• Korean Journal of Weed Science
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• v.5 no.1
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• pp.50-55
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• 1985

Effects of weed removal time on maize growth and yield were evaluated in the fields dominated with Poligonum spp., Chenopodium album, Echinochloa crusgalli and Digitaria adsendens from 1982 to 1983 in Suweon. Weed removal treatments were as follows: (a) kept weedfree all season, (b) weeded at 10 day intervals after maize emergence but stopped weeding at 3,5,7,9 leaf stages, (c) weeds initially removed at 3,5,7 and 9 leaf stages and the plots then kept weed free, (d) weeds left all season. Maize kept weed free from maize emergence to 7 leaf stages showed no grain yield reduction due to competition from weeds emerging later, but weeding from emergence to 3 and 5 leaf stages reduced grain yield 46 and 44%, respectively, in 1982 and 29 and 18%, respectively, in 1983. Weeding at 3 leaf stage and thereafter did not influence grain yield but initial weedings at 5, 7 and 9 leaf stages reduced grain yield 10, 36, and 67%, respectively, in 1982 and 14,18, and 21%, respectively, in 1983. Responses of maize to weeding time in the dry matter yields were same as in the grain yields.

• Weed & Turfgrass Science
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• v.1 no.4
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• pp.24-30
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• 2012

This study was conducted to select the cover crops in organic apple orchard by estimating the coverage of each cover crops and time-periodic weed occurrence. Seeding of Festuca myuros and Trifolium repens showed high contents of soil organic matter and phosphorus as compared with control. Seeding of Trifolium sp., Hordeum vulgare and Secale cereal reduced relatively occurrence of weed in May and S. cereal among others showed the greatest effect in June. In July, seeding F. arundinaceae and Poa pratensis showed low coverage and a lot of weeds occurred in their field. Fifty one species were occurred as weeds and it needs to removal of high and broadleaf weeds such as Chenopodium ficifolium, C. album var. centrorubru and Humulus japonicus in spring to increase the rate of ground cover. P. pratensis having the lowest cover rate showed the similar dry weight of weeds as compared with control. Trifolium sp. and Persicaria hydropiper had a high correlation with contents of soil organic matter and C. album var. centrorubru had a correlation with contents of soil phosphorus by CCA analysis.

• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.2
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• pp.73-81
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• 2024

Recently, mobile manipulators have been utilized in agriculture industry for weed removal and harvest automation. This paper proposes a domain adaptive fruit detection method for harvest automation, by utilizing OWL-ViT model which is an open-vocabulary object detection model. The vision-language model can detect objects based on text prompt, and therefore, it can be extended to detect objects of undefined categories. In the development of deep learning models for real-world problems, constructing a large-scale labeled dataset is a time-consuming task and heavily relies on human effort. To reduce the labor-intensive workload, we utilized a large-scale public dataset as a source domain data and employed a domain adaptation method. Adversarial learning was conducted between a domain discriminator and feature extractor to reduce the gap between the distribution of feature vectors from the source domain and our target domain data. We collected a target domain dataset in a real-like environment and conducted experiments to demonstrate the effectiveness of the proposed method. In experiments, the domain adaptation method improved the AP50 metric from 38.88% to 78.59% for detecting objects within the range of 2m, and we achieved 81.7% of manipulation success rate.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.179-188
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• 2020

Weeding refers to the process of removing weeds around crop trees, which cause competition in nutrients, moisture, and light, and has a great effect on the early growth and survival of crop trees for establishing forest resources. This study was conducted to find out the timing and method of weeding that is the most suitable for the major afforestation species in national forests. We investigated (1) weeding time and frequency for each afforestation species and (2) the height of crop trees and the length of weeds. Up to 99% weeding operation was carried out until 5 years following afforestation. Pinus densiflora, Larix kaempferi, Chamaecyparis obtusa, Prunus sargentii, and Betula platyphylla plantations accounted for more than 70% of the total weeding sites. Once-a-year weeding process was conducted from late June to late July (67%), and twice-a-year weeding process was the highest in June-August by 31%. Most species were shorter than the weeds until the first and second year of planting, but the height of the crop trees was higher than that of the weeds by 48% in average from the third year. Therefore, from the third year of afforestation, except for some species, it is possible to reduce the cost of weeding operations while reducing nutrient competition by the weeds through the removal of weed sprouts, mainly woody weeds, rather than clear cutting. This study contributes to efficiently develop forest resource establishment while reducing operational costs through a detailed weeding schedule and species-specific method.

• Korean Journal of Weed Science
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• v.12 no.1
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• pp.52-60
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• 1992

There was no significant difference in the final germination percentages(Experiment 1-3) as affected by sunflower root exudates between the control and the treated for the test species. In general(Experiment 1), however, germination onset was delayed the treated bottles. Germination rate was, also, reduced for both radish(Raphanus sativus L.) and rice(Oryza sativa L.). Therefore, the germination index was low in the treated bottles but germination gradually increased with time in the greated bottles in all test species so that the final germination percentages were similar between treatments. The root exudates of sunflower had significant inhibitory effects(Experiment 1-3) on the lengths of the shoots and roots of all the test species. Fresh weight was also significantly reduced in all test species. Sunflower seedlings(Experiment 3) in the treated(with the XAD-4 resin column) were larger and healthier than those in the control (without XAD-4 resin column) because of the removal of allelochemicals. The fresh weight of sunflower seedlings was markedly inhibited by sunflower root exudates. These mean that sunflower probably is an autotoxic crop.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.36-43
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• 2010

Changes in runoff and soil erosion at slightly hilly erosive plots with pear trees over a three-year period were monitored under two distinct types of weed treatment by herbides : (1) pre-emergence herbicide with glyphosate; (2) post-emergence herbicide with paraquat. The numbers of rainfall events from June to Nov for three years of experimental periods were approximately 50 times in the plots having 5.5%to 10.2%slope at an altitude of 125 m. The steady-state infiltration rate was generally increased in the bare plot from which all weeds were removed while it was decreased in the herbicide treated plots and control. The runoffs from the control plot during the experimental periods were always less than those from plots of the herbicide-treated and the bare. The runoff under the same rainfall intensity was decreased in the order of bare, glyphosate, paraquat, and control. This results indicated that the removal time of weed by the different types of herbicides might influenced the runoff rate. For the first two years of the experimental periods, loss of fine fraction was much greater than that of coarse fraction while soil loss was correlated neither with total rainfall nor amount of runoff. The soil erosion rate under the same rainfall intensity was increased in the order of control, glyphosate, paraquat, and bare plot. However, there were not much differences in the soil loss for all plots under a relatively lower rainfall intensity less than 30 mm $day^{-1}$, resulting in rainfall intensity was important factor on soil erosion.