Do Interactions between Residue Management and Direct Seeding System Affect Wheat Stem Sawfly and Grain Yield?

Abstract

Most semiarid regions of the northern Great Plains are prone to wheat stem sawfly (Hymenoptera: Cephidae, Cephus cinctus Norton) attack. As an alternative to the wheat (Triticum aestivum L.)–fallow system, our objective was to determine if continuous cropping infested wheat stubble would inhibit wheat stem sawfly (WSS) emergence. Adult sawfly emergence from undisturbed stubble was compared to stubble harrowed with heavy tine or rotary drum harrows before recropping. Adult emergence from a control of “no recropping” was compared to direct seeding infested stubble with (i) air drills configured with knife‐type openers spaced 23 or 30 cm apart, (ii) an air drill configured with high disturbance shovel‐type sweep openers, and (iii) a low disturbance air drill equipped with disc openers. Pre‐seed heavy tine harrowing reduced adult sawfly emergence but usually required a high tension setting. No‐till planting into infested spring wheat stubble also lowered WSS emergence compared to leaving the field fallow. A system of heavy tine harrows and an air drill equipped with knife openers spaced 30 cm apart reduced WSS adult emergence in spring by 50 to 70%. Grain yield was optimized in spring wheat with air drills equipped with narrow knife openers; in winter wheat optimal yield was obtained with the low disturbance disc drill configurations. Our results indicate incremental benefits from continuous cropping rather than fallowing fields infested with WSS, which is a sustainable alternative to conventional tillage. A systems approach is recommended that integrates these practices with diversified nonhost crop phases and resistant cultivars.

Farming system and wheat cultivar affect infestation of, and parasitism on, Cephus cinctus in the Northern Great Plains

“…There has been limited success in controlling C. cinctus in agricultural systems, although researchers have spent decades investigating the efficacy of cultural, chemical, and biological control . The type of farming system can affect C. cinctus abundance.…”

“…There has been limited success in controlling C. cinctus in agricultural systems, although researchers have spent decades investigating the efficacy of cultural, 17,18 chemical, 19,20 and biological control. 5,17,21,22 The type of farming system can affect C. cinctus abundance. For example, compared with tilled fields where stubble is incorporated into the soil, no-till wheat followed by chemical fallow has more stubble which provides more habitats for C. cinctus overwintering and potential colonization of adjacent wheat fields.…”

Sowing Density and Cultivar Effects on Pith Expression in Solid‐Stemmed Durum Wheat

“…Similar studies have previously reported that pith expression in common wheat was inversely related to sowing density (Beres et al, 2011b, 2012), and was optimized at sowing densities of 250 to 350 seeds m −2 (Beres et al, 2011b). In contrast, grain yield was positively related to sowing density, and was highest at sowing densities of 350 to 450 seeds m −2 (Beres et al, 2011a).…”

“…Adult sawflies emerge from infested stubble over a period of several weeks, making them difficult to control with a single chemical application, and multiple applications may be too costly to justify (Knodel et al, 2009). In western Canada, peak sawfly emergence has been shown to coincide with growing degree days (GDD) (between 578 and 595 GDD), which could be used to predict the optimum time for chemical application (Beres et al, 2011a). Delaying seeding to avoid peak sawfly emergence time can substantially reduce damage, but this is not a practical strategy considering the short growing season on the Canadian prairies (Beres et al, 2007).…”

Influence of Seeding Rate, Nitrogen Management, and Micronutrient Blend Applications on Pith Expression in Solid‐Stemmed Spring Wheat

“…The inconsistency in pith development should not dissuade producers from growing solid‐stemmed wheat in areas prone to attack because cultivar selection is critical to a successful integrated pest management system for WSS (Beres et al, 2011a). Beres et al (2009, 2007) demonstrated that solid‐stemmed wheat can be agronomically superior to hollow‐stemmed wheat in the presence of sawfly pressure, and newer cultivars with the solid stem trait have further improved yield and quality even in the absence of sawflies (DePauw et al, 2005).…”