PAA Meeting Highlights

Research abounds in North Carolina meeting

Published in the November 2011 Issue Published online: Nov 07, 2011
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Wilmington, N.C., was the site for the 95th Annual Meeting of the Potato Association of America, held at the Hilton Wilmington Hotel in August. Here are some of the highlights:

K.G. Haynes, USDA/ARS.

Foliar Resistance to Late Blight is Improved Through Recurrent Maternal Half-Sib Selection in a Diploid Hybrid Solanum phureja-S. stenotomum Population with No Reduction in Additive Genetic Variance Through Two Cycles of Selection. Foliar resistance to late blight was found in a hybrid population of the cultivated diploid species Solanum phureja-S. stenotomum (phu-stn). The objective of this study was to determine if resistance to late blight could be improved by recurrent maternal half-sib selection in the phu-stn population. Recurrent maternal half-sib selection continues to improve the levels of resistance to late blight in this diploid population with no adverse affect on the amount of additive genetic variance. Additional improvements for late blight resistance are likely to occur if this approach is continued.

D.H. Lambert, University of Maine.

Effectiveness of Alternative Fungicides for Prevention of Late Blight (Phytophthora infestans) Transmission in Potato Seed. Late blight-infected seed may remain viable during winter storage. During handling and subsequent storage of cut seed, healthy potato pieces may be infected by spores or mycelium from such tubers. Seven Oomycete-specific fungicides were compared with the two fungicides currently labeled for seed treatment, mancozeb and cymoxanil. None of the five systemics delayed or reduced shoot emergence or gave indications of significant bacterial growth problems. They all appear to be effective candidates either for inclusion in potato seed protection formulations or for tank mix partners with liquid seed treatments and would complement products lacking Phytophthora activity.

Alexander D. Pavlista, University of Nebraska.

Impact of Limited Irrigation and Nitrogen Levels on the Chip Potato Atlantic. A 3-year study began in 2009 to determine periods during potato production in which limiting irrigation by six inches would least impact market yield of the chipping cultivar Atlantic. Planted in May 2010, Atlantic was exposed to full irrigation, 61 cm total adjusted for rain, or to a limited irrigation regime when 15 cm of water were withheld, early season, late season and some early and some late. Stress between three and eight weeks after emergence (WAE) resulted the greatest yield loss. Increased N partially overcame yield losses. Limiting water between 5 and 8 WAE resulted in lower tuber specific gravity, darker chips and greater incidence of common scab. These results will promote a better understanding of water and N interaction on market yield of potato in semi-arid environments. Growers forced to reduce irrigation of potato will know better how to manage the available water.

Mary Jo Frazier, University of Idaho.

The Effects of Seed Potato Exposure to Low-rates of Chlorpropham on Field Performance. Chlorpropham (CIPC) is a highly effective sprout inhibitor in potato. Due to trucking and temporary storage issues, seed potatoes are sometimes inadvertently exposed to CIPC. This 2-year research study was undertaken to document the effects of low rates of CIPC application or contamination on emergence, yield, and grade in the subsequent crop. In 2010, total yield decreased from 36 percent (1.2 ppm CIPC) to 94 percent (10 ppm CIPC) of the untreated control. Harvested size profile was significantly altered by CIPC applications. These dramatic reductions in yield reinforce the importance of avoiding all potential for CIPC contamination of seed and documents consequences of planting commercial potatoes treated with CIPC for export purposes.

Harlene M. Hatterman-Valenti, North Dakota State University.

Glyphosate Drift Injury to Three Red Potato Cultivars. Field research has been conducted the past four years at the NPPGA Dryland Research site to evaluate potato injury from simulated glyphosate drift. The pattern of yield reduction (current season or following season) from glyphosate drift to specific growth stages was similar to those observed with `Russet Burbank' under irrigation. Glyphosate drift to red cultivars may cause greater losses due to visual symptoms and the inability for most graders/sorters to eliminate visually unattractive tubers. Further research is focusing on cultivar sensitivity for russet types as well as round white cultivars used for chips.

N. Olsen, University of Idaho.

The Use of Diabetic Test Kits to Assess Glucose Concentrations in Potatoes. Fresh market growers and packers are concerned with tuber glucose content due to the increased demand for fresh-cut fries. The objective of this study was to evaluate currently available diabetic glucose test kits for accuracy and reliability in analyzing tuber tissue glucose levels. A total of 76 tubers were evaluated using two brand-name diabetic glucose meters and disposable test strips. These diabetic test meters displayed error readings for tubers with extremely low and high glucose levels. There appears to be value in utilizing diabetic test strips to follow the general level of glucose in stored potatoes or after transport and for retail markets to assess whether potatoes are acceptable for fresh-cut fries.

G.A. Porter, University of Maine

Soil and Fertilizer Effects on Blackspot Bruise Susceptibility, Specific Gravity, and Chip Color of `Atlantic' Chipping Potatoes. Research conducted at Aroostook Research Farm, Presque Isle, Maine, was designed to determine whether potato yield and quality could be optimized by controlling total potassium supply from soil and fertilizer sources. Yield increased linearly with total K availability, while hollow heart incidence decreased in two of three seasons. Blackspot bruise susceptibility and specific gravity decreased linearly with increasing total K availability and tuber K concentration. The information gained from this study will be used to help assure that soil-test recommendations provide a reasonable balance of costs, yield and processing quality.

Paul C. Bethke, USDA/ARS University of Wisconsin, Madison.

Atmospheric Ethylene Concentrations in Research and Commercial Potato Storages. In order to better understand the impact ethylene may be having on potato tuber quality and how it may influence potato storage management, scientists monitored the ethylene concentration in the return air in research storages at the Wisconsin Potato and Vegetable Research Storage Facility and in commercial potato storages. Most frequently, the observed amounts of ethylene were less than 50 ppb. The significance of these findings will be discussed in the context of recommended best practices for potato storage management.

CH Wohleb, Washington State University.

A Regional Sampling Network for Insect Pests of Potato in the Columbia Basin of Washington. A regional sampling program for insects was established in the Columbia Basin of Washington to provide potato growers with current information about the size and location of important insect pest populations. The sampling network functions as an early warning system that prompts growers to intensify scouting in and around their potato fields when pests are identified in the area. Results from the sampling network are presented to growers in weekly "potato pest alerts" sent via e-mail. The results are also posted on the project website, which includes area maps showing the insect counts at each location, graphs of insect population trends and pest management recommendations. At the end of each season, insect population trends are evaluated and reported to potato growers

L.K. Woodell, University of Idaho.

Utilizing Pathogen Detection Test Kits for Rapid In-field Potato virus Y Diagnosis. The ability to quickly identify PVY-infected plants in the field using a serological test would benefit growers, fieldmen, extension and research personnel. The objectives of this study were to evaluate accuracy and identify strengths and weaknesses of commercially available serological test kits for PVY and PVY"N" virus detection in foliar plant tissue. Results indicated the kits tested were reliable and accurate, but some limitations were apparent. In this study, using a general PVY test kit identified infection by common strains of PVY.

S.Y.C. Essah, Colorado State University.

Maximizing Nitrogen Use Efficiency for Optimum Tuber Yield and Quality of a New Colorado Potato Cultivar.

Field studies were conducted in the San Luis Valley of Colorado to evaluate the effect of nitrogen application rate and in-season N application timing on tuber yield and quality of a new advanced russet selection CO99053-3RU. Results of this study indicate that for an economically sustainable and environmentally responsible production of CO99053-3RU, available N rate should not exceed 122 kg N ha-1.

Felix M. Navarro, University of Wisconsin, Madison.

Tundra: A New Long Storage Potato Chipping Variety with Consistently High Specific Gravity. Tundra, previously known as W2310-3, was selected from a population of Pike x S440 made in 1995. This variety has low tuber internal defects. The glucose and sucrose profile of Tundra out of 7.2 degrees C and 10 degrees C is better than Snowden, especially after six or seven months in cold storage. Glucose and sucrose typically occurs one month or more for Tundra as compared to Snowden. In addition, Tundra has strong vine type, and tolerance to Verticillium wilt and early blight similar to Snowden. Scientists expect that Tundra provides a better choice for chip potato growers that require longer storage ability and more consistently higher specific gravity than Snowden

Grant Mehring, North Dakota State University.

Weed Suppression with Cover Crops in Irrigated Potatoes. A study was conducted to determine if cover crop treatments including no cover crop, winter triticale, winter rye, turnip/radish and winter rye/canola were more effective than current weed control in organic potato. The three cover crop desiccation methods and subsequent potato planting presented mechanical difficulties, as potatoes are typically planted into well-worked soil, as opposed to no-till or high residue soil. It was found that these mechanical differences did not result in a yield reduction, as yields were similar throughout all treatments. The use of cover crops to control weeds in organic potato production shows promise as an alternative method for producers looking for sustainable weed control methods.

J.E Munyaneza, USDA-ARS, Yakima Agricultural Research Laboratory.

Impact of the Potato Psyllid and Zebra Chip Disease on Potato Seed Quality. Zebra chip (ZC), a newly emerging and economically important disease of potato in southwestern United States, Mexico, Central America, and New Zealand, is associated with the bacterium "Candidatus Liberibacter solanacearum" transmitted by the potato psyllid, Bactericera cockerelli.Studies were conducted to increase the understanding of the role of the potato seed in ZC spread. The study results provide further evidence that ZC-infected potato tubers do not play a major role in ZC disease spread as they do not sprout. If they do, they usually produce ZC-free plants.