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  • Author or Editor: Bradley D. Hanson x
  • HortScience x
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New plant-based products can be produced from seed harvested from Brassica species used for phytomanaging selenium (Se) in the west side of central California. Se-enriched seed meals produced from canola (Brassica napus) and mustard (Sinapis alba) plants were tested as potential bioherbicides and green fertilizers in strawberry production under controlled and field conditions for two seasons. Treatments consisted of adding each meal (containing 2.2 mg Se/kg dry mass) to the soil at rates equivalent to 0, 2, and 6 t/acre, respectively, 7 days before planting. In growth chamber studies, the highest rates of either meal lowered berry yields by a high of 30% compared with no application (control). Among the nutrient accumulation, berry Se, calcium (Ca), manganese (Mn), and zinc consistently increased with most Brassica meal treatments and most significantly with the mustard meal. In the field studies, mustard treatments lowered the emergence of summer-germinating and resident winter annual weeds more than canola and control treatments. Strawberry fruit yields increased with all Brassica treatments, except a 42% fruit yield reduction was observed at a 6 t/acre rate of mustard meal. Increases in fruit Se concentrations and increases in Ca, phosphorus, and Mn were often observed for all Brassica treatments. Amending soils with Brassica seed meals may have more practical viability in organic agriculture as a potential bioherbicide and green fertilizer.

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Grape growers are concerned about the potential impact of drift from commonly used auxinic herbicides. In California, this is frequently related to herbicides used in cereals and noncrop areas, whereas in other parts of the United States concerns are often related to dicamba- and 2,4-D-resistant cropping systems. Our objective was to compare the relative sensitivity of winegrapes to simulated auxinic herbicide drift, including grapevine symptomology, grape yield, and grape quality. In a small-plot herbicide evaluation, we applied 1/900×, 1/300×, 1/100×, and 1/33× rates of 2,4-D, aminopyralid, dicamba, and triclopyr based on 1× field rates of 1454, 122.5, 280, and 2240 g⋅ha–1 ae, respectively. Aminopyralid resulted in similar symptomology to 2,4-D and dicamba—namely, leaf cupping, leaf crinkling, excessive tendril twisting, and tendril death, although these symptoms were generally subtle. Triclopyr resulted in much greater levels of necrosis compared with the other herbicides. In our study, triclopyr was the only herbicide associated with grape yield loss, and greater triclopyr rates were also associated with increased grape sugar levels. This study demonstrates that grapes are sensitive to low rates of simulated herbicide drift, but symptoms do not necessarily indicate yield loss or quality effects. This study indicates that auxin-type herbicide simulated drift symptoms are not reliable markers for winegrape yield or quality reduction.

Open Access