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Trace amounts of acrylamide are present in many foods cooked at high temperatures. Acrylamide in processed potato products is formed from reducing sugars and asparagine and is a product of the Maillard reaction; this reaction typically occurs during frying and baking of food products. Processed potato products, including fries and chips, are relatively high in acrylamide compared with other foods and contribute substantially to dietary acrylamide. Acrylamide content in potato products is strongly affected by processing conditions, potato variety, field management, environmental conditions during tuber growth, and tuber storage conditions. Numerous approaches have been described that could potentially reduce the acrylamide content of potato products, but many influence finished product sensory attributes and may be difficult to implement. Health concerns related to acrylamide in food center on its role as a potential carcinogen. Research using feeding studies with rodent models and epidemiological studies with humans are ongoing and are likely to provide future guidance for acceptable amounts of acrylamide in food.

Global consumption of potato (Solanum tuberosum L.) continues to shift from fresh potatoes to value-added processed food products such as potato chips. One serious tuber quality defect of chipping potatoes is stem-end chip defect, which results in chips with dark-colored vasculature and adjacent tissues at the tuber stem end after frying. In this study, treatments of moderate water deficit for 14 days, alone or in combination with moderate daytime heat stress at 30 °C, as well as varied chemical maturity of tubers at harvest were imposed in controlled-environment greenhouses. Only temperature stress for 14 days in 1 of 2 years significantly changed the occurrence of stem-end chip defects. Water deficit for 14 days and chemical maturity of tubers harvested at four time points from early tuber bulking to after vine senescence did not have significant impacts on defect incidence or severity. Biochemical analyses showed that more severe defects with larger areas of dark color on the stem end of chips were associated with increased amounts of tuber stem-end glucose and increased stem-end acid invertase activity. We conclude that moderate environmental stresses and maturity of tubers at harvest are not sufficient to consistently cause stem-end chip defect.

There is significant interest from vegetable processors, growers, and consumers in organic sweet corn (Zea mays) production. Organic nitrogen (N) management is particularly challenging in high N consuming crops such as sweet corn because of the low N content and low N to phosphorus (P) ratios of organic soil amendments. Various management programs were compared to determine the optimal combination of soil amendments and green manure crops for organic sweet corn production. Alfalfa (Medicago sativa), rye (Secale cereale), and field pea (Pisum sativum) were used as green manure crops. Composted poultry manure and a high N content organic fertilizer were used as organic amendments. Ammonium nitrate was used in a conventional management program for comparison. Treatments were designed to deliver a full rate of N (150 lb/acre), a half rate of N (75 lb/acre), and to limit the amount of P applied. Phosphorus can become a source of pollution when applied to erodible soils, particularly when soils already contain excessive P. Sweet corn yield in many of the organic programs was highly variable among years while the yield was more consistent in the conventional program. This was attributed to differences in organic N mineralization in both the green manure crops and the amendments. The most stable yield from an organic treatment, among years, was achieved using the commercially available organic N fertilizer. Commercially available amendments were costly, and although organic sweet corn received a premium price in years when organic yields were lower, profit was reduced by the high cost of N management.

Environmental stress during the growing season can reduce the quality of stored Solanum tuberosum (potato) tubers. Changes in greenhouse grown Russet Burbank tuber water potential and tuber composition following periods of moderate drought, heat, or drought and heat stress were characterized. Decreased leaf and tuber water potentials were observed at the end of stress treatments. Decreased tuber water potential caused dramatic declines in tuber pressure potential. Tuber sucrose content increased with the severity of stress. Changes in tuber glucose and malic acid contents were also observed. Stress during early tuber bulking had a larger effect on tuber sugars at the end of the stress period than stress during late bulking. Stem-end glucose concentration of tubers at harvest after vine senescence was greater in tubers from plants stressed at early tuber bulking compared to late bulking.

Maleic hydrazide has been reported to increase the proportion of US #1 (> 113 g) potatoes and lower the concentration of reducing sugars of potato tubers in storage, thus improving fry color. We tested the effect of three different application timings of maleic hydrazide on total and US #1 yields, average tuber weight, “b” and cull yields, and tuber glucose and sucrose concentrations at harvest and after storage. The cultivars evaluated included two round white potatoes, Atlantic and White Pearl, and one russeted cultivar, Freedom Russet. Maleic hydrazide had no effect on total yield or US #1 yield for either round white cultivar, but increased both total and US #1 yield for Freedom Russet. In addition, maleic hydrazide reduced average tuber weight for Atlantic. These yield effects were dependent on application timing. Maleic hydrazide had no effect on yield of cull tubers. Maleic hydrazide did not lower glucose or sucrose concentrations at harvest or during storage for any of the cultivars tested, and increased Atlantic tuber glucose concentration at harvest. In summary, the effect of maleic hydrazide on yield was cultivar-dependent and maleic hydrazide did not reduce tuber glucose concentrations for any cultivar tested.

Uncontrolled kochia plants that regrow after small-grain harvest can produce substantial numbers of seeds. An average of 4,100 seeds per plant were produced between harvest (late July to mid August) and the first killing frost (late September) at three locations in Montana. Field experiments were conducted to determine the optimal timing of postharvest herbicide applications to prevent kochia from producing viable seeds. Herbicide treatments were applied at three timings from late August to mid September. The most effective treatments were glyphosate (631 g/ha) and paraquat (701 g/ha) applied at the second application timing (late August to early September). These treatments reduced kochia seed production by 92% or greater at each site. Kochia regrowth by this time had sufficient leaf area for herbicide absorption, but few viable seed had been produced. Herbicide treatments at the first and third application timings were generally less effective and more variable in reducing kochia seed production. Sulfentrazone (157 g/ha) and 2,4-D (561 g/ha) were not as effective at reducing seed production as other herbicide treatments.

Glyphosate-resistant crop species have increased in number over the past decade as growers eagerly adopt this simple and effective weed management technology. Glyphosate-resistant wheat cultivars are being developed and may soon be available to growers. The objective of this paper is to discuss the pest management implications of glyphosate-resistant wheat in the western United States, a region stretching from the Great Plains to the Pacific Ocean that produces more than 80% of the nation's wheat crop. The benefits of glyphosate-resistant wheat include: (1) improved weed control, particularly of difficult-to-control weeds, such as winter annual grasses belonging to the Aegilops, Avena, Bromus, Lolium, Poa, Secale, and Setaria genera; (2) an ability to control weeds resistant to currently available wheat herbicides; (3) an extended application window for control of late-emerging weeds; and (4) improved crop safety. Although these benefits are not to be minimized, they need to be considered in the light of ...

Field studies were conducted in 1995 and 1996 to determine the rate response of velvetleaf seedling survival, seed production, and shoot biomass to postemergence herbicides in corn and soybean. Dicamba and imazethapyr were applied to corn and soybean, respectively, at 1, ½, ¼, ⅛, 1/16, 1/32, and 0× labeled rates. Velvetleaf mature plant density was linearly related to seedling density, thus indicating that seedling survival was not density dependent, even after seedling densities exceeded 150 plants m−2. Seedling survival as influenced by herbicide was described by a dose–response curve in corn and soybean. In corn, seedling survival ranged from 0 to 48% across herbicide treatments and years. Seedling survival was greater at the ½× or lower herbicide rates than at the 1× rate. In soybean, maximum seedling survival was 61 and 14% in 1995 and 1996, respectively, and minimum seedling survival was less than 2% in each year. Seedling survival was less in 1996 than in 1995 because velvetleaf was infect...

Quality and storability of potato tubers harvested for storage are affected by their chemical, physiological and physical maturity. The sucrose concentration in potato tubers is indicative of the chemical maturity of the crop and of the potential processing quality of the crop after storage. High reducing sugar concentrations result in undesirable discoloration of Med potato products. Sucrose does not directly contribute to the discoloration of tuber tissue upon frying, but it influences reducing sugar concentrations during storage. Physiologically mature tubers have maximized their dry matter content, resulting in high specific gravities that are desirable for most aspects of potato processing. We examined the effect of different planting and vine-kill dates on the sucrose and glucose concentrations and specific gravity of five processing potato cultivars grown at Hancock, WI, during 2002 and 2003. Although planting date usually had no effect on sugar content at harvest, sucrose and glucose content decreased with earlier planting date at vine-kill in one of two years. Greater sucrose and glucose concentrations and specific gravities were found at harvest with later vine-kill dates. Of particular concern for processing, stem-end glucose concentrations consistently exceeded bud-end glucose concentrations for all cultivars, regardless of the cultural parameters implemented. Physically immature tubers have poor skin set and are prone to skinning and mechanical damage during harvest, which renders them more vulnerable to dehydration and infection by rotting pathogens in storage. Skin set of ‘Russet Burbank’ tubers in 2003 improved with late vine-kill timing. Our data indicate that chemical maturity does not necessarily correlate with either physiological or physical maturity in processing cultivars, thus rendering the use of cultural practices to improve tuber maturity at harvest problematic.

Sugar-end defect is a tuber quality disorder and persistent problem for the French fry processing industry that causes unacceptable darkening of one end of French fries. This defect appears when environmental stress during tuber growth increases post-harvest vacuolar acid invertase activity at one end of the tuber. Reducing sugars produced by invertase form dark-colored Maillard reaction products during frying. Acrylamide is another Maillard reaction product formed from reducing sugars and acrylamide consumption has raised health concerns worldwide. Vacuolar invertase gene (VInv) expression was suppressed in cultivars Russet Burbank and Ranger Russet using RNA interference to determine if this approach could control sugar-end defect formation. Acid invertase activity and reducing sugar content decreased at both ends of tubers. Sugar-end defects and acrylamide in fried potato strips were strongly reduced in multiple transgenic potato lines. Thus vacuolar invertase silencing can minimize a long-standing French fry quality problem while providing consumers with attractive products that reduce health concerns related to dietary acrylamide.