Variability in specific gravity of Russet Burbank potatoes was documented in a single 32 hectare field. Maximum variation was 40 units among individual tubers within hills (one unit equals one part in 1000th of specific gravity measurement) and 15 units among hills. Field site variability of 10-15 units was common between sampled grid lines in the field; but bulked samples (truckloads) reduced the sampled variability to 8-10 units. When the samples were taken from bulked lots as opposed to single hill samples, the variability decreased. Grower lots, which were pooled samples from several truckloads, showed specific gravity differences of 2-7 units even though all lots were from the same field. These variations among specific gravity samples should be taken into account when considering total solids content in any lot of potatoes.Degree of russetting of the skin and hollow heart also influenced specific gravity measurements. Measured differences between peeled and unpeeled lots of 10 units in specific gravity corresponded to 2% difference in total solids content. Statistically, the variance of the peeled lot was one half that of the unpeeled lot, therefore, to minimize the measured differences due to skin type, peeled potatoes could be used for the specific gravity measurements. CompendioSe probe) la variabilidad en la gravedad especifica de las papas Russet Burbank en un solo campo de 32 hectareas. La variaciOn maxima entre tuberculos individuales dentro de los puntos de siembra fue de 40 unidades (una unidad es igual a una parte por milesimo de la gravedad especifica medida) y 15 unidades entre puntos de siembra. Fue comtin encontrar una variabilidad de 10-15 unidades entre las diferentes muestras tomadas en el terreno convenientemente dividido; pero muestras al granel (camionadas) redujeron la variabilidad de las muestras a 8-10 unidades. Cuando las muestras fueron tomadas de lotes al granel en oposiciOn a muestras de un ' solo golpe o punto de siembra, la variabilidad disminuy6. Los lotes de los productores, que fueron una mezcla de muestras tomadas de varias camionadas, mostraron diferencias de 2-7 unidades en la gravedad especifica aim en el caso que todos los lotes fueran del mismo campo. Estas variaciones en las muestras, en cuanto a gravedad especifica, deben tomarse en cuenta cuando se considere el contenido total de sOlidos en cualquier lote de papas.El grado de reticulado de la piel y el de corazOn vacio influencian tambièn las mediciones de la gravedad especifica. Las diferencias en las mediciones de la gravedad especifica entre lotes pelados y sin pelar, que fueron de 10 unidades, corresponden a un 2% de diferencia en el contenido de sOlidos totales. Estadisticamente, la variancia de los lotes pelados fue la mitad que la de los lotes sin pelar, por lo canto, para minimizar las diferencias en las mediciones, debidas a las condiciones de la piel, se podrian usar papas peladas para las medici6n de la gravedad especifica.

The efficacy of current wild oat herbicides and their high cost have resulted in use rates that are less than those recommended. While acceptable weed control may be attained at less cost, this practice does not consider the potential for increased wild oat seed production. The objective of this experiment was to determine the interaction of wild oat density and reduced imazamethabenz rates on wild oat seed production in spring barley. As wild oat densities increased from 8 to 1,100 plants m−2, wild oat seed production increased from 180 to 9,950 seed m−2without herbicide, and from 0 to 2,810 seed m−2using 0.53 kg ai ha−1imazamethabenz. This general pattern was modeled using a cumulative logistic function. Estimates from this model indicated that < 1 wild oat seed m−2was produced at population densities of ≤ 20 plants at any imazamethabenz rate. Imazamethabenz rates of 0.26 kg ha−1or greater at wild oat densities of less than approximately 190 plants m−2did not result in wild oat seed production above the initial population density. As wild oat density increased, however, imazamethabenz rates below 0.40 kg ha−1resulted in substantially greater wild oat seed production compared to the recommended rate.

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