2008

The main objective of the study was to analyze the weather conditions of frost occurrence for protecting crops against frost damage in Korea. The primary data used for the analysis of meteorological characteristics of frost occurrence days are the airmass pattern, minimum temperature, grass minimum temperature, daily temperature range, relative humidity, minimum relative humidity, mean wind speed in autumn and spring. Frost often occurs when the migratory anticyclone passes the southwest of Korea. The importance of grass minimum temperature measurements for agricultural purposes has previously been recognized. The grass minimum thermometer is capable of detecting ground frosts which are often not recorded by the minimum thermometer. The minimum temperature of frost occurrence days is above $0^{\circ}C$ in the coastal area, but the grass minimum temperature of frost occurrence days is below $0^{\circ}C$ in the whole area. The daily temperature of frost occurrence days is about 9 to $12^{\circ}C$ in the coastal area and is over $14^{\circ}C$ in the inland area. The minimum relative humidity of frost occurrence days is about 30 to 50%. The mean wind speed of frost occurrence days is less than 2m/sec.

• The Korean Journal of Applied Statistics
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• v.35 no.4
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• pp.543-552
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• 2022

When frost occurs, crops are directly damaged. When crops come into contact with low temperatures, tissues freeze, which hardens and destroys the cell membranes or chloroplasts, or dry cells to death. In July 2020, a sudden sub-zero weather and frost hit the Minas Gerais state of Brazil, the world's largest coffee producer, damaging about 30% of local coffee trees. As a result, coffee prices have risen significantly due to the damage, and farmers with severe damage can produce coffee only after three years for crops to recover, which is expected to cause long-term damage. In this paper, we tried to predict frost using frost generation data and weather observation data provided by the Korea Meteorological Administration to prevent severe frost. A model was constructed by reflecting weather factors such as wind speed, temperature, humidity, precipitation, and cloudiness. Using XGB(eXtreme Gradient Boosting), SVM(Support Vector Machine), Random Forest, and MLP(Multi Layer perceptron) models, various hyper parameters were applied as training data to select the best model for each model. Finally, the results were evaluated as accuracy(acc) and CSI(Critical Success Index) in test data. XGB was the best model compared to other models with 90.4% ac and 64.4% CSI, followed by SVM with 89.7% ac and 61.2% CSI. Random Forest and MLP showed similar performance with about 89% ac and about 60% CSI.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.448-455
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• 2020

This study was carried out to investigate reduction of the frost damage using the mesh net used for the purpose of non-bagged cultivation. A device measuring the weight of frost was developed and installed in both the control and the experimental, and the effect of frost reduction was evaluated with their weights. As a result, weight of frost in the control was reduced from 37% to 59% with mesh net on the day the frost was observed. In addition, the device for automatically observing the amount of frost was developed and the height of the windbreak of the frost measuring device was determined to be 30 cm through wind tunnel experiment. The results of this study are expected to reduce frost damage during the flowering season of fruit trees by installing mesh net and it is expected to be used as basic data for agricultural use of mesh net.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.11a
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• pp.227-229
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• 2000

• Korean Journal of Agricultural and Forest Meteorology
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• v.26 no.1
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• pp.63-74
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• 2024

In agriculture, frost can be devastating, which is why observation and forecasting are so important. According to a recent report analyzing frost observation data from the Korea Meteorological Administration, despite global warming due to climate change, the late frost date in spring has not been accelerated, and the frequency of frost has not decreased. Therefore, it is important to automate and continuously operate frost observation in risk areas to prevent agricultural frost damage. In the existing frost observation using leaf wetness sensors, there is a problem that the reference voltage value fluctuates over a long period of time due to contamination of the observation sensor or changes in the humidity of the surrounding environment. In this study, a datalogger program was implemented to automatically solve these problems. The established frost observation system can stably and automatically accumulate time-resolved observation data over a long period of time. This data can be utilized in the future for the development of frost diagnosis models using machine learning methods and the production of frost occurrence prediction information for surrounding areas.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.32-37
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• 2013

Relationships among climate changes, early frost, and fruit growth were studied during the final month to harvest of late-maturing 'Fuyu' persimmon (Diospyros kaki) to assess the changes in fruit characteristics during this critical period. The heavy frost on Nov. 16 defoliated more than 70% of the leaves, but with little damage on the fruits. However, all the leaves were defoliated by the heavy frost on Nov. 20, and all the fruits were cold-damaged by $-3.3^{\circ}C$ on Nov. 21. Fruit weight increased by 8-25 g per week from Oct. 25 (142 days after full bloom) to Nov. 15, reaching to 250 g, but it decreased by 3-4 g per week after the frost. Hunter a value of fruit skin gradually increased until the last harvest on Nov. 29 with a temporary halt in early Nov. when temperature was high, whereas fruit firmness rapidly decreased after the frost on Nov. 21. Fruit soluble solids were $15.7-16.1^{\circ}Brix$ for the final month. When some branches were covered with non-woven fabrics to avoid direct contact with frost, the fruits on the branches were not visually damaged by the low temperature although 40-60% of their leaves were defoliated on Nov. 16. However, low temperature on Nov. 20 and 21 defoliated all the leaves, causing cold damage on the fruits. There was a highly significant correlation between the fruit diameter and its weight ($R^2$ = 0.73-0.91). So, the regression equations could be used to estimate weight from diameter of the fruits sampled from the branches with the non-woven fabrics. The calculated fruit weight reached to a maximum of 240 g on Nov. 15. Daily increases in fruit weight were 1.1-2.5 g from Oct. 25 to 31, 1.9-3.5 g from Oct. 31 to Nov. 7, and 1.4-1.6 g from Nov. 7 to 12. However, fruit weight decreased by 0.3-1 g per day after the cold damage on Nov. 21. The results indicate that the most appropriate harvest time could be dependent on relationship of fruit growth to climate.

• Journal of the Korean Geographical Society
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• v.41 no.3 s.114
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• pp.361-372
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• 2006

The purpose of this paper is to analyze temporal trends and spatial distribution of frost occurrence days using 54 weather stations under the Korea Meteorological Administration during the recent 30years ($1971{\sim}2000$). The frost occurrence days in the middle inland area was more than in the coastal area, but the period of free-frost days in the coastal area was longer than that in the middle inland. In the southern and eastern coastal areas, the frost day was more than in the western coastal area. The distribution of the first frost day was similar to that of the last frost day. The first frost day in the coastal area appeared a month later than that in the middle inland. The last frost day in the coastal area appeared $20{\sim}25$ days later than that in the middle inland. At most of stations which the first frost day was getting delayed and the last frost day earlier, the frost occurrence days showed a decreasing trend. However, in some stations, the frost occurrence day was increasing. As the frost days in October, March and April at some stations showed an increasing trend, the damage due to the frost might be increased in some areas in South Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.2
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• pp.83-94
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• 2022

In order to actively prepare to frost damage that occurs in the process of growing crops, the spatial and temporal distribution of frost occurrence in South Korea was derived using frost observation data from 20 regions over the past 21 years (2000~2020). The main products are the number of frost days, first frost day, and last frost day by region. And the climatic trends of these results were identified by performing the Mann-Kendall trend test and Sen's slope estimator. In South Korea, a lot of frost occurs in the inland area to the west of the Taebaek and Sobaek Mountains. Relatively closer to the coastal area, the number of frost days is small, the first frost day is slow, and the last frost day is early. The east coast region has fewer frost days, the first frost day is later, and the last frost day is earlier than the west coast region. The southern sea, the southeastern sea region, and the island region rarely experience frost. As a result of the annual time series trend analysis, although South Korea is a country where climate warming is progressing, there was no trend in reducing the number of frost days and slowing the first frost day, and it was found that the last frost day is delayed by 0.5 days per year.