Weed Control in Yellow Squash Using Sequential Postdirected Applications of Pelargonic Acid

Abstract

<jats:p>Squash (<jats:italic>Cucurbita pepo)</jats:italic> producers could benefit from additional herbicide options that are safe to the crop and provide effective weed control. Research was conducted in southeastern Oklahoma (Atoka County, Lane, OK) during 2010 and 2011 to determine the impact of pelargonic acid (PA) on weed control efficacy, crop injury, and squash yields. The experiment included PA applied unshielded postdirected at 5, 10, and 15 lb/acre, plus an untreated weedy control and an untreated weed-free control. ‘Enterprise’ yellow squash was direct-seeded in single rows into raised beds. Weeds included smooth crabgrass (<jats:italic>Digitaria ischaemum</jats:italic>), cutleaf groundcherry (<jats:italic>Physalis angulata</jats:italic>), spiny amaranth (<jats:italic>Amaranthus spinosus</jats:italic>), and yellow nutsedge (<jats:italic>Cyperus esculentus</jats:italic>). Pelargonic acid was applied each year in mid-July and then reapplied 8 days later. The maximum smooth crabgrass control (98%), broadleaf weed control (94%), and yellow nutsedge control (41%) was observed with the 15-lb/acre PA treatment at 9 days after initial spray treatment (DAIT), 1 day after sequential treatment (1 DAST). Pelargonic acid at 15 lb/acre provided equal or slightly greater smooth crabgrass and broadleaf (cutleaf groundcherry and spiny amaranth) control compared with the 10-lb/acre application, and consistently greater control than the 5-lb/acre rate and the weedy control. Pelargonic acid was less effective at controlling yellow nutsedge than smooth crabgrass and broadleaf weeds. Yellow nutsedge control peaked at 9 DAIT (1 DAST) with 10-lb/acre PA (41%). As the rate of PA increased from 5 to 15 lb/acre, yellow nutsedge control also increased significantly for all observation dates, except for 28 DAIT. Increasing the PA application rate increased the crop injury rating at 1 and 3 days after each application (1 and 3 DAIT, 1 and 3 DAST). Maximum squash injury occurred for each application rate at 9 DAIT (1 DAST) with 4.4%, 8.0%, and 12.5% injury for PA rates 5, 10, and 15 lb/acre, respectively. The 10-lb/acre PA treatment produced the highest squash yields (kilograms per hectare) and fruit number (fruit per hectare) compared with either the 5- or 15-lb/acre rates, and equivalent yields and fruit number as the hand-weeded weed-free treatment. The 10-lb/acre PA rate applied in a timely sequential application has the potential of providing good weed control with minimal crop injury resulting in yields equivalent to weed-free hand-weeding conditions.</jats:p>

Pelargonic Acid for Weed Control in Organic Vidalia® Sweet Onion Production

“…Arboleya et al (2005) found pelargonic acid to have desiccant properties in onion production, although other herbicides were more effective. Pelargonic acid effectively controlled weeds in squash (Cucurbita pepo) when applied with a precision directed sprayer (Webber et al, 2014).…”

Flaming, Glyphosate, Hot Foam and Nonanoic Acid for Weed Control: A Comparison

“…Nonanoic acid was not effective in controlling weeds probably because the species in these experiments were too developed for the herbicide to have an effect. Previous research reported that nonanoic acid needs to be applied to very young or small plants for acceptable weed control [36], and repeated applications are suggested [8]. Rowley et al [37] obtained a moderate reduction in weed coverage, density, and dry biomass compared to the untreated control, but the dose of nonanoic acid used (39 L a.i.…”

“…Alternative methods to the use of chemical-synthesis herbicides are alternative organic herbicides and thermal weed control [3,8,9]. Nonanoic acid (also called pelargonic acid) is a contact, non-selective, non-translocating, post-emergence non-synthetic herbicide [8,10].…”

“…Alternative methods to the use of chemical-synthesis herbicides are alternative organic herbicides and thermal weed control [3,8,9]. Nonanoic acid (also called pelargonic acid) is a contact, non-selective, non-translocating, post-emergence non-synthetic herbicide [8,10]. It is a fatty acid, which kills plants by destroying the cell membranes, leading to rapid desiccation of plant tissues, and providing non-residual weed control [8,10].…”

“…Nonanoic acid (also called pelargonic acid) is a contact, non-selective, non-translocating, post-emergence non-synthetic herbicide [8,10]. It is a fatty acid, which kills plants by destroying the cell membranes, leading to rapid desiccation of plant tissues, and providing non-residual weed control [8,10]. Thermal weed control involves heat being transferred to plant material (leaves, stems, flowers, propagules, etc.)…”