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AbstractPotato is the third most important staple food crop globally following rice and wheat. In the United States, potato is grown on approximately 410,000 ha with a farm-gate value of US$1,032 million. In Canada, potato is grown on approximately 134,000 ha with a farm-gate value of US$235 million. The objective of this manuscript, compiled by the Weed Science Society of America Weed Loss Committee, was to estimate potato yield loss caused by weed interference. Potato yield data from weedy and weed-free plots (or plots with >95% weed control) was obtained from researchers working on weed management in potato in the United States and Canada or from published manuscripts from 2000 to 2018. Potato yield loss from weed interference was 12% to 61% when no weed management tactics were implemented. The average yield loss for all states/provinces (where data was obtained) due to weed interference was 44%. Weed interference would cause a farm-gate loss of approximately US$465 million and US$61 in the United States and Canada, respectively, if weeds are not controlled. These results indicate that weed management is critical for successful potato production, and that an ongoing need for research exists on weed management in this crop.

ABSTRACT:The creation of attractive, sustainable wildflower meadows in private and public green spaces is becoming increasingly popular. Establishment failure rate for new meadow plantings can be very high, primarily because of the initial annual weed pressure. We proposed a 3-step grass-first establishment protocol based on plant augmentative succession principles: 1) spring planting of grass component species; 2) application of standard turf-appropriate weed-control methods; and 3) early fall overseeding or outplanting of forbs into the established grasses. This grass-first meadow establishment protocol was successful, regardless of standard weed-control method employed (mowing; 2,4-D application; or application of a three-way pre-mix containing mecoprop, 2,-4-D, and dicamba [Ortho Weed B Gon]). Among the weed-control treatments, weed density during the establishment year did not affect ultimate meadow establishment success, as long as weeds were controlled sufficiently to allow grass and forb survival. Seeding resulted in a greater density of forbs and, ultimately, an overall more aesthetically pleasing mix of flowering plants and grasses as compared to outplanting. Among the grasses in the species mix, slender wheatgrass (Elymus trachycaulus(Link) Gould ex Shinners [Poaceae]) was dominant. Among the forb species, 5 Asteraceae species persisted over the period of the study and contributed good color to the meadow plantings. An augmented succession protocol based on grass-first establishment will be valuable where native meadow plantings are desired for urban habitat development and beautification.

Field studies were conducted in 2008 and 2009 in Aberdeen, ID, Ontario, OR, and Paterson, WA to determine the effect of simulated glyphosate drift on ‘Ranger Russet’ potato during the application year and the crop growing the next year from the daughter tubers. Glyphosate was applied at 8.5, 54, 107, 215, and 423 g ae ha−1which corresponds to 1/00, 1/16, 1/8, ¼, and 1/2 of the lowest recommended single-application rate for glyphosate-resistant corn and sugar beet of 846 g ha–1. Glyphosate was applied when potato plants were at 10 to 15 cm tall (Early), or at stolon hooking (H), tuber initiation (TI), or during mid-bulking (MB). In general, the MB applications caused less visual foliar injury to the mother crop than earlier applications at ID or OR, and H applications at WA. Mother crop injury increased as glyphosate rate increased regardless of location, application timing, and rating date. U.S. No.1 and total tuber yields were usually related to the injury level resulting from glyphosate application timings and rates. Although injury to the mother crop from glyphosate applied at MB usually was the lowest compared to injury from other application timings, when daughter tubers from that timing were planted the following year, emergence, plant vigor, and yield was most detrimentally impacted compared with that of daughter tubers from other timing treatments. MB daughter tuber emergence was less than 30 % of the nontreated control tuber emergence while emergence of daughter tubers from the other treatments was 60 to 95 %. As rate of glyphosate applied to the mother crop increased, daughter tuber emergence decreased. When MB daughter tubers did emerge, plants were chlorotic and stunted as if the plants had been directly sprayed with glyphosate. Regardless of whether the daughter tubers had defects or not, results the following year were the same. Implications are that if a mother seed crop encounters glyphosate during bulking, injury may not even be noticeable on the foliage or the tubers, however, emergence, vigor, and yield of the crop growing the following year from the daughter tubers could be greatly impacted. En Aberdeen, ID, Ontario, OR, y Paterson, WA, se desarrollaron estudios de campo en 2008 y 2009, para determinar el efecto de simulación de acumulación de glifosato en papa “Ranger Russet” durante el año de aplicación y el crecimiento del cultivo del siguiente año de semilla de esa cosecha. Se aplicó el glifosato a 8.5, 54, 107, 215 y 423 g ia ha–1, lo que corresponde a 1/00, 1/16, 1/8, ¼, y ½ de la dosis más baja recomendada para una sola aplicación para maíz resistente al glifosato y remolacha de 846 g ha–1. Se aplicó el producto cuando las plantas de papa alcanzaron de 10 a 15 cm de altura (temprano), o al enganchamiento del estolón (H), a la iniciación del tubérculo (TI), o a medias de la tuberización (MB). En general, las aplicaciones a MB causaron menos daño foliar visual al cultivo madre que las aplicaciones más tempranas en ID u OR, y que las aplicaciones H en WA. Aumentó el daño del cultivo madre a medida que aumentó la dosis del glifosato, independientemente de la localidad, tiempo de aplicación, y fecha de lectura. La calidad U.S. No. 1 y los rendimientos totales de tubérculo estuvieron generalmente relacionados al nivel del daño que resultó de los tiempos y dosis de aplicación del producto. Aun cuando el daño al cultivo madre por el glifosato aplicado a MB generalmente fue el más bajo comparado con otras etapas de aplicación, cuando los tubérculos resultantes de esa etapa se plantaron al año siguiente, la emergencia, el vigor de la planta y el rendimiento estuvieron más impactados en detrimento, en comparación con aquellos de tubérculos hijos de otros tratamientos o etapas de aplicación. La emergencia de tubérculos resultantes de MB fue menor al 30 % de la de los tubérculos del testigo no tratado, mientras que la emergencia de los tubérculos hijos de los otros tratamientos fue de 60 al 95 %. A medida que aumentó la dosis del glifosato aplicado al cultivo madre, disminuyó la emergencia de los tubérculos hijos. Cuando emergieron los tubérculos resultantes de MB, las plantas fueron cloróticas y pequeñas, como si hubieran sido asperjadas directamente con glifosato. Independientemente de que si los tubérculos hijos tuvieran o no defectos, los resultados del año siguiente fueron los mismos. Las implicaciones son de que si un cultivo madre para semilla se encuentra con el glifosato durante plena tuberización, posiblemente el daño no podría notarse en el follaje o en los tubérculos, no obstante, la emergencia, el vigor y el rendimiento del cultivo del siguiente año con tubérculo-semilla hijo pudiera impactarse grandemente.

Potato virus Y (PVY) is an economically important and reemerging potato pathogen in North America. PVY infection reduces yield, and some necrotic and recombinant strains render tubers unmarketable. Although PVYO is the most prevalent strain in the United States, the necrotic and recombinant strains PVYNTN and PVYN:O are becoming more widespread. Infection rates in aphid-inoculated (Myzus persicae (Sulzer)) and mechanically inoculated plants were compared across two potato genotypes ('Yukon Gold' and A98345-1), three PVY strains (PVYO, PVYN:O, and PVYNTN), and two growth stages at inoculation (pre- and postflowering). Susceptibility of genotypes was measured as infection rate using a double-antibody sandwich-enzyme-linked immunosorbent assay; virus titer and tuber mass also were recorded from the infected plants. Yukon Gold generally was more susceptible than A98345-1 to all three PVY strains, especially following mechanical inoculation. Within genotypes, Yukon Gold was most susceptible to PVYO and A98345-1 was most susceptible to PVYN:O. Plants exhibited age-based resistance, with both genotypes showing higher susceptibility at the pre- than postflowering stage. The overall ranking pattern of virus titer in infected plants was PVYO > PVYNTN > PVYN:O; across all three strains, infected Yukon Gold had higher titer than infected A98345-1 plants. Yukon Gold plants had lower tuber mass than A98345-1 when infected, and there were differences between the two inoculation methods in regard to tuber mass for the three stains. The results showed differences in infection response between inoculation methods and as a function of genotype, strain, inoculation stage, and their interactions. These factors should be considered when screening genotypes for resistance.