Weed Management Practices for Organic Production of Trailing Blackberry: I. Plant Growth and Early Fruit Production

Abstract

<jats:p>Weed management practices were evaluated in a new field of trailing blackberry (<jats:italic>Rubus</jats:italic> L. subgenus <jats:italic>Rubus</jats:italic> Watson) established in western Oregon. The field was planted in May 2010 and certified organic in May 2012. Treatments included two cultivars, Marion and Black Diamond, grown in 1) non-weeded plots, where weeds were cut to the ground just before harvest; 2) hand-weeded plots, hoed two to three times per year; and 3) weed mat plots, covered with black landscape fabric. Each treatment was fertilized with fish emulsion and irrigated by drip. Weeds increased from 2010 through 2012 in both non-weeded and hand-weeded plots and required 38 and 90 h·ha<jats:sup>−1</jats:sup> of labor to remove the weeds in the latter treatment in 2011 and 2012, respectively. Weeds in weed mat plots, in comparison, were confined primarily to the planting holes in the fabric and required only 1 h·ha<jats:sup>−1</jats:sup> of labor for weed removal each year. Blackberry growth, in terms of number and dry weight of the primocanes, was similar among treatments during the first year after planting but differed with cultivar and weed management the next season. In 2011, ‘Black Diamond’ produced shorter but an average of three more primocanes per plant than ‘Marion’, whereas plants in hand-weeded and weed mat plots produced nearly twice as many primocanes as non-weeded plots. Hence, when fruit were produced on floricanes (the previous year’s primocanes) for the first time in 2012, ‘Black Diamond’ had 15% more yield than ‘Marion’, and weed control increased yield by 67% with hand-weeding and 100% with weed mat, on average. ‘Black Diamond’ and weed control also produced larger berries (measured as average individual fruit weight) with a greater water content but a lower soluble solids concentration. So far, of the three practices studied, weed mat was best suited to organic production of blackberries. The initial cost of the weed mat was far less than the cost of hand-weeding during the first 3 years after planting, and after only one season of fruit production, the yield benefit of weed mat provided enough profit to warrant its use over no weeding or hand-weeding.</jats:p>

Weed Management, Training, and Irrigation Practices for Organic Production of Trailing Blackberry: II. Soil and Aboveground Plant Nutrient Concentrations

“…Oregon primarily grows trailing types used for the processed market, and nearly all of the fruit is harvested by machine (Strik and Finn, 2012;USDA, 2014). Although there is an increasing body of knowledge about organic blackberry production (Fernandez-Salvador et al, 2015a, 2015bHarkins et al, 2013Harkins et al, , 2014Kuepper et al, 2003), some gaps still remain, such as how cultivars other than Marion, which was used to develop the Oregon caneberry nutrient management guide (Hart et al, 2006), use and allocate nutrients.…”

“…Some blackberry growers allow weeds to grow in the row (B.C. Strik, personal observation), although this has been shown to be detrimental to blackberry plant growth and yield Harkins et al, 2013;Meyers et al, 2014). Weed mat, or porous landscape fabric, has been used successfully to manage weeds in various production systems Harkins et al, 2013;Makus, 2011;Meyers et al, 2014).…”

“…Strik, personal observation), although this has been shown to be detrimental to blackberry plant growth and yield Harkins et al, 2013;Meyers et al, 2014). Weed mat, or porous landscape fabric, has been used successfully to manage weeds in various production systems Harkins et al, 2013;Makus, 2011;Meyers et al, 2014). It is particularly well suited to trailing blackberry because, unlike many other types of caneberry, trailing types only produce canes from the crown of the plant, so only a small hole in the weed mat is needed for the plant.…”

“…However, drip irrigation is usually used in organic production systems because it has the potential to decrease weeds outside of the drip zone, reduce disease presence in the canopy, and can be used to apply fertilizers (fertigation). Fertigation has been used effectively with OMRI-listed materials in blackberry Fernandez-Salvador et al, 2015a;Harkins et al, 2013).…”

“…Organic fertilizers are often applied for a certain N rate [55 to 80 kg • ha -1 for mature blackberry (Hart et al, 2006)], but unlike many conventional fertilizers, they contain varying levels of other macro-and micronutrients. The effect of organic fertilizers on blackberry growth and soil properties was studied by Harkins et al (2013) during establishment and by Fernandez-Salvador et al (2015a, 2015b, although effects over a longer time period and combined with other management practices are still unknown.…”