Simmons, Rhonda

Central Oregon Potato Extension Program, 2014

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Series/Report number: 
COARC2014
Abstract: 
Insect pests were monitored in potato fields to assess potential risk of disease transmission. Aphid, tuberworm moths, and potato psyllids were collected and counted weekly using water pans for aphids, delta traps for potato tuberworm and yellow sticky traps for psyllids. This information was distributed to growers, fieldman and industry representatives through the Potato Patches newsletter. During 2014 aphid numbers were moderately high at the beginning of the season, averaging fifteen to seventy-seven aphids per trap before decreasing to below twenty in mid-July, followed by a slight rebounded in mid-September. Potato tuberworm moths were found in very low numbers through the season. During 2014 the first recorded incidence of potato psyllid was detected in Jefferson County. Specimens were tested for the pathogen causing zebra chip, (Candidatus Liberibacter solanacearum), and all tested negative. Early blight prediction modeling and crop water use data provided helpful information for seed potato management. Weekly monitoring and reporting through the Potato Patches newsletter continues to be a significant source of information for integrated pest management in Central Oregon potato fields.

Evaluation of an Onion Soil Amendment to Reduce White Rot Sclerotia in Garlic

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Series/Report number: 
COARC2014
Abstract: 
White rot is one of the most important diseases of onion, garlic, and other Allium crops. The pathogen survives in the soil as sclerotia, which specifically germinates in response to chemical compounds elicited by Allium species. Onion soil amendment, a byproduct of onion processing activities, is a potential source of naturally occurring sclerotia germination stimulant compounds. The objective of this research is to determine the effectiveness of onion soil amendment, with and without tarping and fungicides, at reducing S. cepivorum populations in field soils. Field plots were established and treated with onion soil amendment or left untreated. One half of the plots were covered with tarps for 6 days after onion soil amendment application and the other half were left uncovered. Soils were sampled before treatment applications and periodically throughout the season to quantify the number of viable sclerotia in each plot. Garlic was planted and an in-furrow treatment of tebuconazole was applied to half of the plots. Significant effects of onion soil amendment or tarping were not observed and significant interactions were not detected (P > 0.05). The combined effects of onion soil amendment, tarping, and tebuconazole on white rot symptoms, marketable yield, and post-harvest sclerotia populations will be determined after harvesting garlic in 2015.
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