| dc.contributor.author | Pooran-DeSouza, Scmwattie | |
| dc.description.abstract | Rhizoctonia root rot caused by Rhizoctonia solani (Kuhn), is the most important
problem faced by sugarbeet (Beta vulgaris L.) grm.vers in North Dakota and Minnesota.
Research was conducted that may be used to manage the disease. Six cultivars from 2 to 8-
leaf stage were evaluated for their ability to withstand infection after soil inoculation by R.
solani AG 2-2 IIIB. All leaf stages of the cultivars evaluated were susceptible to R. solani.
Sugarbeet plants at the 2-leaf stages were most susceptible and had significantly higher
root rot severity than plants at the 4, 6 and 8-leaf stages. Cultivars Crystal 454 and Hillshog
3035 had the lowest root rot severity of the cultivars evaluated, but root rot severity was
still greater than 50%. The cultural practice of planting early in soils when the temperature
is about 10°C at the 10 cm depth may result in plants being older and more tolerant by the
time the pathogen becomes infective at warmer soil temperatures. However, the fact that all
plant stages were susceptible to R. solani may require additional protective measures in
highly infested fields with a knovm history of severe Rhizoctonia root rot.
During greenhouse research, it was observed that azoxystrobin fungicide applied as
a hypocotyl drench provided excellent control of Rhizoctonia root rot. It is recommended
that growers use a foliar banded application of azoxystrobin at the 4-leaf stage to control
Rhizoctonia root rot. Research was conducted to compare and evaluate the effect of foliar
band and hypocotyl drench applications of azoxystrobin to control R. solani. The study showed that foliar banded and hypocotyl drench applications of azoxystrobin provided
significantly similar disease control under conditions that were ideal for disease
development However, disease from plants with a hypocotyl drench application was not
significantly different than the non-inoculated control suggesting that further testing should
be done to determine the utility of this application methodology in field conditions.
Research was conducted to determine the best time to apply azoxystrobin fungicide
for effective R. solani control relative to timing of soil inoculation. Sugarbeet hypocotyls
were drenched at the 4-leaf stage at 0, 7, 14, 21, and 28 days pre-inoculation and at 0, 3, 10,
14, and 21 days post-inoculation. Azoxystrobin applications prior to inoculation resulted in
significantly lower root rot compared to fungicide applications at post inoculation. Among
the post inoculation applications, treatments where the fungicide was applied within 2
hours provided the best disease control. Fungicide application at pre-inoculation provided
effective control at all timings evaluated: This research reinforces the need for azoxystrobin
application before infection to control the disease in field conditions.
The depth at which R. solani caused root rot infection of sugarbeet was studied after
burying R. solani AG 2-2 IIIB inoculurn at depths of 2.54, 7 .62, and 12. 7 cm. R. solani AG
2-2 IIIB infections occurred at all depths of inoculation. However, inoculum buried at 2.54
cm depth had significantly higher root rot severity than inoculum buried deeper. Root rot
symptoms were prevalent on the upper portion of the sugarbeet root just below the soil line
irrespective of the depth of inoculurn placement. This suggests that the upper part of the
root below the soil line is most vulnerable to R. solani infection. Consequently, in the soil
fungicide application should target the root area just below the soil line for effective
disease control. | en_US |
| dc.publisher | North Dakota State University | en_US |
| dc.rights | NDSU policy 190.6.2 | en_US |
| dc.title | The Impact of Plant Age, Fungicide Application Methodology and Timing, and Depth of Soil Inoculation on Infection by Rhizoctonia solani on Sugarbeet. | en_US |
| dc.type | Thesis | en_US |
| dc.date.accessioned | 2024-02-02T16:08:37Z | |
| dc.date.available | 2024-02-02T16:08:37Z | |
| dc.date.issued | 2010 | |
| dc.identifier.uri | https://hdl.handle.net/10365/33643 | |
| dc.subject.lcsh | Sugar beet -- Diseases and pests -- Control. | en_US |
| dc.subject.lcsh | Rhizoctonia solani -- Control. | en_US |
| dc.subject.lcsh | Root rots -- Control. | en_US |
| dc.rights.uri | https://www.ndsu.edu/fileadmin/policy/190.pdf | en_US |
| ndsu.degree | Master of Science (MS) | en_US |
| ndsu.college | Agriculture, Food Systems and Natural Resources | en_US |
| ndsu.department | Plant Pathology | en_US |
| ndsu.program | Plant Pathology | en_US |
| ndsu.advisor | Khan, Mohamed F. R. | |
