Cereal rye (Secale cereale L.) as a cover crop can be an effective nonchemical tool for waterhemp [Amaranthus tuberculatus (Moq.) Sauer] suppression in crop production. Previous studies have evaluated A. tuberculatus suppression by cereal rye as part of weed management programs but have not investigated the underlying mechanism of suppression by the cover crop. This study aimed to investigate the effect of cereal rye biomass on A. tuberculatus emergence and development, and on soil environmental parameters (temperature, moisture, and light transmittance) that are key triggers of A. tuberculatus germination to elucidate the mechanism of suppression by the cover crop. A dose–response study was conducted under field conditions in Brooklyn and Janesville, WI, from 2021 to 2023. Cereal rye biomass from a fall-planted field was harvested at anthesis in the spring and dried to constant weight at 60 C to provide 0.0, 0.6, 1.2, 2.4, 4.8, 7.2, 9.6, and 12.0 Mg ha−1 of dry biomass that was evenly distributed over 1.9 m−2 plots. Increasing cereal rye biomass reduced A. tuberculatus height, biomass, and density. An average ED50 of 5.2 Mg ha−1 of biomass was needed to reduce A. tuberculatus density by 50%. Low levels of biomass (≤2.38 Mg ha−1) augmented A. tuberculatus density due to an increase in soil moisture underneath the mulch compared with bare soil. Cereal rye biomass decreased the amount of sunlight reaching the soil, which resulted in lower mean soil temperature and temperature amplitude throughout the day (9.3 and 2.7 C temperature amplitude at 0 and 12.0 Mg ha−1, respectively). Prevention of A. tuberculatus germination by this thermal effect is likely the main mechanism of A. tuberculatus suppression from the cereal rye cover crop. Our results support biomass from cereal rye cover crop effectively suppressing A. tuberculatus and contributing to the integrated management of A. tuberculatus.

Preemergence herbicides associated with cereal rye (Secale cereale L.) cover crop (hereafter “cereal rye”) can be an effective waterhemp [Amaranthus tuberculatus (Moq.) Sauer.] and Palmer amaranth (Amaranthus palmeri S. Watson) management strategy in soybean [Glycine max (L.) Merr.] production. Delaying cereal rye termination until soybean planting (planting green) optimizes biomass production and weed suppression but might further impact the fate of preemergence herbicides. Limited research is available on the fate of preemergence herbicides applied over living cereal rye in the planting green system. Field experiments were conducted in Illinois, Kansas, Pennsylvania, and Wisconsin to evaluate the fate of flumioxazin and pyroxasulfone and Amaranthus spp. residual control under different cover crop management practices in soybean in 2021 and 2022 (8 site-years). A flumioxazin + pyroxasulfone herbicide premix was applied preemergence at soybean planting under no-till without cereal rye, cereal rye early terminated before soybean planting, and cereal rye terminated at soybean planting. Flumioxazin and pyroxasulfone concentrations in the soil were quantified at 0, 7, and 21 d after treatment (DAT), and Amaranthus spp. density was determined at postemergence herbicide application. The presence of cereal rye biomass intercepted flumioxazin and pyroxasulfone at preemergence application and reduced concentration in the soil when compared with no-till, mainly at 0 DAT. Main differences in herbicide concentration were observed between no-till and cereal rye treatments rather than cereal rye termination times. Despite reducing herbicide concentration in the soil, the presence of the cereal rye biomass did not affect early-season residual Amaranthus spp. control. The adoption of effective preemergence herbicides associated with a properly managed cereal rye cover crop is an effective option for integrated Amaranthus spp. management programs in soybean production systems.

Perennial grain crops are emerging as a promising addition to sustainable agricultural systems because of their low-input requirements and delivery of ecosystem services. However, adoption of these crops is expected to bring novel management challenges, including those related to plant diseases. In New York, fungal pathogens of annual grains have a significant impact on crop yield and value and are generally controlled through a combination of host resistances, cultural practices and chemical fungicides. Without the availability of crop rotation and soil tillage practices, disease control in perennial grain systems may be problematic, and little is known about perennial grain crop susceptibility to local plant pathogen populations. During 2017 and 2018, ongoing field trials of two perennial grain crops recently introduced in New York, intermediate wheatgrass (IWG; Thinopyrum intermedium) and perennial cereal rye (PCR; Secale cereale), were assessed for the presence of putative fungal pathogens on actively growing plants, overwintered crop residue and harvested grain. A total of nine potential host–pathogen combinations were recorded based on symptomology, pathogen morphology and DNA sequences. Common annual crop pathogens were recovered most frequently, but, at one site, Phyllachora graminis, causal fungus of tar spot and a pathogen not previously reported on crops in New York, was found on IWG. Residue colonization by an important toxigenic pathogen (Fusarium graminearum) was high in both crops, though mycotoxin levels in associated grain were low, indicating either the hosts or environment were unsuitable for disease development. Seed-borne fungal communities differed across crops and locations, and black point, a condition caused by Alternaria and Bipolaris fungi and indicative of compromised grain quality, was prevalent in PCR under some conditions. Growing PCR with intercropped red clover (Trifolium pratense L.) resulted in less Stagonospora colonization of stem residue, and PCR grown with an oat (Avena sativa L.) nurse crop had a reduced incidence of black point. These alternative cultural practices may prove useful for managing disease in perennial grains. Our results suggest that the incorporation of perennial crops into the agricultural landscape will lead to familiar plant disease problems requiring new solutions as well as new problems that may require significant research investments.

Harvest weed seed control (HWSC) may control problematic weeds by decreasing contributions to the weed seedbank. However, HWSC practices will not be effective if plants have shed a great part of their seeds before harvest or if a low proportion of seed production is retained at a height that enables collection during harvest. The seed-shattering pattern of several weed species was evaluated over three growing seasons to determine their potential to be controlled with HWSC in the Pacific Northwest (PNW). The studied weed species were downy brome (Bromus tectorum L.), feral rye (Secale cereale L.), Italian ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot], and rattail fescue [Vulpia myuros (L.) C.C. Gmel.]. Seed retention at harvest, seed production, and plant height differed among species, locations, and years. Environmental conditions influenced seed-shattering patterns, particularly the time plants started to shatter seeds and the rate of the shattering. Agronomic factors such as herbicide use, interrow space, or crop height/vigor also seemed to affect shattering patterns and seed production, but more specific studies must be conducted to determine their individual effects. Bromus tectorum, L. perenne ssp. multiflorum, and V. myuros had an average seed retention at harvest of less than 50%. In addition, the low seed retention height of V. myuros makes this species a poor candidate for HWSC. Secale cereale had average seed retention at harvest greater than 50%, and seed retention height was greater than 30 cm. The variability of seed retention in different species will make the efficacy of HWSC practices species and environment dependent in PNW winter wheat (Triticum aestivum L.) cropping systems. Harvesting the wheat crop as early as possible will be crucial to the success of HWSC.

Indaziflam, a PRE herbicide option for weed management on rangeland and natural areas, provides long-term control of invasive winter annual grasses (IWAGs). Because indaziflam only provides PRE control of IWAGs, POST herbicides such as glyphosate can be mixed with indaziflam to control germinated IWAG seedlings. Field trials were conducted at three sites on the Colorado Front Range to evaluate glyphosate dose required to provide adequate POST IWAG control and compare long-term downy brome (Bromus tectorum L.), Japanese brome (Bromus arvensis L.), and feral rye (Secale cereale L.) control with indaziflam and imazapic. Two of the three sites were void of desirable species, so species establishment through drill seeding was assessed, while the remnant native plant response was assessed at the third site. Herbicide applications were made March 2014 through April 2015, and two sites were drill seeded with native species 9 mo after herbicide application. Yearly visual control evaluations, biomass of all plant species, and drilled species stand counts were collected. Glyphosate at 474 g ae ha−1 reduced B. tectorum biomass to zero, while glyphosate at 631 g ae ha−1 was needed to reduce biomass to near zero at the S. cereale site. At all three sites, only indaziflam treatments had significant reductions in IWAG biomass compared with the nontreated check at 3 yr after treatment (YAT). By 3 YAT in the drill-seeded sites, cool-season grass frequency ranged from 37% to 69% within indaziflam treatments (73 and 102 g ai ha−1), while imazapic treatments ranged from 0% to 26% cool-season grass frequency. In the site with a remnant native plant community, indaziflam treatments resulted in a 3- to 4-fold increase in native grass biomass. These results indicate that the multiyear IWAG control provided by indaziflam can aid in desirable species reestablishment through drill seeding or response of the remnant plant community.

Conservation tillage systems for cotton production were monitored for their influence on horseweed populations. Without fall tillage, horseweed became established and was present the following spring. Disking in the fall or spring controlled horseweed for the subsequent cotton crop.

A reduced-till (RT) experiment determined the effect of rye seeding density and method of kill on rye biomass persistence, weed suppression, and tomato yield. ‘Wheeler’ rye was seeded at 56, 110, and 170 kg ha−1 in the fall of 1988 and 1989 in Champaign, IL; Lexington, KY; and Lafayette, IN. One wk before transplanting tomatoes, rye was desiccated either by applying glyphosate at 1.1 kg ha−1 and mowing (RT-glyphosate) or by mowing alone (RT-mowed). Both methods left rye residues on the soil surface as a mulch. Seeding density did not affect rye biomass, weed control, or tomato yield. Rye biomass differed depending on location and year, ranging from 320 to 1150 gm−2. Rye was completely killed by glyphosate, but regrew following mowing. RT-glyphosate suppressed weeds for 4 to 8 wk, which was similar to the suppression from conventional tillage (fall plowing with spring disking and harrowing) with trifluralin and metribuzin (CT-herbicide). Weed communities varied, but redroot pigweed and giant foxtail were present at all three locations. All treatments required supplemental weed management for commercially acceptable control. Except for IL in 1990, processing tomato yields (kg ha−1) in RT-glyphosate with hand-weeding were equal or better than yields in the CT treatments.

In the greenhouse, glyphosate [N-(phosphonomethyl)glycine] at 0.6 kg ae/ha applied directly to seeds alone or seeds on the soil surface reduced germination and shoot dry weight of common rye (Secale cereale L. ♯3 SECCE). Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) applied similarly at 0.6 kg ai/ha reduced germination and shoot dry weight of downy brome (Bromus tectorum L. ♯ BROTE) and wheat (Triticum aestivum L. ‘Daws' ♯ TRZAX). Metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5 (4H)-one] at 0.6 kg ai/ha applied to seeds, soil, or seeds and soil had very little effect on germination, but significantly reduced shoot dry weight of common rye, downy brome, wheat, and jointed goatgrass (Aegilops cylindrica Host. ♯ AEGCY). Pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide] at 0.6 kg ai/ha, and propham (isopropyl carbanilate) at 3.4 kg ai/ha plus extender (p-chlorophenyl-N-methylcarbamate) at 0.4 kg ai/ha substantially reduced shoot height and dry weight of all species, regardless of application method, with pronamide completely inhibiting shoot elongation and dry-weight production in three of the four species.

Sweet corn was grown with a living mulch of white clover, a dead mulch of rye, and without mulch, in both till and no-till conditions. Unplanted controls were also included in the experimental design. Corn yields were highest in clover treatments early in the experiment but lowest in later years. The declining yields in the clover living mulch were related to the strip application of glyphosate which allowed establishment of perennial and biennial weeds, notably dandelion and horseweed. These overwintering weeds apparently prevented effective control of summer annuals, especially redroot pigweed, common lambsquarters and large crabgrass, by atrazine and metolachlor. Presence of a rye mulch decreased weed biomass and had no detrimental effect on corn yield. In general, corn yield was not affected by tillage, although the number of marketable ears was reduced in the no-till treatments during the drought year of 1988. The much greater weed biomass in the unplanted control treatments showed the importance of crop competition for weed control in sweet corn cropping systems.

Field experiments were conducted in 1982 through 1986 to evaluate the effect of six postemergence grass herbicides, clethodim, the methyl ester of diclofop, the butyl ester of fluazifop-P, the methyl ester of haloxyfop, the methyl ester of quizalofop, and sethoxydim, on 31 seedling grass species. All herbicides except diclofop controlled most of the species tested. None of the herbicides controlled rattail fescue or red fescue. Only clethodim and haloxyfop controlled annual bluegrass.

Experiments were conducted to evaluate the effect of tillage, rye residue levels, and control strategies on weed suppression and potato yield. Reduced tillage (RT) yields in 1989 were lower than in conventional tillage (CT) due to high hairy galinsoga populations. However, in 1990, potato yields were greater in RT when early emerging weeds were suppressed. Increasing residue levels up to 2300 kg ha−1 had no effect on weeds or yields in either year. In a separate study, preemergence herbicides (linuron plus metolachlor, 1.7 kg ai ha−1 each) applied 10 d after planting (DAP) in reduced tillage controlled weeds for 6 wk, but efficacy decreased after hilling. Metribuzin applied postemergence (0.19 kg ai ha−1) 7 d after hilling controlled late germinating weeds. Potato yields were greatest when the preemergence herbicides were applied.

Field experiments were conducted at two locations in Virginia to evaluate the following herbicides: alachlor, diphenamid, diuron, metolachlor, napropamide, norflurazon, oryzalin, oxyfluorfen, paraquat, pendimethalin, and simazine. One experiment involved newly-transplanted apple trees; the others, three in apple and one in peach trees, involved one-year-old trees. Treatments were applied in the spring (mid-April to early-May). Control of annual weed species was excellent with several treatments. A broader spectrum of weeds was controlled in several instances when the preemergence herbicides were used in combinations. Perennial species, particularly broadleaf species and johnsongrass, were released when annual species were suppressed by the herbicides. A rye cover crop in nontreated plots suppressed the growth of weeds. New shoot growth of newly-transplanted apple trees was increased with 3 of 20 herbicide treatments and scion circumference was increased with 11 of 20 herbicide treatments compared to the nontreated control. Growth of one-year-old apple trees was not affected. Scion circumference of one-year-old peach trees was increased with 25 of 33 herbicide treatments.

Field experiments were conducted in central Missouri in 1989 and 1990 to evaluate weed control practices in conjunction with cover crops and cover management systems in reduced tillage corn. There was no difference in weed control among soybean stubble, hairy vetch, and rye soil cover when averaged over cover management systems and herbicide treatments. However, mowed hairy vetch and rye covers provided greater weed control in the no-till plots than soybean stubble when no herbicide was used. Differences in weed control among cover management systems were reduced or eliminated when a PRE herbicide was applied. corn population and height were reduced by hairy vetch and rye soil cover. Corn grain yield was reduced in rye plots both years. There was no difference in grain yield between tilled and no-till plots.

Total weed density increased after 1 yr of no-tillage and after 2 yr of conventional tillage in a 4-yr experiment with repeated assignment of the same treatment to the same plots. Large crabgrass, goosegrass, and carpetweed densities were higher in the no-tillage compared with the conventional-tillage treatment in at least 1 yr whereas common lambsquarters density was greater in the conventional-tillage treatment the last year of the experiment. Within the no-tillage treatment, rye or hairy vetch residue reduced total weed density an average of 78% compared to the treatment without cover crop when cover crop biomass exceeded 300 g m–2 and when residue covered more than 90% of the soil. Goosegrass, stinkgrass, and carpetweed densities were reduced by cover crop residue in at least 1 yr whereas large crabgrass was unaffected. Common lambsquarters density increased where rye was grown as a cover crop prior to conventional tillage. Despite differences in weed density among treatments, weed biomass was equivalent in all treatments during the last 2 yr.

Experiments were conducted to evaluate the effect of tillage, rye residue levels, and control strategies on weed suppression and potato yield. Reduced tillage (RT) yields in 1989 were lower than in conventional tillage (CT) due to high hairy galinsoga populations. However, in 1990, potato yields were greater in RT when early emerging weeds were suppressed. Increasing residue levels up to 2300 kg ha-1 had no effect on weeds or yields in either year. In a separate study, preemergence herbicides (linuron plus metolachlor, 1.7 kg ai ha-1 each) applied 10 d after planting (DAP) in reduced tillage controlled weeds for 6 wk, but efficacy decreased after hilling. Metribuzin applied postemergence (0.19 kg ai ha-1) 7 d after hilling controlled late germinating weeds. Potato yields were greatest when the preemergence herbicides were applied.

Termination of cover crops prior to no-till planting of soybean is typically accomplished with burndown herbicides. Recent advances in cover-crop roller–crimper design offer the possibility of reliable physical termination of cover crops without tillage. A field study within a no-till soybean production system was conducted in Urbana, IL, from 2004 through 2007 to quantify the effects of cover crop (cereal rye, hairy vetch, or bare soil control), termination method (chemical burndown or roller–crimper), and postemergence glyphosate application rate (0, 1.1, or 2.2 kg ae ha−1) on soybean yield components, weed–crop interference, and soil environmental variables. Biomass of weeds surviving management within a soybean crop following either a vetch or rye cover crop was reduced by 26 and 56%, respectively, in the rolled system compared to the burndown system. Soybean yield loss due to weed interference was unaffected by cover-crop termination method in soybean following a rye cover crop, but was higher in the rolled than burndown treatment in both hairy vetch and bare soil treatments. In soybean following a rye cover crop, regardless of termination method, yield loss to weed interference was unaffected by glyphosate rate, whereas in soybean following a vetch cover crop or bare soil, yield loss decreased with glyphosate rate. Variation in soybean yield among cover crops and cover-crop termination treatments was due largely to differences in soybean establishment, rather than differences in the soil environment. Use of a roller–crimper to terminate a cover crop preceding no-till soybean has the potential to achieve similar yields to those obtained in a chemically terminated cover crop while reducing residual weed biomass.

It is proposed that desiccation tolerance in the embryo of seeds depends upon the capacity to repair damage to genomic DNA when the desiccated embryo is rehydrated. From a study of imbibed and hydrated embryos of rye (Secale cereale) and wild oat (Avena fatua) evidence is provided that it is neither the extent of water uptake by the cells, the ensuing stability of the DNA to desiccation, nor the onset of S-phase DNA synthesis in the first cell cycle of germination that determines whether the desiccated embryo will survive. It is shown that when α- and β-polymerases of DNA repair are inhibited by aphidicolin and dideoxythymidine-5'-triphosphate, respectively, a γ-irradiation-induced DNA fragmentation cannot be fully repaired. It is shown that in hydrated embryos, at a stage when desiccation tolerance is lost, embryo cells still repair irradiation-induced damage, but this repaired DNA is unstable to desiccation and cannot be rerepaired when water is again made available. The failure to re-repair on rehydration appears to be critical to embryo survival and successful germination.

Integration of rye (Secale cereale L.) cover crops into the corn (Zea mays L.) soybean [(Glycine max (L.) Merr.] rotation of the upper Midwest USA can provide many agronomic and agroecological benefits. Integration is made difficult by short growing seasons, but may be facilitated by management of key agroecological interactions such as those between rye and soil microbiota. Rye growth was measured and colonization by arbuscular-mycorrhizal fungi (AMF) was determined in greenhouse experiments using soils from seven different management systems from a long-term cropping-systems experiment in southwest Minnesota. Microbial effects on rye growth were not evident before vernalization, but at final harvest (4 weeks after vernalization) soil microbial populations reduced rye shoot and root growth, relative to a pasteurized control inoculum. At final harvest, shoot biomass in 2-year rotations was 17% greater than 4-year rotations, indicating that microbial populations selected for by 4-year rotations may be more deleterious or pathogenic than those selected for by 2-year rotations. Growth of three rye cultivars was examined in all inocula; cultivars differed in their mean response to soil microbiota and their ability to host AMF. These findings suggest that management factors affect interactions between rye and soil microbiota resulting in altered rye growth.