Weed Control Efficacy of Organic Mulches in Two Organically Managed Bell Pepper Production Systems

Abstract

<jats:p>A 2-year field study in Lexington, Ky., evaluated weed control efficacy and influence on yields of several organic mulches in two organically managed bell pepper (<jats:italic>Capsicum annuum</jats:italic>) production systems. Five weed control treatments [straw, compost, wood chips, undersown white dutch clover (<jats:italic>Trifolium repens</jats:italic>) “living mulch,” and the organically approved herbicide corn gluten] were applied to two production systems consisting of peppers planted in double rows in either flat, bare ground or on black polyethylene-covered raised beds. In the first year, treatments were applied at transplanting and no treatment was found to provide acceptable season-long weed control. As a result, bell pepper yields in both production systems were very low due to extensive weed competition. First year failures in weed control required a modification of the experimental protocol in the second year such that treatment application was delayed for 6 weeks, during which time three shallow cultivations were used to reduce early weed pressure and extend the control provided by the mulches. This approach increased the average weed control rating provided by the mulches from 45% in 2003 to 86% in 2004, and resulted in greatly improved yields. In both years, polyethylene-covered raised beds produced higher yields than the flat, bare ground system (8310 lb/acre compared to 1012 lb/acre in 2003 and 42,900 lb/acre compared to 29,700 lb/acre in 2004). In the second year, the polyethylene-covered bed system coupled with mulching in-between beds with compost or wood chips provided excellent weed control and yields. When using the wood chip mulch, which was obtained at no cost, net returns were $5587/acre, which is similar to typical returns for conventionally grown peppers in Kentucky. Net returns were substantially decreased when using compost due to the purchase cost. Results from this study indicate that shallow cultivation following transplanting, combined with midseason mulch application, resulted in high yields in an organically managed bell pepper system that were comparable to yields of most varieties grown conventionally in a variety trial conducted on the same farm.</jats:p>

The Effect of Organic Mulching and Irrigation on the Weed Species Composition and the Soil Weed Seed Bank of Tomato

“…In our experiment, weed mass, or weed mass expressed in the time needed for weeding, was significantly reduced by mulching, and, unlike Law et al (2006) [29], who found that one mulching at the beginning of the season was not sufficiently able to control weeds throughout the season, we experienced a different tendency: less and less time was needed for weeding as the season progressed. In one of our earlier studies [30], a thick layer of straw provided suitable suppression against weeds, but the thickness of mulch (and year, and time of season) were important factors to determine the efficiency of mulching.…”

Effects of Organic Fertilization and Cover Crops on an Organic Pepper System

“…The straw mulch was needed for supplemental weed control in 2003 despite a %153% increase in hairy vetch/rye biomass from 2002 to 2003. For complete weed management, additional hand weeding may also be required in straw mulch systems (Law et al, 2006).…”

Carbon and Nitrogen Mineralization and Persistence of Organic Residues under Conservation and Conventional Tillage

“…There is evidence that mulching several weeks after transplanting bell pepper (Capsicum annuum) can improve weed suppression mainly by improving mulch persistence later into the growing season (Law et al, 2006), but mulch application should be done with care to prevent lodging of the crop (Boyhan et al, 2006) and shading of prostrate crop growth (Pedreros et al, 2008). Inhibition of light transmittance appears to be the greatest factor for weed suppression by mulches (Steinmaus et al, 2008).…”