• Research in Plant Disease
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• v.10 no.2
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• pp.142-144
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• 2004

Effect of potassium phosphonate on control of potato basal stem rot caused by Pythium myriotylum in hydroponics system was evaluated at spring and fall cultivation in Jeju island in 2001. Potassium phosphonate 200 ppm treatment, which was directly supplemented into the nutrient solution, showed 90.5%, and 100 ppm treatment showed 50.5% control value in spring cultivation. Fall cultivation, potassium phosphonate 200 ppm treatment showed 100%, and 100 ppm treatment showed 69.9% control value. Potassium phosphonate 200 ppm treatment, basal stem rot of potato started to develop 10 days ofter inoculation into the hydroponics system showed 8.0% in infection rate. Potassium phosphonate 100 ppm treatment, after 5 days showed 10.0%, and after 10 days showed 20.0% infection rate, but the non-treated was after 5 days showed 56.7%, and after 10 days showed 96.9% infection rate.

• Journal of Ginseng Research
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• v.33 no.4
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• pp.311-315
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• 2009

Potassium phosphonate inhibited less mycelial growth of Phytophthora cactorum in vitro than metalaxyl-M. But the net protection rate in leaflet test and whole plant pot test was greater in potassium phosphonate than metalaxyl-M. P. ginseng appeared to have an induced resistance against P. cactorum with phosphonate around 50~100 ppm.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.142-146
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• 2002

The effect of potassium phosphonate ($KH_2PO_3 or $K_2 HPO_3$) on the control of Phytophthora root rot of lettuce was evaluated in a liquid hydroponic culture. Phosphonate 100 ppm strongly inhibited mycelial growth of Phytophthora species in vitro but did not affect normal growth of lettuce in a greenhouse test. Application of the chemical before infection showed over 94% control value, while it was less than 35% when applied after infection. In a field trial, phosphonate 100 ppm, which was directly supplemented into the nutrient solution, satisfactorily controlled the disease as it did not develop until 28 days after transplanting and remained at less than 2% infection rate at the end of cultivation. Meanwhile, in the control plot, the disease initiated at 7 days after transplanting and developed rapidly reaching over 70% infection rate at 28 days. Population density of the causal pathogen, R drechsleri, in a heavily infested farm was 22.0-25.0 cfu/100 ml of nutrient solution. However, it decreased to 1.3-2.0 cfu/100 ml at 7 days after treatment with phosphonate 200 ppm.

• YAKHAK HOEJI
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• v.34 no.1
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• pp.22-33
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• 1990

Aqueous solution of bis(2,4-diaminophenyl)phosphonate(APP) was very stable, especially below pH 2.0 and the red-color compound formed by the reaction of APP and $IO_3-$ was stable at room temperature. A simple and rapid spectrophotometric method for the determination of ascorbic acid, potassium antimonyl tartrate (PAT), and isonicotinic acid hydrazide (INAH) was established by the reaction of $IO_3-$ and these reducing drugs, and the absorbance measurements were made at 500 nm. In the reaction of $IO_3-$ and each of the reducing drugs, the conditions of pH were suitable below 2.5 for ascorbic acid, below 2.0 for PAT, and below 1.5 for INAH. Beer's law did hold in the range of $17.6{\sim}1549.9\;ug$ for ascorbic acid, $33.4{\sim}2871.8{\mu}g$ for PAT,and $6.9{\sim}548.6\;{\mu}g$ for INAH. Many common ingredients present in pharmaceutical dosage forms did not interfere. The average recoveries for ascorbic acid and INAH in pharmaceutical formulations were 99.8 $-100.3\;{\pm}\;0.2{\sim}0.4%$, $99.8\;{\pm}\;0.3%$, respectively.

• Research in Plant Disease
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• v.9 no.3
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• pp.179-182
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• 2003

Effect of potassium phosphonate on control of potato late blight was evaluated at two fields in Jeju island. The chemical showed 82.5% control value in field located at low seacoast with 100 m elevation, while dimethomorph copper oxychloride showed 75.9 % control value. However, its control value was only 40% in another field located at mid-hilly area with 300 m elevation, in which environmental conditions of high hummudity and often rainfall were favorable to the disease development. Application intervals of the phosphonate from 7 to 15 effectively suppressed the disease and did not show statistically different control values among the spraying intervals. Results indicated that phosphonate similarly or more effectively controls potato late blight than fungicide, however, its control value could be vared according to enviromental conditions for the disease development and 15-d spraying intervals ware sufficient to suppress ther disease.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.2
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• pp.114-119
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• 2022

The objective of this study was to determine phosphorus effects on drought stress-induced oxidative stress in Kentucky bluegrass. Drought stress was induced by reducing of water to plants in pots. Two types of phosphorus were applied as potassium phosphate (P) or potassium phosphonate (PA). Application of phosphorus was efficient to ameliorate the adverse effects of drought. Osmotic potential, total chlorophyll and carotenoid content were significantly decreased by drought stress, but was relieved by P or PA application. Superoxide (O₂^•-) concentration was significantly increased more than 14-fold under drought-stressed plants, was accompanied with increase of hydrogen peroxide (H₂O₂) and lipid peroxidation (MDA). However, malondialdehyde (MDA) was much less in P or PA applied plants under drought stress condition. Activities of catalase (CAT), ascorbate peroxidase (APX) and guaiacol-peroxidase (GPX) were largely increased by drought stress and its increase rate was much higher in P or PA applied plants except APX. These results indicate that drought stress-induced oxidative stress is alleviated by P or PA application due to the increase of activities of antioxidant enzymes.

• Research in Plant Disease
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• v.20 no.1
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• pp.31-36
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• 2014

Alternative spraying was developed using fungicides and potassium phosphonate to control watermelon powdery mildew (WPM) caused by Sphaerotheca fusca under greenhouse condition. In 2010 trial, a total of 9 combinations of 6 fungicides which are legally registered in Korea and currently used on watermelon farms were tested for the control efficacy against WPM. Though the combination of chlorothalonil (Chl)-myclobutanil (My)-fenarimol (Fen)-hexaconazole (Hex) was the most effective (82.6%) in the first-year trial, it had the problem that My, Fen and Hex have the same mode of action. Therefore, in the second-year trial to improve the fungicide combination and to reduce fungicide application, fungicides and potassium phosphonate (P) combinations were tested for WPM control using 500 ppm aqueous potassium phosphonate solution which is both eco-friendly and showing different mode of action from the fungicides tested. The P-My-Fen-Hex applied at 10-day intervals provided relatively high control (75.6%), whereas Chl-My-Fen-P provided 31.8% control. To improve the control, fungicides and P were applied at 7-day intervals in the third-year trial. Though Chl-My-Fen-Hex provided the highest control (89.6%), P-My-Fen-Hex also provided relatively high control (83.5%) compared to 65.9 % control with Chl-My-Fen-P, which suggests that Chl-My-Fen-Hex could be replaced with P-My-Fen-Hex for WPM control.

• Research in Plant Disease
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• v.14 no.2
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• pp.107-111
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• 2008

For the eco-friendly control of fruit rot of fig, disease incidences according to the cultural practices at 51 fig orchards in south coast area of Korea were surveyed in 2002, and the effect of soil mulch and potassium phosphonate on fruit rot of fig was evaluated from 2002 to 2004. Diseased fruits of fig orchards of open field, rain shading, and vinyl house were 33.3%, 7.5%, and 0%, respectively. Diseased fruits were rated at 34.6%, 35.7%, and 27% as the tree spacing of $2m{\times}2m,\;2m{\times}3m,\;and\;3m{\times}4m$, respectively. Among the soil mulching materials, barley straw showed disease incidence of 1.8% and 3.5% of diseased fruits compared to 42.1% and 48% of no mulching in 2002 and 2003, respectively. Diseased fruits in dark paper film mulching were recorded at 4.8% and 12% in 2002 and 2003, respectively, which were lower than those in dark polyethylene film mulching at 11.2% and 26.2%. When potassium phosphonate(1,000 ppm) was sprayed 3 times with 10 days intervals from the beginning of disease occurrence, disease incidences were rated at 3.0% and 2.0% in 2003 and 2004, respectively, which were much lower than those of control at 45.9 % and 39.3%.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1999.04a
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• pp.41.2-41
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• 1999

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.2
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• pp.120-126
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• 2022

The objective of this study was to determine effects of phosphorus on lignification and carbohydrate metabolism in Kentucky bluegrass under drought stress. Drought stress was induced by reducing of water to plants in pots. Two types of phosphorus were applied as potassium phosphate (PO₄^3-; P) or potassium phosphonate (PO₃^3-; PA) in drought-stressed plants. Drought had significant negative effects on plant growth, as revealed by reduced biomass of shoot. Drought-induced increase of lignin content was concomitant with the increase of phenylalanine ammonia-lyase (PAL). Soluble sugar content was highly increased but fructan content was largely decreased by drought stress. However, the application of phosphorus was efficient to ameliorate the adverse effects of drought. PA application improved reduced shoot growth and relative water content, and inhibited lignification synthesis with a reduction of PAL activity. P or PA application maintained soluble sugar and fructan content at similar levels to controls under drought stress. These results indicate that phosphorus application may mitigate the drought stress by inhibiting the lignification and promoting the fructan assimilation.