Performing Department
Geneva - Horticultural Sciences
Non Technical Summary
Given the limited potential for designing effective, herbicide-based weed control systems in conservation-tillage vegetables, integrated weed management strategies that rely on agroecological principles are needed to help New York vegetable growers realize both soil quality and sustainable weed management goals. The primary objective of this proposal is to: 1) increase understanding of how alternative conservation-tillage and cover cropping practices influence weed seed emergence periodicity and critical life-history transitions of problematic weeds in NY vegetable crops, 2) evaluate the efficacy of novel in-row and between-row cultivation tools within alternative reduced-tillage systems, and 3) develop and disseminate guiding principles for the design of multi-tactic, agroecological weed management for various NY vegetable crops via extension programming efforts.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
Weed management remains a primary contributor to economic losses across a range of vegetable productions systems in New York (Baker and Mohler, 2014; NYFVI, 2016). In comparison to field crop production, few effective herbicides and a limited number of herbicide modes of action are available for use by NY vegetable growers. Several vegetable crops are limited to one effective product or herbicide mode of action to control emerged broadleaf weeds in the crop (post-emergent applications), including cabbage, carrots, beets and onions. In some of these systems, over-reliance on herbicides to control weeds during summer annual cash crop phases has led to the evolution of herbicide-resistant weed populations (Kikkert and Bellinder, 2014). As a result, multiple cultivation passes or hand-labor, both high costalternatives, are employed to control weeds. Without cost-effective OMRI-approved herbicides, organic vegetable growers are similarly reliant on tillage, cultivation, and hand-labor for weed control within the cash crop phase. Looking forward, development of sustainable weed management in NY vegetable systems will require novel strategies for diversifying crop rotations in order to disrupt weed life cycles, coupled with complementary, multi-tactic weed control tactics for managing weeds during cash crop phases of the rotation. New York vegetable growers are also increasingly interested in conservation-tillage and cover cropping practices to improve soil health (NYVI, 2016). Reducing the intensity or frequency of tillage while integrating cover crops can improve long-term soil health in annual crop systems by decreasing topsoil erosion, nutrient depletion, pollution, compaction, and loss of organic matter (Magdoff and VanEs, 2009). No-till vegetable production is likely to remain infeasible given the agronomic benefits of tillage, which include incorporation of soil amendments and crop residues, preparation of fine seedbeds, increased soil temperatures, disruption of disease, weed and invertebrate-pest cycles. Consequently, the most promising conservation-tillage practice for vegetable production is strip-tillage, which is also referred to asdeep- or shallow-zone tillage, depending on the depth of soil disturbance (Brainard et al., 2013a). In this type of system, deep vertical-tillage (fall or spring) is utilized in the intrarow (IR) zone where crops will be planted and the between-row (BR) zone is left undisturbed by tillage, retaining the surface residue. The timing and intensity (depth) of zone tillage in the IR zone, and residue management in the BR zone, is likely to vary depending on soil characteristics, crop rotation, cover cropping strategy, the level of herbicide-inputs and grower management objectives (Brainard et al. 2013b). Surface residues may produce agronomic challenges, such as disruption of machine-harvest efficiency, in certain vegetable crops. Consequently, some growers couple deep zone-tillage in the IR zone with shallow, vertical-tillage (i.e., turbo-till) in the BR zone. Turbo-till equipment is designed to break up surface residues without producing horizontal movement or inversion of top soil. Adoption of conservation-tillage vegetable systems has important implications for weed management systems. Conservation-tillage in vegetable crops may require greater reliance on herbicides to effectively control weeds in the absence of primary tillage. Increased herbicide inputs in response to reduced tillage intensity or frequency has been well-documented in field crop production systems that have adopted reduced-tillage practices, which predictably leads to the evolution of herbicide-resistance in weed populations (Norsworthy et al., 2012). Given the limited potential for designing effective, herbicide-based weed control systems in conservation-tillage vegetables, integrated weed management strategies that rely on agroecological principles are needed to help New York vegetable growers realize both soil quality and sustainable weed management goals. The primary objective of this proposal is to: 1) increase understanding of how alternative conservation-tillage and cover cropping practices influence weed seed emergence periodicity and critical life-history transitions of problematic weeds in NY vegetable crops, 2) evaluate the efficacy of novel in-row and between-row cultivation tools within alternative reduced-tillage systems, and 3) develop and disseminate guiding principles for the design of multi-tactic, agroecological weed management for various NY vegetable crops via extension programming efforts.OBJECTIVES: The overall objective of this proposal is to increase foundational knowledge of:1) weed life-history characteristics in conservation-tillage systems, and 2) weed species-level responses to modern cultivation tools, to enable the design of agroecological weed management strategies in NY vegetable production systems.Objective 1: Evaluate weed germination periodicity in response to alternative zonal tillage ´cover cropping management practices across a range of soil textures.Objective 1a: Develop empirical hydrothermal models for cumulative seedbank emergence of summer annual weed species with varying life-history traits across a gradient of zone tillage ´cover crop ´ soil texture factors.Objective 1b: Evaluate seedbank to seedling life-history transition rates of summer annual weed species with varying life-history traits across a gradient of zone tillage ´ cover crop ´ soil texture factors.Objective 2: Evaluate weed control efficacy and cash crop tolerance of novel in-row and between-row cultivation control tactics across a range of soil textures that are representative of NY vegetable growing regions.Objective 2a: Quantify the effects of in-row cultivation tools on weed mortality and crop survival using a range of weed life-history traits and vegetable crops.Objective 2b: Quantify the effects of between-row cultivation tools on weed mortality and crop survival using a range of weed life-history traits and vegetable crops.Objective 3: Develop and disseminate extension-outreach materials to NY vegetable growers that support the development of agroecologically-based weed management systems using research results in Objective 1 and 2.
Project Methods
Objective 1: Evaluate weed germination periodicity in response to alternative zonal tillage ´cover cropping management practices across a range of soil textures. Field experiments will be conducted in 2018-2019 and 2019-2020 growing seasons at Cornell University's New York State Agricultural Experiment Station (NYSAES) in Geneva, NY. Mature seeds of 12 horticulturallyimportant weed species will be collected at multiple local vegetable field sites throughout the late summer and fall of 2018. Seeds from different collections will be composited, generating seed lots representative of NY vegetable production systems. Seed lots will be processed through a series of sieves (mesh screens) and a seed blower to separate coarse and fine debris, respectively. After visual inspection of cleaned samples, 500 live seed per species will be counted with a seed counter, placed in coin envelopes, and stored dry at room temperature. The 12 weed species willencompass a range of life-history characteristics that are representative of weed communities in vegetable productions systems (Table 1). Vegetable growers will be engaged during winter extension meetings and conferences (Jan to Mar, 2018) to refine the species list in order to include the most commercially important weed species.Experimental treatments will be imposed in mid- to late-September as a randomized complete block with four replications at a location without recent history of vegetable production (sod) to prevent resident weed seedbanks from interfering with experimental procedures. Main plots will include five cover crop by tillage management strategies that are employed for various vegetable planting scenarios common to New York vegetable production (Table 2). Cover crop by tillage management scenarios will alter edaphic conditions that influence weed seed germination via changes in: 1) cover crop growing season length (winter hardy species terminated with herbicides vs. winter-kill cover crops), 2) cover crop functional traits (N scavenging grasses, N provisioning legumes), 3) timing of zone tillage (fall vs. spring), and 4) frequency of vertical, turbo-tillage (fall only vs. fall and spring). Plot size will be a function of available equipment width (turbo-till, zone-till and small grain drill).Objective 1a. Seeds of targeted weed species (n = 12) will be distributed in both IR and BR zones (n = 2) in permanently marked quadrats (total no. experimental units = 24) just prior to tillage and cover cropping field operations to simulate seed rain in the previous vegetable crop. Experimental units will be monitored weekly in the fall, spring and summer growing seasons. Emerged seedlings will be counted and removed. Soil temperature and soil water matric potential (5 cm depth) will be recorded at the main plot level. At the end of following growing season, emergence data will be converted to cumulative emergence (%) based on total seedlings emerged per experimental unit and fitted to hydrothermal models using candidate models (Gompertz, Weibull) and candidate threshold values (temperature, matric potential) described in Werle et al.(2014). In anticipation that cover cropping and tillage differences will result in fine-scale differences in edaphic conditions (soil temperature and moisture) that influence germination, we will fit and compare (goodness-of-fit tests) hydrothermal models using both coarse (weather station data) and fine-scale (in-situ) measurements for predictor variables.Objective 1b. In each experimental unit, cumulative seed emergence will be expressed as a proportion of the initial seedbank (n = 500 live seed) to describe the transition rate from seedbank to seedling phase. ANOVA procedures will be employed to determine the effects ofalternative tillage ´ cover crop treatments on emergence rates, which may be utilized in subannual population matrix model simulations.Objective 2. Evaluate weed control efficacy and cash crop tolerance of novel in-row and between-row cultivation control tactics across a range of soil textures that are representative of NY vegetable growing regions. Preliminary field trials will be conducted in the 2018 growingseason at the NYSAES with project collaborator, B. Brown, to evaluate the potential of various in-row (finger weeder, torsion weeder, tine weeder) and between-row (high-residue sweeps, knives) cultivation tools for vegetable crops (n = 5; see Obj 1) in conservation tillage systems.These field trials will focus on vegetable crop tolerance (% mortality) to identify the combination of stacked in-row tools (2 to 3 way combinations of finger weeds, torsion weeder, tine weeder) and between-row tool (high-residue sweep vs. knives) that provides the greatest crop tolerance for inclusion in subsequent studies.Field experiments will be fully implemented in the 2018-2019 growing season and replicated across three soil-textures at Cornell University's New York State Agricultural Experiment Station (NYSAES) in Geneva, NY. Treatments will be imposed using a randomizedcomplete block with a split-plot design and four replications. Main plots will be comprised of two alternative tillage strategies (CTL, T3), described in Obj 1, which will enable evaluation of cover crop surface residue effects (no residue, cereal rye residue) and zone-tillage management (full width tillage, zone tillage) on the efficacy of in-row and between-row cultivation. Split plotswill include five vegetable crops (sweet corn, snap bean, transplanted cabbage, beets, carrots) planted near May 15. Weed seed collection of 12 target species and the processing and implementation protocols, described in Obj 1, will be utilized in this experiment. Crop-specific cultivation strategies will be imposed based on adaptive management criteria (weed scouting and crop phenological stage) during the growing season. Weed and cropdensity counts will be conducted before and after cultivation events. For each crop, the effect of tillage strategy (full width tillage, zone tillage) on weed control efficacy (% of emerged cohort controlled) in the IR (Obj 2a) and BR (Obj 2b) zone and crop tolerance (final population / established population) will be analyzed using ANOVA procedures.Objective 3. Develop and disseminate extension-outreach materials to NY vegetable growers that support the development of agroecologically-based weed management weed management systems using research results in Objective 1 and 2. Development of extension outreach materials will take place in year 3 and will be designed, executed, promoted and distributed in coordination with listed collaborators. Description of expected outputs and target audiences is described in the following sections of the proposal.