Northern highbush blueberry is an important fresh market product in New Jersey where the plant was first domesticated in the early 20th century. Because of the short period for safely and timely applying postemergence (POST) herbicides, reliance on residual herbicides that provide season-long control of weeds is essential for blueberry growers to minimize the detrimental effect of weed competition on berry yield and quality and bush growth. Field studies were conducted from 2018 to 2020 in Chatsworth, New Jersey, on ‘Bluecrop’, ‘Duke’, and ‘Elliott’ blueberry cultivars growing on sandy acidic soil to evaluate weed control and crop tolerance in response to repeated annual applications of indaziflam at 73 or 146 g ai ha−1 applied in fall or spring. The efficacy of indaziflam treatments were compared to those of fall-applied dichlobenil at 3,300 g ai ha−1 or a spring-applied mix of diuron at 1,800 g ai ha−1, oryzalin at 3,360 g ai ha−1, and mesotrione at 210 g ai ha−1. Indaziflam at the currently labeled rate of 73 g ai ha−1 provided ≥85% and season-long control of horseweed, Canadian toadflax, and large crabgrass with fall applications on dormant blueberry, whereas spring applications were less effective. Whereas minor (≤8%) and transient leaf crinkling was noted in response to spring-applied indaziflam at 146 g ai ha−1, a fall application never caused leaf crinkling greater than that observed in the nontreated weedy and weed-free controls, regardless of rate. No negative effects on plant growth or fruit production were observed from indaziflam applied at 73 or 146 g ai ha−1 in fall or spring. Findings of this study suggest that indaziflam applied at 73 (1× commercial use rate) and 146 g ai ha−1 is safe to use on blueberry grown on New Jersey sandy acidic soils despite restrictions for using this herbicide on such soils.

The anthelmintic dinitroaniline oryzalin interferes with the formation of microtubules and inhibits meiosis and mitosis in nematodes. Exposure to oryzalin resulted in deterioration in morphology of the oocytes and loss of synaptonemal complexes at meiotic prophase I. The nuclear matrix and envelope were poorly formed, and the central rachis was diminished. These results provide the basis for the loss of fecundity after treatment with the oryzalin resulting in control of parasitic nematodes.

Laboratory and greenhouse studies were conducted to evaluate the effects of chemical treatments applied to Palmer amaranth seeds or gynoecious plants that retain seeds to determine seed germination and quality. Treatments applied to physiologically mature Palmer amaranth seed included acifluorfen, dicamba, ethephon, flumioxazin, fomesafen, halosulfuron, linuron, metribuzin, oryzalin, pendimethalin, pyroxasulfone, S-metolachlor, saflufenacil, trifluralin, and 2,4-D plus crop oil concentrate applied at 1× and 2× the suggested use rates from the manufacturer. Germination was reduced by 20% when 2,4-D was used, 15% when dicamba was used, and 13% when halosulfuron and pyroxasulfone were used. Use of dicamba, ethephon, halosulfuron, oryzalin, trifluralin, and 2,4-D resulted in decreased seedling length by an average of at least 50%. Due to the observed effect of dicamba, ethephon, halosulfuron, oryzalin, trifluralin, and 2,4-D, these treatments were applied to gynoecious Palmer amaranth inflorescence at the 2× registered application rates to evaluate their effects on progeny seed. Dicamba use resulted in a 24% decrease in seed germination, whereas all other treatment results were similar to those of the control. Crush tests showed that seed viability was greater than 95%, thus dicamba did not have a strong effect on seed viability. No treatments applied to Palmer amaranth inflorescence affected average seedling length; therefore, chemical treatments did not affect the quality of seeds that germinated.

Field studies were conducted to determine sweetpotato tolerance to and weed control from management systems that included linuron. Treatments included flumioxazin preplant (107 g ai ha−1) followed by (fb) S-metolachlor (800 g ai ha−1), oryzalin (840 g ai ha−1), or linuron (280, 420, 560, 700, and 840 g ai ha−1) alone or mixed with S-metolachlor or oryzalin applied 7 d after transplanting. Weeds did not emerge before the treatment applications. Two of the four field studies were maintained weed-free throughout the season to evaluate sweetpotato tolerance without weed interference. The herbicide program with the greatest sweetpotato yield was flumioxazin fb S-metolachlor. Mixing linuron with S-metolachlor did not improve Palmer amaranth management and decreased marketable yield by up to 28% compared with flumioxazin fb S-metolachlor. Thus, linuron should not be applied POST in sweetpotato if Palmer amaranth has not emerged at the time of application.

PRE herbicides are the backbone of a successful weed management program in Christmas tree production. In a 2-yr field study, weed control efficacy and tolerance of newly transplanted Canaan fir to different PRE treatments were evaluated. Herbicide treatments consisted of two rates of each of atrazine plus mesotrione plus S-metolachlor at 561 + 150 + 1,504 and 1,122 + 300 + 3,008 g ai ha−1, flumioxazin at 214 and 429 g ai ha−1, hexazinone plus sulfometuron methyl at 289 + 27 and 480 + 46 g ai ha−1, indaziflam at 20 and 41 g ai ha−1, simazine plus oryzalin at 3,366 + 1,683 and 3,366 + 3,366 g ai ha−1, and a nontreated control. Averaged over 2 yr, all PRE treatments controlled giant foxtail, large crabgrass, and redroot pigweed at least 80% throughout the summer. Only the high rates of atrazine plus mesotrione plus S-metolachlor maintained >80% season-long control of yellow foxtail. Horseweed was controlled >85% with flumioxazin at both rates and at high rates of atrazine plus mesotrione plus S-metolachlor, hexazinone plus sulfometuron methyl, and indaziflam. The season-long PRE control of both red sorrel and wild carrot was maintained ≥80% with atrazine plus mesotrione plus S-metolachlor and hexazinone plus sulfometuron methyl regardless of application rate. By 16 wk after treatment, within-row densities of weeds evaluated in this study were reduced >75% in plots treated with atrazine plus mesotrione plus S-metolachlor at both application rates or hexazinone plus sulfometuron methyl at 480 + 46 g ai ha−1. Within-row weed densities in the nontreated control plots were 50, 32, 36, 25, 27, 31, and 19 plants m−2 for large crabgrass, giant foxtail, horseweed, redroot pigweed, red sorrel, wild carrot, and yellow foxtail, respectively. No discernible injury was observed in Canaan fir with any PRE treatment in both study years.

The investigation of potential herbicides for weed control in sweetpotato is critical due to the limited number of registered herbicides and the development of populations of herbicide- resistant weeds. Therefore, field studies were conducted at the Horticultural Crops Research Station, Clinton, NC and the Pontotoc Ridge–Flatwoods Branch Experiment Station, Pontotoc, MS to determine the effect of oryzalin application rate and timing on sweetpotato tolerance. Oryzalin at 0.6, 1.1, 2.2, 3.4, and 4.5 kg ai ha–1 was applied immediately after transplanting or 14 d after sweetpotato transplanting (DAP). At Clinton, oryzalin applied immediately after transplanting resulted in ≤1% leaf distortion 4 and 6 wk after transplanting (WAP) regardless of application rate. However, when oryzalin was applied 14 DAP, greater sweetpotato leaf distortion was observed from 2.2, 3.4, and 4.5 kg ha–1 (≤8%) than 0.6 and 1.1 kg ha–1 (≤4%). At Pontotoc, oryzalin applied immediately after transplanting resulted in ≤6% leaf distortion 4 WAP regardless of application rate. However, when oryzalin was applied at 14 DAP, greater leaf distortion was reported from 3.4 and 4.5 kg ha–1 (11 to 13%) than 0.6, 1.1, and 2.2 kg ha–1 (4 to 6%). Oryzalin application rate and timing did not affect yield of no.1, jumbo, or marketable sweetpotato. Based on these results, oryzalin herbicide has potential for registration in sweetpotato.

Field studies were conducted in Clinton, NC in 2007 and 2009 to determine sweetpotato crop response and Palmer amaranth control with metribuzin and oryzalin. Treatments consisted of 140 and 202 g ai ha−1 metribuzin applied immediately after transplanting [0 wk after transplanting (WAP)] or 2 WAP, 560 and 1121 g ha−1 oryzalin 0 WAP, and tank mixes of metribuzin (140 or 202 g ha−1) and oryzalin (560 or 1,121 g ha−1) 0 WAP. At 2 WAP, metribuzin alone applied 0 WAP resulted in greater crop injury (33%) than oryzalin alone (1%), and the tank mix of metribuzin plus oryzalin resulted in greater crop injury (49%) than either herbicide applied alone. Greater crop injury occurred when metribuzin was applied at 202 g ha−1 (54%) than 140 g ha−1 (34%). Levels of injury were similar at 4 WAP (34, 8, and 52% for metribuzin, oryzalin, and the tank mix, respectively). At 4 WAP, injury from metribuzin was greater when it was applied 0 WAP (34%) compared to 2 WAP (18%). By 10 WAP, injury from metribuzin applied at 2 WAP was only 4%. At 4 WAP, Palmer amaranth control was excellent for all treatments and ≥98%. At 10 WAP, control among treatments ranged from 77% to 85%. Palmer amaranth control provided by metribuzin was similar for applications made 0 WAP (78%) and 2 WAP (77%). Oryzalin alone provided similar control (85%) to metribuzin alone 0 WAP, but greater control than the tank mix (77%). Neither metribuzin nor oryzalin rate differed in weed control provided at 10 WAP. Oryzalin 0 WAP and metribuzin 2 WAP provided no. 1 sweetpotato yields equivalent to the hand-weeded check. No. 1 yields of all other treatments were less than the hand-weeded check but greater than the weedy check.

Diuron, fluorochloridone, hexazinone, metribuzin, norflurazon, oryzalin, prodiamine, simazine, and terbacil controlled seedling asparagus planted in sprinkler-irrigated plots similarly (>89%). In furrow-irrigated plots, cinmethylin, diuron, fluorochloridone, hexazinone, napropamide, oryzalin, and prodiamine provided similar control (>86%) of planted seedling asparagus. Herbicides with high water solubilities that depended upon root uptake for maximum activity tended to control seedling asparagus better in sprinkler-irrigated tests than in furrow-irrigated tests. Fluorochloridone, norflurazon, and prodiamine provided partial control of volunteer asparagus (48 to 84%) in an established stand of furrow-irrigated asparagus.

Factors affecting the germination and seedling growth of leafflower were evaluated. Germination required exposure to light. Seeds covered with a 1-cm deep layer of pine bark mulch failed to emerge. Maximum seedling development occurred in full exposure to sunlight; shading that reduced light intensity more than 26% was inhibitory. Maximum seed germination (79%) occurred between 25 and 35 C; temperatures outside this range were inhibitory. Germination was strongly influenced by osmotic potential. Osmotic potentials of 0, 304, and 507 kPa resulted in 85, 24 and 14% germination, respectively. PRE applications of either granular formulated oxadiazon at 4.5 kg ha–1, or premixed granular formulated oxyfluorfen + oryzalin at 4.6 + 2.3 kg ha–1, provided a minimum of 85% control. The following POST treatments provided a minimum of 90% control of mature plants: paraquat at 0.21 kg ha–1, glyphosate at 0.56 kg ha–1, oxyfluorfen at 1.12 kg ha–1, and acifluorfen at 2.24 kg ha–1.

Broadleaf weed control and tulip, daffodil, and iris response to alachlor, dithiopyr, diuron, isoxaben, napropamide, oryzalin, oxadiazon, oxyfluorfen, pendimethalin, pronamide, and thiazopyr applied preemergence were evaluated. All herbicides controlled broadleaf weeds for five months after application, but control with oxyfluorfen, pendimethalin, alachlor, pronamide, and napropamide decreased six months after application. The greatest weed control was with oxadiazon, isoxaben, thiazopyr, dithiopyr, and diuron, whereas the least weed control was with napropamide and alachlor. In general, tulip was more sensitive to herbicides than daffodil and iris. All herbicides injured tulips at early growth stages but bulb yield of tulip was reduced only by oxadiazon, oxyfluorfen at 0.28 kg ai/ha, pronamide, and dithiopyr. Tulip flower quality was reduced only by oxadiazon, oxyfluorfen at 0.28 lb/ha, and pronamide. Daffodil and iris were tolerant to thiazopyr, isoxaben, pronamide, alachlor, oryzalin, napropamide, and diuron.

Pea (Pisum sativum L. ‘Elf’) root rot suppression by dinitroaniline herbicides could not be explained by a direct effect on the host. Pre-incubation of pea roots with 0.1 ppmw of oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) or trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) in solution culture did not alter their resistance to root rot. Furthermore, 0.1 ppmw of oryzalin or trifluralin did not alter the exudation of electrolytes or α-amino compounds from pea roots. Most of the dinitroaniline herbicides significantly inhibited mycelial radial growth of pathogen, Aphanomyces euteiches Drechs., at 1.0 ppmw and inhibited asexual spore production at 0.1 to 1.0 ppmw. Dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], and oryzalin inhibited A. euteiches mycelial growth and asexual reproduction more effectively than the other dinitroaniline herbicides studied. The production of motile zoospores, the infecting propagule of the pathogen, was the most sensitive stage in the life cycle and was completely inhibited by 0.01 ppmw of all dinitroaniline herbicides tested. Since this concentration is below that estimated in the soil solution at registered rates of application, inhibition of motile zoospore production is sufficient to explain root rot suppression. Inhibition of pathogen motility resulted in a 2-week delay in the infection of pea roots. This delay allowed sufficient additional plant growth that the peas could better withstand the effects of subsequent disease development.

Linuron, metribuzin, oryzalin, and metolachlor were applied at recommended (1X) and two-thirds (0.67X) rates to evaluate control of redroot pigweed and common lambsquarters in conventional and rye-stubble reduced-tillage potato production systems. Regardless of tillage, common lambsquarters control was satisfactory during both seasons at both rates of linuron, metribuzin, and oryzalin. Redroot pigweed control by these three herbicides, although excellent in 1988, was poor in RT plots during 1987. Yields did not differ between tillage systems. Reduced weed control with metolachlor during both seasons, and possible crop injury with linuron in 1987 resulted in significant yield reductions.

Field research to determine the influence of weed control systems in winter barley on subsequently no-till-planted grain sorghum was conducted from 1985 to 1987 in northwest Georgia. Herbicide treatments applied to fully tillered winter barley included 2,4-D, dicamba, metribuzin, oryzalin, oryzalin plus metribuzin, fluorochloridone, or thiameturon. None of these herbicides affected barley grain yields compared to nontreated plots. Treatments containing oryzalin reduced johnsongrass fresh weights in the subsequently planted grain sorghum. Oryzalin plus metribuzin, in 1 of 2 yr, resulted in higher seed yields of subsequently planted grain sorghum compared to the other treatments except for oryzalin used alone. Treatments containing paraquat plus propazine plus metolachlor applied to grain sorghum provided good weed control when averaged across barley treatments and resulted in the highest grain sorghum yield. No grain sorghum injury from herbicides used in the previous winter barley crop was observed.

Green kyllinga is a relatively new weed species in well-irrigated turfs in the southwest US. To understand the germination requirements of green kyllinga, the effects of planting depth, temperature, pH, and osmotic potential were determined. Green kyllinga emergence was sensitive to planting depth. At 21 days after planting (DAP), emergence of green kyllinga was 60% when planted at the soil surface but only 20% at 0.5 cm and less than 5% at 1 cm. Germination occurred at temperatures between 17 and 30 C but was notably better between 20 and 24 C. Germination was uniform from pH 5.5 to 9.5. Germination decreased between the water potentials −0.1 to −0.6 MPa, although germination was high at water potentials found in irrigated turf. The environmental conditions found in nonstressed turf areas in Arizona will likely support the establishment of green kyllinga. The efficacy of herbicides for the control of green kyllinga was also determined. Control of kyllinga (95% or greater) was obtained with preemergence applications of oxadiazon, dithiopyr, and metolachlor, and with postemergence applications of DSMA, halosulfuron-methyl, and imazaquin.

Dinitroaniline herbicides are absorbed readily by roots and emerging shoots, but shoot exposure is more phytotoxic. Translocation within the plant varies by specific herbicide but commonly is minor. Dinitroaniline herbicides injure plants by binding to tubulin, a dimer protein in the ceil that polymerizes to form microtubules (MTs). MTs form the major part of the mitotic apparatus, including spindle fibers, which enable chromosomes to separate during cell division. Dinitroaniline herbicides prevent tubulin from polymerizing into MTs, thus arresting mitosis. This leads to abnormal cells with more than the normal complement of chromosomes and, frequently, lobed nuclei. MTs also are responsible for orienting cell wall microfibrils in such a way that they prevent lateral enlargement of cells. Treatment with dinitroaniline herbicides leads to disorientation of the microfibrils, leading to one of the common symptoms—spherical cells instead of rectangular ones. Studies on the metabolism of trifluralin in plants have shown that amination, dealkylation, and cyclization all can occur. However, metabolites often amount to a small percentage of the original herbicide. In general, trifluralin seems quite stable within the plant.

Field experiments were conducted in Princeton, KY, in 1982, 1983, and 1984 to evaluate johnsongrass [Sorghum halepense (L.) Pers. # SORHA] control programs in no-tillage, doublecropped soybeans [Glycine max (L.) Merr. ‘Essex′]. Sequential applications of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} or fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} at 0.2 kg ai/ha provided 36 to 94% johnsongrass control. The lower control values from these treatments were obtained in the droughty 1983 growing season while the higher and acceptable control ratings were obtained in 1982 and 1984 when rainfall was more plentiful. Preplant applications that contained glyphosate [N-(phosphonomethyl)glycine] provided johnsongrass control greater than those containing paraquat (1,1′-dimethyl-4,4′-bypyridinium ion). Soybean yields and soil moisture were greater with preplant applications of glyphosate than with preplant applications of paraquat or foliar applications of sethoxydim, fluazifop, or glyphosate. Greatest yields were obtained with a combination of a preplant application of glyphosate and a postemergence application of sethoxydim.

Weed control in no-till soybeans [Glycine max (L.) Merr. ‘Wells’] planted into shredded corn (Zea mays L.) residue was evaluated at Concord, NE, over a 3-yr period. Herbicide factors evaluated were time of herbicide application for no-till soybeans, efficacy of glyphosate [N-(phosphonomethyl)glycine] relative to paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) for control of emerged weeds, and the efficacy of alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl)acetanilide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide), and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] for residual weed control. Combination residual and contact herbicide treatments were applied either as a preplant surface application or preemergence after no-till-planted soybeans. Removal of existing weed growth was not consistently better with the preplant surface application compared to later removal after soybean planting. Paraquat and glyphosate gave nearly equal control of emerged weeds. Addition of 2,4-D [(2,4-dichlorophenoxy)acetic acid] with paraquat in the tank mix did not improve weed control. Use of narrow, ripple coulters on the no-till planter resulted in minimal disturbance of the preplant surface herbicide so that additional preemergence herbicide at planting was seldom beneficial.

Several field studies were conducted during 1981 and 1982 to determine whether early preplant (EPP) applications of residual herbicides would prevent the establishment of vegetation before planting no-till soybeans [Glycine max (L.) Merr. ‘Williams’]. Early preplant applications of either cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile} or cyanazine plus oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) were applied in the fall and 3, 2, and 1 month(s) before planting no-till soybeans. In all studies, the treatments prevented vegetation from becoming established before planting, and season-long weed control was achieved with several different treatments. Early preplant cyanazine plus oryzalin provided greater than 90% control for the entire season where grass densities were low. Where grass densities were high (greater than 90% ground cover), EPP cyanazine plus a preemergence application of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] plus metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] or a postemergence application of sethoxydim {2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} controlled 90% of the weeds, which was equal to or better than the standard preemergence treatments used (80 to 98% weed control).

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.

A new machine consisting of a detachable hopper of containerized granules with a preselected circular orifice to regulate flow of granules, and a revolving hollow-cone spreader turned by an electric motor, was tested. Flow of herbicide granules at typical use rates was linearly correlated with orifice diameter. Coefficients of determination for flow rates of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide], trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine], and norflurazon [4-chloro-5-(methylamino)-2-(3-(trifluoromethyl)phenyl)-3 (2H)-pyridazinone] were 0.96 or greater. Based on patterns of distribution of commercial trifluralin granules parallel and perpendicular to a linear path, the machine could be used to apply herbicide granules in row crops. Control of johnsongrass [Sorghum halepense (L.) Pers. # SORHA] with alachlor plus oryzalin [4-(dipropylamino)-3,5-dinitrobenzenesulfonamide] applied preemergence (pre) as sprays and granules did not differ significantly in soybean [Glycine max (L.) Merr. ‘Forrest′]. Trifluralin granules applied preplant incorporated (ppi) at 1.1 kg ai/ha controlled 80 to 95% of the johnsongrass and doubled soybean yield compared to the cultivated control plot. Norflurazon plus alachlor pre at 1.7 to 2.2 plus 2.2 to 3.0 kg ai/ha controlled annual grasses and prickly sida (Sida spinosa L. # SIDSP) equally with sprays and granules.